H NI, 2009Vin Chin lc, Chnh sch ti nguyn v mi trngBIN I KH HU VIT NAMBIN I KH HU VIT NAMVIN CHIN lC, CHNH sCH TI NgUyN V MI TrNgH NI, 2009Bo co Bin i kh hu Vit Nam c Vin Chin lc, Chnh sch ti nguyn v mi trng Vit Nam cng b vi s h tr v k thut v ti chnh t Chng trnh Mi trng Lin Hp Quc (UNEP).Bn quyn 2009, thuc Vin Chin lc, Chnh sch ti nguyn v mi trng Vit Nam (ISPONRE) ISBN: 0-893507-779124Bn quyn v giy phpNi dung v nhng quan im th hin trong n phm ny khng nht thit phn nh quan im ca cc chuyn gia,tchchaycaVinChinlc,ChnhschtinguynvmitrngVitNamcngnhcaChng trnh Mi trng Lin Hp Quc. n phm ny c th c ti xut bn mt phn hoc ton b ni dung cung cp thng tin phc v gio dc hoc phi li nhun m khng cn xin php bn quyn, min l c li cm n v dn ngun xut bn. Vin Chin lc, Chnh sch ti nguyn v mi trng cng nh Chng trnh Mi trng Lin Hp Quc nh gi cao nu nhn c mt bn sao ca bt c n phm no c pht hnh c s dng n phm ny tham kho.n phm ny khng c s dng bn li hoc v bt c mc ch thng mi khc trc khi c s cho php bng vn bn ca Vin Chin lc, Chnh sch ti nguyn v mi trng Vit Nam v Chng trnh Mi trng Lin Hp Quc.Tit k, ch bn: Kimdo Design.Chu trch nhim ni dung: Vin Chin lc, Chnh sch ti nguyn v mi trng Vit Nam (ISPONRE)Chu trch nhim xut bn: Nguyn Vn KhngGiyphpxutbns270-2009/CXB/21/05-14/VHTdoNhxutbnVnha-Tngtincpngy 24/11/2009. TI NGUYNVMI TRNGiiiVinChinlc,ChnhschtinguynvmitrngxinbytlngcmntiChng trnh Mi trng Lin Hp Quc h tr k thut v ti chnh cho vic xy dng bo co ny; cm n cc n v, c nhn cung cp s liu, thng tin cng nh cc t chc/chuyn gia tham gia xy dng v hon thin bo co ny.c bit xin cm n Nhm cn b ca ISPONRE: TS. Nguyn Vn TiB Kim T Ty Ngcng Phan Tun HngB L T L QuynB Nguyn T Ngc nhNhm cn b ca UNEP:B Anna Stabrawa ng Jinhua Zhang B Tunnie Srisakulchairak B Nguyn T T GS. TS. Murari LalNhm chuyn gia trong nc: GS. TS. Nguyn Trng HiuB Phm T Tanh Hngng Nguyn Mnh CngLi cm nivBin i kh hu, trc ht l s nng ln ton cu v mc nc bin dng ang l mt trong nhng thch thc ln nht i vi nhn loi trong th k 21. Tin tai v cc hin tng kh hu cc oan ang gia tng, nh hng n cuc sng ca ton nhn loi.Vit Nam c d bo l mt trong nhng quc gia b nh hng bt li ln nht t bin i kh hu. Trong khong 50 nm qua, nhit trung bnh nm tng khong 0,5 - 0,70C, mc nc bin dng khong 20cm. Hin tng El-Nino, La-Nina ngy cng tc ng mnh n Vit Nam. Bin i kh hu thc s lm cho thin tai, c bit l bo, l, hn hn ngy cng khc lit hn. Cng vi cng ng th gii, Vit Nam c nhng cam kt mnh m trong cuc chin chng li bin i kh hu nh tham gia Cng c khung ca Lin Hp Quc v bin i kh hu, ph duyt Chng trnh mc tiu quc gia ng ph vi bin i kh hu v gn y cng b kch bn bin i kh hu, nc bin dng. Nhn thc tnh cht tim tng, tc ng lu di v trn din rng ca bin i kh hu, Vit Nam cng ang hng ti cc chnh sch di hn, tm nhn xa trong gim nh v thch ng vi bin i kh hu, ch trng lng ghp cc gii php ng ph vi bin i kh hu trong chin lc, k hoch v cc chnh sch pht trin kinh t - x hi pht trin bn vng t nc.Trong khun kh h tr ca Chng trnh Mi trng Lin Hp Quc (UNEP), Vin Chin lc, Chnh sch ti nguyn v mi trng (ISPONRE) thuc B Ti nguyn v Mi trng ch tr, cng vi cc chuyn gia trong v ngoi nc xy dng bo co Bin i kh hu Vit Nam. y l bo co in hnh c xy dng theo hng dn ca UNEP nhm cung cp bc tranh tng quan v bin i kh hu, cc tc ng tiu cc ca bin i kh hu v cc bin php ng ph ca cc quc gia trn th gii. Ni dung chnh ca bo co gm: Khi qut v bin i kh hu ton cu; Biu hin v cc kch bn bin i kh hu Vit Nam; v Tc ng v chin lc, gii php ng ph vi bin i kh hu Vit Nam. y l ti liu tham kho tt i vi cc nh hoch nh chnh sch, cn b qun l, cc nh khoa hc v nhng ai quan tm n bin i kh hu v n lc ng ph vi bin i kh hu Vit Nam.B Ti nguyn v Mi trng chn thnh cm n Chng trnh Mi trng Lin Hp Quc h tr ti chnh v k thut, cm n cc chuyn gia trong v ngoi nc, cc c quan, t chc tham gia tham gia xy dng v hon thin bo co, cng nh nh gi cao n lc ca Vin Chin lc, Chnh sch ti nguyn v mi trng trong vic xy dng thnh cng bo co quan trng ny. TS. Phm Khi NguynB trng B Ti nguyn v Mi trngTng 11 nm 2009Li m uB trng B Ti nguyn v Mi trngvChng trnh Mi trng Lin Hp Quc (UNEP) ang thc hin cc nh gi thng xuyn v s pht trin v xu th ca cc vn mi trng chnh, bao gm cc nh gi ton cu, khu vc, tiu vng, quc gia v cp tnh, thnh ph. Qu trnh nh gi c thc hin vi s tham gia, tham vn ca cc bn lin quan nhm a ra cc thng tin khoa hc phc v cng tc qun l mi trng v xy dng chnh sch cho cc nhm i tng c lin quan. Bo co Bin i kh hu Vit Nam do Vin Chin lc, Chnh sch ti nguyn v mi trng (ISPONRE) ch tr thc hin l mt trong nhng kt qu ca chng trnh xy dng nng lc ny. Bo co nh gi cc tc ng ca bin i kh hu v cc vn lin quan ti bin i kh hu, gip cc nh hoch nh chnh sch hiu c s cn thit trong vic thc hin cc hnh ng cp thit cng nh vic huy ng s tham gia v nhn thc ca cng ng.Nm khu vc nhit i gi ma ng Nam , Vit Nam l mt trong nhng quc gia c nhiu kh nng chu cc tc ng tiu cc ln nht t bin i kh hu. Vit Nam tri qua nhng thay i ca cc yu t kh hu c bn cng nh cc hin tng thi tit cc oan nh bo, ma ln v hn hn. Nhit tng 0,5 - 0,70C/50 nm, tn sut front lnh gim xung 2,45 t/50 nm. Vng ven bin phi gnh chu cc cn bo nhit i xut pht t bin ng vi trung bnh khong 7 cn bo/nm. Tn sut cc xoy thun nhit i cng tng ln 2,15 t/50 nm v mc nc bin tng ln khong 20cm/50 nm. Cc phn tch kch bn trong bo co ch ra rng nhit trung bnh ca Vit Nam nm 2100 so vi thi k 1980-1999 c xu hng tng trong khong 1,1 1,90C v 2,1 3,60C, lng ma hng nm tng 1,6 14,6%, mc nc bin dng khong 11,5 68cm. Trong s nhng tc ng ny, mc nc bin dng vi tc 0,5 0,6cm/nm l tc ng ng lo ngi nht, c bit khu vc pha Nam Vit Nam. Bin i kh hu tc ng mnh n cc lnh vc nng nghip v ti nguyn nc. Ngp lt v hn hn xy ra thng xuyn hn do s gia tng cng ma v gim s ngy ma. ng bng sng Hng v sng Cu Long c th s b xm nhp mn do nc bin dng. Bin i kh hu cng s dn ti gia tng nguy c suy gim a dng sinh hc, c bit l cc loi thc vt bn a v cc loi c gi tr kinh t cao. Nc bin dng c th lm gim din tch rng ngp mn, gy tc ng bt li i vi cc rng trm v rng trng trn t phn min Nam, thay i phn b rng nguyn sinh v rng th sinh. ng bng sng Hng, tnh Qung Ninh, ng bng duyn hi Bc Trung B, Nam Trung B v ng bng sng Cu Long l nhng khu vc d b tn thng nht. Bo co cng a ra cc sng kin ca chnh ph nhm gim pht thi kh nh knh trong nhiu lnh vc nh s dng hiu qu nng lng, bo v rng v tng che ph rng, tng cng pht trin cc h thng quan trc v gim st kh hu.Chin lc trung hn ca UNEP (2010 2013) a ra nh hng tng cng nng lc ca cc quc gia nhm lng ghp cc ng ph vi bin i kh hu vo trong cc qu trnh pht trin ca cc quc gia, h tr bi cc thng tin khoa hc, cc nh gi tc ng kh hu tng hp v cc d liu kh hu a phng. Ti tin tng rng bo co ny p ng c nhim v t ra ca UNEP, cung cp cc thng tin v gii php quan trng cho chnh ph Vit Nam thng qua B Ti nguyn v Mi trng nhm duy tr cht lng cuc sng v sinh k ca ngi dn Vit Nam. TS. Young-Woo Parki din ca Chng trnh Mi trng Lin Hp quc ti chu - Thi Bnh Dng Thng 11 nm 2009Li m ui din ca UNEP ti Chu - Ti Bnh DngviADB Ngn hng Pht trin Chu ALGAS Chin dch gim thiu kh nh knh vi chi ph thp nht Chu BKH Bin i kh huC CacbonCH4M tanCO2i xt CacbonCCS Cng ngh ct gi CO2FRL Front lnhGEF Qu mi trng ton cuIPCC Ban Lin Chnh ph v BKHISPONRE Vin Chin lc, Chnh sch ti nguyn v mi trng Vit Nam KH&TNKHVN Kh hu v Ti nguyn kh hu Vit NamKNK Kh nh knhKP Ngh nh th KyotoPPB Phn tPPM Phn triuSRES Bo co c bit v cc kch bn pht thi kh nh knhTBTVN Tng bo u tin ca Vit Nam cho Cng c khung ca Lin Hp Quc v bin i kh huUNDP Chng trnh Pht trin Lin Hp QucUNEP Chng trnh Mi trng Lin Hp QucUNFCCC Cng c khung ca Lin Hp Quc v bin i kh huXTN Xoy thun nhit iXTNB Xoy thun nhit i hot ng trn Bin ngXTNVN Xoy thun nhit i nh hng n Vit NamWB Ngn hng T giiWMO T chc Kh tng T giiCc t vit ttviiCC T VIT TT ........................................................................................................................................................................................... viMC LC .......................................................................................................................................................................................................... viiDANH MC CC BNG ............................................................................................................................................................................... ixDANH MC CC HNH .................................................................................................................................................................................xTM TT ............................................................................................................................................................................................................ xiCHNG 1: KHI QUT BIN I KH HU TON CU ........................................................................................................... 11.1 Khi qut v h thng kh hu tri t ....................................................................................................................................................... 11.2 Hiu ng nh knh v cc kh nh knh (KNK) ....................................................................................................................................... 21.2.1 Hiu ng nh knh ............................................................................................................................................................................... 21.2.2 Cc kh nh knh .................................................................................................................................................................................. 21.3 Lch s bin i kh hu ............................................................................................................................................................................... 31.3.1 Bin i kh hu hng chc vn nm. .............................................................................................................................................. 31.3.2 Bin i kh hu trong 20.000 nm gn y. .................................................................................................................................. 31.3.3 Nguyn nhn ca bin i kh hu hin i ................................................................................................................................... 41.4 Nhng bin i quan trc c trong 150 nm qua .............................................................................................................................. 41.4.1 Bin i kh hu mt t .................................................................................................................................................................... 41.4.2 Bin i kh hu trong tng i lu ca kh quyn ....................................................................................................................... 91.4.3 Bin i v cc h t nhin v cc h sinh thi .............................................................................................................................. 