"1. The past six years (2005–2010) have been the warmest period ever recorded in the Arctic. Higher surface air temperatures are driving changes in the cryosphere.
2. There is evidence that two components of the Arctic cryosphere--snow and sea ice--are interacting with the climate system to accelerate warming.
3. 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.
4. 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.
5. Model projections reported by the Intergovernmental Panel on Climate Change (IPCC) in 2007 underestimated the rates of change now observed in sea ice. [Deniers rejoice! The IPCC was wrong. But alas, wrong in the wrong direction.]
6. 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.
7. The Arctic Ocean is projected to become nearly ice-free in summer within this century, likely within the next thirty to forty years. [It's not hard to find people on the Web, who know what they are talking about, who believe this will happen before 2020. While 2012 is, at this writing, on a record pace for Arctic sea ice melt, it remains to be seen whether a new ultimate summer low will result. What we can say, however, is that there has been no recovery from the 2007 summer low, which was sharply lower than the summer lows in previous years going back to 1979 (when measurements began). You can check out sea ice area through this wonderful interactive graphic, which provides data by day and year. You can "erase" years by clicking on them at the right, and if you erase back to 2007, you will see that the summer low was roughly 3 million square kilometers, almost exactly a whopping 25% below the low of 4 million reached in 2006.]
8. 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. [OK, now I know we are getting into stuff many people who don't live in the Arctic don't care about. Before you lose interest, though, be sure to check out Key Findings 12 and 13 below.]
9. 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.
10. 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.
11. Arctic infrastructure faces increased risks of damage due to changes in the cryosphere, particularly the loss of permafrost and land-fast sea ice.
12. 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. [Emphasis added. For one of the apparent first unexpected impacts, see Linking Weird Weather to Rapid Warming of the Arctic, by Jennifer Francis, who is studying how the melting Arctic appears to be changing the behavior of the jet stream and causing weather patterns--drought, rainfall, heat--to stay in one place for longer periods. Oops.]
13. 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 Arctic ice loss will make a substantial contribution to this.
14. 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.
15. 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."