Arctic climate change: the past 100 years

By: Dr. Jeff Masters , 1:56 AM GMT on February 12, 2007

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The Arctic is a region particularly sensitive to climate change, since temperatures are, on average, near the freezing point of water. Slight shifts in the average temperature can greatly change the amount of ice and snow cover in the region, due to feedback processes. For example, as sea ice melts in response to rising temperatures, more of the dark ocean is exposed, allowing it to absorb more of the sun's energy. This further increases air temperatures, ocean temperatures, and ice melt in a process know as the "ice-albedo feedback" (albedo means how much sunlight a surface reflects). The 20% loss in Arctic sea ice in summer since 1979 has given rise to concerns that this "ice-albedo feedback" has taken hold and will amplify until the Arctic Ocean is entirely ice-free later this century. Should we be concerned? Has the Arctic been this warm in the past and the sea ice survived? The answers are yes, and yes.



Figure 1. Annual average change in near surface air temperature from stations on land relative to the average for 1961-1990, for the region from 60 to 90° north. Image credit: The Arctic Climate Impacts Assessment (ACIA).

The past 100 years
The Arctic Climate Impact Assessment (ACIA), published in November 2004, was a uniquely detailed study of Arctic climate compiled by 300 scientists over three years. The study found that while temperatures in the Arctic have increased significantly since 1980 (Figure 1), there was also a period in the 1930s and 1940s when temperatures were almost as warm. If one defines the Arctic as lying poleward of 62.5° north latitude (Polyakov, 2003), the 1930s and 1940s show up being warmest period in the past 100 years. Looking at Figure 1, one cannot dismiss the possibility that temperatures in the Arctic oscillate in a 50-year period, and we are due for a cooling trend that will take temperatures below normal by 2030.

However, the period since 1980 was a time when the entire globe (except the bulk of Antarctica) warmed, and the 1930s and 1940s were not. Thus, the 1930s and 1940s warming in the Arctic is thought to be fundamentally different. Furthermore, the past 20 consecutive years have all been above normal in temperature, whereas during the 1930s and 1940s there were a few cooler than average years interspersed with the very warm years. A detailed breakdown by month and region of the 100-year history of Arctic temperatures was performed by Overland et al. (2004). They found no evidence of a 50-year cycle in Arctic temperatures, and concluded that the warming since 1980 was unique. However, they stopped short of blaming the recent warming on human-emitted greenhouse gases (anthropogenic forcing). The ACIA, though, concluded that humans were likely to blame for the recent Arctic warming, but not definitely:

It is suggested strongly that whereas the earlier warming was natural internal climate-system variability, the recent surface air temperature changes are a response to anthropogenic forcing. There is still need for further study before it can be firmly concluded that the increase in Arctic temperatures over the past century and/or past few decades is due to anthropogenic forcing."

This is the first in a series of five blogs on climate change in the Arctic that will appear every Monday and Thursday over the next two weeks. Next blog: The skeptics attack the ACIA report--and how the position of the pole star is indicative of Arctic climate change.

Also, be sure to visit our new Climate Change blog, written by Dr. Ricky Rood of the University of Michigan.

Jeff Masters

References

Overland, J.E, M.C. Spillane, D.B. Percival, M. Wang, H.O. Mofjeld (2004), "Seasonal and Regional Variation of Pan-Arctic Surface Air Temperature over the Instrumental Record", Journal of Climate, 17:17, pp3263-3282, September 2004.

Polyakov, V., et al. (2003), "Variability and Trends of Air Temperature and Pressure in the Maritime Arctic, 1875-2000", Journal of Climate, 16, 2067-2077.