91.5 Kch bn bin i kh hu trn th gii ...................................................................................................................................................101.5.1 Phn loi cc kch bn gim pht thi nh knh ...........................................................................................................................101.5.2 Cc kch bn pht thi nh knh .....................................................................................................................................................101.5.3 Kch bn bin i kh hu ................................................................................................................................................................121.6 Tc ng ca bin i kh hu ..................................................................................................................................................................131.6.1 Tc ng ca bin i kh hu i vi cc lnh vc ....................................................................................................................131.6.2 Tc ng ca BKH i vi cc khu vc .....................................................................................................................................141.7 Chin lc thch ng vi BKH ..............................................................................................................................................................151.7.1 Trin vng ca cc gii php thch ng .........................................................................................................................................151.7.2 Tch ng vi BKH trong mt s lnh vc ................................................................................................................................161.8 Chin lc gim nh BKH .....................................................................................................................................................................161.8.1 Tim nng thc hin cc gii php gim nh BKH .................................................................................................................161.8.2 Mt s chnh sch, gii php gim nh BKH ...........................................................................................................................161.8.3 L trnh pht thi bn vng .............................................................................................................................................................171.9 Kt lun chng 1........................................................................................................................................................................................17Mc lcviiiCHNG 2: BIU HIN CA BKH V KCH BN BKH VIT NAM ..............................................................................192.1 Khi qut c im kh hu Vit Nam.....................................................................................................................................................192.1.1 Cc nhn t kh hu...........................................................................................................................................................................192.1.2 Phn b cc yu t kh hu ..............................................................................................................................................................212.1.3 Phn vng kh hu Vit Nam...........................................................................................................................................................272.2 Biu hin ca bin i kh hu trong khong 100 nm qua ................................................................................................................292.2.1 Mc bin i ca mt s yu t kh hu tiu biu ................................................................................................................292.2.2 Xu th bin i ca mt s yu t kh hu tiu biu Vit Nam .............................................................................................362.3 Cc kch bn BKH Vit Nam .............................................................................................................................................................402.3.1 Xy dng cc kch bn BKH ........................................................................................................................................................402.3.2 Kch bn nm 1994 ...........................................................................................................................................................................422.3.3 Cc kch bn nm 1998 ....................................................................................................................................................................422.3.4 Kch bn nm 2009 ...........................................................................................................................................................................432.4 Kt lun chng 2........................................................................................................................................................................................45CHNG 3: TC NG CA BKH V CHIN LC, GII PHP NG PH VI BKH VIT NAM ..............473.1 Tc ng ca bin i kh hu Vit Nam ............................................................................................................................................473.1.1 Tc ng ca bin i kh hu i vi cc lnh vc ch yu .....................................................................................................483.1.2 Tc ng ca BKH i vi cc khu vc ch yu ......................................................................................................................503.2 Chin lc v gii php gim nh bin i kh hu Vit Nam ........................................................................................................543.2.1 Cc chnh sch gim KNK..............................................................................................................................................................543.2.2 Cc gii php nng cao hiu qu nng lng ...............................................................................................................................543.2.3 Tc y nghin cu, trin khai v tng cng s dng cc ngun nng lng mi v ti to ..........................................553.2.4 Bo v v tng cng cc b cha v b hp th KNK ...............................................................................................................573.2.5 nh hng pht trin nng nghip v tng cng cc phng thc canh tc bn vng ng ph vi bin i kh hu ....583.2.6 Nghin cu gim pht thi KNK thng qua thu hi CH4 trong sn xut v vn ti nng lng .......................................583.3 Chin lc v gii php thch ng vi bin i kh hu Vit Nam .................................................................................................593.3.1 Xy dng v thc hin cc bin php gim nh tc ng ca BKH i vi cc nghnh kinh t ....................................593.3.2 T chc quan trc theo di nghin cu v BKH Vit Nam ................................................................................................603.4 Kt lun .........................................................................................................................................................................................................66TI LIU THAM KHO ...............................................................................................................................................................................67PH LC 1: MT S THUT NG BIN I KH HU CHNH..............................................................................................68PH LC 2: TNH HNH PHT THI KH NH KNH VIT NAM ......................................................................................69ixBng 1.1. Cc thnh phn ca p lc bc x (W/m2) ................................................................................................................................... 5Bng 1.2. Chun sai nhit trn cc chu lc trong th k 20 (0C) ........................................................................................................ 5Bng 1.3. Nng CO2 trong kh quyn theo cc kch bn (ppm) .........................................................................................................11Bng 1.4. D kin mc tng nhit v mc nc bin dng vo cui th k 21 ................................................................................11Bng 2.1. S XTN hot ng trn Bin ng v nh hng trc tip n Vit Nam (cn) .....................................................................27Bng 2.2. Mt s c trng ch tiu ca cc min v vng kh hu ..........................................................................................................28Bng 2.3. Tr s ph bin ca mt s c trng ti nguyn kh hutrn cc vng kh hu ................................................................30Bng 2.4. lch tiu chun v bin sut ca tn s FRL .........................................................................................................................30Bng 2.5. lch tiu chun v bin sut ca XTNB .........................................................................................................................32Bng 2.6. lch tiu chun v bin sut ca tn s XTN nh hng n Vit Nam .....................................................................32Bng 2.7. Tn s XTN bt u, cao im v kt thc ..............................................................................................................................33Bng 2.8. lch tiu chun ca mt s c trng yu t nhit trn mt s a im tiu biu (0C) .......................................34Bng 2.9. Tn sut thng lnh nht v thng nng nht .............................................................................................................................34Bng 2.10. lch tiu chun (S;m) v bin sut ca lng ma (Sr; %) trn mt s a im tiu biu .....................................35Bng 2.11. Tn s ca mt s loi hnh thi tit trong cc thp k gn y: ..........................................................................................36Bng 2.12. Nhit trung bnh nm (N), nhit trung bnh thng I (I) v nhit trung bnh thng VII (VII) trong ccthp k gn y (0C) ..........................................................................................................................................................................................37Bng 2.13. Nhit thi k 1957 - 2007 (0C) .............................................................................................................................................38Bng 2.14. Lng ma nm trung bnh trong cc thp k gn y (mm) ..............................................................................................39Bng 2.15. Mc tng hay gim ca lng ma nm thi k 1957 2007 .........................................................................................40Bng 2.16. Kch bn bin i kh hu vo nm 2070 ..................................................................................................................................41Bng 2.17. Cc kch bn bin i kh hu theo kch bn 1998 .................................................................................................................42Bng 2.18. Mc tng nhit trung bnh (0C) qua cc thp k so vi thi k1980-1999 ..................................................................43Bng 2.19. Mc thay ilng ma (%)qua cc thp k so vi thi k 1980-1999 ...........................................................................43Bng 2.20. Kch bn nc bin dng (mm) so vi thi k 1980-1999 ....................................................................................................44Bng 