Averaging together antarctic and arctic sea ice hides an important truth
Since my last post designating arctic sea ice loss as the top climate story of 2008, I've heard a lot comments like this one: "Jeff, you just can't seem to understand the that man-made global warming is a fable and complete hoax. In all that blathering about the falsified IPCC reports and the study of the arctic ice sheet, you somehow neglected to mention that the ice recovered not only what it lost last year, but is now larger than the previous known record measured in 1978".
Well, I can understand this point of view, given complexity of the climate change issue, and the large amount of conflicting information one sees in the media. Let's look at the facts about global sea ice. You can look at the data yourself at the excellent University of Illinois Cryosphere Today web site. Reliable sea ice records go back to 1979, when satellite measurements began. Antarctic sea ice reached its greatest extent on record during the winter of 2007. Summertime ice coverage also increased in 2007-2008 compared to 2006 levels (Figure 1). However, as one can see from Figure 1, there is high variability in antarctic sea ice from winter to summer, and antarctic sea ice can best be described as having stayed constant since 1979 (as stated in the 2007 report of the Intergovernmental Panel on Climate Change (IPCC). The IPCC did find that there had been a significant decline in arctic sea ice, in all seasons, between 1979-2006. Despite this decline, there have been three periods during the past two years when the sum of the arctic and antarctic sea ice was the same or even higher than it was at the start of the satellite era (1979). An article published January 1 on Daily Tech noted that "global sea ice levels now equal those seen 29 years ago". This was pretty close to the truth on December 31, 2008, despite the fact that arctic ice was 1 million km^2 below 1979 levels, since antarctic ice was 0.5 million km^2 above 1979 levels. Although arctic sea ice extent has steadily declined since 1979, especially in summer, this decline is not as great during the winter months. One can find periods in winter when summing together antarctic and arctic sea ice area makes it appear that arctic sea ice loss is no big deal.
However, this is the wrong way to look at the issue. We don't care much about global sea ice in winter. We care about arctic sea ice in the summer. Sharp declines in summertime arctic ice are likely to cause significant and damaging alterations to Earth's climate. Cleverly quoting irrelevant facts about global wintertime sea ice data to hide the summertime loss of arctic sea ice is a tremendous disservice. It's like hiding the potential impact of a major hurricane in a one-week forecast by saying, "the average peak wind speed for the next seven days will be 17 mph", and neglecting to mention that the wind will be calm six of those days, but 120 mph on the other day. The loss of arctic sea ice the past two summers, is, in my view, the most important human-caused climate change event yet--even more significant and dangerous than the opening of the antarctic ozone hole in the 1980s. It's great that we're not seeing loss of sea ice in Antarctica. But, both the Antarctic and the Arctic can be thought of as important internal organs in our living Earth. The fact that the Antarctic has not undergone significant warming and sea ice loss in no way diminishes the urgency with which climate scientists view the diseased state of our Arctic. Fully 88 presentations on arctic sea ice were made last month at the world's largest scientific climate change conference, the American Geophysical Union (AGU) meeting in San Francisco. None of these scientists averaged together the arctic and antarctic sea ice together to show that the overall state of Earth's cryosphere was a healthy one. There was widespread concern for the health of the Arctic among all the scientists I spoke with, and none of the speakers at the talks I attended expressed the idea that the recent melting of arctic sea ice was predominantly natural, with human-caused climate change an insignificant factor. One view (Stroeve et al., 2007) is that human-emitted greenhouse gases are responsible for 47-57% of the arctic sea ice loss since 1979. Heat-absorbing black soot from fires and pollution settling on the white ice is thought to also be a significant contributor.
Figure 1. Antarctic sea ice area as observed via satellite since 1978. The maximum area in winter has ranged between 14-16 million square kilometers, about the same amount of ocean that the Arctic ice covers in winter. However, the antarctic sea ice almost entirely melts away in summer, something the Arctic sea ice does not do (yet). Antarctica is a huge continent that rises thousands of feet above the ocean. It holds about 90% of the world's fresh water, locked up in its massive ice cap. The presence of such a titanic block of ice at the bottom of the world completely dominates the weather and climate of the region, and the year-to-year fluctuations of sea ice don't have a lot of impact on temperatures there. Image credit: University of Illinois Cryosphere Today.
What is the current state of Antarctic climate?
