Arctic climate change: the past 100 years
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.
Reader Comments
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...A FEW STRONG STORMS POSSIBLE MAINLY EXTREME SE COAST AND
ADJACENT WATERS TONIGHT...
...POTENTIAL COLD WEATHER EVENT LATE THIS WEEK...
Now where's the number of that Florida travel agency?....
Orlando, FL
TUESDAY
Scattered Afternoon T-Storms
Hi: 75F
Pop: 50%
Tuesday...Considerable cloudiness. Scattered afternoon showers and thunderstorms. Some thunderstorms May become strong. Highs in the mid 70s. East winds 5 to 10 mph shifting to the south in the afternoon. Chance of rain 50 percent.
.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.
.DAYS TWO THROUGH SEVEN...NO HAZARDOUS WEATHER CONDITIONS ARE
EXPECTED AT THIS TIME.
hmm could a drought be on the way
Elderly woman killed in Pontchartrain Park area
07:42 AM CST on Tuesday, February 13, 2007
WWL-TV and Associated Press reports
An 85-year-old woman was killed and at least seven people were injured as a tornado touched down twice this morning first in Westwego and then jumped over the Mississippi River and hit in the Carrollton and Gentilly areas of New Orleans. The tornado was part of a heavy line of storms that blew through around 3 a.m.
Bill Haber / Associated Press
A tree and power line sit on top of a car in the Carrollton area of New Orleans after a tornado struck early Tuesday.
The woman who was killed lived in the Pontchartrain Park area, according to New Orleans Fire Department officials. The Gentilly area was especially hard hit.
Entergy spokesman Morgan Stewart says that approximately 17,000 customers are without power in the Carrollton area. In Westwego about 650 customers are out, mainly in the heavily-damaged area. Another 8,000 outages are reported in New Orleans East and Gentilly and sporadic outages of about 2,500 in Metairie and Kenner.
Colonel Jerry Sneed of the New Orleans Department of Emergency Preparedness said he has reports of 'fewer than 20 injuries' in Orleans, many of them who were treated and released.
Also Online
VIDEO: Carrollton residents afraid as storms slammed area
VIDEO: Westwego hotel destroyed
VIDEO: Homes destroyed, trees, power lines ripped down
On Carrollton Avenue Uptown, there was plenty of visible damage with businesses having signs down and some windows out. A huge hole was seen in the brick facade of Ronald McNair School on Carrollton.
Several homes near S. Claiborne and Carrollton had severe damage. At least one family had the roof of their FEMA trailer ripped off with a family inside. All were able to escape alive.
On the West Bank, nine people were reported injured, six of them who were staying at the Bon Soir motel when the roof was ripped off by the tornado. WWL-TV reporter Jonathan Betz said the motel looks as if a 'bomb went off' and that it is completely gutted.
A six-block area near the hotel was hit by the tornado and at least 15 homes were damaged.
The hotel's roof was torn off and is lying in the middle of the Westbank Expressway, causing traffic to be shut down in both directions on the West Bank Expressway.
Authorities say trailers were overturned in the area, and at least six homes collapsed. So far, there's no word on the condition of the residents.
Jefferson Parish authorities are sending teams through the area to check on residents.
In New Orleans, damage is widespread in the Carrollton area and many areas of New Orleans are without power this morning
Regarding your blog on the HRD research money being cut from NOAA's budget...here is the response from Florida Senator Mel Martinez, to an email of concern I sent him the other day:
Thank you for contacting me regarding the National Hurricane Research Initiative Act of 2006 (S. 4005). I appreciate hearing from you, and would like to take this opportunity to respond.
In the wake of the devastation wrought on the Gulf Coast in 2005 by Hurricanes Katrina, Rita, and Wilma, on September 29, 2006, I introduced bipartisan legislation to implement a national hurricane research initiative designed to better research, predict and prepare for hurricanes. This comprehensive proposal was crafted from the recommendations presented by the National Science Foundations new draft report entitled, Hurricane Warning: The Critical Need for a National Hurricane Research Initiative. A coordinated research initiative is necessary given the enormous cost associated with hurricanes, in both dollars and human lives, combined with the fact that 90 percent of the nations population lives within 200 miles of the coast.
S. 4005 will take the general recommendations from the National Science Foundations report and assemble the expertise of our nations science and engineering capabilities through a multi-agency effort that is focused on improving our understanding of hurricane prediction, intensity, and mitigation on coastal populations, infrastructure, and the natural environment. The bill sets out specific goals for research, including predicting hurricane intensification, storm surge, rainfall, and inland flooding, improved observations, assessment of vulnerable infrastructure, interaction of hurricanes with engineered structures, improved computational ability, improved disaster response and recovery, and evacuation planning. This legislation calls for gathered research to be formulated into a national and standardized database so that it may be put to use in real world situations through the creation of the National Hurricane Research Test Bed.
Florida and other Gulf Coast states have a lot at stake every hurricane season and there are still far too many unknowns. These unknowns carry great costs. Better, more intense, and more coordinated research can better help us prepare for the future.
Again, thank you for contacting me. If you have any additional questions or comments, please do not hesitate to contact me. In addition, for more information about issues and activities important to Florida, please sign up for my weekly newsletter at http://martinez.senate.gov.
Sincerely,
Mel Martinez
United States Senator
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