2.21. Kch bn bin i kh hu v nc bin dng cho Vit Nam ................................................................................................45Bng PL1. Lng pht thi KNK ca cc ngnh do tiu th nng lng nm 1994 ............................................................................69Bng PL2. Lng CH4 pht tn t cc loi hnh khai thc nm 1994 .....................................................................................................70Bng PL3. Lng KNK pht thi t cc hot ng cng nghip nm 1994 ..........................................................................................70Bng PL4. Lng pht thi, hp th KNK trong lnh vc lm nghip v s dng t nm 1994.. ........................................................71Bng PL5. Lng pht thi KNK trong lnh vc nng nghip nm 1994 ..............................................................................................71Bng PL6. Lngpht thi KNK t cc ngun cht thi nm 1994 .......................................................................................................73Bng PL7. Tng hp kt qu kim k KNK nm 1994 ..............................................................................................................................73Bng PL8. Lng pht thi kh nh knh trong cc lnh vc ch yu vo nm 1998 ............................................................................73Bng PL9. D tnh lng pht thi kh nh knh cho nm 2010, 2020 ...................................................................................................73DANH MC CC BNGxDANH MC CC HNHHnh 1.1. S minh ha hiu ng nh knh ................................................................................................................................................. 2Hnh 1.2. Chun sai nhit b mt trung bnh ton cu trong thi k 1880-2007 (0C) .................................................................... 4Hnh 1.3. Chun sai nhit quan st c ti cc lc a chnh .............................................................................................................. 6Hnh 1.4. Cc phng thc bin i ca nhit v lng ma th k 21 ............................................................................................. 6Hnh 1.5. Chun sai lng ma nm trn lc a ton cu thi k 1900-2007 ....................................................................................... 7Hnh 1.6. Din tch bng Bc cc gim i trong thp k gn y ..........................................................................................................18Hnh 1.7. Mc nc bin trung bnh ton cu tng 43mm vo nm 2007. ......................................................................................19Hnh 1.8. D kin mc pht thi CO2 thng qua cc kch bn khc nhau ca SRES ..........................................................................11Hnh 1.9. D kin cc thay i ca nhit b mt trung bnh ton cu do tng pht thi KNK trong kh quyn theo cc kch bn khc nhau ca SRES ..................................................................................................................................................................................11Hnh 1.10. D kin nc bin dng do s tng ln ca KNK trong kh quyn .....................................................................................12Hnh 1.11. nh hng chung ca BKH nh mt hm tng nhit ..................................................................................................13Hnh 2.1. Bin i kh hu ti cc khu vc Vit Nam ..............................................................................................................................23Hnh 2.2. Lng ma trung bnh nm ...........................................................................................................................................................25Hnh 2.3. S phn vng kh hu Vit Nam ..............................................................................................................................................31Hnh 2.4. S thay i nhit trung bnh hng nm (0C) v lng ma hng nm (%) ca cc vng kh hu Vit Nam so vi mc trung bnh thi k 1980 1999 .......................................................................................................................................................46Hnh 3.1. Xu th ton cu hin nay (3,3%/nm) v ng pht thi kh nh knh d kin ca SRES; v cc ng pht thi cho cc kch bn n nh ..................................................................................................................................................................................47Hnh 3.2. Mt s hnh nh D n trng mi 5 triu ha rng ....................................................................................................................49Hnh 3.3. Nng lng gi c khai thc ti Bnh Tun ..........................................................................................................................55Hnh 3.4. Trm thy in nh ti sng Mc ................................................................................................................................................56xi1.Trit,hnhtinhduynhttronghmttricssng, ngi nh chung ca chng ta, c kh hu ang bin i nhanh. Vin cnh nhit gia tng, mc nc bin dng cao, thm ha thinnhin,mtma,dchbnh,v.v.edassngtrntri t ang hin hu hn bao gi ht. Trong khi khoa hc hin i cha c bng chng xc thc v mt ni no khc trong v tr m con ngi c th n tr th cuc u tranh gim nh v thch ng vi bin i kh hu l li thot duy nht con ngi duy tr s sng ca mnh. 2. S hnh thnh v pht trin ca kh hu trn Tri t l mt qu trnh phc tp vi s tham gia v tc ng qua li gia nhiu yutkhcnhau.Triquanhiulnbiniln,gyracc thmhakinhhongtronglchs,khhutrittrli vi cc quy lut t nhin vn c ca n nui dng s sng trn Tri t. t, nc, khng kh v sinh vt l cc yu t c nh hng ln ln kh hu ton cu. Cc kh t nhin nh hi nc, CO2, CH4, O3 v N2O lm cho nhit trung bnh b mt tri t tng thm khong hn 300C thng qua hin tng gi l hiu ng nh knh. Tuy nhin, cc hot ng ca con ngi pht tn kh nh knh vi khi lng ln ang lm cho nhit b mt tri t tng nhanh, c bit trong nhng th k gn y. Nng ca cc kh CO2, CH4, N2O v CFC trong kh quyn cao cha tng thy, lm gim kh nng trao i nhit ca b mt Tri t vi khng trung dn n nhit trung bnh tng ln khong 0,750C. Cng vi s nng ln ton cu, tn s ma ln tng ln, lng bng trn ton cu gim i, ring lng bng Bc cc t u nm 1974 n nay gim i 2,7% mi nm, mc ncbintrungbnhtoncutng1,8mmminmtnht 1961 v 3,1mm mi nm tnh t 1993.3. Cc kch bn bin i kh hu cho th k 21 c xy dng da trn cc kch bn ca SRES v xu hng pht thi kh nh knh. Teo kch bn thp nht (B1), vo cc nm 2090 2099 so vi thi k 1980-1999, nhit trung bnh b mt tri t s tng ln khong 1,80C, mc nc bin trung bnh s dng ln t 0,18 0,38mm. Teo kch bn cao nht (F1), vo cc nm 2090 2099 so vi 1980 1999, nhit tng ln khong 4,00C v mc nc bin dng ln t 0,26 0,59mm cha k n cc bin i ng lc do bng tan.Cng vi nhit tng v nc bin dng cn c s gia tng cc tnngnng,xoythunnhiti.Nnglnvmcnc bin dng s tip tc cho n sau th k 21, k c khi nng kh nh knh trong kh quyn c n nh.4. Vit Nam c kh hu nhit i gi ma c trng ca bn o ng Nam thuc i lc u - , ko di trn 15 v , nm hon tontronginichtuynbncuBc,chunhhngsu sc ca Bin ng. Trn lnh th Vit Nam, cao mt tri kh ln, thi gian chiu sng ng u, tng lng bc x mt tri phong ph v cn cn bc x lun lun dng.Hon lu kh quyn Vit Nam l mt b phn ca hon lu gi ma ng Nam va lin kt vi gi ma Nam , nht l trong ma h va chu tc ng ca gi ma ng . V ma ng, mi khi khng kh cc i bo pht trn xung Vit Nam theo sau front lnh cc i. S front lnh trn xung Vit Nam trong mi thng ma ng trung bnh l 3 4 t. V ma h, di hi t nhit i dch chuyn theo chiu Bc Nam km theo hotngcaxoythunnhititonnthititrtxu, my dy c v ma rt ln. Hng nm trn khu vc Bin ng trungbnhc11txoythunnhitihotng,khong 2/3 s trc tip nh hng n cc khu vc a l Vit Nam, nht l vng ven bin. Trong nm hnh thnh hai ma gi: ma gi ng Bc v ma gi Ty Nam hay ng Nam. Tc gi trung bnh nm khong 0,8 6,2m/s tng dn t vng ni n ng bng ven bin v hi o. Tc gi k lc l 59 m/s quan trc c Quy Nhn trong cn bo b vo b bin Nam Trung B thng IX nm 1972.Sginngtrungbnhnmkhong1.4003.000gi,gim dntNamraBc,tngbnglnvngni,tnithp lnnicao.Nhitthpnhtklcl3,70Cvcaonht klcl42,90C.Lngmatrungbnhnm7005.000m, vi11trungtmmaln(>2.400m)v8trungtmma b( 50mm/ngy) trung bnh nm ph bin l 5-15, ni nhiu nht khng qu 30 v ni t nht khng di 2.Lng ma ngy ln nht ch c 107mm Sng M (Sn La) v ln n 788mm Lng (Ngh An). Tr s ca c trng ny tng i cao Bc B, Bc Trung B v tng i thp Nam Trung B, Ty Nguyn v Nam B.Ma ma, vi hm ngha l thi gian c lng ma trung bnh thng trn 100m, ph bin nh sau: TyBc,ngBc:MamabtuvothngIV,thngV, caoimvothngVII,thngVIII,ktthcvothngIX, thng X.ngbngBcB:MamabtuvothngIV,thngV, caoimvothngVII,thngVIII,ktthcvothngX, thng XI.Bc Trung B: Ma ma bt u vo thng V, thng VI, c bit tht thng trong thng VII, na u thng VIII, cao im vo thng IX, thng X, kt thc vo thng XI, thng XII.Nam Trung B: Ma ma bt u vo thng VIII, thng IX, cao im vo thng X, thng XI, kt thc vo thng XII.Cc Nam Trung B: Ma ma bt u vo thng IV, thng V, cao im vo thng VIII, kt thc vo thng XI.Ty Nguyn: Ma ma bt u vo thng IV, thng V, cao im vo thng VIII, kt thc vo thng X, thng XI.Nam B: Ma ma bt u vo thng V, cao im vo thng IX, thng X, kt thc vo thng XI. m tuyt i trung bnh nm ph bin khong 13 - 30hPa, gim rt nhanh theo cao a l. m tuyt i trung bnh thng ph bin khong 13 - 30hPa, tng i cao vo ma h, cao nht vo thng VII, thng VIII v tng i thp vo ma ng, thp nht vo thng XII, thng I.mtngitrungbnhnmphbinkhong80-85%, ln n 86 - 87% cc vng ni cao ma nhiu Bc B v ch cn 77 - 78% mt s ni thuc duyn hi Nam Trung B, Ty Nguyn,NamB.Bintrnhnmcamtngichu CHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM25Ngun: Nguyn Duy Chinh, Vin Khoa hc Kh tng Thu vn v Mi trngHnh 2.2. Lng ma trung bnh nmBI NI KH HUVI TNA M26nh hng su sc ca ch ma. ng Bc, ng bng Bc B m tng i kh thp vo u v gia ma ng, tng lnvonasaumangnhmaphnnhiu,saugim inhngrilitnglnvoccthngmah.BcTrung B, Nam Trung B, m kh thp trong cc thng ma h v kh cao trong ma ng. Ty Bc, Ty Nguyn, Nam B, m kh thp vo gia v cui ma ng v kh cao trong sut ma h.Lngbchi(PICHE)trungbnhnmphbinl800- 1.500mm, nhiu nht ln n 2.326mm (Cam Ranh), t nht l 494mm trn vng ni cao ma nhiu Hong Lin Sn. Lng bc hi min Bc t hn min Nam, vng ni cao t hn vng thp.Bintrnhnmcalngbchitrncckhuvcrtkhc nhau:ngBc,ngbngBcB,BcTrungBvpha Bc Nam Trung B, lng bc hi tng i t vo ma ng v tng i cao vo ma h. Ngc li, Ty Nguyn, cc Nam Trung B, Nam B, lng bc hi ma ng hn hn ma h.Ch s m t nm A = ERtrong : R l lng ma; E l lng bc hi PICHE) ph bin khong 1 - 5. C ch s m t 5 l Bc Quang (7,69), Tr My (5,88) v 1 l Nha H (0,41), Cam Ranh (0,69), Phan Tit (0,79) v Nha Trang (0,96). Ni chung, ch s m t min Bc cao hn min Nam, vng cao cao hn vng thp.Ch s m t c bin trnh nm kh r rt. T thng XII, thng I n thng II, thng III, A ph bin trn c nc 1. T thng VnthngXI,chsphbintrnnhiukhuvcu1. c bit, trn khu vc Bc Trung B v Nam Trung B, ch s m t thng VI, thng VII, thng VIII nhiu ni 1 do nh hng ca gi Ty kh nng.Mt s thi tit c bitSng muiMttrongnhngthititcbitnhttrongmangl sngmui.Trn160trmkhtngckhong70trm quantrccsngmuihngnmtrongmang.Tl trmquantrccsngmuirtcaocctnhvngni, trung du Bc B: Lai Chu, Sn La, Lo Cai, Yn Bi, H Giang, Cao Bng, Lng Sn, Bc Giang, Bc Cn, Ph T, Ha Bnh, HTy,QungNinh.NgaygiangbngBcB,vngni cctnhBcTrungB,vngcaoTyNguyncngxuthin sngmui.Nichung,sngmuicthxuthintrong ma ng, nhiu nht vo thng XII, thng I.Ma phnCng nh sng mui, ma phn l thi tit c sc vo ma ng min Bc. S ngy ma phn trung bnh nm