The natural rhythm that has characterised climate on Earth during the last 3 million years is broken. It has taken humans less than 200 years to accomplish this. The industrial extraction and burning of fossil-fuels have fed the atmosphere and oceans with huge quantities of CO2, with impacts that are manifest all over the planet. In a devastating twist, the regions that are warming up the fastest are the world's coldest places: among them Antarctica and the Arctic. These remote and harsh areas are practically devoid of people and have only minimal industry. In one sense that is fortunate, because it buys humans time when none can be wasted.  

Øyvind Paasche is a scientist, specialising in palaeoclimates, at the Bjerknes Centre of Climate Research, University of Bergen, Norway

A system in change

The variability of the climate system is no longer only natural, nor will it be for generations to come. The innocence of the 1950s, when it was believed that CO2 remained at stable levels in the atmosphere regardless of what humans did, is long lost. The CO2 shock-treatment of this latest half-century of intense global development has produced severe side-effects, which scientists must demonstrate but every citizen can witness. What exactly the climate of the 21st century will bring remains to be experienced, but indicators are already being observed: among them large-scale changes in temperature and precipitation patterns, vegetation covers, sea-levels and the extent of sea-ice. True, part of these changes can be attributed to natural variability; but the other part of it is due to added CO2. At the heart of climate research is finding the elusive triggers that instigate these changes in the climate.

An understanding of past climate dynamics guides awareness of the way that under certain conditions the climate system can be extremely responsive to minor pressures to change. Again, the precise forces or mechanisms that lead to change remain hard to identify. This is true for example with regard to the sudden shift in the extent of Arctic-summer sea-ice, although there is no shortage of plausible candidates. The lack of knowledge notwithstanding, the coming of a new climate system is underway. James Hansen of Nasa, one of the world's foremost experts, is only one of those convinced that the threshold to a new regime has already been passed. 

An Arctic focus

In 2007, the shrinking Arctic-summer sea-ice astonished scientists. Since the late 1970s, its maximum extent had fallen from 7.5 to 4.5 million square kilometres; many experts now argue that the Arctic will in a few decades be "open" during the summer.

Indeed, the scientific focus on such high-latitude areas makes perfect sense, precisely because of their unparalleled sensitivity to changes in atmospheric CO2 levels. Paleodrake, an International Polar Year (2007-08) project, seeks to learn more about climate change in the past in such regions, in order better to assess whether natural trends are accelerating or slowing such change today. One way to do so is to look at how glaciers respond to changing climate conditions. 

A glacial experience

Glaciers worldwide are in a state of demise. The ones occupying the western part of South Georgia, a small island in the south Atlantic, are no exception. Today, glaciers still cover half of the island, but fresh glacier forelands are exposed every year. The island's very position, close to both the maximum extent of Antarctic winter sea-ice and the Polar Front, makes it climatologically interesting. By reconstructing glacier activity here it is possible to identify large-scale shifts in precipitation and temperature patterns that can be used to constrain the range of natural variability.  

The Hodges glacier was intensely studied by the British Antarctic Survey in the 1970s, and up to the onset of the Falkland/Malvinas war of April-June 1982 (which began with the Argentinean incursion into South Georgia). An outline of the glacier's extent was observed in 1955 and 1958; historical data indicate that the glacier was larger at the turn of the 21st century. In January 2008, I visited the corrie together with two colleagues - to discover that the glacier had melted completely away. We are now in the progress of discovering whether or not this has happened earlier during the last 10,000 years, or if what we observed last year truly represents an anomaly that can (to whatever extent) be attributed to global warming. 

A warmer planet

It is hard to picture a world without permafrost, glaciers and icecaps. Yet this still represents one of many potential future scenarios that are gaining scientific credibility by the year. The loss of ice on land will undoubtedly alter ecosystems and societies, and cause a dramatic increase in sea level.

The large icecaps covering Greenland and Antarctica will persist, but - given the ongoing increase in CO2 - not forever. The formation of the Greenland ice-sheet 3 million years ago depended on sufficiently low atmospheric CO2 levels, predominantly below 300 parts per million (ppm). Similarly, the Antarctic ice-sheet formed when the CO2 level dropped below 425 ppm, some 35 million years ago. Most of the scenarios presented by the latest (2007) report of the Intergovernmental Panel on Climate Change (IPCC) suggest that the atmospheric CO2 level in 2100 will be above 425 ppm. At present it is 387 ppm, and it is currently rising by about 2 ppm a year.  

There is a chance - still - that this IPCC report will become a historic turning-point. It has made possible the realisation, albeit reluctant, that humans' way of living on Earth has a devastating global impact. This is perhaps the most frightening thing to face, especially for political leaders: that to accept reality and acknowledge responsibility - something politicians usually try very hard not to do - is also to create a necessity to act.

In this sense, global warming and poverty are not so different: we know how to eliminate it, but it's not on our list of priorities. Putting it on that list, and at the very top, is of the utmost importance. How to do it? I am a scientist, and I know only this: it will take a lot more than scientists documenting yet another disappearing glacier.

openDemocracy writers explore the politics of climate change, including the debate of that name (edited by Caspar Henderson) in 2004-05:

Stephan Harrison, "Kazakhstan: glaciers and geopolitics" (27 May 2005)

Camilla Toulmin, "Climate change, global justice: letter to Al Gore" (27 July 2006)

Simon Retallack, "Climate change: the global test" (10 November 2006)

Tom Burke, "Climate change: choosing the tools" (21 December 2006)

Dougald Hine, "Climate change: a question of democracy" (2 March 2007)

Andrew Dobson, "A politics of global warming: the social-science resource" (29 March 2007)

Andrew Dobson, "A climate of crisis: towards the eco-state" (19 September 2007)

Mike Hulme, "Climate change: from issue to magnifier" (19 October 2007)

David Shearman, "Democracy and climate change: a story of failure" (7 November 2007)

Tom Burke, "The world and climate change: all together now" (7 December 2007)

Saleemul Huq, Oliver Tickell, David Steven, Camilla Toulmin, Andrew Dobson and Alun Anderson, "Was Bali a success?" (18 Dec 2007)

Mike Hulme, "Climate security: the new determinism" (20 December 2007)

Mike Hulme, "Amid the financial storm: redirecting climate change" (30 October 2008)

Camilla Toulmin, "Climate change futures: postcard from Poznan" (11 December 2008)

Paul Rogers, "Climate change: rock the state, save the planet" (21 April 2009)

Paul Rogers, "Climate change: a failure of leadership" (8 May 2009)

Simon Maxwell, "The politics of climate change" (15 June 2009)

External Relations Authority, "Report on World 87" (20 August 2009)