the changing arctic:

The Changing Arctic:The Changing Arctic:Recent Events & Global ImplicationsRecent Events & Global Implications

Martin O. JeffriesMartin O. JeffriesNational Science FoundationNational Science Foundation

Office of Polar ProgramsOffice of Polar ProgramsDivision of Arctic SciencesDivision of Arctic Sciences

Presentation to theSeasons and Biomes Workshop

Fairbanks, AK, 27 September 2007

Sou

rce:

BB

C

Increasing Greenhouse Gas Concentrations in the Atmosphere

CO2 CO2 CO2 CO2

CO2 CO2 CO2 CO2

CO2 CO2 CO2 CO2

CO2 CO2 CO2 CO2

CO2 CO2 CO2 CO2

CH4Radiative effect 20:1 NO2

Radiative effect 1:300

Sou

rce:

BB

C

Greenhouse Gases and Increasing Global Temperature

Computer models can not simulate the 20th Century global air temperature trend unless increased atmospheric greenhouse gas concentrations are included.

Sou

rce:

BB

C

Computer Simulation of Global Temperatures

IPCC: Inter-governmental Panel on Climate Change

Non-uniform geographic distribution of temperature

increase.

Arctic amplification of global warming.

Why arctic amplification?

Regional positive feedback processes.

Albedo ()The ratio of reflected solar radiation to total incoming solar radiation.

A black object has an albedo of 0 (zero). That is, all solar

radiation is absorbed.

A white object has an albedo of 1 (one). That is, all solar

radiation is reflected.

Sou

rce:

Nat

iona

l Sno

w a

nd Ic

e D

ata

Cen

ter (

NS

IDC

)

16 August 2007 21 September 2005

Arctic Sea Ice Retreat:A Positive Feedback

August ice extent, 1979-2007

Ext

ent (

106 k

m2 )

2007

5.3 x 106 km2 5.3 x 106 km2

16 September 2007

Record minimum, 4.1 x 106 km2

Sea Ice Loss:The Real World

Outpaces the Virtual World

Consequences of a Declining Sea Ice Cover

On 7 September 2007, the US Geological Survey reported the results of a study that predicts that by 2050 the polar bear population will be reduced by 66%. The reduction will not be evenly distributed - polar bear populations in some regions will not survive the loss of sea ice - they will disappear completely. Changing polar bear populations are a very visible and emotional sign of ecosystem change.

279 species of migratory bird breed in significant numbers in the Arctic. Of those, 30 reach southern Africa, 26 reach Australia and New Zealand, 22 reach southern South America, and several species reach the Southern Ocean. Arctic Change has the potential to affect biodiversity far from the Arctic.

Arctic tern

Natural Resources, International Trade and Geopolitics

Northern Sea Route

Northwest Passage

Sou

rce:

NS

IDC

Sou

rce:

BB

C

S.S.Manhattan, NW Passage, 1969

Sou

rce:

BB

C

2 August 2007

People & Communities

Shi

shm

aref

, Ala

ska

Arctic Coast Central Alaska

Rising Ground Temperatures

Sou

rce:

Vla

dim

ir R

oman

ovsk

y

Thawing Permafrost

Thermokarst

Landscape Change

& Methane (CH4)

Methane gas

Bacteria make methane(decomposition)

Arctic methane & permafrost

Methane Mobilized:Another Positive Feedback

Sou

rce:

MO

J

Increased Melting on the Greenland Ice Sheet