20071212_AR
Source: BBC News
URL: http://news.bbc.co.uk/1/hi/7139797.stm
Date: 12/12/2007
Event: Arctic summers ice-free by 2013
People:
- Jonathan Amos: BBC science reporter
- Dr Wieslaw Maslowski: Professor of Oceanography
Wieslaw Maslowski: We are predicting that ice, possibly - projecting that the ice possibly might be gone by 2013, in summer, completely. And the reason, we think, that our projections are more realistic than the climate model predictions - or even the extended projections from the satellite observations of the ice extent - is that in our model, I believe, we're more realistically accounting for some additional forcing, namely the oceanic forcing of the heat advected into the Arctic Ocean, which is quite a significant contributing and forcing on the melting sea ice.
Jonathan Amos: So just explain that to me. What has your model got, that the others haven't?
Wieslaw Maslowski: Well, I think our model, in particular, has much better representation of the oceanic circulation coming from the Bering Sea, through the Bering Strait into the Chukchi and then the proper Arctic Basin. Same way, on the Atlantic side, we have the Atlantic water entering the Arctic Ocean through Franz Strait, one pathway, and then the second pathway is the passage through the Barents Sea into the eastern Arctic. The climate models, to our understanding - and we've done some analysis and comparison - might underestimate the amount of heat delivered by the Atlantic or the Pacific side through those pathways, by maybe an order of 50% below what we see in our model simulations.
Jonathan Amos: And the ocean warming, in your view, is the most important - the single most important factor in this retreat of the ice?
Wieslaw Maslowski: Our calculations - trying to understand the effect of atmospheric forcing, the ice albedo effects and the oceanic forcing - are indicating that probably the total contribution from the atmosphere to melting the Arctic sea ice cover and the oceanic contributions are roughly 50/50. 50% ocean, 50% atmosphere.
Jonathan Amos: Is there anything that can - that can stop the decline now, or has the system been so weakened that it's inevitable?
Wieslaw Maslowski: Well, the main detail to eventually look at and pay attention, I believe, is that the changes in the ice thickness. Our model results, which are validated against submarine and the satellite observations, are indicating that actually we have lost, so far, maybe 35 to 30% of the total ice thickness, on the average for the Arctic Basin. And the thinner the ice, the easier it is actually to move it by winds, and the easier it is to be melted by the underneath warmer ocean and above surface air temperature. So, in my opinion, actually, we are on the accelerating path and we probably will see, in the near future - next two, three years - another record minima ice extent observed by satellites, beating the last year, 2007 summer ice extent minimum.
Jonathan Amos: Does your latest projection take account of the dramatic events of this past summer and 2005, which was the previous minimum?
Wieslaw Maslowski: Our projections for 2013, the removal of ice in summer, actually are not accounting for the last two minima, in 2005 and 2007. So, given that fact, actually, you already can argue that the acceleration of the Arctic melting is already being [sic] taking place, and possibly our projections of 2014 - '13, I'm sorry - are already too conservative.
Jonathan Amos: I mean, we've had numbers come down and down and down. 2013 is really quite dramatic. What's the reaction you get from people when you say this to them?
Wieslaw Maslowski: Well, that's a very interesting question. So, in the recent - this year, at least, and in the past last two years, maybe, when I'm discussing and presenting - and presenting my projections on the recent or sooner decline of the Arctic sea ice, nobody has necessarily jumped at me or objected, from the scientific community. People from the news and media are getting very excited about this, but as far as my concern, my colleagues, my peers, I believe, are on our side, agreeing more and more. And the percentage of the community probably gets increased every day, probably, that the sooner decline of the Arctic summer ice is more probable than the climate polar projections.
Jonathan Amos: It'll be quite a moment, when summer ice is gone, won't it.
Wieslaw Maslowski: Well, it will be a big change, but we know how possibly this might be working, because we have an equivalent in the Southern Ocean, where we have the seasonally ice-covered ocean, and I believe this possibly might be the case for the Arctic. However, we are still not certain how the system - the regional climate in the Northern Hemisphere - will react to this change, both in terms of changing the reflectivity of the northern sea ice into the darker open ocean, for the whole Arctic Ocean, as well as the delivery of the anomalous amount of fresh water where we end up melting every summer all the sea ice in the Arctic, and delivering to the North Atlantic. There might be some changes in the North Atlantic circulation, which might affect the regional - maybe - climate change. But the main issue, at this point at least, is that those feedbacks from the sea ice and ocean changes into the atmosphere have not been realistically accounted in the existing models yet. So that's the work to be done, and if we develop new models that more realistically account for feedbacks between ice, ocean and atmosphere in the Arctic Ocean - which in my opinion requires very high resolution, to do this properly - we might be able to address this question and maybe we'll be able to do much better proje- predictions.