The world experienced unprecedented high-impact climate extremes during the 2001–2010 decade, which was the warmest since the start of modern measurements in 1850 and which continued an extended period of pronounced global warming. More national temperature records were reported broken than in any previous decade. The Global Climate 2001-2010, A Decade of Climate Extremes, published by WMO in July, analyzes global and regional temperatures and precipitation as well as extreme events such as the heat waves in Europe and Russia, Hurricane Katrina in the United States of America, Tropical Cyclone Nargis in Myanmar, droughts in the Amazon Basin, Australia and East Africa, and floods in Pakistan.
The decade was the warmest for both hemispheres and for both land and ocean surface temperatures. The record warmth was accompanied by a rapid decline in Arctic sea ice and accelerating loss of net mass from the Greenland and Antarctic ice sheets and from the world’s glaciers. As a result of this widespread melting and the thermal expansion of sea water, global mean sea levels rose about 3 millimetres (mm) per year, about double the observed 20th century trend of 1.6 mm per year. Global sea level, averaged over the decade, was about 20 cm higher than that of 1880, according to the report.
The report, which also charts rising atmospheric concentrations of greenhouse gases, noted that the global-average concentrations of CO2 in the atmosphere rose to 389 parts per million in 2010 (an increase of 39% since the start of the industrial era in 1750). In the same period, methane concentrations rose to 1808.0 parts per billion (158%) and nitrous oxide to 323.2 parts per billion (20%).
Between 2001 and 2010, there was no major El Niño event, which normally leads to higher temperatures (as occurred in the then-record warm year of 1998). Much of the decade experienced either cooling La Niña or neutral conditions, except for 2009/2010, in which a moderate to strong El Niño was recorded.
The 100-page report incorporates findings from a unique survey of 139 NMHSs as well as socio-economic data and analysis from several UN agencies and partners. It was released to coincide with the first session of the Intergovernmental Board on Climate Services. The publication is available free-of-charge in the WMO online library.