ph bin l2-20TyBc,5-50ngBc,ngbngBcBv 4 - 40 ngy Bc Trung B. c bit, mt vi ni duyn hi Nam Trung B cng quan trc c ma phn. Ma phn ch yu xy ra vo ma ng, nhiu nht vo 3 thng gia v cui ma: I, II, III.Sng mSngysngmtrungbnhnmphbinnctal10- 80. Nhng ni c trn 80 ngy sng m hng nm l Mng T(LaiChu),TunGio(inBin),HongLinSn,Sa Pa(LoCai),YnChu,McChu(SnLa),ChR(Cao Bng),BcCn,ALi(TaTin-Hu),TrMy(Qung Nam), Lt (Lm ng).Hu nh tnh no cng c ni trung bnh hng nm c di 10 ngy sng m. Sng m min Bc nhiu hn min Nam, min ni nhiu hn ng bng v t lin nhiu hn hi o.Sngmtnginhiutrongmang,nhiunht vo thng I, thng II, thng III, tng i t vo ma h, t nht vo thng VII, thng VIII.DngS ngy dng trung bnh nm ph bin nc ta l 20 - 80. Tr s ca c trng ny vt 80 Bc Quang (H Giang), Mai Chu (HaBnh),HiXun(TanhHa),SSao(BnhDng), PhcLong,McHa(LongAn),RchGi(KinGiang). Nhng ni ch c di 20 ngy dng l Cn C (Qung Bnh), HongSa(QungNam),BaT(QungNgi),NhaTrang, Cam Ranh, Trng Sa, (Khnh Ha), An Kh (Gia Lai)S ngy dng Nam B nhiu hn Bc B v Trung B. Trn cng khu vc, dng vng ni nhiu hn ng bng ven bin v t nht cc hi o.Dng xy ra hu nh quanh nm, song ch yu vo ma ma. Km theo dng thng c ma . S ngy ma trung bnh nm nc ta ph bin l 0,1 - 1,0. Ch mt vi ni Ty Bc c tr s ca c trng ny trn 1,0: Tam ng, Mng T, Sn H, Lai Chu, Pha in (Lai Chu), Mc Chu (Sn La), Tan Uyn (Yn Bi), Ph Bng (H Giang).Gi Ty kh nngMt trong nhng loi hnh thi tit c sc ca ma h l gi Tykhnng.Tititkhnnglmthayichma nhiu vng duyn hi Bc Trung B, Nam Trung B.S ngy thi tit kh nng trung bnh nm ph bin l 20-40 vng ni thp Ty Bc, 5-20 vng ni thp ng Bc, 10-20 ngbngBcB,30-60vngngbngduynhiBc Trung B v Nam Trung B. Mt s ni vng thp Bc Trung CHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM27BvNamTrungB,hngnmtrungbnhctrn60ngy kh nng.Ma thi tit kh nng bt u t thng III, thng IV, cao im vo thng V, thng VI, thng VII cc khu vc pha Bc, hoc thngVI,thngVII,thngVIIINamTrungBvktthc vothngVIII(cckhuvcphaBc)hocthngIX(Nam Trung B).Hn hnHn hn c nh gi thng qua ch s kh hn K (K = ER, trongEllngbchiPICHE;Rllngma)vtn sut thng hn, thng c lng ma khng n 10mm (i vi ccthngXI,XII,I,II);khngn30mm(iviccthng III,IV,IX,X);vkhngn80mm(iviccthngV,VI, VII, VIII). Tnh hnh kh hn trn cc khu vc nh sau:TyBc:Tnsuthnrtcaotrongccthngmang, ma xunngBc:Tnsuthnrtcaotrongccthngmang, ma xun.ng bng Bc B: Tn sut hn kh cao trong cc thng ma ng, u ma xun.Bc Trung B: Tn sut hn rt cao trong thng VI, thng VII.Nam Trung B: Hn nhiu khng nhng trong cc thng ma h m c cc thng cui ma ng, ma xun.Cc Nam Trung B: Hn nhiu sut t thng I n thng VIII, nht l nhng ni ma t nh Ninh Tun.Ty Nguyn: Hn nhiu gn sut ma ng v u ma xun, t thng XII n thng III.NamB:Hnnhiutgiamangnhtmaxun,t thng XII n thng IV.Bo v p thp nhit iHng nm trn khu vc Bin ng trung bnh c 11 cn bo v p thp nhit i (Bng 2.1), trong khong trn mt na l s bo t vng bin Ty Bc Ti Bnh Dng di chuyn vo.HotngcabotrnBinngdinratrongttccc thng v tp trung vo cc thng ma h. Ma bo Bin ng l t thng V n thng XII, trong cc thng VII, VIII, IX, X c nhiu bo nht, trung bnh mi thng khong 2 cn. Tn sboBinngbinngnhiuquaccnm,nmnhiu nhtcti18cn(1973,1974),nmtbonht(1966)ch c 4 cn.Trong45nm(1956-2000),trntondibbinVitNam chu nh hng trc tip ca 311 XTN, trung bnh mi nm c 6.9 cn bng 62.7% s XTN hot ng trn Bin ng.MabonctaltthngVInthngXII,trong mithngtrungbnhctnht0.3cn(XII),nhiunht 1.4 cn (IX).S bo v p thp nhit i nh hng n Vit Nam cng bin ng nhiu qua cc nm.2.1.3 Phn vng kh hu Vit NamH thng phn v v ch tiu phn vng kh huH thng phn v trong s phn vng kh hu c xy dng da trn cc quy lut phn ha kh hu c bn v ph bin trn lnhth.Biuhinphnhakhhurtadngvmc phn ha kh hu rt phc tp, song cc phn ha kh hu u btnguntmtsnhntcho,thhinmtcchtp trung thng qua cc yu t kh hu phn nh ti nguyn nhit bao gm bc x mt tri, nng, nhit v cc yu t phn nh ti nguyn ma - m bao gm ma, m v ch s m t. V c bn, h thng phn v ca s phn vng kh hu Vit Nam c trng cho hai nhm phn ha kh hu ch yu:Phn ha v ti nguyn nhit, ch yu l s h thp cc tr1. s c trng cho ti nguyn nhit ma ng ca min Bc bt ngun t s khc bit quan trng v c ch hon lu, trc ht l tc ng ca hon lu ma ng i vi cc v pha Bc.Phn ha v ti nguyn m, ch yu l s khc bit su sc2. v ma ma, ma m gia cc khu vc duyn hi Trung B vi Bc B v Nam B do nh hng ca dy Trng Sn, s lch pha v ma ma gia pha Ty Bc B vi pha ng BcBdotcngcadyHongLinSn,giavng Bng 2.1. S XTN hot ng trn Bin ng v nh hng trc tip n Vit Nam (cn)S XTN I II III IV V VI VII VIII IX X XI XI NmHot ng trn Bin ng 0,1 0,1 0,1 0,1 0,5 1,0 1,8 1,9 1,8 1,9 1,3 0,4 11,0nh hng trc tip n Vit Nam 0,0 0,0 0,1 0,1 0,1 0,7 0,7 1,2 1,4 1,3 1,0 0,3 6,9Ngun: Vin Khoa hc Kh tng Thu vn v Mi trngBI NI KH HUVI TNA M28ni,trungduVitBcvingbngBcBvgiaTy Nguyn vi Nam B do cc iu kin a l, trc ht l a hnh. V vy, h thng phn v trong s kh hu Vit Nam c 2 cp: min kh hu v vng kh hu.Min kh hu. Phn nh min kh hu nhm tch bit cc bphnlnhthkhcnhauvtinguynnhit.Min kh hu lin kt cc vng c s ng nht tng i v ti nguyn nhit theo cc yu t ch tiu sau y:Bin nhit nm Lng bc x tng cng trung bnh nm S gi nng trung bnh nmVng kh hu. Phn nh vng kh hu nhm tch bit cc a phng trn cng min kh hu c s ng nht tng i v ch ma, m theo mt hoc c hai trong hai ch tiu sau y:Ti gian xy ra ma ma Ba thng ma nhiu nht RanhgiigiahaiminkhhutrnlnhthVitNam c xc nh bng cc tr s ch tiu sau y:Bin nhit nm bng 9 0CLngbcxtngcngtrungbnhnmbng140kcal/cm2S gi nng trung bnh nm bng 2.000 gi Ranhgiigiaccvngkhhucxcnhbngdi phn cch gia cc a phng c ma ma hoc thi k cao im ca ma ma khc nhau.Kt qu phn vng kh hu c th hin trn s phn vng kh hu (Hnh 2.1) v bng 2.2.Ti nguyn kh hu trn cc vngVng kh hu B1 (Ty Bc)VngkhhuB1thucaphnTyBc,baogmtnhLai Bng 2.2. Mt s c trng ch tiu ca cc min v vng kh huMin kh hu Bc (B) Nam (N)Bin nhit trung bnh nm (0C) > 90C < 90CLng bc x tng cng trung bnh nm (kcal/cm2/nm) >140 > 140S gi nng trung bnh nm >2000 > 2000Vng kh hu B1 B2 B3 B4 N1 N2 N3Ma ma IV - IX IV - X V - X VIII-XII VIII-XII V - X V - XBa thng ma nhiu nht VI-VIII VI-VIII VII-IX VIII-X IX-XI VII-IX VIII-XNgun: Bo co Kh hu v Ti nguyn Kh hu Vit NamChu, tnh Sn La v tnh in Bin vi cao a l ph bin 100 - 800m c im chung ca kh hu vng B1 l: ma ng nng tng i nhiu, lnh, nhiu nm c sng mui, t ma phn, ma h nng, nhiu gi Ty kh nng, khng chu nh hng trc tipcabovpthpnhiti(ATN),manhiu,ma ma gn trng vi ma nng.Vng kh hu B2 (ng Bc)VngkhhuB2chyulaphncctnhVitBc,ng Bcbaogm:LoCai,YnBi,HaBnh,HGiang,Tuyn Quang, Ph T, Cao Bng, Lng Sn, Bc Kn, Ti Nguyn, Qung Ninh vi cao a l ph bin 50 - 500m.c im chung ca kh hu vng B2 l ma ng nng t, lnh, nhiu nm c sng mui, nhiu ma phn. Ma h nng, t gi Ty kh nng, chu nh hng trc tip ca kh nhiu XTN, nhtlphangBc,manhiu,mamagntrngvi ma nng.Vng kh hu B3 (ng bng Bc B)Vng kh hu B3 ch yu l a phn cc tnh, thnh ph ng bng Bc B v cc tnh trung du k cn bao gm Ph T, Vnh Phc,BcGiang,BcNinh,HNi,HiPhng,HiDng, Hng Yn, H Nam, Nam nh, Ti Bnh v Ninh Bnh vi cao a l ph bin di 50m.c im chung ca kh hu vng B3 l: Ma ng lnh, nng t, c nm xy ra sng mui, ma phn nhiu; ma h nng, t gi Ty kh nng, chu nh hng trc tip ca XTN, ma nhiu, ma ma gn trng vi ma nng.Vng kh hu B4 (Bc Trung B)Vng kh hu B4 ch yu l a phn cc tnh Tanh Ha, Ngh An, H Tnh, Qung Bnh, Qung Tr v Ta Tin - Hu vi cao a l ph bin di 100m.CHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM29cimchungcakhhuvngB4lmanghilnh, nng tng i t, c nm xy ra sng mui mt vi ni, c ma phn. Ma h nhiu gi Ty kh nng, nhit cao, ma nhiu vo na cui nm, ma ma khng trng vi ma nngVng kh hu N1 (Nam Trung B)Vng kh hu N1 bao gm a phn thnh ph Nng v cc tnhQungNam,QungNgi,Bnhnh,PhYn,Khnh Ha,NinhTunvBnhTunvicaoalphbin di 100m.c im chung ca kh hu vng Nam Trung B l ma ng khnglnh,nngnhiu,nhiugiTykhnng.Mama vo cui ma h, u ma ng. Ma c bit t, nng c bit nhiu phn pha Nam (cc Nam Trung B).Vng kh hu N2 (Ty Nguyn)Vng kh hu N2 bao gm a phn cc tnh Kon Tum, Gia Lai, kLk,kNngvLmngvicaoalphbin 100 - 800m.c im ni bt ca vng kh hu Ty Nguyn l nn nhit tng i thp (so vi cc khu vc k cn, do nh hng ca caoal),gimingk(xungdi200C)vogiama ng (XII, I), sau tng nhanh, t ti cc i vo cc thng qu t ng sang h (IV - V); ma nhiu trong ma h, rt t ma trong ma ng, kh hn gay gt vo cc thng nhit cao, cui ma ng, u ma h. Ty Nguyn cng nh Nam B c s tng phn v ma ma r rt hn nhiu so vi ma nhit.Vng kh hu N3 (Nam B)Vng kh hu N3 bao gm cc tnh thuc Ty Nam B v c cc tnh thuc ng Nam B, ko di v pha Bnh Tun cht t, vi cao a l ph bin di 50m.c im chung ca vng kh hu Nam B l nng nhiu, nhit cao quanh nm, ma ma v c bn l ma h, ma kh ch yu l cc thng gia v cui ma ng, u ma h, s tng phn v ma ma r rt hn nhiu so vi ma nhit.2.2 biu hin ca bin i kh hu trong khong 100 nm qua2.2.1 Mc bin i ca mt s yu t kh hu tiu biuMc bin i ca mt s yu t kh hu ln hn rt nhiu so vi tc bin i xu th. Ngoi ra, mt s yu t kh h cn c bin i ma, chng hn bin i ma XTN, ma ma.Bin i ca tn s front lnh Bc Bnh hng ca khng kh cc i n kh hu Vit Nam thng c phn nh bng tn s front lnh qua Bc B (FRL). Bin i ca FRL c coi l mt trong nhng bin i kh hu tiu biu Vit Nam. Teo s liu thi k 1961 - 2000, bin i ca yu t ny c nhng im ng lu sau y:Bin i v tn s FRL nm: lch tiu chun (S =1. 62 2.2.1 Mc bin i ca mt s yu t kh hu tiu biu Mc bin i ca mt s yu t kh hu ln hn rt nhiu so vi tc bin ixuth.Ngoiramtsyutkhhcncbinima,chnghnbini ma XTN, ma ma, v..v. 2.2.1.1 Bin i ca tn s front lnh Bc B nh hng ca khng kh cc i n kh hu Vit Nam thng c phn nh bngtnsfrontlnhquaBcB(FRL).BinicaFRLccoilmttrong nhng bin i kh hu tiu biu Vit Nam. Theo s liu thi k 1961 - 2000, bin i ca yu t ny c nhng im ng lu sau y: a. Bin i v tn s FRL nm: (1) lch tiu chun (S = ( )2112 1((

=nttx xn, trong ==nttxnx11l trung bnh shc)catnsFRLnml2,93.Vitrstrungbnhl27,3,FRLcbinsut nm l 16%, kh thp so vi cc yu t khc (bng 3.4) (2) Ch c 17 nm (42,5%) FRL t hn trung bnh (chun sai m), song c n 23 nm (57,5%) FRL nhiu hn trung bnh (chun sai dng). (3) Khng c trng hp no 3 nm lin FRL nhiu hn trung bnh, song c 5 nm lin (1961 - 1965) FRL t hn trung bnh. (4)StFRLnm1994(16)thpnmcccoildthngvnm 1970 (40) cao n mc c coi l d thng. b. Bin i v tn s FRL thng (1)lchtiuchuncatnsFRLtrongccthngthucmaFRL(IX- VI) l 1 - 1,5, cn trong cc thng ngoi ma FRL l 0,1 - 0,2, song bin sut ph bin ca cc thng thuc ma FRL ch khong 30 - 50%, ca cc thng ngoi ma FRL trn di 200%. Bng 2.4. lch tiu chun v bin sut ca tn s FRL c trngIIIIIIIVVVIVIIVIIIXXXIXIINm lch tiu chun (t) 1,571,041,041,39 1,07 1,36 0,220,361,10 1,10 1,680,944,36 Bin sut (%)39,330,230,253,5 41,1 97,1 220,0 180,0 91,7 45,8 46,727,616,0 (2) FRL t ti mc d thng cao vo cc thng sau y: ,trong 62 2.2.1 Mc bin i ca mt s yu t kh hu tiu biu Mc bin i ca mt s yu t kh hu ln hn rt nhiu so vi tc bin ixuth.Ngoiramtsyutkhhcncbinima,chnghnbini ma XTN, ma ma, v..v. 2.2.1.1 Bin i ca tn s front lnh Bc B nh hng ca khng kh cc i n kh hu Vit Nam thng c phn nh bngtnsfrontlnhquaBcB(FRL).BinicaFRLccoilmttrong nhng bin i kh hu tiu biu Vit Nam. Theo s liu thi k 1961 - 2000, bin i ca yu t ny c nhng im ng lu sau y: a. Bin i v tn s FRL nm: (1) lch tiu chun (S = ( )2112 1((