At the December 2008 AGU meeting, scientists gave Antarctica a mixed bill of health. Isabella Velicogna of UC Irvine reported that satellite gravitational variation measurements of Antarctica's ice cap showed significant loss of ice between 2002-2008, but that the large natural variations in melting with the seasons made it difficult to be confident of the results. A somewhat different result was reported by J. Zwally of NASA. Using data from a higher-resolution satellite-borne laser altimeter, he found that there was no major loss of Antarctica's ice sheet between 2003-2007. Regardless of which data set is correct, Antarctica is in better shape than the Arctic because Antarctica has stayed relatively cool in recent decades (Figure 2). For example, the surface temperature at the South Pole cooled 0.05° C between 1980 and 1999 (Kwok and Comiso, 2002). The majority of Antarctica has shown no statistically significant warming over the past 50 years (Turner et al., 2005), and cooling has just been dominant between 1982-2004. In the period 2004-2007, much of the Antarctic warmed (Figure 3), but it is too early to say if this is the beginning of a warming trend. Check out the January 22 issue of Nature when new results about whether or not Antarctica is warming will be published.
Figure 2. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1982 and 2004. Much of Antarctica cooled during this period. Image credit: IPCC The Physical Science Basis, Figure 3.32.
Figure 3. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1981 and 2007. Note that the cooling trend observed from 1982-2004 reversed, thanks to warming from 2004-2007. Image credit: NASA
Why did Antarctica cool between 1982 and 2004 if there was global warming going on?
The weather of the Antarctic is dominated by a strong band of westerly winds that blow around the pole. This circumpolar vortex extends from the surface to the stratosphere, and can attain very high wind speeds, thanks to the absence of large land masses to slow it down. This vortex tends to isolate Antarctica from the rest of the globe, keeping global warming from influencing Antarctica's weather, and allowing the surface to cool. The Antarctic Peninsula, which sticks out from Antarctica towards South America, frequently lies outside the vortex. This has allowed the peninsula to warm significantly, compared to the rest of Antarctica (Figures 2 and 3). The antarctic circumpolar vortex has strengthened in the past 25-30 years, forming an even stronger barrier than usual. Tree ring records (Jones and Widman, 2004) suggest that the circumpolar vortex has shown similar strengthening in the past, so the current cooling trend in Antarctica may be natural.
Another possibility, favored by climate modelers, is that the strengthening of the circumpolar vortex and recent cooling in Antarctica are primarily due to a combination of the recent increase in greenhouse gases and the opening of the Antarctic ozone hole. The ozone hole opened up at about the same time as the recent cooling began. Ozone absorbs UV radiation which heats the atmosphere around it, so the absence of ozone has led to cooling in the stratosphere over Antarctica. This cooling has been about 10° C in October-November since 1985 (Thompson and Solomon, 2002). This has acted to intensify the circumpolar vortex, leading to surface cooling. If the climate modelers are right, the circumpolar vortex will weaken as the ozone hole diminishes in coming decades. This will allow the Antarctic to begin warming with the rest of the globe, in a decade or two.
References and resources
Intergovernmental Panel on Climate Change (IPCC), 2007, The Physical Science Basis.
Jones, J.M., and M. Widman, "Atmospheric science: Early peak in Antarctic oscillation index," Nature 432, 290-291 (18 November 2004) | doi:10.1038/432290b; Published online 17 November 2004.
Kwok, R., and J.C. Comiso, "Spatial patterns of variability in Antarctic surface temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation", GEOPHYSICAL RESEARCH LETTERS, VOL. 29, NO. 14, 10.1029/2002GL015415, 2002.
Thompson, D.W.J., and S. Solomon, "Interpretation of Recent Southern Hemisphere Climate Change", Science 3 May 2002: Vol. 296. no. 5569, pp. 895 - 899 DOI: 10.1126/science.1069270.
Stroeve, J., M.M. Holland, W. Meier, T. Scambos, and M. Serreze, Arctic sea ice decline:Faster than forecast", GRL 34 L09501, doi:1029/2007GL029703, 2007.
Turner, J. et al., 2005, "Antarctic climate change during the last 50 years", International Journal of Climatology, Volume 25, Issue 3, pp 279-294.
Arctic sea ice
"Antarctic cooling, global warming?" RealClimate.org post, 3 December 2004.
Volunteers needed for disaster relief fund-raising
The portlight.org disaster relief charity is in the process of wrapping up its Hurricane Ike relief efforts, and is looking ahead to the future. According the new wunderground featured blog, Portlight Disaster Relief, "Our goals are to expand our network of supporters, continue to create a sense of ownership and community and create a financial reserve. Achieving these goals is critical to us being able to serve future hurricane victims in a strategic, pro-active and efficient manner." To this end, Portlight is sponsoring a fund-raising effort this March and April in 40 cities--a Spring Relief Walk. Volunteers in twenty cities have already committed to the effort, and more volunteers are needed! Check out the Portlight Disaster Relief blog for more information.
