observed climate variability and change
DESCRIPTION
Observed Climate Variability and Change. Jay H. Lawrimore NOAA’s National Climatic Data Center Asheville, North Carolina. Overview. Trace Gases Temperature Sea ice/Snow Cover/Sea Level Precipitation/Drought Tropical Cyclones/Tornadoes New Transportation-related activities. - PowerPoint PPT PresentationTRANSCRIPT
Observed Climate Variability and ChangeMarch 29, 2006
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Observed Climate Variability and Change
Jay H. Lawrimore
NOAA’s National Climatic Data Center
Asheville, North Carolina
Observed Climate Variability and ChangeMarch 29, 2006
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Overview
• Trace Gases
• Temperature
• Sea ice/Snow Cover/Sea Level
• Precipitation/Drought
• Tropical Cyclones/Tornadoes
• New Transportation-related activities
Observed Climate Variability and ChangeMarch 29, 2006
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Trace Gases – CO2 and CH4
CO2 has increased from ~280 ppm at start of industrial revolution to ~380 ppm today 2005 global avg: 378.9 ppm
Since 1900, there has been a 22% increase Avg annual increase of 1.6
ppm since 1980
Rate of CH4 increase has slowed in recent years Global mean: 1774.8 ppb in
2005
CO2 - Mauna Loa
CH4 - Mauna Loa
Observed Climate Variability and ChangeMarch 29, 2006
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Trace Gases – N2O and SF6
Present in lower concentrations than CO2
Radiative forcing per molecule is much greater SF6: 22,000 more times effective IR absorber
Total radiative forcings relatively small Rapid growth rates and IR absorbing effectiveness = concern for future
SF6: ~5%/year increase since 1996 N2O: 0.25%/year since 1978
N2O SF6
Observed Climate Variability and ChangeMarch 29, 2006
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1000-Year Temperature Record
Temperature reconstruction created from tree rings, ice cores, ice melt, corals, lengthy instrumental records.
Jones, PD & ME Mann, 2004. Climate Over Past Millenia. Reviews Of Geophysics 42 (2): Art. No. RG2002
Observed Climate Variability and ChangeMarch 29, 2006
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• Global surface temperature above 1998 record without strong El Niño episode
• Continuation of steep warming trend brought global temperature to 1998 levels in only 7 years
• 9 of 10 warmest years on record have occurred since 1995
New NOAA/NCDC Land & Ocean BlendGlobal Mean Temperature over Land & Ocean
Preliminary: New NOAA Surface Temperatures
Observed Climate Variability and ChangeMarch 29, 2006
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• No one year definitively warmest on record
• Sampling, Random and Bias Errors analyzed to estimate uncertainty in annual anomalies
– Sampling and Random Errors decrease with time due to improved coverage and better instruments and measurement techniques
New NOAA/NCDC Land & Ocean BlendGlobal Mean Temperature over Land & Ocean
Preliminary: New NOAA Surface Temperatures
Observed Climate Variability and ChangeMarch 29, 2006
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Global Temperature Change vs CO2 Change
Observed Climate Variability and ChangeMarch 29, 2006
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Global TemperaturesLand, NMAT, SST
Temperature changes over 20th century are extremely consistent across land and oceans
Both show pronounced warming in 2 phases 1915-1945 and 1976-present
Much stronger warming over land in current period Continental warming in mid-latitude
Northern Hemisphere Likely due to atmospheric circulation
changes in winter half Oceanic cooling in S. Hem.
Possibly due to Pacific Decadal Oscillation & AAO
Observed Climate Variability and ChangeMarch 29, 2006
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Annual Temperature Trends1901 - 2005 1979 - 2005
• Increasing temperatures across most land and ocean surfaces
• 1901-2005, warming is global with a few exceptions, e.g. Southeast US and N. Atlantic
• 1979-2005, warming largest in mid & high latitude regions of N.H.