=nttx xn, trong ==nttxnx11l trung bnh shc)catnsFRLnml2,93.Vitrstrungbnhl27,3,FRLcbinsut nm l 16%, kh thp so vi cc yu t khc (bng 3.4) (2) Ch c 17 nm (42,5%) FRL t hn trung bnh (chun sai m), song c n 23 nm (57,5%) FRL nhiu hn trung bnh (chun sai dng). (3) Khng c trng hp no 3 nm lin FRL nhiu hn trung bnh, song c 5 nm lin (1961 - 1965) FRL t hn trung bnh. (4)StFRLnm1994(16)thpnmcccoildthngvnm 1970 (40) cao n mc c coi l d thng. b. Bin i v tn s FRL thng (1)lchtiuchuncatnsFRLtrongccthngthucmaFRL(IX- VI) l 1 - 1,5, cn trong cc thng ngoi ma FRL l 0,1 - 0,2, song bin sut ph bin ca cc thng thuc ma FRL ch khong 30 - 50%, ca cc thng ngoi ma FRL trn di 200%. Bng 2.4. lch tiu chun v bin sut ca tn s FRL c trngIIIIIIIVVVIVIIVIIIXXXIXIINm lch tiu chun (t) 1,571,041,041,39 1,07 1,36 0,220,361,10 1,10 1,680,944,36 Bin sut (%)39,330,230,253,5 41,1 97,1 220,0 180,0 91,7 45,8 46,727,616,0 (2) FRL t ti mc d thng cao vo cc thng sau y: l trung bnh s hc) ca tn s FRL nm l 2,93. Vi tr s trung bnh l 27,3, FRL c bin sut nm l 16%, kh thp so vi cc yu t khc (Bng 3.4)Ch c 17 nm (42,5%) FRL t hn trung bnh (chun sai2. m),songcn23nm(57,5%)FRLnhiuhntrung bnh (chun sai dng).Khngctrnghpno3nmlinFRLnhiuhn3. trung bnh, song c 5 nm lin (1961 - 1965) FRL t hn trung bnh.StFRLnm1994(16)thpnmcccoil4. dthngvnm1970(40)caonmcccoil d thng.Bin i v tn s FRL thng1.lchtiuchuncatnsFRLtrongccthngthuc maFRL(IX-VI)l1-1,5,cntrongccthngngoima FRL l 0,1 - 0,2, song bin sut ph bin ca cc thng thuc ma FRL ch khong 30 - 50%, ca cc thng ngoi ma FRL trn di 200%.2. FRL t ti mc d thng cao vo cc thng sau y:I/1996: 9 tII/1964:5 tII/1988:5 tIII/1970:5 tIII/1985:5 tVI/1970: 4 tVI/1976: 4 tc bit, cc t FRL him hoi xut hin vo thng VII, thng VIII mt s nm cng c coi l d thng.3. FRL t ti mc d thng thp vo cc thng sau y:I/1965:1 tI/1993:1 tII/1994:0III/1990:0XII/1994: 1 tBin i v ma FRLBin i v ma FRL c nhng c im ng lu sau y:C 23 nm (57,5%) ma FRL bt u ng vo thng IX1. BI NI KH HUVI TNA M30Bng2.3. TrsphbincamtsctrngtinguynkhhutrnccvngkhhuVng kh hu Ty Bc ng Bc B Bc B Bc Trung B Nam Trung B Ty NguynNam B cao a l ph bin (m) 100-800 50-500 0-50 0-100 0-100 100-180 0-50Ti nguyn bc x- nngLng bc x tng cng trung bnh nm (kcal/cm2) 120-135 105-130 105-130 105-140 140-160 150-170 150-170Cn cn bc x tb nm (kcal/cm2) 65-75 60-70 65-75 65-80 75-100 75-100 75-100S gi nng trung bnh nm 1.800-2.000 1.400-1.700 1.400-1.700 1.500-2.000 2.000-2.500 2.000-2.500 2.400-3.000S thng trn 200 gi nng 1-2 0-1 0-1 1-3 3-5 4-6 6-9S thng di 100 gi nng 0-1 1-3 3-4 2-3 0-1 0 0Ti nguyn nhit Nhit trung bnh nm (0C) 18-22 18-23 23-24 23-25 25-27 21-24 26.5-27.5Nhit trung bnh thng nng nht (0C) 26-27 26-28 28,5-29,5 28-30 28,5-30 24-28 28-29Nhit cao nht tuyt i (0C) 38-41 38-41 38-41 40-42 40-42 37-40 38-40Nhit trung bnh thng lnh nht (0C) 13-16 12-16 15-16,5 16,5-19,5 20-24 19-21 24-26Nhit thp nht tuyt i (0C) -2-2 -2-2 2-5 3-8 8-13 3-9 14-18S thng c nhit trn 250C 2-4 3-5 5 5-6 6-9 3-5 11-12S thng c nhit di 200C 3-4 3-4 3 0-3 0 0-2 0Ti nguyn giTc gi trung bnh nm (m/s) 0,8-1,5 1-2 2-3 1,5-3 1,5-3,5 1,5-3 1,5-3,5Tc gi mnh nht (m/s) 30-40 30-40 30-40 30-40 30-40 20-35 20-35Hng gi thnh hnh ma ng B, , N , B B, TB, B, B TB, B, B B, B B, , NHng gi thnh hnh ma h B, , N , N N, TN, N, N TN, N, N T, TN TN, TTi nguyn ma mLng ma trung bnh nm (mm) 1.200-2.000 1.400-2.000 1.400-1.800 1.400-2.000 1.200-2.000 1.400-2.000 1.600-2.000S thng c lng ma trn 200mm 9-5 4-7 4-5 3-4 3-4 4-6 4-6S thng c lng ma di 50mm 3-5 9-5 3-4 2-4 3-4 3-5 4-5Ma ma IV-IX IV-X V-X VIII-XII VIII-XII V-X V-XBa thng ma nhiu nht VI-VIII VI-VIII VII-IX VIII-X IX-XI VII-IX VIII-XLng ma ngy ln nht (mm) 200-500 150-500 300-500 300-500 300-500 200-400 150-350Lng bc hitrung bnh nm (mm) 800-1.000 600-1.000 700-1.000 700-1.000 1.000-1.600 900-1.600 1.100-1.500 m tng i trung bnh nm 82-85 82-85 84-85 84-86 80-84 78-84 78-84Ch s m t 1,2-2,2 1,2-2,2 1,5-2,2 1,2-2,2 0,6-2,2 1,2-2,0 1,2-2,0Ngun: Bo co Kh hu v Ti nguyn Kh hu Vit NamBng 2.4. lch tiu chun v bin sut ca tn s FRLc trng I II III IV V VI VII VII IX X XI XII Nm lch tiu chun (t) 1,57 1,04 1,04 1,39 1,07 1,36 0,22 0,36 1,10 1,10 1,68 0,94 4,36Bin sut (%) 39,3 30,2 30,2 53,5 41,1 97,1 220,0 180,0 91,7 45,8 46,7 27,6 16,0Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngCHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM31Hnh 2.3. S phn vng kh hu Vit NamNgun: Bo co Kh hu v Ti nguyn Kh hu Vit NamBI NI KH HUVI TNA M32v c 6 nm (15%) sm hn, 11 nm (27,5%) mun hn 1 - 2 thng.C 28 nm (70%) ma FRL kt thc ng vo thng VI, 102. nm (25%) sm hn v 2 nm (5%) mun hn 1- 2 thng. Tng cao im ca ma FRL c th ri vo mt trong 63. thng,tthngXInthngIV.Tuynhin,tnsutcao nhtvnrivothngI(42,5%),thngXII(27,5%)v thng XI (22,5%). Cng c nm FRL vo thng II, thng III, thng IV nhiu hn cc thng khc.Bin i ca tn s xoy thun nhit i (XTN)Bin i ca tn s XTN hot ng trn Bin ng (XTNB)Tnm1961nnm2000c439XTNB,trungbnh minmc11cn.MaXTNBviquyclthigian ckhngdi1cn/thngbtuvothngVIvktthc vo thng XI.Trong 40 nm ni trn, bin i ca XTNB c nhng im ng lu sau y:X 1.TNBclchtiuchunl2,93vbinsutl 27%.Trscalchtiuchunvbinsutphbin caXTNBvoccthngtrongmaXTNBln lt l 0,75 - 1,24 v 57 - 95% (Bng 2.5). Trong cc thng ngoima,lchtiuchunbhn,songbinsutli ln hn gp bi.C15nm(37,5%)XTNBnhiuhntrungbnhv2. 16nm(40%)XTNBthntrungbnh.Nhvy,s nm c chun sai dng xp x s nm c chun sai m v gn gp i s chun sai khng.XTNBnhiunhtvonm1981(20)vtnhtvo3. nm 1969 (5). Tnh theo tng na thp k, XTN nhiu nht vo 5 nm 1971-1975 (68) v t nht vo 5 nm gn y ca th k 20, t 1996-2000 (43).SXTNBgimdntthpk1961-1970(114)n4. 1971-1980(113)ri1981-1990(109)vthpnhtvo thp k 1991-2000 (103).C17nmmaXTNBbtuvotrcthngVI5. (42,5%), 17 nm ng vo thng VI (42,5%) v 6 nm vo sau thng VI (15%). Tng t, c 14 nm ma XTNB kt thc vo sau thng XI (35%), 17 nm ng vo thng XI (42,5%) v 9 nm trc thng XI (22,5%). Bin i ca tn s XTN nh hng n Vit Nam (XTNVN)Trongthik1961-2000,binicatnsXTNVNc nhng im ng lu sau y:Bin i ca tn s XTNVN nm lch tiu chun v bin sut ca tn s XTNVN nm1. ln lt l 2,58 v 35%. Nh vy, bin i ca XTN nh hng n Vit Nam c phn r rt hn so vi XTN hot ng trn Bin ng (Bng 2.6)C19nmXTNVNnhiuhntrungbnhv21nm2. XTNVN t hn trung bnh. V c bn, s chun sai dng cn bng vi s chun sai m.Nhng nm c chun sai dng thng xen k vi nhng3. nm c chun sai m. Tuy vy, cng c 4 nm lin (1983, 1984, 1985, 1986) XTN nhiu hn trung bnh v 4 nm lin (1997, 1998, 1999, 2000) XTN t hn trung bnh.XTNVN nhiu nht vo nm 1973 (12 cn), tip l4. ccnm1964,1970,1971,1989,11cnminmvt nht vo nm 1976 (2 cn), tip l cc nm 1969, 1977, 1987,minmc3cn.Nhvy,nmnhiuXTNB nhtkhngtrngvinmXTNnhhngnVit Nam nhiu nht. Tng t, nm t XTNB nht khng phi l nm XTN nh hng n Vit Nam t nht.Bng 2.5. lch tiu chun v bin sut ca XTNBc trng I II III IV V VI VII VIII IX X XI XII Nm lch tiu chun (cn) 0,26 0,22 0,33 0,33 0,77 0,75 1,08 1,09 1,03 1,42 1,24 0,60 2,93Bin sut (%) 347 440 264 264 64 75 60 61 57 75 95 150 27Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngBng2.6.lchtiuchunvbinsutcatnsXTNnhhngn VitNamc trng I II III IV V VI VII VIII IX X XI XII Nm lch tiu chun (cn) 0,016 0,022 0,022 0,37 0,75 0,70 0,89 1,35 1,39 1,07 0,73 2,58 2.93Bin sut (%) 63 44 44 45 107 77 99 123 87 97 243 35 27Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngCHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM33Bin i v tn s XTNVN thnglchtiuchuncatnsXTNVNl0,7-1,4i1. vi cc thng trong ma XTNVN (VI-XI) v 0,010-0,73 iviccthngngoima(XII-V).Binsutvtns XTNVN ca 2 nhm thng ni trn ln lt l 75-125% v 44-243%.XTNVN cao nht vo thng X/1983 (6 cn), i vi cc2. thngtrongmavthngV/1983(3)iviccthng ngoi ma.Vo bt c thng no, trong ma cng nh ngoi ma, cng3. cnmkhngcXTNnonhhngnVitNam. D nhin, kh nng khng XTN tng i cao trong cc thng ngoi ma XTN v tng i thp trong cc thng thucmaXTN.Hnna,ccthngctnsXTN trungbnhtngicaouctngitkhnng khng xut hin XTN.Bin i v ma XTN Trong thi k 1961-2000, tn s XTN rt khc nhau gia cc thng. Tng s XTN trong thng X ln n 64 cn v trong thng I ch vn vn 1 cn. R rng l c s phn bit gia thi k nhiu XTN vi thi k rt t hoc khng c XTN.Nu quy c ma XTN l thi gian tn s XTN trung bnh thng khng di 0,5 cn th ma XTN nh hng n nc ta l t thng VI n thng XI. Nh vy, nhng XTN xy ra trong thng XII hoc sang thng I, thng II nm sau c coi l XTN mun v nhng XTN xut hin trong thng III, thng IV, thng V c coi l XTN sm.Bin i ca ma XTN nc ta c nhng c im sau y:MaXTNbtusmmunkhcnhaugiaccnm,1. song ph bin vo thng VI, thng VII.15% ma XTN bt u vo thng III, thng IV, thng V2. vcngvitlmaXTNbtuvothngVIII, IX, v thng X. 70% ma XTN bt u vo thng VI, VII, ring thng VI chim 45%.Ma XTN kt thc cng sm mun rt khc nhau gia3. cc nm, song ch yu vn vo thng XI.30%maXTNktthcvothngIX,thngXv20%4. kt thc vo thng XII, thng I. C nm sang thng II vn cn XTN. C 42,5% XTN kt thc vo thng XI, ng vi ma XTN trung bnh.Tng c tn s XTN cao nht cng thay i nhiu qua5. ccnm.Trong40nm,thngcnhiutnsXTN nht tng l thng VI (2,5%), thng VII (7,5%), thng VIII (17,5%), thng IX (35%), thng X (30%) v thng XI (7,5%). Nh vy, thng IX vi tn s XTN trung bnh l 1,4cn/nmvthngX,vitnsXTNtrungbnhl 1,6 cn/nm l thi k cao im ca a s ma XTN nc ta (Bng 2.7).Bin i ca nhit Bin i ca nhit trung bnhBin i t nm ny qua nm khc ca nhit trung bnh c mt s c im sau y:Bng 2.7. Tn s XTN bt u, cao im v kt thcMa XTN Bt u Cao im Kt thcc trng S nm T l (%) S nm T l (%) S nm T l (%)III 1 2,5 0 0,0 0 0,0IV 2 5,0 0 0,0 0 0,0V 3 7,5 0 0,0 0 0,0VI 18 45,0 1 2,5 0 0,0VII 10 25,0 3 7,5 0 0,0VIII 3 7,5 7 17,5 0 0,0IX 1 2,5 14 35,0 5 12,5X 2 5,0 12 30,0 7 17,5XI 0 0,0 3 7,5 19 47,5XII 0 0,0 0 0,0 8 20,0I 0 0,0 0 0,0 0 0,0II 0 0,0 0 0,0 1 2,5Tng s 40 100,0 4,0 100,0 40 100,0Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngBI NI KH HUVI TNA M34Binicanhittrungbnhtnginhiutrong1. ma ng, nhiu nht vo cc thng chnh ng (XII, I, II) v tng i t trong ma h, t nht vo cc thng chnh h (VI, VII, VIII). lch tiu chun ph bin ca nhit trung bnh thng I l 1,2 - 1,80C cc khu vc pha Bc v 0,6 - 1,20C cc khu vc pha Nam. i vi nhit trung bnhthngVII,trsphbincalchtiuchunl 0,3 - 0,80C trn ton lnh th (Bng 2.8).Bin i ca nhit trung bnh thng IV v thng X, tiu2. biu cho thi k qu gia cc ma, khng nhiu nh ca thng I v khng t nh ca thng VII. Tr s ph bin ca lch tiu chun ca hai thng ny l 0,5-1,20C. C iu l, trn mt s vng cao pha Bc, lch tiu chun ca nhit trung bnh thng IV vn rt ln, khng thua km thng I, thng II.Binicanhittrungbnhnmthncabtc3. thng no, k c cc thng gia ma h.Trncngkhuvckhngcskhcbitngkvcc4. ctrngphnnhbininhitgiavngniv ng bng, gia vng ni cao v vng ni thp, gia cc hi o v vng t lin k cn.Bin i ca nhit cc trBinitnmnyquanmkhccanhitcaonhtv nhit thp nht c mt s im ng lu sau y:Bi 1.n i ca nhit cao nht c phn ging vi nhit trungbnhthngVIIcngnhccthngmah.Tng t, bin i ca nhit thp nht cng c phn ging vi nhit trung bnh thng I v cc thng ma ng.lchtiuchuncanhitthpnhtphbinl2. 1-20C.cckhuvcphaBc,thphnichtsovi nhit trung bnh thng I, song cc khu vc pha Nam li cao hn. lch tiu chun ca nhit cao nht ph bin l 0,7- 3. 