Coming Monday: Inauguration Weather. Wednesday: is the globe cooling? A report on temperatures for 2008, merely the 9th warmest year on record.
Jeff Masters
Reader Comments
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WHat if we place millions of wind power turbines on the earth and in the currents off of our coast and covered the deserts with solar panels. What happens to the climate when we alter the natural flow of our weather and extract the energy that is required by nature in those areas.
or tunnels?
;)
South Florida StormWatch
Think about it. No wind in the summer for the turbines ate it all up. But we can use that energy to make big fans blow on NYC to cool it off since there is no natural wind left to feel.
There is no right or wrong with speculation. My piont is not to accept without challeng that which is being forced down your throat by teh media and self proclaimed experts. There are no experts in climate change, only those who think they are.
Wow...
You sound like you have an open mind...
Corporate shills and Rush, huh?
Believe it or not there's TONS of other competing theories from credible scientist, by the way, that try to explain why our climate is changing. Greenhouse gasses is simply one facet in a multifaceted chaotic system.
OH, and as many people you believe are 'paid off' by the oil companies are the same amount of people that are being paid off by 'green' groups and lobbys. It's the same on both sides. That's why once a day there's a fanatical story about the supposed doom global warming/climate change will bestow upon us. Like methane exploding out of the oceans and spontaneously igniting to burn every living thing on the planet...
I find it hilarious that you actually believe that someone that doesn't believe in the catastrophic form of runaway global warming is somehow a religious fanatic that belongs on a 'creationist site'. Great stereotyping there
/snark
Plastic bags instead of (renewable) paper to save the trees.
Didn't do a thing for the rainforest and has been an environmental disaster of incredible proportions, IMHO.
Cure did not fit the cause, and created a much worse situation.
just like there is no crying in baseball?
;)
But good points.
It's also the same reason why I made the reply I did in comment #246.
National Weather Service Anchorage AK
1208 am akst Fri Jan 16 2009
... Record high minimum temperature set in Anchorage Thursday...
A record high minimum temperature of 36 degrees was set in Anchorage
yesterday. This breaks the old record of 33 degrees previously set in
1981.
Records have been kept in Anchorage since 1917.
Nrh Jan 09
The official temperature in Anchorage reached 50 degrees earlier
this morning... shattering the previous record high of 44 degrees set
in the years 1992 and 1926. This also ties for the second highest
official January temperature reading for the municipality of
Anchorage. The January record high temperature is 56 degrees set
January 7, 1934. Temperatures could possibly rise above 50 degrees
later today.
In addition to today's record high, a record high minimum
temperature was set yesterday when the official temperature dropped
only to a low of 36 degrees. This surpassed the previous record high
minimum temperature of 33 degrees set in 1981.
Official temperatures for the municipality of Anchorage are taken at
the NWS forecast office on Sand Lake Road. Records have been kept
in Anchorage since 1917
Gee, I hope you don't think of me that way.
As a science guy, I hope you recognize the difference between the above and my usual poke-at-whatever-holes-I-see methods.
357. Don't forget plastic containers for just about everything. At least glass sinks.
Some may think I am a "tree hugging weirdo" but I always ask for paper. Renewable - easier to recycle and it decomposes.
Ossgss- Do you work for an oil company or what?
Of course there are natural cycles involved. Unfortunately, we will never have the ability to prove the outcome would be any different if we change now, later, or never.(see my last post several pages back) That doesn't mean we can't do better. Burn less coal and petroleum - it will last longer for other uses and future generations. I'm all for solar panels and we may need tons of petroleum to produce them. We will need it to lubricate certain things as well until something better is discovered.
Just like I teach my wolf cubs.....Do your best!
That basically means there is always room for improvement.
Room for improvbement, certainly. Facts and forethought are the factors that must come into play. Not the wealthy pushing their platform nor the green community waiting for the end to come. We live here together and should form our future together without dispute. How can that be done? Communication and sharing facts not fiction. No one can say they know the truth about sea ice, climate change or anything this big blue ball does. Only time will provide that which we seek. THe question is, do we have enough time to figure it out or is the big asteroid coming to take us away. Be well all and thanks for the challenging bloggin today. I always tune in, but rarely participate. Adios
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