• 1979-2005, portions of southern oceans show cooling
Deg C/Decade
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Tropospheric Temperatures1958-2005
Global Seasonal Tropospheric Temperature Anomalies
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006
K
RATPAC 850-300
HadAT2 LT
UAH LT
1979-2005
RATPAC: +0.15C/decade (+0.15C*)
HadAT2 LT: +0.16C/decade (+0.15C*)
UAH LT: +0.13C/decade (85N-50S)
*Decadal trend since 1958
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Global Max and Min Temperature1950-2004
Minimum temperatures rising faster than maximum
Overall Trends 1950-present Min: +0.20C/decade Max: +0.14C/decade
Trends 1979-present Min&Max: +0.29C/decade
Cloud cover & Precip trends accounted for >80% of variance in DTR in U.S., Australia, mid-Latitude Canada, and former Soviet Union
Alexander et al. 2005
1951-2003; At least 40 yrs of data required 74% of sampled land area showed an increase in warm nights
Affect of Warming on Temperature Extremes
Warm nightsMinimum daily temp >90th
percentile Globally- Annual #warm
nights increased ~25 days since 1951Largest over EurasiaDoubling over N. Africa,
N. South Am.
Alexander et al. 2005
1951-2003; At least 40 yrs of data required Black lines enclose regions where trends significant at 5% level
Affect of Warming on Temperature Extremes
Warm daysMaximum daily temp >90th
percentile Increasing trend not as
large as #warm nightsLarger areas of
decreasing trends
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Temp and Apparent Temp Trends in US(June-August, DegC/Decade)
Gaffen and Ross, 1998
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Temperature Summary
• Global mean temperatures increased at a rate of 0.6 – 0.7 C/century since 1900– Much more rapid warming since 1976– Similar trends on land and oceans
• Temperatures increasing in troposphere• Minimum temperature rising faster than maximum
temperature since 1950• Other effects
– Lengthening the freeze and frost-free seasons in many mid- and high-latitude regions
– Widespread decreases in number of days below freezing– Increases in number of warm days and nights
Observed Climate Variability and ChangeMarch 29, 2006
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Arctic Sea IceSnow Cover
Sea Level Changes
Observed Climate Variability and ChangeMarch 29, 2006
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Arctic Climate• Arctic-wide annual avg anomalies
(60N-90N)• Large region-to-region differences
in 1930s• More widespread and stretching into
mid-latitudes in 1990s and beyond
Observed Climate Variability and ChangeMarch 29, 2006
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Arctic Sea Ice Extent – March/September
• Rate of decrease in March: -2%/Decade• In September: -7%/Decade
March Mean Extent: 15.7 Million km2; 2005: 14.8 Million km2
Sept Mean Extent: 6.9 Million km2; 2005: 5.6 Million km2
7% Decrease in end-of-summer Arctic sea ice in past 25+ years
Observed Climate Variability and ChangeMarch 29, 2006
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Arctic Sea Ice Extent – March/September
March Mean Extent: 15.7 Million km2; 2005: 14.8 Million km2
Sept Mean Extent: 6.9 Million km2; 2005: 5.6 Million km2
Courtesy: David Robinson, Rutgers Snow Lab
Northern Hemisphere Snow Cover Extent
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N. Hem. Spring Snow Cover Extent
Observed Climate Variability and ChangeMarch 29, 2006
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Global Sea Level Changes from Satellite Altimeter Observations
2424
Observed Climate Variability and ChangeMarch 29, 2006
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Global Sea Level Trends since 1993
2525
Equatorward winds, upwelling, reduced sea level
Observed Climate Variability and ChangeMarch 29, 2006
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Sea Level Rise
• Geographical patterns similar to upper ocean heat content change– Suggests that regional sea level changes are largely
controlled by thermal processes– Smaller of total trend is likely due to melting of
grounded ice on Greenland &/or Antarctica• Trend (2.9 + 0.4mm/year) is significantly higher
than 20th century rate of 1.8 + 0.3 mm from tide gauge measurements over past 50-100 yrs– Is this part of a longer-term trend or just decadal
variability?
Observed Climate Variability and ChangeMarch 29, 2006
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Ice Sheets
• Vast majority of Sea Level rise was due to warming ocean
temperatures during 20th century• Thermal expansion is expected to be biggest contributor in
21st century• BUT..• Recent research (Rignot and Kanagaratnam, 2006; Science)
has found acceleration in ice discharge on the Greenland ice sheet.– Doubling of ice sheet mass discharge in last decade from 90 to 220
cubic kilometers per year.
