The year 2013 is on course to becoming the seventh-warmest year since climate records began in 1850. The average surface temperature during January to September has been 0.48 °C above the 1961–1990 average, according to the World Meteorological Organization’s provisional State of the Climate report, released today.
The first nine months of 2013 were slightly warmer than the same period in both 2011 and 2012, according to the WMO. If no major outliers occur in what remains of the year, the global surface temperature in 2013 will have been close to the average during 2001–2010, the warmest decade on record.
In the Northern Hemisphere, weather patterns were influenced this year by a negative phase of the so-called Arctic Oscillation, a pressure system which tends to bring cold air to lower latitudes. This has caused the relatively cool spring temperatures in Europe and some parts of North America and Asia, says the WMO. Australia, on the other hand, experienced the hottest summer on record.
Despite the slow-down in the rise of the average global temperature in recent years, nothing suggests that global warming might not continue, the WMO warns. The atmospheric concentration of heat-trapping greenhouse gases, which in 2012 reached a record high carbon dioxide equivalent of 476 parts per million, is expected to reach a new record high in 2013 and will likely climb further in the forthcoming years, says the report.
The global sea level, which currently rises by around 3 millimetres per year, has also reached a new record high.
In late May and early June, extreme rainfall in central Europe led to major floods along the Danube and Elbe Rivers. Owing to unusually early and heavy monsoon rains, bad flooding also occurred near the India-Nepal border. This year’s monsoon season was relatively friendly to large parts of Africa including the Sahel zone. However, Angola and Namibia suffered their worst droughts in 30 years.
In terms of numbers of storms, the 2013 hurricane and typhoon season was so far only slightly above the 1981–2010 average. Whether climate change has added to the severity of storms, notably to the unprecedented destructiveness of Typhoon Haiyan in the Philippines, is still up for debate.