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203. Thunderstorm2
10:48 PM GMT on February 13, 2007
Its getting worse up north but it's all over here
Member Since: December 22, 2006 Posts: 129 Comments: 7608
202. ryang
6:46 PM AST on February 13, 2007
TS2 is it getting worse????
Member Since: Posts: Comments:
201. Thunderstorm2
10:45 PM GMT on February 13, 2007
Will do......Thats if i had a dog and if i was in that area
Member Since: December 22, 2006 Posts: 129 Comments: 7608
199. Thunderstorm2
10:43 PM GMT on February 13, 2007
Ok............... TAKE COVER! TAKE COVER! AND DO IT NOW!!!!!!!
Member Since: December 22, 2006 Posts: 129 Comments: 7608
197. Thunderstorm2
10:40 PM GMT on February 13, 2007
It's only Tornado's. As long as they don't go into populated areas then there is no need to!
Member Since: December 22, 2006 Posts: 129 Comments: 7608
196. Thunderstorm2
10:40 PM GMT on February 13, 2007
Why?
Member Since: December 22, 2006 Posts: 129 Comments: 7608
194. Thunderstorm2
10:37 PM GMT on February 13, 2007
Yes i know
Member Since: December 22, 2006 Posts: 129 Comments: 7608
190. Thunderstorm2
10:29 PM GMT on February 13, 2007
It looks ugly down here
Member Since: December 22, 2006 Posts: 129 Comments: 7608
187. Thunderstorm2
10:23 PM GMT on February 13, 2007
It's getting it's rotation on
Member Since: December 22, 2006 Posts: 129 Comments: 7608
186. tornadodude
10:19 PM GMT on February 13, 2007
hey guys, about a 10th of an inch of ice right now, but more coming look
look at the swirl...
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183. tornadodude
10:10 PM GMT on February 13, 2007
hey guys, about a 10th of an inch of ice right now, but more coming look
look at the swirl...
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181. Patrap
3:57 PM CST on February 13, 2007
To report Tornado structural damage in Orleans Parish..Dial 311 More contact info for those affected here. Link
Member Since: July 3, 2005 Posts: 414 Comments: 125613
179. Thunderstorm2
9:26 PM GMT on February 13, 2007
i've got scattered clouds
Member Since: December 22, 2006 Posts: 129 Comments: 7608
178. Thunderstorm2
9:25 PM GMT on February 13, 2007
Well.........at last it's over here
Member Since: December 22, 2006 Posts: 129 Comments: 7608
177. weatherboykris
9:16 PM GMT on February 13, 2007
That is interesting,JF.
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176. Patrap
3:15 PM CST on February 13, 2007
Heres a leaning house on Carrollton Jake..is this it?..4
Member Since: July 3, 2005 Posts: 414 Comments: 125613
175. Thunderstorm2
9:06 PM GMT on February 13, 2007
I'm getting rain and lots of it JF. The T-Storms have moved on.
Member Since: December 22, 2006 Posts: 129 Comments: 7608
173. mrpuertorico
5:01 PM AST on February 13, 2007
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO.

.TODAY AND TONIGHT...DRY WEATHER OVER THE PAST SEVERAL WEEKS HAS
INCREASED THE CHANCE FOR FIRES ACROSS PARTS OF SOUTHERN PUERTO RICO.
OTHERWISE...NO HAZARDOUS WEATHER IS EXPECTED.
Member Since: July 10, 2006 Posts: 0 Comments: 833
172. Patrap
2:57 PM CST on February 13, 2007
Heres the WWltv.com link...Link
Member Since: July 3, 2005 Posts: 414 Comments: 125613
171. Patrap
2:56 PM CST on February 13, 2007
Hey jake..just been busy,Was hairy morning...Daughter was in Fountainbleu on Versailles .They okay..hows you?Dominican did not have classes.No power
Member Since: July 3, 2005 Posts: 414 Comments: 125613
170. Thunderstorm2
8:53 PM GMT on February 13, 2007
Jake435 where do you live?
Member Since: December 22, 2006 Posts: 129 Comments: 7608
169. jake436
8:45 PM GMT on February 13, 2007
PATRAP, long time no speak. Did you guys check out the Carrolton area? I have a friend on Willow St. that received heavy damage this morning, but not as bad as her next door neighbor. She said her neighbors house is now leaning on her house. She had 5 windows blown out, and tree and roof damage. The neighbor's house was basically bisected. Glad you fared well in the storm.
Member Since: Posts: Comments:
168. Thunderstorm2
8:36 PM GMT on February 13, 2007
Severe T-Storm Warning up for my area. It's still hitting me hard
Member Since: December 22, 2006 Posts: 129 Comments: 7608
167. Skyepony (Mod)
8:32 PM GMT on February 13, 2007
I look to be having another round of deadly lightning on the way.
Member Since: Posts: Comments:
166. hurricane23
3:31 PM EST on February 13, 2007
Posted By: floodzonenc at 2:30 PM EST on February 13, 2007.

