Ice free Arctic Barrow by 2020?
(Pic. I.Quaile)

The statement by  veteran Arctic researcher Peter Wadhams that the Arctic could be ice-free in summer as early as 2020 sparked a lot of discussion. Recently I had the chance to talk to Professor Stefan Rahmsdorf, Professor of Physics of the Oceans and head of Earth System Analysis at Germany’s Potsdam Institute for Climate Impact Research (PIK) about Wadham’s  forecast.

At the recent Arctic Circle Assembly in Iceland, Wadhams, professor of applied mathematics and theoretical physics at Cambridge University, said data showed the ice volume was “accelerating downward” and the summer sea ice could be expected to disappear by 2020. This prompted Craig Medred, writing for Alaska Dispatch News, (AND) to quip “get ready to order those beach umbrellas in Barrow”. (Arctic Barrow is the northernmost settlement in the USA).

Not 2020, but soon

It is not the first time Wadhams has predicted that the Arctic ice will melt faster than most of the models estimate. He says he bases his assumptions on data, much of it from submarines measuring below the ice since 1979, rather than on models. I asked Rahmstorf for his view. This was his reply:

“In science there is always a range of opinions, and I think Peter Wadhams marks one extreme of the range of opinions. I find it unlikely that in ice-free Arctic can be seen that soon, I think it is a few decades into the future, but it is extremely worrying that we have already lost almost half the ice cover in the Arctic ocean”.

I asked Rahmstorf about the above-average rise in temperature in the Arctic over the last 20 years or so:

Climate expert Rahmstorf (Pic: PIK)

“We do see a disproportionate rise in temperatures in the Arctic. And in the summer, we have lost almost half of the sea ice cover that is usually on the Arctic Ocean since the 1970s. To some extent it is expected that the Arctic is a hotspot of global warming, because there is an amplifying feedback. If the ice cover shrinks, you absorb more of the solar radiation, less gets reflected back into space, because the ice normally acts like a mirror to the sunlight. To some extent what is happening in the Arctic is expected, and predicted by climate models. I say to some extent because it is a bit stronger than we expected and there are some aspects we still need to research. There is a similar issue in earth history, where there are some warmer periods in climate history where data consistently shows that the poles have warmed much more than the climate models would predict for these past periods in history, so there may be some amplifying factors at work in the Arctic that we haven’t include in the models yet. “

Wild weather ahead

So reality could be overtaking the modeled scenarios, and we don’t know why. Worrying?

Rahmstorf has been involved in various studies of how changes in the Arctic affect our weather. He summarized the findings in brief:

“Our weather is strongly affected by the jet stream, which is meandering around the planet in the mid-latitudes in the upper atmosphere, and this jet stream is driven by the temperature difference between the warm tropics and the cold Arctic. With this disproportionate Arctic warming, this temperature gradient is weakening, and to put it simply, it seems to make the jet stream more unstable, and more frequently you see very large meanders in the jet stream,  which can cause extreme weather on the ground.”

Rahmstorf, like most experts in the field, expects a further increase in extreme weather events and cites the massive flooding of the Elbe river in 2002 and heat waves in 2003 and 2010 as examples of what could increasingly be in store for us here in Europe.

Message for UN climate talks

With negotiators gearing up for this year’s UN climate conference in Lima, Peru, in just over two weeks’ time, and the publication of the Summary for Policymakers of the latest IPCC report, I asked Rahmstorf what he would say to politicians to convince them of the need to cut emissions. This is what he told me:

… And the ice continues to melt. (Pic: I. Quaile, Greenland)

“We see that global temperatures have risen by almost one degree Centigrade in the last 100 years, we see that global sea level has risen by nearly 20 cm in the last 100 years, we see that the mountain glaciers are in rapid retreat, the Arctic ice cover is in retreat, the continental ice sheets in Greenland and Antarctica are shrinking, losing mass, contributing to sea level rise, we see extreme events on the rise, for example the number of record-breaking hot months has increased five fold as compared to what you get by chance in a stationary climate. So climate change is here and is affecting people already, after a relatively small amount of global warming, of only one degree centigrade. And if we don’t stop this process, we will go well beyond two degrees centigrade, and we will leave the range we are familiar with throughout human history, throughout the Holocene, we will be way outside that into uncharted and, I think, very dangerous waters.”

Rahmstorf is convinced we can still stop warming from going above the two-degree target and cites the IPCC report and recommendations.  Although the current pledges for emissions reductions by the EU and just this week by China and the USA are still way below what is necessary, Rahmstorf is still optimistic.