1,30C,xpxcanhittrungbnhccthngqu, songbhncanhittrungbnhthngIvcaohn ca nhit trung bnh thng VII.Bin i v bin trnh nm ca nhit Binivtrskotheosbinivbintrnhnmca nhit(Bng2.9).Biuhinchyucabininh sau: Bc B, ngy bt u v ngy kt thc thi k nhit 1. trung bnh trn 250C dao ng trong mt khong thi gian trn di 2 thng. Ngy bt u thi k nhit di 200C cng dao ng vi mc tng t. Ring phm vi dao ng ca ngy kt thc ma lnh th rng hn.Tng c nhit thp nht Bc B, Bc Trung B, duyn2. hi Nam Trung B nhiu nm l thng I, c nm l thng XII v c nm l thng II. Song, Ty Nguyn, Nam B, 3 thng l XI, XII v thng I.Bng 2.8. lch tiu chun ca mt s c trng yu t nhit trn mt s a im tiu biu (oC)Khu vc Trm tiu biuNhit trung bnhNhit cao nht nm Nhit thp nht nmI IV VII X NmTy Bc Lai Chu 1,0 0,9 0,5 0,8 0,3 1,33 2,45ng Bc Sa Pa 1,5 1,1 0,4 0,7 0,4 0,72 1,17ng bng Bc B H Ni 1,4 1,2 0,5 0,9 0,5 1,07 1,46Bc Trung B Vinh 1,4 1,3 0,7 0,7 0,5 0,82 1,37Nam Trung B Nng 1,1 0,7 0,5 0,6 0,3 0,93 1,51Ty Nguyn Lt 0,7 0,6 0,3 0,4 0,3 1,29 1,72Nam B Tn Sn Nht 0,9 0,6 0,5 0,5 0,4 0,69 1,38Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngBng 2.9. Tn sut thng lnh nht v thng nng nhtc trng Lnh nht Nng nhtThng XI XII I II III IV V VI VII VIIIH Ni 24 47 29 40 53 7 Nng 25 68 7 49 36 15Tn Sn Nht 6 45 49 0 3 77 20Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngCHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM35Bin i v ma maMamacngbinimnhmtnmnyquanm1. khc, v thi gian bt u, thng cao im cng nh v thi gian kt thc. Ni chung, ma ma c th dao ng trong phm vi 3-4 thng hoc hn na, tu thuc vo bin trnh ma ca khu vc:Ty Bc, ng Bc, ng bng Bc B: Ma ma btu sm nht vo thng III, thng IV, kt thc mun nht vo thng XI, thng XII. Tng cao im ca ma ma c th l mt trong cc thng thuc ma ma (V, VI,VII,VIII,IX,X),thmchrivothngXInh nm 1984 H Ni.Bc Trung B: Ma ma bt u sm nht vo thngIV, thng V, kt thc mun nht vo thng XII. Tng caoimcamamacthrivomttrongcc thng ma ma hoc sm hn: VI, VII, VIII, IX, X v XI.DuynhiNamTrungB:Mamabtusmnht vo thng VII, kt thc mun nht vo thng XII, thngI.Tngcaoimcamamacthlmt trong 3 thng: IX, X, XI.TyNguyn,NamB:BcTrungB:Mamabtu sm nht vo thng III, thng IV, kt thc mun nht vo thng XI, thng XII. Tng cao im ca ma ma c th ri vo mt trong cc thng ma ma hoc sm hn: IV, V, VI, VII, VIII, IX v X. Tng bt u (kt thc, cao im) ca ma ma xc nh2. c theo lng ma trung bnh, cng l thng c tn sut bt u (kt thc, cao im) ma ma cao nht.Do ma ma c xc nh theo tr s tuyt i ca lng3. Hng nm, thng c nhit cao nht Bc B, Bc Trung3. B, duyn hi Nam Trung B l thng VI, thng VII, thng VIII, song Ty Nguyn, Nam B ba thng l III, IV, V.Bin i v maBin i v lng maBinicalngmavacctrngbngtrstuyt i(lchtiuchun)vacctrngbngbinsut tngi(Sr= xS).Binilngmacmtscim sau y:Trn cng a im, lch tiu chun ca lng ma nm1. ln hn ca lng ma thng v ca thng ma nhiu ln hn ca thng ma t. Ngc li, bin sut ca lng ma nm thp hn ca lng ma thng v ca cc thng ma ma thp hn ca cc thng ma kh (Bng 2.10).Binsutcalngmanmvt20%trncckhuvc2. Bc Trung B, duyn hi Nam Trung B v Ty Nguyn v di 20% trn cc khu vc Ty Bc, ng Bc, ng bng Bc B v Nam B. Nh vy, lng ma nm ca cc khu vc Trung B khng n nh nh Bc B v Nam B.Vo thng I, bin sut lng ma vt 100% trn cc khu3. vcTyBc,ngBc,ngbngBcB,TyNguyn, Nam B ang gia ma kh v ch xp x 50-80% trn khu vc Bc Trung B v duyn hi Trung B va ra khi ma ma. Vo thng VII, bin sut lng ma xp x 100% trn cc khu vc Bc Trung B, duyn hi Nam Trung B ang giamagiTykhnngvch25-50%trncckhu vc Ty Bc, ng Bc, ng bng Bc B, Ty Nguyn v Nam B ang gia ma ma.Bng 2.10. lch tiu chun (S;m) v bin sut ca lng ma (Sr; %) trn mt s a im tiu biuKhu vc Trm tiu biu c trng I IV VII X NmTy Bc Lai ChuS 29,0 55,5 129,3 61,9 286,7Sr 99 42 28 68 14ng Bc Sa PaS 46,4 75,2 161,9 113,6 402,8Sr 69 36 36 54 14ng bng Bc B H NiS 21,6 53,4 101,8 104,8 320,0Sr 102 55 39 72 19Bc Trung B VinhS 29,0 37,7 119,2 353,0 514,0Sr 55 59 102 69 25Nam Trung B NngS 76,6 50,7 83,1 276,6 545,4Sr 98 143 98 44 26Ty Nguyn LtS 12,1 89,8 83,2 100,3 237,1Sr 159 55 36 41 13Nam B Tn Sn NhtS 19,3 50,7 93,5 91,8 284,9Sr 140 101 32 34 15Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngBI NI KH HUVI TNA M36ma thng nn ma ma hng nm cng nh bin i ca ma ma trn cc trung tm ma nhiu hay t khng ng nht vi cc a im k cn trn cng khu vc.2.2.2 Xu th bin i ca mt s yu t kh hu tiu biu Vit NamXu th bin i ca mt s loi hnh thi tit quan trngTn s font lnh qua Bc BTrongthpk1961-1970c268tfrontlnhquaBcB. Sang thp k 1971-1980, tr s ca c trng ny ln n 288 v gi nguyn trong thp k 1981-1990. n thp k gn y, s front lnh qua Bc B ch cn 249, thp hn c thp k 1961-1970 (Bng 2.11)PhngtrnhxuthcatnsfrontlnhquaBcBthik 1961 - 2000 c dng:Yx = 28,3 - 0,049xXu th gim ca FRL trn thc t ch bt u vo thp k 1971 - 1980Tn s xoy thun nhit i hot ng trn bin ngTrongthpk1961-1970c114tXTNhotngtrn binng.Consgimxung133trongthpk1971-1980 v 109 trong thp k 1981-1990. n thp k 1991-2000, s XTN hot ng trn Bin ng l 103.Phng trnh xu th ca XTNB c dng:Yx = 12,1 0,0548xXu th gim ca XTNB tng i nht qun trong sut 4 thp k 1961- 2000, song r nht vo cc nm gn y.Tn s XTN nh hng n Vit NamS XTN nh hng n Vit Nam l 74 trong thp k 1961-1970,lnn76,77tronghaithpktip,1971-1980v 1981-1990.nthpk1991-2000,sXTNgiming k, ch cn 68.Phng trnh xu th ca XTNVN c dng:Yx = 8,0 0,0303xTrn thc t, xu th gim i bt u vo thp k 1971 - 1980 v tng i r vo nhng nm gn y.S ngy ma phn H NiSngymaphntrungbnhnmHNitrongthpk 1961-1970 l 29,7, tng ln 35,8 trong thp k 1971-1980, sau gim dn trong thp k 1981-1990 v xung n mc 14,5 ngy/nm trong 10 nm gn y.Phng trnh xu th ca s ngy ma phn nm H Ni thi k 1956-2007 c dng:Yx = 37,6 0,51xXu th gim bt u t cui thp k 1971 - 1980 v duy tr cho n nhng nm gn y nht.Xu th bin i ca nhit Nhit trung bnh nmHNi,nhittrungbnhnmtnhchothpk1931-1940 l 23,30C, thp nht trong sut lch s 70 nm quan trc nhit . Sang thp k 1941 -1950, tr s ca c trng ny ln n 23,60C. Nhit gim i cht t trong sut 3 thp k sau .Sangthpk1981-1990,nhittrungbnhnmtrli 23,60Cvlnn24,10Ctrongthpk19912000(Bng 2.12).Phng trnh xu th ca nhit trung bnh nm H Ni thi k 1900-2004 c dng:Yx = 23,4 + 0,006xCngnhHNi,Nng,nhittrungbnhthpk 1931-1940 l 25,40C, thp nht trong 70 nm quan trc nhit .Tnhittngdnvttinhcaovothpk 1961-1970, 26,00C. Sang thp k 1971-1980, tr s ch cn 25,80C v gi nguyn trong sut 3 thp k gn y.Bng 2.11. Tn s ca mt s loi hnh thi tit trong cc thp k gn yThp k Front lnh qua Bc B Xoy thun nhit i bin ng Xoy thun nhit i nh hng Vit Nam S ngy ma phn trung bnh nm H Ni1961-1970 268 114 74 29,71971-1980 288 113 77 35,81981-1990 287 109 76 28,71991-2000 249 103 68 14,5Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngCHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM37PhngtrnhxuthcanhittrungbnhnmNng c dng:Yx = 25,5 + 0,0056x Tn Sn Nht, nhit trung bnh thp k cng mc 26,9-27,00C trong sut thi k 1931-1960. Tr s ln n 27,20C trongthpk1971-1980,27,30Ctrongthpk1981-1990v 27,60C trong thp k 1991-2000.PhngtrnhxuthcanhittrungbnhnmTnSn Nht thi k 1921-2004 c dng:Yx = 26,8 + 0,0130xNhvy,xuthcanhittrungbnhnmtrong7thpk va qua l tng ln, tng i r v nht qun Tn Sn Nht, H Ni v khng r lm Nng.Nhit trung bnh thng IHNi,nhittrungbnhthngIca1931-1940l 15,90C, thp nht trong lch s 70 nm quan trc nhit . Tp k 1941-1950 vi nhit thng I t ngt tng ln, tr thnh thp k c nhit thng I cao nht. Sau , nhit thng I gim dn, ch cn 16,50C trong thp k 1971-1980. Sang thp k1981-1990,nhitlitiptctnglnchonhtthp k 1991-2000.Phng trnh xu th ca nhit trung bnh thng I H Ni thi k 1900-2004 c dng:Yx = 16,5 + 0,003x Nng, nhit trung bnh thng I ca thp k 1931-1940 l 21,10C thp nht trong cc thp k c quan trc nhit . T , nhit tng dn cho n cui thp k 1961-1970. Nhit trungbnhthngIgimdnitronghaithpktipsau (1971-1980v1981-1990)ritnglnnhanhchngtrong thp k 1991-2000.Phng trnh xu th ca nhit trung bnh thng I Nng c dng:Yx = 21,2 + 0,0067x Tn Sn Nht, nhit trung bnh thng I trong sut 3 thp k1931-1940,1941-1950,1951-1960ul25,80Crigim i cht t trong thp k 1961-1970. Sau , nhit trung bnh thng I tng ln trong sut hai thp k 1971-1990 v n thp k 1991-2000 tng ln nhanh chng, nht l trong nm 1998.Phng trnh xu th ca nhit trung bnh thng I Tn Sn Nht c dng:Yx = 25,6 + 0,0095xNh vy, c 3 a im trn, xu th ca nhit trung bnh thng I u khng r rt. S d nh vy v trn thc t, nhit thng I ch mi tng ln trong khong 10-20 nm gn y.Nhit trung bnh thng VII H Ni, nhit trung bnh thng VII l 28,60C trong thp k1931-1940,tngln28,80Ctronghaithpk1941-1950, 1951-1960 ri t ti 29,20C trong thp k 1961-1970, sau gimichtttrongthpk1971-1980.Vothpk1981-1990,trscactrngnylnn29,30C.Tpkcui cng ca th k trc, 1991-2000, c nhit trung bnh thng VII cao nht trong 7 thp k quan trc nhit , 29,40C.PhngtrnhxuthcanhittrungbnhthngVIIH Ni c dng:Yx = 28,6 + 0,0099xBng 2.12. Nhit trung bnh nm ( TN), nhit trung bnh thng I (T I), v nhit trung bnh thng VII (T VII) trong cc thp k gn y (0C)Thp kT N TI TVIIH Ni Nng Tn Sn Nht H Ni Nng Tn Sn Nht H Ni Nng Tn Sn Nht1931-1940 23,3 25,4 27,0 15,9 21,1 25,8 28,6 28,7 26,81941-1950 23,6 25,5 26,9 17,5 21,4 25,8 28,8 28,9 26,81951-1960 23,5 25,8 27,0 16,5 21,5 25,8 28,8 29,2 27,21961-1970 23,5 26,0 27,2 16,3 21,6 25,6 29,2 29,5 27,41971-1980 23,4 25,8 27,3 16,0 21,4 25,9 29,0 29,5 27,41981-1990 23,6 25,8 27,4 16,4 21,3 25,9 29,3 29,1 27,41991-2000 24,1 25,8 27,6 17,0 21,7 26,3 29,4 29,2 27,4Ngun: Bo co Kh hu v Ti nguyn Kh hu Vit NamBI NI KH HUVI TNA M38 Nng, nhit trung bnh thng VII ca thp k 1931-1940l28,70C,lnn28,90Ctrongthpk1941-1950,ri 29,20Ctrongthpk1951-1960vtti29,50Ctronghai thpk1961-1980.Sangthpk1981-1990,nhittrung bnh thng VII ch cn 29,10C v tng ln cht t trong thp k 1991-2000, 29,20C.PhngtrnhxuthcanhittrungbnhthngVII Nng c dng:Yx = 28,9 + 0,0066 x Tn Sn Nht, nhit trung bnh thng VII l 26,80C trong 2 thp k 1931-1940 v 1941-1950, ln n 27,20C trong thp k1951-1960ri27,40Ctrongthpk1961-1970vduytr mc cho n ht th k 20.Phng trnh xu th ca nhit trung bnh thng VII Tn Sn Nht c dng:Yx = 26,7 + 0,0142xNhvy,xuthtnglncanhitthngVIIHNiv Tn Sn Nht tng i r nt v nht qun. Trong khi , xu thcanhitthngVIIkhngthhinnhtqundonn nhit kh cao trong hai thp k 1961-1980 Nng.Xu th bin i ca lng maXu th bin i ca lng ma trong khong 100 nm qua H Ni, lng ma nm trung bnh l 1.521mm trong thp k 1911-1920, thp nht trong chui quan trc kh hu 90 nm. Sangthpk1921-1930,lngmatrungbnhnmtngln 1.889 mm, nhng li gim xung 1.691mm trong thp k 1931-1940.Vilngmatrungbnhl1.845mm,thpk1941-1950 c coi l c lng ma cao nht.Hai thp k 1951-1960, 1961-1970 cng l giai on c lng ma kh thp. Sau , lng ma tng ln trong thp k 1971-1980,nhngrigimilintctronghaithpkgny, 1981-1990 v 1991-2000.Phng trnh xu th ca lng ma nm H Ni c dng:Yx = 1644,8 + 0,3391xNng,lngmanmtrungbnhl1.919mmtrong thpk1931-1940,thpnhttrong7thpkquantrc.Sau lngmalnn2.223mmtrongthpk1941-1950ri li gim xung 1.970mm trong thp k 1951-1960. Hai thp k Bng 2.13. Nhit thi k 1957 2007 (0C)Vng kh hu Trm Kh tng Thi k quan trc Tng (0C/nm)Ty Bcin Bin 1958 2007 0,0232Mc Chu 1961 2007 0,0121ng BcSa Pa 1958 2007 0,0037H Giang 1960 2007 0,0176Bc Quang 1961 2007 0,0160ng bng Bc BPh Lin 1958 2007 0,0111Bch Long V 1958 2007 0,0106Ninh Bnh 1960 2007 0,119Bc Trung BVinh 1958 2007 0,0167Tng Dng 1961 2007 0,0177Ba T 1980 2007 0,0110Nam Trung BQuy Nhn 1958 2007 0,0150Nha Trang 1958 2007 0,0090Ty NguynBun Ma Thut 1958 2007 0,0148 Lt 1964 2007 0,0047Nam B Cn Th 1958 2007 0,0054Rch Gi 1957 2007 0,0045Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngCHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM391961-1970 v 1971-1.980, c lng ma kh ln: 2.095mm v 2.019mm. Lng ma thp i ng k trong thp k 1981-1990 ri tng vt ln 2.434mm trong thp k 1991-2000.Phng trnh xu th ca lng ma nm Nng c dng:Yx = 1930,7+ 1,0261xTnSnNht,lngmanmtrungbnhl1.829trong thp k 1911-1920 ln n 2.063mm trong thp k 1921-1930. y l thp k c lng ma cao nht trong chui quan trc 90 nm ca Tn Sn Nht.Haithpk1941-1950v1951-1960clngmavoloi trung bnh: 1.924, 1.926mm. n thp k 1951-1960 c lng matrungbnhl1.805mm,thpnhttrong9thpkva qua.Tp k 1961-1970 cng c lng ma kh cao: 2.005mm. Sau lngmagimivduytrtrongsutc3thpkgn y.PhngtrnhxuthcalngmanmTnSnNhtc dng: Yx = 1793,6 - 4,674xNgha l trong gn 50 nm qua, trung bnh mi nm lng ma Tn Sn Nht tng ln2,1373mm.Trn tng a im, xu th bin i ca lng ma trong 9 thp kvaquakhngnhtqun:Cgiaiontnglnvcgiai on gim xung. Trn lnh th Vit Nam, xu th bin i ca lng ma cng rt khc nhau gia cc khu vc (Bng 2.14).Xu th bin i ca lng ma trong khong 50 nm quaTrong khong 50 nm qua, qu trnh tng ln (xu th tng) hay gimi(xuthgim)calngmakhngcquanhcht