No More Arctic Ice Cap by 2030?
by Jeremy Elton Jacquot, Los Angeles on 09. 5.07
Just how bad has the situation in the Arctic gotten? In the past week alone, scientists estimate that an area almost twice the size of Britain disappeared as a result of the unprecedented heat. So much ice has now melted, in fact, that the Northwest Passage has become fully navigable for the first time in history, and the Northeast Passage — which straddles Russia's Arctic coast — could follow suit by the end of this month.
If present trends continue, scientists predict that the Arctic could become ice-free within 23 years. To put that into context, it took the last 30 years for it to lose almost a third of its ice. "It's amazing. It's simply fallen off a cliff and we're still losing ice. If you asked me a couple of years ago when the Arctic could lose all of its ice, then I would have said 2100, or 2070 maybe," said Mark Serreze, an Arctic expert at the University of Denver's National Snow and Ice Data Center (NSIDC).
The latest estimates put the area of the ice cap at about 1.7 million sq mi (or 4.4 million sq km) — a sharp decline from the 7.7 million sq km average recorded from 1979-2000 and a dwindling figure that has yet to hit bottom. Not surprisingly, Serreze lays most of the blame for this rapid fall squarely at the feet of anthropogenic global warming: "The rules are starting to change and what's changing the rules is the input of greenhouse gases. This year puts the exclamation mark on a series of record lows that tell us something is happening."
God forbid we'd need any more exclamation marks before we start taking some serious action...
Via ::Guardian Unlimited Environment: Ice-free Arctic could be here in 23 years (news website)
See also: ::In Harpers Magazine: The Battle for the Melting North, ::Arctic Emissaries Head to Washington
Image courtesy of AP/John McConnico
Refer to "Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century", Science, 24 August 2007, Vol 317, pp 1064-1067: yearly ice melt from ALL glaciers, ice caps, greenland ice sheet, Antarctica ice sheets in the world is 645+/-170 Gt. It did not explicitly state how much of this is due to the Arctic ice cap, but for the sake of argument ("No More Arctic Ice Cap by 2030"), let's assume that ALL the ice melt in the world is from the Arctic. Fun with numbers!
The winter area of the Arctic ice pack is 15,000,000 square kilometers. The average thickness of it is 3-4 m. So, lets say 3.5 meters across the pack. This results in an area of 45,000 cubic kilometers.
Now, if the global ice melt of 645 km^3/yr was from the Arctic, that would give the Arctic another 70 years.
Yes, I fudged with the numbers to expedite the melting of the ice pack. So, 2030????
Brain, your calculation is not accurate because the rate of melting in the future will not be the same as past. It keeps increasing as there is less ice and therefore less sunlight is reflected back into the atmosphere. Thus increasing sea surface temperature at a faster rate year by year.
Yes Manu, you are correct. The article I referred to included the second time derivative of mass change of ice, but I wasn't in the mood for the integration. However, notice that I used the melting rate for the ENTIRE WORLD on but one ice pack. I'll post the data if you really want though...
fine, here are my notes of the article.
http://remindmetogo.googlepages.com/melt.jpg
"I used the melting rate for the ENTIRE WORLD on but one ice pack."
That does not matter since we're talking about the rate of melting, not geographical area. Just as world population growth rate could be used to approximately predict population growth of a particular country.
Also note that the rate of melting isn't linear. Earlier this year James Hansen wrote a paper highlighting this very issue. He strongly criticised IPCC reports because one can't very well safely predict when the ice-caps will disappear. There is every possibility that it can happen very suddenly. I recommend reading George Monbiot's article on Hansen paper.
BTW, there are more details about these Arctic projections on National Snow And Ice Data Center website.
Manu, I applaud you on your thoroughness. But all I meant that, barring any unforseen and sudden disintegrations of the Artic icepack, given current melting rates (and acceleration rates), is it likely that the Arctic ice pack will completely disappear by the year 2030 as this article claimed? And to think of it, is the whole act of predicting melting futile as there are so many variables beyond our comprehension that we cannot hope to predict. Is the same not true for climate modelling? Because that is what it is: modelling, trying to give an approximation for the future given incomplete knowledge of variables and mechanisms?
Brian, you raise an important point. I have to agree climate modeling isn't quite reliable as yet. For example, two days after the above NSIDC study, comes another one, this time by National Oceanic and Atmospheric Administration (NOAA) which suggests that Arctic will lose 40% ice by 2050. This is dramatic variation - from 100% in 2030 to 40% in 2050.
Looking closely, it appears that NOAA study used IPCC climate data which is actually quite dated (IPCC did not consider any data observed after 2005) so they may not be up to the mark. All recently released studies point a much more grim picture than painted by IPCC fourth assessment reports.
That said, I wouldn't call modeling futile. All decision making occurs without complete data. You never have everything. You only get to examine every piece of information *after* the event. So the scientists are try to make the best of what they have. If they keep waiting for all the assumptions to be absolutely certain, then it may be too late to take action. The risk of not taking action is so enormous that we can't afford it. Besides, we DO have a lot of evidence by now.
Scientific uncertainty has for a long time been used as a ploy by governments for delaying action. This is why we are in such a mess today. There was consensus by early 90s that we need to take urgent action to reduce emissions to prevent global warming. It's only now when the govt can't possibly hide behind scientific uncertainty in the light of all the evidence that they have acknowledged this to be a problem. We are still a long way from when our leaders truly understand the scale of the problem.
A recent article in the Financial Times argued (and I'm in total agreement) that "a revolution of society on a scale never witnessed in peacetime is needed if climate change is to be tackled successfully." This is the view of World Business Council for Sustainable Development which says the govt.s aren't going to do anything until there is a crisis. I couldn't agree more.
Manu, I could not agree with you more.
But then again, in the context of my personal environmental actions, global warming is irrelevant. Whether of not anthropogenic carbon dioxide is fuelling climate change, I do not put much thought into. What I am trying to say is that even if this whole mess was not occuring, I would still want to take action and reduce my impact. But then again, some others out there may need incentive.
We live at the crossroads at where conjecture can be proven as fact, in regards to the ice cap melting. As we all know, the ice cap hit a low level of 1,590,000 sq miles this year. As it melts in an ever increasing rate, 1.25 million sq miles is only a couple or so summers away. A rational estimate would say, that between 2025 and 2035, the Summer Arctic ice cap may very well be roughly the size of Texas, and perhaps less.
the estimate of the thickness of the winter ice is way too high - the 3-4 metres is the average for perennial ice. try under 2 meters across the winter area instead to get the real number...