“We are just  celebrating 25 years of the Berlin Wall coming down, and if you had asked people just a few months before that how likely it was that the wall comes down, nobody would have said it’s going to happen. I think processes like this in society cannot easily be predicted, but I can see very encouraging signs:  the huge success story of renewable energies, we can see parts of the world like the European Union have already greatly reduced their emissions of greenhouse gases since 1990, while still experiencing good economic growth, which shows you can decouple emissions from economic growth and welfare. We have the technologies to solve this problem, and the economic analysis of a number of different groups of economists from around the world as summarized by the IPCC shows that at just surprisingly little cost you will hardly notice as a normal person, if we go through this investment into the energy system that will transform it into a truly sustainable energy supply, and not a fossil fuel based one. “

I will end on that positive note. If you’d like to listen to the Professor for yourself, here he is:

NOAA scientists in Arctic Canada basin, July 2005
Photo: NOAA, Jeremy Potter

Scientists studying Arctic sea ice say ice-free summers could be on the horizon sooner than many expected. A new analysis by NOAA scientists James Overland (NOAA Pacific marine Environmental Laboratory) and Muyin Wang (NOAA Joint Institute for the Study of Atmosphere and Ocean at the University of Washington) considered three methods of predicting when the Arctic will be nearly ice free in the summer. All three suggest nearly ice-free summers in the Arctic before the middle of this century, says Wang, although the actual dates differ widely. One method suggests the Arctic could be nearly sea ice free in summer as early as 2020.

“Rapid Arctic sea ice loss is probably the most visible indicator of global climate change; it leads to shifts in ecosystems and economic access, and potentially impacts weather throughout the northern hemisphere,” said Overland. “Increased physical understanding of rapid Arctic climate shifts and improved models are needed that give a more detailed picture and timing of what to expect so we can better prepare and adapt to such changes. Early loss of Arctic sea ice gives immediacy to the issue of climate change.”

The paper was published recently online  in Geophysical Research Letters.

Overland said the differences between the models could lead some people to conclude that models are not useful. In fact the opposite is the case, he said. “Models are based on chemical and physical climate processes and we need better models for the Arctic as the importance of that region continues to grow.”

Taken together, the range among the multiple approaches still suggests that it is very likely that the timing for future sea ice loss will be within the first half of the 21st century, with a possibility of major loss within a decade or two, the authors say.

Other recent studies have indicated the key role of shrinking Arctic sea ice in influencing our weather. The shrinking sea ice is shifting polar weather patterns, especially in autumn and winter, according to one new climate modeling study.

Researchers looked at weather patterns in 2007, when sea ice covering the Arctic Ocean hit one of its lowest summer extents since satellite tracking began in the late 1970s.

In autumn and winter, when sea ice would normally insulate the ocean from frigid Arctic air temperatures, the small ice pack meant lots of heat could escape from the ocean into the atmosphere, the study found. The heating changed  atmospheric circulation patterns in the Arctic, said study leader Elizabeth Cassano, a climate scientist at the Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder, Colorado. The results were published May 21 in the International Journal of Climatology.

Becky Oskin from LiveScience talked to Cassano about the study and quotes:  “What we saw, particularly in the fall and winter, was a decrease in [atmospheric] pressure over the areas of open water.” Areas of high and low pressure drive weather, with low pressure producing stormier weather and high pressure leading to clear, calm days, Cassano said. The group’s computer model generally agreed with weather records from the latter half of 2007, according to the study.

While the summer ice melt had a significant effect into the winter, there was little change in weather patterns in early 2007, before the ice pack shrank, the study found. However, Cassano points out that the climate model doesn’t include a major high-pressure system that was in the Beaufort Sea north of Alaska and played a role in the big ice melt. Its absence could affect the modeling results.

Arctic sea ice, courtesy NOAA

The researchers now plan to examine how the feedback between sea ice and the atmosphere alters weather in the United Statse and other regions, Cassano said. “There’s an open question of how these changes that we see in the Arctic influence the weather that we see here in the mid-latitudes,” she said.

 Given the weird weather we are experiencing in different parts of Europe at the moment, interest in whether climate change could be directly or indirectly responsible is high. Finnish Lapland has been experiencing a heatwave. Colleagues of mine have returned from the south of France complaining it was unexpectedly cold. Here in the normally mild Rhineland, we have also had very low temperatures and heavy rain. Meanwhile southern and eastern parts of Germany are being hit by severe flooding.

Renowned German scientist Stefan Rahmstorf and his colleagues at the Potsdam Institute for Climate Impact Research have apparently been contacted by various media, asking them if the rain and flooding are connected to climate change. He refers readers to a study on extreme weather they published in Nature Climate Change a year ago. Let me close by sharing his quote from that study, which he shares again in the climate blog SciLogs:

“Many climate scientists (including ourselves) routinely answer media calls after extreme events with the phrase that a particular event cannot be directly attributed to global warming. This is often misunderstood by the public to mean that the event is not linked to global warming, even though that may be the case — we just can’t be certain. If a loaded dice rolls a six, we cannot say that this particular outcome was due to the manipulation — the question is ill-posed. What we can say is that the number of sixes rolled is greater with the loaded dice (perhaps even much greater). Likewise, the odds for certain types of weather extremes increase in a warming climate (perhaps very much so). Attribution is not a ‘yes or no’ issue as the media might prefer, it is an issue of probability. It is very likely that several of the unprecedented extremes of the past decade would not have occurred without anthropogenic global warming. Detailed analysis can provide specific numbers for certain types of extreme, as in the examples discussed above.

In 1988, Jim Hansen famously stated in a congressional hearing that “it is time to stop waffling so much and say that the evidence is pretty strong that the greenhouse effect is here”. We conclude that now, more than 20 years later, the evidence is strong that anthropogenic, unprecedented heat and rainfall extremes are here — and are causing intense human suffering.”