A major new multi-country scientific assessment of the Arctic has concluded that on our current greenhouse gas emissions path, we face 3 to 5 feet of sea level rise — far greater than the 2007 IPCC warned of. This is fully consistent with several recent studies (see “Sea levels may rise 3 times faster than IPCC estimated, could hit 6 feet by 2100”).
The Arctic Monitoring and Assessment Programme — formed in 1991 to advise the eight Arctic countries on threats to the Arctic from pollution — has released the Executive Summary of their Snow, Water, Ice and Permaforst in the Arctic (SWIPA) assessment on their website [big PDF here]. SWIPA “brings together the latest scientific knowledge about the changing state of each component of the Arctic cryosphere.”
The report notes that, “The observed changes in sea ice on the Arctic Ocean and in the mass of the Greenland Ice Sheet and Arctic ice caps and glaciers over the past ten years are dramatic and represent an obvious departure from the long-term patterns.” I’ll have more to say shortly on the effort by the anti-science crowd to mislead on this key point.
Here are the “key findings” of this must-read warning to humanity:
- The past six years (2005–2010 have been the warmest perio ever recorded in the Arctic Higher surface air temperature are driving changes in the cryosphere.
- There is evidence that two components of the Arctic cryosphere — snow and sea ice are interacting with the climate system to accelerate warming.
- The extent and duration of snow cover and sea ice have decreased across the Arctic. Temperatures in the permafrost have risen by up to 2 °C. The southern limit of permafrost has moved northward in Russia and Canada.
- The largest and most permanent bodies of ice in the Arctic — multiyear sea ice, mountain glaciers, ice caps and the Greenland Ice Sheet — have all been declining faster since 2000 than they did in the previous decade.
- Model projections reported by the Intergovernmental Panel on Climate Change (IPCC) in 2007 underestimated the rates of change now observed in sea ice.
- Maximum snow depth is expected to increase over many areas by 2050, with greatest increases over Siberia. Despite this, average snow cover duration is projected to decline by up to 20% by 2050.
- The Arctic Ocean is projected to become nearly ice-free in summer within this century, likely within the next thirty to forty years.
- Changes in the cryosphere cause fundamental changes to the characteristics of Arctic ecosystems and in some cases loss of entire habitats. This has consequences for people who receive benefits from Arctic ecosystems.
- The observed and expected future changes to the Arctic cryosphere impact Arctic society on many levels. There are challenges, particularly for local communities and traditional ways of life. There are also new opportunities.
- Transport options and access to resources are radically changed by differences in the distribution and seasonal occurrence of snow, water, ice and permafrost in the Arctic. This affects both daily living and commercial activities.
- Arctic infrastructure faces increased risks of damage due to changes in the cryosphere, particularly the loss of permafrost and land-fast sea ice.
- Loss of ice and snow in the Arctic enhances climate warming by increasing absorption of the sun’s energy at the surface of the planet. It could also dramatically increase emissions of carbon dioxide and methane and change large-scale ocean currents. The combined outcome of these effects is not yet known.
- Arctic glaciers, ice caps and the Greenland Ice Sheet contributed over 40% of the global sea level rise of around 3 mm per year observed between 2003 and 2008. In the future, global sea level is projected to rise by 0.9–1.6 m by 2100 and Arcticice loss will make a substantial contribution to this.
- Everyone who lives, works or does business in the Arctic will need to adapt to changes in the cryosphere. Adaptation also requires leadership from governments and international bodies, and increased investment in infrastructure.
- There remains a great deal of uncertainty about how fast the Arctic cryosphere will change in the future and what the ultimate impacts of the changes will be. Interactions (‘feedbacks’) between elements of the cryosphere and climate system are particularly uncertain. Concerted monitoring and research is needed to reduce this uncertainty.
Yes, the findings are on the conservative side — we are all but certain to be nearly ice-free in the Arctic by 2030, and likely to be so by 2020, I think. But that’s what happens when you a consensus-based process involving scientists from “eight Arctic countries (Canada, Denmark/Greenland, Finland, Iceland, Norway, Russia, Sweden and the United States).”
How do we know the findings are conservative — underestimates of what is likely to happen? Consider this line from the report:
The climate models used for SWIPA do not include possible feedback effects within the cryosphere system that may release additional stores of greenhouse gases from Arctic environments.
Yet the feedbacks are likely to be large and positive — see “NSIDC bombshell: Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100.”
Here’s what the Exec Sum says on permafrost:
Permafrost — permanently frozen ground — underlies most of the Arctic land area and extends under parts of the Arctic Ocean. Temperatures in the permafrost have risen by up to 2 °C over the past two to three decades, particularly in colder sites (typical permafrost temperatures range from -16 °C to just below 0 °C, depending on the location). The depth of soil above the permafrost that seasonally thaws each year has increased in Scandinavia, Arctic Russia west of the Urals, and inland Alaska. The southern limit of the permafrost retreated northward by 30 to 80 km in Russia between 1970 and 2005, and by 130 km during the past 50 years in Quebec.
I’ll have more to say when the full report is online.