chvithigian.Tuynhin,nuchxtvmctnghay gim trung bnh cho cc thi k quan trc, c th nhn thy, xu thcalngmatrong50nmquaminBcphbinl gim i v min Nam ph bin l tng ln (Bng 2.15).Mc tng hay gim trung bnh cho thi k 50 nm ph bin l di 10mm/nm.Ringmtstrmmaln(Namng,BaT),mctng trong 30 nm (1978 -2007) ln n vi chcm.Xu th bin i ca mc nc binPhng trnh xu th ca mc nc bin trung bnh nm (cm) titrmHnDutiubiuchoonbbinBcBthik 1965 2006 nh sau:Yx = 185,6 + 0,205xNgha l trm Hn Du, trung bnh mi nm nc bin dng ln 0,205cm.Phng trnh xu th tng ng ca trm Sn Tr tiu biu cho on b bin Trung B thi k 1978 2006 nh sau:Yx = 90,1+0,260xNghaltrmSnTrtrungbnhminmncbindng ln 0,260cm.Ti trm Vng Tu, tiu biu cho on b bin Nam B, phng trnh xu th ca mc nc bin dng trung bnh mi nm (cm) thi k 1981 2006 nh sau:Bng 2.14. Lng ma nm trung bnh trong cc thp k gn y (mm)Thp k H Ni Nng Tn Sn Nht1911-1920 1521 18291921-1930 1789 20631931-1940 1691 1919 19241941-1950 1845 2223 19261951-1960 1622 1970 18051961-1970 1557 2095 20051971-1980 1788 2019 18281981-1990 1697 1962 18131991-2000 1590 2434 1850Ngun: Bo co Kh hu v Ti nguyn Kh hu Vit NamBI NI KH HUVI TNA M40Bng 2.15. Mc tng hay gim ca lng ma nm thi k 1957 2007Vng kh hu Trm kh tng Thi k quan trc Mc tng (mm/nm) Mc gim (mm/nm)Ty BcLai Chu 1957 - 2007 0,262Sn La 1961 - 2007 1,979Mc Chu 1961 - 2007 2,967ng BcSa Pa 1958 - 2007 6,013H Giang 1958 - 2007 3,854Bc Quang 1959 - 2007 0,587ng bng Bc BH Ni 1961 - 2007 1,893Bch Long V 1960 - 2007 1,567Ninh Bnh 1959 - 2007 5,464Bc Trung BTng Dng 1961 - 2007 1,810ng H 1974 - 2007 12,325Nam ng 1977 - 2007 43,402Nam Trung BBa T 1980 - 2007 29,624Nha Trang 1961 - 2007 6,454Phan Thit 1958 - 2007 0,079Ty NguynPleiku 1960 - 2007 0,832Bun M Thut 1960 - 2007 7,258c Nng 1978 - 2007 20,473 Lt 1954 - 2007 1,038Nam BVng Tu 1954 - 2007 0,531Cn Th 1961 - 2007 6,935Rch Gi 1958 - 2007 6,909C Mau 1958 - 2007 2,600Cn o 1957 - 2007 0,649Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngYx = 257,2 + 0,398xNgha l trm Vng Tu trung bnh mi nm mc nc bin dng ln 0,398cm.2.3 Cc kch bn bin i kh hu Vit Nam2.3.1 Xy dng cc kch bn bin i kh hui tng v ni dung nghin cu kch bn bin i kh huCng nh cc nc khc trong khu vc, cc kch bn bin i khhuVitNamcxydngcho3yutchnhl nhit,lngma,caomcncbinvccmcthi gian ch yu l 2010, 2050 v 2070.Ccvnlinquannhiunhtnnidungkchbnbin i kh hu bao gm:Tnh cht v mc bin i ca cc yu t trong tonb qu trnh quan trc kh huXu th bin i kh hu trong thi gian quan trc KhnngpdngcckchbnbinikhhudoCSIRO xut.La chn cc kch bn bin i kh huTeo S tay phng php nh gi tc ng ca bin i kh hu v Chin lc ng ph cc ni dung bin i kh hu c la chn phi p ng cc yu cu sau y:Yu cu 1: Cc kch bn bin i phi nm trong khun kh ca cc gi nh v kch bn nng ln ton cu.lginhnngCO2trongkhquyntnggpi. Nidungcacckchbnlnhittngln1,53,50C (Houghton, 1996) hoc 1,54,50C (IPCC, 2001).CHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM41Vtngyut,xuthbinitrncckhuvchaya3. im khng hon ton nh nhau.Ngoi ra, trn cng mt trm, cng mt yu t, xu th bin i ca cc thng trong cng mt nm c th rt khc nhau.Kin ngh la chn cc kch bn bin i kh hu Vit NamNhngbinikhnghontonrrtvnhtquncacc chui nhit , lng ma trong gn 100 nm qua v chui cao mc nc bin cc trm Ca ng, Hn Du trong 3 thp k gn y khng cung cp c nhng c s ng tin cy xydngmththngmphngbinikhhuringca Vit Nam. Tuy nhin, tnh cht c th ca cc khu vc v nhit v lng ma vn c phn nh y trong cc c trng binikhhu.Vvy,cnthitsdngccmphngi th ca CSIRO vi s phn bit cc khu vc khc nhau v tnh duyn hi (hay ni a) v v ch gi ma gy ma (ng Bc hay Ty Nam).Vcckchbnnhittheocckchbndownscalingtheo khu vc Vit Nam, c th phn bit thnh nhm khu vc:Nhmvenbin:ngbngBcB,DuynhiBcTrungB,TrungTrungB,NamTrungBvNam B.Nhm ni a: Ty Bc, ng Bc v Ty Nguyn. V cc kch bn ma, phn bit hai nhm khu vc: NhmmagimaTyNam:TyBc,ngBc,ng bng Bc B, Ty Nguyn, phn cc Nam Nam Trung B v Nam B.Nhm ma gi ma ng Bc: Bc Trung B, TrungB v phn cc Bc Nam Trung B.Cthcnhngclngnmngoiphmvinitrnsong nhngclngcrtratnhngmhnhcxy dng trn c s l lun bin i kh hu.Yucu2:Cckchbnphitincyvphngphpvt l. iu c ngha l cc ni dung kch bn khng phn nh nhng s kin tri quy lut vt l.Yu cu 3: Cc kch bn phi c lng cho mt s lng yu t va trn phm vi khng gian v thi gian ph hp vi kh nng nh gi tc ng ca bin i kh hu i vi cc ngnh kinh t quc dn.Yu cu 4: Cc kch bn phn nh phm vi hay gii hn c th c ca bin i kh hu trong tng lai cho khu vc nghin cu.Cc c tnh kh hu lin quan n kch bn bin i kh hu la chn cc m phng bin i kh hu cn ch cc c tnh sau y trong bin i cc yu t kh hu trong thi gian va qua:Bin i ca nhit , lng ma l ng k v tr s yu t1. cng nh v thi gian bt u, cao im, kt thc ca cc ma song khng ln thay th quy lut ma ca tng khu vc.Bin i ca cc yu t l ng k song bin i c tnh xu2. th t nm ny qua nm khc li rt nh.V nhit , tc bin i ph bin l 0,005 0,00150C/nm i vi nhit trung bnh thng v 0,001 0,010C/nm i vi nhit trung bnh nm.Vlngma,tcbiniphbinl0,12,0mm/nm i vi lng ma cc thng ma ma v 0,5 5,0mm/nm i vi lng ma nm.Bng 2.16. Kch bn bin i kh hu vo nm 2070 Khu vc Mc tng nhit (0C) Mc tng (+) hay gim lng ma (%) Mc nc bin dngTy Bc 1,2 4,5 + 0-1,0 -10-+10ng Bc 1,2 4,5 + 0-1,0 -10-+10 15- 90ng bng Bc B 1,2 4,5 + 0-1,0 -10-+10 15- 90Duyn hi Bc Trung B 1,2 4,5 -5-+10 + 0-10 15- 90Duyn hi Nam Trung B 0,5 3,0 -5-+10 + 0-10 15- 90Ty Nguyn 0,5 3,0 + 0-1,0 -10-+10 -Nam B 0,5 3,0 + 0-1,0 -10-+10 15- 90Ngun: ADB, Bin i kh hu chu BI NI KH HUVI TNA M422.3.2 Kch bn nm 1994Nm 1994, da trn kch bn BKH ca T chc nghin cu Khoa hc sc kho cng ng v cng nghip ca c (CSIRO), nhm cc chuyn gia tham gia d n Bin i kh hu Chu xut kch bn BKH u tin ca Vit Nam, tm gi l BKH 1994 (Bng 2.16).Teo kch bn ny, vo cui th k 21 (2070) s c nhng bin i sau so vi thi k 1980-1999:Nhit tng ln 1,2 4,5 0C min Bc v 0,53,00C min NamkhuvcgimaTyNam(BcB,TyNguyn,NamB)lngmatngln010%trongmama v tng hoc gim n 10% trong ma kh. khu vc gi ma ng Bc (Duyn hi Bc TrungB,NamTrungB,lngmatgim5%ntng 10% trong ma ma v tng n 10% trong ma kh.Mc nc bin dng t 15 dn 90cm. Nichung,mctngnhitvmcncbindngtrong kch bn 1994 ph hp vi kch bn chung ca khu vc ng Nam , th hin kh nng nng ln khc nhau gia min Bc v min Nam v c nhn nhn c th v tc ng ca nng ln ton cu i vi cc c ch hon lu.2.3.3 Cc kch bn nm 1998Cc kch bn BKH nm 1998 c th hin ti bng 2.17.Cc kch bn nhit , lng ma, mc nc bin trn cc khu vc Vit Nam cho thy mc tng gim lng ma khng thay i my nhng mc tng nhit t hn so vi kch bn 1994. Kch bn kh hu 1998 cng phn nh tc ng ca BKH i vi ch nhit trn cc min v khc nhau v trn cc khu vc c ma ma khc nhau nh kch bn kh hu 1994.Bng 2.17. Cc kch bn bin i kh hu theo kch bn 1998Yu t Khu vc Ma 2010 2050 2070Nhit tng (oC)Ty Bc, ng Bc - 0,5 1,0 2,5ng bng Bc B - 0,3 1,1 1,5Bc Trung B - 0,3 1,1 1,5Trung Trung B - 0,3 1,1 1,5Nam Trung B - 0,3 1,1 1,5Ty Nguyn - 0,3 1,0 2,5Nam B - 0,3 1,1 1,5Lng ma tng (+) hay gim (-)Ty Bc, ng BcMa 0 0- 5 0-5Kh 0 -5-+5 -5-+5ng bng Bc BMa 0 0 5 0 5Kh 0 -5-+5 -5-+5Bc Trung BMa 0 0- 10 0- 10Kh 0 0 -5 0 -5Trung Trung BMa 0 0 10 0 10Kh 0 0 5 0 5Pha Bc ca Nam Trung BMa 0 0 10 0 10Kh 0 0-5 0-5Ty NguynMa 0 0-5 0-5Kh 0 -5-+5 -5-+5Nam B v Cc Nam Trung BMa 0 0-5 0-5Kh 0 5-+5 5-+5Ton di b bin- - 33 45Kh 0 -5-+5 -5-+5Nc bin dng (cm) Ton di b bin - 9 33 45Ngun: Thng bo u tin ca Vit Nam, 2003CHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM432.3.4 Kch bn nm 2009Tng 6 nm 2009, B Ti nguyn v Mi trng cng b vnbnKchbnbinikhhu,ncbindngchoVit Nam.Nhngcpnhtvkchbnbinikhhuvnc bin dng cho Vit Nam c trnh by nh sau:SdngccphngphpStatisticalDownscalingvphng phpMAGIC/SCENGEN,sdngccmhnhmphng trongbocolnth4caIPCC,cctcgixcnhc mc tng nhit trung bnh nm, mc tng gim lng ma v mc nc bin dng cho tng thp k trong th k 21.ng ch l kch bn c chia thnh 3 nhm cn c vo kch bn pht thi ca IPCC bao gm:Nhm pht thi cao: A1FI, A2 Nhm pht thi va: A1B, B2 Nhm pht thi thp: A1T, B1 V nhit :Teo kch bn thp, mc tng nhit trung bnh nm so vi thi k 1980-1999 vo cc nm 2020; 2050; 2070 v 2100 ln lt l: 0,3 0,60C, 0,8 1,40C, 1,0 1,70C v 1,1 1,90C.Bng 2.18. Mc tng nhit trung bnh (0C) qua cc thp k so vi thi k 1980-1999Vng kh hu Kch bn pht thiNhit trung bnh nm Nhit trung bnh XII-II Nhit trung bnhVI-VIII2050 2070 2100 2050 2070 2100 2050 2070 2100Ty BcA1FI 1,7 2,9 4,2 1,9 3,2 4,6 1,4 2,6 3,8B1 1,6 1,9 2,2 1,6 1,9 2,3 1,4 3,1 2,3ng BcA1FI 1,7 2,8 4,5 1,9 3,1 4,6 1,8 1,8 4,6B1 1,6 1,9 2,2 1,6 1,9 2,3 1,4 2,7 1,3ng bng Bc BA1FI 1,6 2,8 4,1 1,9 3,1 4,6 1,6 1,7 4,0B1 1,4 1,8 2,1 1,6 1,9 2,3 1,3 1,6 2,1Bc Trung BA1FI 1,6 2,6 3,7 1,5 2,6 3,9 1,5 2,7 3,9B1 1,3 1,6 2,0 1,4 1,7 2,0 1,3 1,7 1,9Nam Trung BA1FI 1,6 2,7 3,9 1,3 2,5 3,6 1,6 2,7 3,9B1 1,4 1,7 2,1 1,3 1,7 1,9 1,4 1,7 2,1Ty NguynA1FI 1,7 2,8 4,0 1,4 2,7 3,8 1,6 2,7 4,4B1 1,5 1,8 2,1 1,4 1,6 1,9 1,4 1,7 2,1Nam BA1FI 1,6 2,6 3,7 1,3 2,4 3,4 1,6 2,7 3,9B1 1,4 1,6 1,9 1,2 1,5 1,8 1,4 1,7 2,0Ngun: Nguyn Vn Thng, Hong c Cng Vin Khoa hc Kh tng Thy vn v Mi trngBng 2.19. Mc thay ilng ma (%)qua cc thp k so vi thi k 1980-1999Vng kh huKch bn pht thiLng ma nm Lng ma XII-II Lng maVI-VIII2050 2070 2100 2050 2070 2100 2050 2070 2100Ty BcA1FI 6,0 10,0 14,6 15,1 25,4 37,1 5,1 8,6 12,6B1 5,1 6,4 7,2 13,0 16,1 18,4 4,4 5,5 6,2ng BcA1FI 3,8 6,4 9,3 5,3 8,9 13,1 1,5 2,5 3,7B1 3,2 4,0 4,6 4,6 5,7 11,5 1,3 1,6 1,9ng bng Bc BA1FI 4,6 7,7 11,2 3,1 5,2 7,6 3,8 7,4 9,2B1 3,9 4,9 5,6 2,7 3,3 3,8 3,2 4,0 4,6Bc Trung BA1FI 4,2 7,1 10,3 5,6 9,4 13,8 7,6 12,8 18,8B1 3,6 4,5 5,2 4,9 6,0 6,8 6,6 8,2 9,3Nam Trung BA1FI 2,7 4,6 6,7 3,5 5,9 8,7 12,3 20,7 30,3B1 2,3 2,9 3,5 3,1 3,8 4,3 10,6 13,2 15,1Ty NguynA1FI 2,8 4,7 6,9 -2,5 -3,6 -6,2 3,3 5,5 8,1B1 2,4 3,0 3,5 -2,2 -2,7 -3,1 2,9 3,5 4,0Nam BA1FI 1,2 2,0 3,0 -4,8 -8,2 -11,9 0,3 0,5 0,8B1 1,0 1,3 1,6 -4,2 -5,2 -5,9 0,4 0,6 0,9Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngBI NI KH HUVI TNA M44Teo kch bn va, nu tng nhit trung bnh nm vo cc mc thi gian nu trn ln lt l 0,3 0,50C, 0,8 1,50C, 1,2 2,10C v 1,6 2,80C.Teo kch bn cao, nu tng nhit trung bnh vo cc mc thi gian ni trn ln ti 0,3 0,60C, 0,8 1,50C, 1,3 2,20C v 2,1 3,60C.Ni chung, v mc tng nhit tng i cao cc vng kh hu pha Bc v tng i thp cc vng kh hu pha Nam.V lng ma:Teokchbnthp,mctnglngmanmsovithik 1980 1999 vo cc nm 2020; 2050; 2070 v 2100 ln lt l 0,3 1,6%; 0,7 3,9%; 0,9 4,8% v 1,0 5,2%.Teokchbnva,mctnglngmanmsovithik 19801999voccmcthigiannitrnlnltl0,3 1,6%, 0,7 4,0%, 1,0 5,9% v 1,4 7,9%.Teo kch bn cao, mc tng lng ma nm vo cc thi gian tng ng l 0,3 1,8%, 0,7 3,8%, 1,1 6,1% v 1,8 10,1%.So vi nhit , mc thay i v lng ma gia cc vng kh hu pha Bc v cc vng kh hu pha Nam nhiu hn. V mc nc bin:Teokchbnthp,mcncbindngvoccnm2020; 2050; 2070 v 2100 ln lt l 11, 28 , 42 v 65cm.Teo kch bn va, mc nc bin dng vo cc nm ni trn ln lt l 12; 30; 46 v 75cm.Teokchbncao,mcncbindngvoccnm2020; 2050chl12cm;33cmsonglnti57cmvonm2070v 100cm vo nm 2100.Bng 2.20. Kch bn nc bin dng (mm) so vi thi k 1980-1999Kch bn 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100A1FI 3,0 4,8 7,1 10,0 13,7 18,2 23,2 28,6 34,1 39,7B1 3,1 5,2 7,7 10,5 13,4 16,3 19,2 21,9 24,6 26,9Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngBng 2.21. Kch bn bin i kh hu v nc bin dng cho Vit NamYu t Vng kh hu 2020 2050 2070 2100Thp Va Cao Thp Va Cao Thp Va Cao Thp Va CaoMc tng nhit (0C)Ty Bc 0,5 0,5 0,5 1,2 1,3 1,3 1,6 1,9 2,0 1,7 2,6 3,3ng Bc 0,5 0,5 0,5 1,2 1,2 1,3 1,5 1,8 1,9 1,7 2,5 3,2ng bng Bc B 0,5 0,5 0,5 1,2 1,2 1,3 1,5 1,8 1,9 1,6 2,4 3,1Bc Trung B 0,6 0,6 0,6 1,4 1,5 1,5 1,7 2,1 2,2 1,9 2,8 3,6Nam Trung B 0,4 0,4 0,4 0,9 0,9 1,0 1,2 1,4 1,5 1,2 1,9 2,4Ty Nguyn 0,3 0,3 0,3 