Observed Climate Variability and ChangeMarch 29, 2006
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Precipitation andExtremes
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Regions where disproportionate changes in heavy and very heavy precipitation occurred
compared to the mean(first half of 20th century to present)
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Drought/Extreme Wetness in the US
Observed Climate Variability and ChangeMarch 29, 2006
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Drought/Extreme Wetness in the US
Observed Climate Variability and ChangeMarch 29, 2006
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Tropical Cyclones
Numerous records established in Atlantic Basin
– Most named storms and hurricanes: 27 & 15
• Previous record 21 (1933) & 12 (1969)
– Three cat 5 storms (Katrina, Rita, Wilma)
• Previous record of 2 in 1960 and 1961
– 7 named U.S. landfalling storms (Tied 2nd) with 8th (Ophelia) brushing N.C. coast
• Record 8 landfalling in 1916 and 2004
– Lowest central pressure for Atlantic Hurricane• Wilma (882 mb) in October. Previous 888 mb (Gilbert, 1988)
Observed Climate Variability and ChangeMarch 29, 2006
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Atlantic Tropical Cyclones
• Recent research points to link between warming ocean temperatures and frequency of strongest tropical cyclones --- BUT
• Active season has been attributed to: Century scale trend in sea surface temperatures contributing to anomalous warmth in Atlantic and Gulf of Mexico
Active phase of multi-decadal oscillation
Jul-Sep SSTs in Gulf of Mexico
Observed Climate Variability and ChangeMarch 29, 2006
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Global Tropical Cyclone Activity
• ACE Index– Sum of
Squared 6-hourly wind speeds
• Difficult to look beyond 1980 on a global basis
– Lack of data in basins such as N. and S. Indian and S. Pacific
Observed Climate Variability and ChangeMarch 29, 2006
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• A relatively quiet year in 2005:– Only Nine F3-F5
tornadoes during March-August
• Decreasing trend since 1970s
• November a very active month– 23 fatalities in Evansville, IN on 6th: Indiana’s deadliest
tornado since 1974 Super Outbreak– More than 30 tornadoes in 6 states on 15th
Wind speeds in excess of 158 mph
Very Strong to Violent Tornadoes
Observed Climate Variability and ChangeMarch 29, 2006
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Storm Losses
Eastlering et al. 2000, Science
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• Inflation adjusted costs due to weather-related extremes continue to rise– Record damages in 2005
• Greatest number of billion-dollar disasters in the southern and southeastern U.S. since 1980
Billion $ Disasters in the US
Observed Climate Variability and ChangeMarch 29, 2006
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Precipitation & Extremes Summary
• Increase in heavy precipitation events• Increase in losses in US during past 50 years largely
due to societal shifts– Future climate change leading to more extreme
events will exacerbate the problem• Some signs of long-term changes in tropical storm
intensity but evidence not conclusive• Little compelling evidence for widespread systematic
long-term changes in severe local weather (tornadoes, thunder days, lightning and hail)
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Conclusions Temperatures over past 100 years have warmed
Greatest warming in high latitudes. Decrease in Arctic Sea Ice. Decrease in NH snow cover More warming in minimum (nighttime) temperature. Observed Sea level rise.
Large-scale precipitation over land has increased. Increase in high latitudes, decrease in Tropics. Evidence for increases in heavy precipitation events. No conclusive evidence of increase in hurricanes or tornadoes.
Uncertainties due to observing system issues, etc. but taken together balance of evidence points to discernable human influence on the climate.
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Future Transportation-related Activities at NCDC
• Archiving/Use of Roadway Weather Information System (RWIS) data
• Development of Evacuation Climatologies
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ACQUIRE DATA FROM HIGHWAY STATIONS via MADISNCDC
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NHTSA reports over 40,000 fatalities associated with automobile accidents per year.
NCDC receives a significant number of requests for weather data at or near accident sites
State DOTs use NCDC archives – Reduce settlement claims Retrospective analysis of event
Immediate benefits are foreseen in archiving highway weather and road condition. Blending satellite, radar, and surface data including highway weather reports will create more compelling products
Climatologies of fog, snow, weatherBy time-of-day, locationCompare city commuting- hour weather
Archiving Highway Weather at NCDC – BenefitsNCDC
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• Proposed by a Western North Carolina community leaders association
• Problem: How best to protect citizens from hazardous weather extremes– Location dependent– No single solution will work for all communities
• Engineering and design based on the most up-to-date climate statistics
Developing a Hazard Resilient Community
Evacuation Climatologies for Strategic Planning
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• Climate is used as the basis of long-range planning operations associated with hazard mitigation and public safety– In what communities is it safe to establish evacuation
shelters – Are existing evacuation shelters structurally sound to
withstand conditions under a changing climate– Are evacuation routes which were planned decades ago
safe under storm surge scenarios likely to occur in today’s climate
– How will the climate of today and tomorrow affect the design of innovative evacuation plans such as the use of railway systems to evacuate the local populace
Developing a Hazard Resilient Community
Evacuation Climatologies for Strategic Planning
Observed Climate Variability and ChangeMarch 29, 2006
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THE END