Page:Impact of Climate Change in 2030 Russia (2009).pdf/12



Climate Observations
Temperature trends over most of the Arctic and northern Russia before about 1920 were likely dominated by natural variability.ii It is difficult to explain increasing temperatures since 1920 without including the impacts of human emissions of greenhouse gases. Average temperatures over the past decade are the warmest ever measured in the documented history of climate records in Russia. Studies by Roshydromet,iii the Federal Service for Hydrometeorology and Environmental Monitoring, show that annual average temperatures over Russia have increased significantly during the past 10 years; the models suggest a continuation of this trend over the next five to 10 years. Such conclusions are supported by the findings of other Russian agencies, the Russian Academy of Sciences in particular, and by most foreign scientists (Figure 1).

Data collected by the Roshydromet surface network of hydrometeorological observations show that during 1990-2000 the mean annual surface air temperature increased by 0.4°C. (During the previous hundred years, the increase was only about 1.0°C.) Warming is more evident in winter and spring and more intensive east of the Urals.iv

Temperatures in the Arctic are rising at almost double the rate of the global average. In many inland Arctic regions, surface air temperatures have warmed 0.2°C per decade over the past 30 years. Sea ice in the Arctic has decreased by 3 percent per decade between 1978 and 1996, and summer sea ice thickness has decreased by 40 percent since the 1950s.v Precipitation at high latitudes has increased by 15 percent over the past decade, with most of this increase occurring over the past 40 years.vi Arctic summers are now warmer than at any time in at least the past 400 years.

The fourth Intergovernmental Panel on Climate Change (IPCC) climate change assessment (AR4)vii reported that in areas of the boreal north, the liquid precipitation season has become longer by up to three weeks over the past 50 years. Increasing winter temperatures in the northern regions has considerably changed the ice regime of the region’s water bodies. Comparing the years 2010-2015 with 1950-1979, the assessment predicts that, in the later period, ice cover duration on the rivers in Siberia is expected to be 15-27 days shorter and maximum ice cover thinner by 20-40 percent. Also, an annual increase of 5 percent was observed in river flow, with a winter increase of 25-90 percent over the base flow due to increased melt and thawing permafrost.

Winter snowfall and snow depth in the Northern Hemisphere’s high latitude regions have increased during the past few decades; this trend is likely to be associated with increasing precipitation related to surface air warming. This trend is supported by significant positive trends in winter temperatures across much of the former Soviet Union in the past 50 years.viii

Most recent research shows that Siberian permafrost temperatures rose considerably during the latter half of the 20th century, although the extent to which this can be attributed entirely to climate warming is currently unknown. Recent research revealed positive warming trends for all permafrost regions in response to positive trends in air temperature, with the strongest warming trend in regions of continuous permafrost. A slight cooling trend is found only for the topmost soil layers in regions of seasonally frozen ground at the southern margins of the region draining into the Arctic.