0,8 0,8 0,8 1,0 1,2 1,3 1,1 1,6 2,1Nam B 0,4 0,4 0,4 1,0 1,0 1,0 1,3 1,6 1,6 1,4 2,0 2,6Mc tng lng ma (%)Ty Bc 1,4 1,4 1,6 3,6 3,8 3,7 4,4 5,4 5,6 4,8 7,4 9,3ng Bc 1,4 1,4 1,7 3,6 3,8 2,8 4,5 5,4 5,7 4,8 7,3 9,3ng bng Bc B 1,6 1,6 1,6 3,9 4,1 3,8 4,8 5,9 6,1 5,2 7,9 10,1Bc Trung B 1,5 1,5 1,8 3,8 4,0 3,7 4,7 5,7 5,9 5,0 7,7 9,7Nam Trung B 0,7 0,7 0,7 1,6 1,7 1,7 2,0 2,4 2,5 2,2 3,2 4,1Ty Nguyn 0,3 0,3 0,3 0,7 0,7 0,7 0,9 1,0 1,1 1,0 1,4 1,8Nam B 0,3 0,3 0,3 0,7 0,8 0,7 0,9 1,1 1,2 1,0 1,5 1,9Mc nc bin dng (mm)C nm 11 12 12 28 30 33 42 46 57 65 75 100Ngun: Vin Khoa hc Kh tng Thy vn v Mi trngCHNG 2: BIU HIN CA BIN I KH HU V KCH BN BIN I KH HU VIT NAM45Nichung,mcncbindngdkinchoVitNamtrong cc thp k sp ti cao hn nhiu so vi d kin ca IPCC.Cng nh cc kch bn 1994 v kch bn 1998, i tng c lng l 7 vng kh hu ch yu ca Vit Nam: Ty Bc, ng Bc,ngbngBcB,BcTrungB,NamTrungB,Ty Nguyn v Nam B.Tr kch bn 2007 A1FI ra c cp n trong bo co ln th 4 ca IPCC, cc kch bn pht thi khc ca SRES u cho nhngc lng nhit khng sai khc nhiu vi kch bn kh hu 1998, ngha l vo cc nm 2050, 2070 v 2010 nhit cc khu vc u tng ln ln lt l 1,31,60C, 1,61,90C v 1,92,20C so vi thi k 1980-1999.Ngoira,kchbnphtthiA1FIccpntrongbo co ln th 4 ca IPCC cng cho nhng c lng c bit cao vmctnglngmamamaduynhiTrungB,c bit l Nam B. SovihaikchbnBKHcxydngnm1994v1998 kch bn kh hu 2009 th hin kt qu c lng tun t cho tng thp k song khng phn nh c tnh h thng trong s phn ho v cc c lng nhit cho cc khu vc vng ni v ng bng Vit Nam.2.4 Kt lun chng 2Vit Nam c kh hu nhit i gi ma ca mt bn o 1. ng Nam i lc u , ko di trn nhiu v , chu nh hngsusccaBinng,nngnhiu,nhitcao, manhiu,nhiuthintainguyhinhsngmui,gi rt,bo,llt,hnhn,vdo,chunhiuthchthc trc BKH.TrnlnhthVitNamhnhthnh7vngkhhukhc2. nhau v ch nhit, ch ma, tn s v cng gi rt, XTN, l lt, hn hn v do tc ng ca BKH ton cu n BKH trn tng vng cng khc nhau.Trong khong 100 nm qua, lch tiu chun, thc o3. mc bin i hng nm ca mi mt yu t kh hu u rt ln, vt xa tc xu th ca yu t kh hu .Xu th ca mt s yu t quan trng ghi nhn c trong4. khong 50 nm gn y nh sau:Nhit tng ln 0,05 0,20 0C mi thp k, tng dn t Nam ra Bc, t ng bng ln vng ni.Lng ma a s ni min Bc tng ln v a s niminNamgiminhngvitcphbindi 16mm/nm.Front lnh gim i 0,49 t mi thp k. XTN nh hng n Vit Nam tng ln 0,43 cn mithp k.Nc bin dng 2 4cm mi thp k. D kin n cui th k 21, so vi thi k 1980-1999, nhit5. tnglntnht1,1-1,90C,nhiunht2,13,60C, lng ma tng t nht 1,0 5,2%, nhiu nht 1,8 10,1%; mc nc bin dng 65 100cm.BI NI KH HUVI TNA M46Hnh 2.4.S thay i nhit trung bnh hng nm (0C) v lng ma hng nm (%) ca cc vng kh hu Vit Nam so vi mc trung bnh thi k 1980 1999TRUNG QUCTHI LANCAM PU CHIANgun: Kch bn BKH, nc bin dng cho Vit Nam, MONRE, 2009Chng 3Tc ng ca bin i kh hu v Chin lc, Gii php ng ph vi bin i kh hu Vit Nam3.1 Tc ng ca bin i kh hu Vit NamCckchbnbinikhhuctrnhbytrongchng trcdavotinphtthikhnhknhtrongtnglai cho th gii thng qua kch bn pht thi thp nht B1 v cao nhtA1FIcaSRESnm2001.Tuynhin,tkhiphduyt cc kch bn pht thi ca SRES trong vic m phng cc bin ikhhutrongtnglaisdngmhnhkhhukhuvc v ton cu, cc quan st ch ra rng th gii vn tip tc pht thi kh nh knh v mc tng kh nh knh ton cu trong cc nm 2000 2006 ti 3,3% so vi mc tng d kin ln nht ca SRES trong kch bn A1FI l 2.4% (Hnh 3.1).Sau khi cng b bo co Stern v Nn kinh t bin i kh hu vo nm 2006, cc nh lnh o trn th gii m phn mt cch nghim tc v phng php v cch thc hn ch nng kh nh knh trong kh quyn ti 450ppm sao cho mc tng nhitbmttrungbnhtoncukhngvtqungng gii hn l 2,00C, khi mt vi tc ng c th gy thm ha v thm ch khng th o ngc ti mt s vng ca th gii (cbitlticconhvccncangphttrinnm dc b bin). Chngtacnghyvngrngkinthctnghpcaccnh lnhotrnkhpthgiisgiptcmtthathun hpltiCopenhagenvothng12nm2009thchin vicctgimmnhmvicphtthikhnhknhtoncu nhmtcmctiubtbucvmtthgiiphttrin thng qua vic gii thiu cc cng ngh tin tin pht thi kh ccbonthpvcngnghctgiccbon,khuynkhchcc tng lp x hi trn ton th gii v ng tiu th bn vng v mt tri t xanh hn v mt tng lai an ton hn.Hnh 3.1. Xu th ton cu hin nay (3,3%/nm) v ng pht thi kh nh knh d kin ca SRES; v cc ng pht thi cho cc kch bn n nh ng pht thi hin ti: CDIACng pht thi hin ti: EIAng n nh 450 ppmng n nh 650 ppmPht thi CO2 (GtC y-1)NmTc tng trng n nh trong vng 50 nm ti nm 2050Quan st c trong thi k 2000-2006 l 3,3%Ngun: Cp nht t http://www.ipcc.ch/graphics/ar4-wg1/jpg/spm5.jpgBI NI KH HUVI TNA M483.1.1 Tc ng ca bin i kh hu i vi cc lnh vc ch yuTc ng ca BKH i vi ti nguyn ncVitNamnmhluhaisngquctlnlsngHngv sngMCng.SngHngcdintchluvc169.000km2, hngnmchuynrabinlngdngchy138tm3vsng M Cng c din tch lu vc 795.000km2, hng nm c lng dngchyvoBinng505tm3.Vitcngca BKH, dng chy sng Hng v sng M Cng c nhng bin i ng lu sau y:So vi hin nay, vo nm 2070, dng chy nm bin i trong khongt(+5,8%)-(19,0%)ivisngHngv(+4,2%)- (-14,5%) i vi sng M Cng; dng chy kit bin i trong khong(-10,3%)-(-14,5%)ivisngHngv(-2,0%) -(-24,0%) i vi sng M Cng; dng chy l bin i trong khong(+12,0%)-(-5,0%)ivisngHngv(+15,0%) -(7.0%) i vi sng M Cng.Nh vy, trn c 2 sng ln, cc bin i m nhiu hn i vi dng chy nm v dng chy kit v bin i dng nhiu hn i vi dng chy l.Trn cc sng va v nh khc, dng chy nm c th gim i v cng c th tng ln vi mc tng t hoc nhiu hn.Tc ng ca BKH i vi nng nghipVi s nng ln trn phm vi ton lnh th, thi gian thch nghi cacytrngnhitimrngvcacytrngnhiti thu hp li. Teo d tnh, v phn b cy trng c th c nhng thay i sau y:Ranh gii ca cy trng nhit i dch chuyn v phavngnicaohnvccvphaBc.Mtkhc, phm vi thch nghi ca cy trng nhit i b thu hp thm. Vo nhng nm 2070, cy nhit i vng ni ch c th sinh trng nhng ai cao hn 100-500m v li xa hn v pha Bc 100-200km so vi hin nay.Daongckhnnggyrangpnghayhnhnxut hin vi tn sut cao hn hin nay.Mtphnngkdintchtrngtrtvngngbng duyn hi, chu th sng Hng, sng M Cng b ngp mn do nc bin dng.Tc ng ca BKH i vi lm nghipDo BKH h sinh thi rng b nh hng theo cc chiu hng khc nhau:Nc bin dng ln lm hp din tch rng ngp mn,mt khc c tc ng xu n rng trm v rng trng trn t b nhim phn cc tnh Nam B.Ranhgiirngnguynsinhcngnhrngthsinhc th dch chuyn. Rng cy h du m rng ln pha Bc v cc ai cao hn, rng rng l vi nhiu cy chu hn pht trin mnh.Nhit cao kt hp vi nh sng di do thc y qutrnhquanghpdnntngcngqutrnhng ho ca cy xanh. Tuy vy, ch s tng trng sinh khi ca cy rng c th gim i do m gim i.Nguy c dit chng ca ng vt v thc vt gia tng,mt s loi thc vt quan trng nh trm hng, hong n, pmu, g , lt hoa, g mt... c th b suy kit.Nhit v mc kh hn gia tng lm tng nguy cchy rng, pht trin su bnh, dch bnh.Tc ng ca BKH i vi ngnh thu snHin tng nc bin dng v ngp mn gia tng dn n cc hu qu sau y:Nc mn ln su vo ni a, lm mt ni sinh sngthch hp ca mt s loi thu sn nc ngt.Rng ngp mn b thu hp, nh hng n h sinh thica mt s loi thu sn.Khnngcnhchthuccahsinhthirongbingim,dnngimnguncungcpsnphm quanghpvchtdinhdngchosinhvty.Do vy,chtlngmitrngsngcanhiuloithu sn xu i.Nhit tng cng dn n mt s hu qu:Gy ra hin tng phn tng nhit r rt trong thuvcncng,nhhngnqutrnhsinhsng ca sinh vt.Mt s loi di chuyn ln pha Bc hoc xung su hnlm thay i c cu phn b thu sinh vt theo chiu su.Qutrnhquanghovphnhuccchthucnhanhhn,nhhngnngunthcncasinh vt.Ccsinhvttiutnnhiunnglnghncho qutrnhhhpcngnhcchotngsngkhc lm gim nng sut v cht lng thu sn.Suy thoi v ph hu cc rn san h, thay i cc qutrnh sinh l, sinh ho din ra trong mi quan h cng sinh gia san h v to (cn gi l c bin).Cng ma ln lm cho nng mui gim i (10- 20%) trong mt thi gian ngn lm cho sinh vt nc lvvenb,cbitlnhuynthhaiv(nghu, ngao, s,...) b cht hng lot do khng chng chu ni vi nng mui thay i.i vi ngun li hi sn v ngh c, BKH gy ra cc tc ng sau y:CHNG 3: TC NG CA BIN I KH HU V CHIN LC, GII PHP NG PH VI BIN I KH HU VIT NAM49McncdngdcbbinVitNamlmchoch thu l, thu ho v thu sinh xu i. Kt qu l cc qun x hin hu thay i cu trc v thnh phn, tr lng gim st.Nhitnctnglmchongunthuhisnbphn tn. Cc loi c nhit i km gi tr kinh t tng ln,ccloiccnnhiticgitrkinhtcaob gim i hoc mt hn. C cc rn san h a phn b tiu dit.Cc loi thc vt ni, mt xch u tin ca chui thcn cho ng vt ni b hu dit, lm gim mnh ng vt ni, do lm gim ngun thc n ch yu ca cc ng vt tng gia v tng trn. Tc ng ca BKH vi ngnh nng lng-giao thng vn ti Nc bin dng gy cc tc ng sau y:nh hng ti hot ng ca cc dn khoan c xydng trn bin, h thng dn kh v cc nh my in chy kh c xy dng ven bin, lm tng chi ph bo dng, duy tu, vn hnh my mc, phng tin.Cc hi cng bao gm cu tu, bn bi, nh kho (cthit k theo mc nc hin ti) phi ci to li hoc di di n ni khc. Tuyn ng st Bc-Nam v cc tuyn giao thng nm st bin cng b nh hng.Cc trm phn phi in trn cc vng ven bin phigia tng nng lng tiu hao cho bm tiu nc cc vngthpvenbin.Mtkhc,dngchyccsng lnccngtrnhthuincngchunhhng ng k.Nhittngcnggytcngnngnhnnglng-giao thng vn ti:Tngchiphthnggi,lmmthmlkhaithcvlm gim hiu sut, sn lng ca cc nh my in.Tiu th in cho sinh hot gia tng v chi ph lm mttrong cc ngnh cng nghip thng mi cng gia tng ng k.Nhit tng km theo lng bc hi tng kt hpvi s tht thng trong ch ma dn n thay i lng nc d tr v lu lng vo ca cc h thu in.BKHtheohnggiatngcngmavlngmabo cng nh hng trc tip n ngnh nng lng, trc ht n h thng dn khoan ngoi khi, h thng vn chuyn du v kh vo b, h thng truyn ti v phn phi in.Tc ng ca BKH vi sc kho con ngiNhittnglnlmtngtcngtiuccivisc kho con ngi, dn n gia tng mt s nguy c i vi tui gi, ngi mc bnh tim mch, bnh thn kinh. Tnh trng nng ln lm thay i cu trc vect Hnh 3.2. Mt s hnh nh D n trng mi 5 triu ha rngBI NI KH HUVI TNA M50truyn nhim theo ma. min Bc, ma ng s m ln, dn ti thay i c tnh trong nhp sinh hc ca con ngi.BKHlmtngkhnngxyramtsbnhnhiti: st rt, st xut huyt, lm tng tc sinh trng v pht trin nhiu loi vi khun v cn trng, vt ch mangbnh,lmtngslngngibbnhnhim khun d ly lan.3.1.2 Tc ng ca BKH i vi cc khu vc ch yuBKH c kh nng gy ra nhiu tc ng tiu cc i vi cc khu vc a l ch yu:Tc ng tim tng ca BKH n vng ni Ty Bc v ng BcBKH chc chn ko theo nhiu bin i v thi tit hng nm v ch kh hu lu di, nht l v cc yu t quan trng.Tn s front lnh trn cc v pha Bc trong cc thpk sp ti c th gim i t nhiu so vi cc thp k va qua.TlfrontlnhxmnhpTyBcsovivng ni ng Bc cng c phn thp hn so vi trc y. Daongvtnsfrontlnhtnmnyquanm khccthmnhmhnvtnhquylutcama frontlnhtrnnbpbnhhn:Mafrontlnhc thnmunhnvktthcsmhn,thikcc thnh ca front lnh vo gia ma ng c th khng tht r rt v thi k gin on front lnh gia ma h c th di hn.Nhit trong cc nm sp ti ph bin cao hn nnchungcaccthpkvaqua.Chcchncsgia tng v tr s ca nhit cao v tn s cc t nng nngvngnivavnithp.Nhiukhnngl ccvnhainhithoctngnhitlivpha ccvngnicaohnvdogiihncacckhu vc c nn nhit thp thu hp li. Ma nng cc vng thp di thm v ma lnh trn cc vng u rt ngn li.Lng ma trong cc nm sp ti c th tng ln ninyvgiminikhcvxpxccthpkva qua.Ciul,trongtnglaixahn,lngma ma ma nhiu ln cn lng ma ma kh tuy khng nhiu ln nhng dao ng mnh hn. S c thm cc nm trung tm ma ln Bc Quang, Sa Pa,... khng c lng ma vt tri cc ni khc v cc trung tm mabnhSngM,YnChu,BoLckhngt ma hn cc vng k cn.c bit, tnh tht thng ca ch ma tr nn su sc hn: Cc k lc cao v ma (lng ma ngy, lng ma thng,...) u tng ln ng thi vi vic gia tng tn s cc t ma ln din rng cng nh cc t hn hn khc lit.Cngcnlul,vngningBcmaphntip tcgimivoccthngchuyntiptmakhsang ma ma.Ma ma cng nh ma kh tr nn thiu quy lut hn: Btuhocktthccthqusmhocqumun, ma dn dp hn trong cc thng cao im ca ma ma v tnh trng kh hn khc lit hn trong cc thng cui ma kh.Lngbchitrongccnmspticthcaohnnn chung ca cc thp k va qua, gp phn thc y qu trnh thiu ht nc, gia tng tn s v cng hn hn. m tng i trong cc nm sp ti c th gim isoviccthpkvaqua,chyudonnnhit tng ln.Cc bin i v thi tit hng nm c kh nng nh hng n cc ngnh kinh t quc dn trn khu vc:Phnphidngchytrnkhu