10 September 2012

On thin ice: Time-frame to save the Arctic is melting away

By David Spratt, first published by ReNew Economy on 5 September 2012

 Something extraordinary is happening when graphs of melting Arctic sea-ice have their vertical axis redrawn because the data are falling off the chart.
     But that’s what has occurred in the last 10 days, since the extent of floating Arctic sea-ice broke the satellite-era minimum record on 24 August. On that date it was 4.2 million square kilometres, according to data from the Japan Aerospace Exploration Agency.
     Since then, an additional half a million square kilometres of sea-ice has melted. The extent on 4 September was just half of the average minimum extent of the 1980s. At the current rate of loss, with one to three weeks left in the northern melt season, the minimum may well shrink below 3.5 million square kilometres. This is an astounding story.
     Whilst there was modest media coverage of the record being broken, the unprecedented further melting has barely rated a mention – despite the profound consequences for both the climate and policy-making. Two weeks ago on these pages I wondered whether policy makers really want to know.
     And it’s not just the extent of the ice. It’s now much thinner: new figures of modelled data from PIOMAS show the volume on 25 August was around 3,600 cubic kilometres. This is just one-quarter of the volume twenty years ago. This fits with data from the first purpose-built satellite launched to study the thickness of the Earth’s polar caps showing that the rate of Arctic summer sea ice loss is 50 per cent higher than predicted.
Arctic sea-ice volume 1979–25 August 2012. Data: PIOMAS. Graph: L. Hamilton
As the ice becomes thinner and vulnerable to break-up from more severe Arctic storms, there are predictions of a summer Arctic Ocean free of sea-ice as early as 2015-16. A week ago ReNew Economy reported on the “big call” of the Cambridge Professor and Arctic expert Peter Wadhams who predicts Arctic summer sea ice “all gone by 2015”, except perhaps for a small multi-year remnant.
       Other Arctic specialists are now saying we will see an ice-free Arctic in summer within a decade or so. Some, relying on global generalised climate models which have a poor record for modelling and projecting Arctic sea-ice loss, are sticking to a 2030-2040 projection, but lament that “We just don’t know exactly why this (sea-ice loss) is moving so fast”.
     With three-quarters of sea-ice by volume gone in the past 20 years and the rate of loss accelerating, Wadhams’s prediction seems well founded. And because the consequences are so great, sensible risk management suggests that this scenario should be taken very seriously and its implications be well understood:
  • Regional and global warming: A 2011 study found that if the Arctic were ice-free for one month a year plus associated ice-extent decreases in other months then, without taking cloud changes into account, the global impact would be about 0.2 degrees Celsius [ºC] of warming. If there were no ice at all during the months of sunlight, the impact would close to 0.5ºC of global warming.
  • With Greenland passing its previous record melt on 8 August 2012 – with more than a month of the melt season left – it seems to be an extraordinary year, but the record suggests this may be the new norm as the Arctic warms at two-to-four times the global average, and increasing areas of exposed sea are absorbing vast amounts of energy that would previously have been reflected by ice. Greenland ice mass loss is accelerating, with big implications for sea-level rises.
  • Extremes: There is evidence connecting sea-ice loss to the more severe and extreme weather patterns in Europe and north America, consistent with research from the US National Oceanic and Atmospheric Administration.
  • Carbon stores: Melting of Arctic permafrost has dramatic consequences, as explained in an interview with Bloomberg on 16 August by NASA’s top climate scientist, James Hansen. A paper published last week in Nature shows that an ancient and large permafrost carbon pool is releasing greenhouse gases along the 7000-km coast of northernmost Siberian Arctic.
The 2007 IPPC report suggested that by 2100 Arctic sea-ice would likely exist in summer, though at a much reduced extent. Because many of the Arctic’s climate system tipping points are significantly related to the loss of sea-ice, the implication was that the world had some reasonable time to eliminate greenhouse emissions, and still be on time to “save the Arctic”. The 2007 IPCC-framed goal of reducing emissions 25 to 40 per cent by 2020 and 80 per cent by 2050 would “do the job” for the Arctic.
    But the physical world didn’t agree. By 2006, scientist Richard Alley had observed that the Arctic was already melting “100 years ahead of schedule”. But the Arctic is not melting 100 years ahead of schedule: the climate system appears to be more sensitive to perturbations than anticipated, with observations showing many climate change impacts happening more quickly and at lower temperatures that projected, of which the Arctic is a prime example.
     Politically, we are 100 years behind where we need to be on emissions reductions.
Yet the policy discourse about climate impacts and political action is still in the 2007 IPCC frame.
     Our scientists, and Australia’s Climate Commission, must lead by presenting today’s climate observations as the necessary basis for resetting the political and policy frame. Their role is crucial.
     In a forthright assessment in the current issue of Nature Climate Change, leading British researchers Kevin Anderson and Alice Bows describe A new paradigm for climate change, saying that:
How climate change science is conducted, communicated and translated into policy must be radically transformed if ‘dangerous’ climate change is to be averted.
They demonstrate that climate science has become intertwined with politics “to the extent that providing impartial scientific analysis is increasingly challenging and challenged” and point to “the scale of the discontinuity between the science (physical and social) underpinning climate change and the economic hegemony”. The challenge to their colleagues is unambiguous:
Civil society needs scientists to do science free of the constraints of failed economics. It also needs us to guard against playing politics while actively engaging with the processes of developing policy; this is a nuanced but nonetheless crucial distinction. Ultimately, decisions on how to respond to climate change are the product of many constituencies contributing to the debate. Science is important among these and needs to be communicated clearly, honestly and without fear.