Weather is quite boring here in eastern NC...

Wish I had some of that snow... but will settle for a few bolts of lightning.

Weather may not be so boring for you guys during the 07 hurricane season.Be thankful its quite cause it may not last.


Member Since: May 14, 2006 Posts: 8 Comments: 13597
165. hurricane23
3:30 PM EST on February 13, 2007
Radar loop from a few hours ago showing line pushing into the florida coast...



Current radar showing thunderstorm activity will be pushing of the coast in the the next hour or so.



Member Since: May 14, 2006 Posts: 8 Comments: 13597
162. Thunderstorm2
7:04 PM GMT on February 13, 2007
I'VE GOT THUNDERSTORMS. RAIN IS THROWING IT DOWN. LOTS OF LIGHTNING
Member Since: December 22, 2006 Posts: 129 Comments: 7608
161. HIEXPRESS
2:02 PM EST on February 13, 2007
JFL - I-75N (or I-95) LOL
Member Since: October 13, 2005 Posts: 4 Comments: 2155
160. Thunderstorm2
7:03 PM GMT on February 13, 2007
O DEAR
Member Since: December 22, 2006 Posts: 129 Comments: 7608
159. HIEXPRESS
1:57 PM EST on February 13, 2007
I have received official notice of the incoming storm - the fish hawk behind my house is going nuts. I guess I shouldn't have washed my truck.
Member Since: October 13, 2005 Posts: 4 Comments: 2155
157. Thunderstorm2
6:53 PM GMT on February 13, 2007
I'm in Orlando FLA at the moment and i have got Dark clouds moving in from the distance.

Stay Safe Chessrascal
Member Since: December 22, 2006 Posts: 129 Comments: 7608
156. chessrascal
6:50 PM GMT on February 13, 2007
im in Sarasota FL right now there is very heavy rain cloud to ground lightning and pea size hail.
Member Since: Posts: Comments:
155. Thunderstorm2
6:41 PM GMT on February 13, 2007
WOW
Member Since: December 22, 2006 Posts: 129 Comments: 7608
153. Thunderstorm2
6:19 PM GMT on February 13, 2007
urgent - immediate broadcast requested
Severe Thunderstorm Watch number 21
NWS Storm Prediction Center Norman OK
1255 PM EST Tue Feb 13 2007

The NWS Storm Prediction Center has issued a
Severe Thunderstorm Watch for portions of

central Florida
coastal waters

Effective this Tuesday afternoon and evening from 1255 PM until
700 PM EST.

Hail to 2 inches in diameter... thunderstorm wind gusts to 70
mph... and dangerous lightning are possible in these areas.

The Severe Thunderstorm Watch area is approximately along and 65
statute miles either side of a line from 20 miles north of Ocala
Florida to 50 miles east of fort Meyers Florida. For a complete
depiction of the watch see the associated watch outline update
(wous64 kwns wou1).

Remember... a Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings. Severe thunderstorms can and occasionally
do produce tornadoes.

Other watch information... continue... ww 20...

Discussion... tstm cluster off the W CST of FL... and additional
storms likely to from in heated environment over the interior... may
pose a threat for high wind and hail as region continues to
destablize downstream from 50 kt wly mid level jet streak. While
low level shear is weak over most of ww area... low level directional
shear will be enhanced invof E CST sea breeze boundary and outflows
from earlier storms. Part of watch number 21 along the immediate E
CST may require upgrade to tornado if it appears that discrete
storms will indeed interact with those boundaries.

Aviation... a few severe thunderstorms with hail surface and aloft
to 2 inches. Extreme turbulence and surface wind gusts to 60
knots. A few cumulonimbi with maximum tops to 450. Mean storm
motion vector 26035.


... Corfidi

;295,0811 270,0800 261,0820 291,0831


Member Since: December 22, 2006 Posts: 129 Comments: 7608

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.