The World Meteorological Organization’s Statement on the Status of the Global Climate which put 2012 joined the ten previous years as one of the warmest — at ninth place — on record made number of other significant observations.
Above-average temperatures were observed during 2012 across most of the globe’s land surface areas, most notably North America, southern Europe, western Russia, parts of northern Africa and southern South America. Nonetheless, cooler-than-average conditions were observed across Alaska, parts of northern and eastern Australia, and central Asia.
Precipitation across the globe was slightly above the 1961-1990 long-term average. There were drier-than-average conditions across much of the central United States, northern Mexico, northeastern Brazil, central Russia, and south-central Australia. Wetter-than-average conditions were present across northern Europe, western Africa, north-central Argentina, western Alaska, and most of northern China.
Snow cover extent in North America during the 2011/2012 winter was below average, resulting in the fourth smallest winter snow cover extent on record, according to data from the Global Snow Laboratory. This was in marked contrast to the previous two winters (2009/2010 and 2010/2011), which had the largest and third largest snow cover extent, respectively, since records began in 1966.
Meanwhile, the Eurasian continent snow cover extent during the winter was above average, resulting in the fourth largest snow cover extent on record. Overall, the northern hemisphere snow cover extent was above average – 590000 km2 above the average of 45.2 million km2 – and was the fourteenth largest snow cover extent on record.
Greenland ice sheet: In early July, Greenland’s surface ice cover melted dramatically, with an estimated 97 per cent of the ice sheet surface having thawed in mid-July. This was the largest melt extent since satellite records began 34 years ago. During the summer it is typical to observe nearly half of the surface of Greenland’s ice sheet melt naturally, particularly across the lower elevations. However, in 2012 a high-pressure system brought warmer-than-average conditions to Greenland, which are associated with the rapid melting.
Arctic sea ice extent reached its record lowest level in its annual cycle on 16 September at 3.41 million km2. This value broke the previous record low set on 18 September 2007 by 18 per cent. It was 49 per cent or nearly 3.3 million km2 below the 1979–2000 average minimum. The difference between the maximum Arctic sea-ice extent on 20 March and the lowest minimum extent on 16 September was 11.83 million km2 – the largest seasonal sea-ice extent loss in the 34-year satellite record.
Antarctic sea-ice extent in March was the fourth largest on record at 5.0 million km2 or 16.0 per cent above the 1979–2000 average. During its growth season, the Antarctic sea-ice extent reached its maximum extent since records began in 1979 on 26 September, at 19.4 million km2. This value surpassed the previous maximum sea-ice extent record of 19.36 million km2 set on 21 September 2006.
Extreme Events: Hurricane Sandy killed close to 100 people and caused major destruction in the Caribbean and tens of billions of US dollars in damage and around 130 deaths in the eastern United States of America. Typhoon Bopha, the deadliest tropical cyclone of the year, hit the Philippines – twice – in December. During the year, the United States and south-eastern Europe experienced extreme drought conditions, while West Africa was severely hit by extreme flooding. The populations of Europe, northern Africa and Asia were acutely affected by extreme cold and snow conditions. Severe flooding occurred in Pakistan or a third consecutive year.
Climate change is aggravating naturally occurring climate variability and has become a source of uncertainty for climate-sensitive economic sectors like agriculture and energy.
“It is vital that we continue to invest in the observations and research that will improve our knowledge about climate variability and climate change,” said Mr Jarraud.
“We need to understand how much of the extra heat captured by greenhouse gases is being stored in the oceans and the consequences this brings in terms of ocean acidification and other impacts. We need to know more about the temporary cooling effects of pollution and other aerosols emitted into the atmosphere. We also need a better understanding of the changing behaviour of extreme weather and climate events as a consequence of global warming, as well as the need to assist countries in the most affected areas to better manage climate-related risks with improved climate early warning and climate watch systems,” said Mr Jarraud.