The year 2010 may have been the most extreme in terms of weather since the explosion of Indonesia's Mount Tambora in 1816, when much of the world experienced reduced daylight and no summer, says one of the world's most prominent meteorologists.
A combination of abnormal climatic phenomena resulted in the year being the hottest, wettest, and in many cases also the driest and coldest in recorded history, says Jeff Masters, co-founder of climate tracking website Weather Underground.
According to Masters 2011 is already on track to be exceptional, with a deepening drought in Texas - where 65% of the state is now in "exceptional drought" conditions - and one of the warmest springs experienced in 100 years taking place across much of Europe. It is also the most extreme tornado year recorded in the US, with Arctic sea ice already at its lowest ever for the time of year.
US and UK government scientists declared in January that 2010 had tied with 2005 as the warmest year of the global surface temperature record - the 34th consecutive year with temperatures above the 20th-century average - but, says Masters, new data on other climatic phenomena suggest that extremes were widespread.
Scientists recorded the second-worst year for coral bleaching (caused by raised sea temperatures), the lowest-ever volume of Arctic Sea ice, highly unusual monsoons in China and a series of abnormal storms across the US and elsewhere. Some of the phenomena have been linked to a strong El Nino/La Nina episode, which follows unexplained temperature changes in the Pacific Ocean near the equator. Global tropical cyclone activity, however, was the lowest on record.
According to Masters, 19 countries - covering nearly 20% of the global land area - experienced their hottest recorded years in 2010. "Hot years tend to generate more wet and dry extremes than cold years. This occurs [because] there is more energy available to fuel the evaporation that drives heavy rains and snows, and to make droughts hotter and drier in places storms are avoiding," he says.
"Many of the flood disasters in 2010-11 were undoubtedly heavily influenced by the strong El Nino and La Nina events that occurred, [but] the ever-increasing amounts of heat-trapping gases humans are emitting into the air puts tremendous pressure on the climate system to shift to a new, radically different, warmer state, and the extreme weather of 2010-11 suggests that the transition is already well underway.
"I don't believe that years like 2010 and 2011 will become the 'new normal' in the coming decade. [But] a warmer planet has more energy to power stronger storms, hotter heat waves, more intense droughts, heavier flooding rains, and record glacier melt that will drive accelerating sea-level rise. I expect that by 20-30 years from now, extreme weather years like we witnessed in 2010 will become the new normal," he says.
Climate abnormalities in 1816 caused average global temperatures to decrease by about 0.4-0.7 degC, resulting in major food shortages across the northern hemisphere. It is believed that this was largely caused by a succession of major volcanic eruptions capped off by the Mount Tambora eruption of 1815 - the largest known eruption in over 1,300 years.
2010: a year of extremes
Heat
Temperatures in Earth's lower atmosphere tied with the warmest year on record. Unofficially, 19 nations set all-time extreme heat records in 2010.
Snowmageddon
The atmospheric circulation in the Arctic took on its most extreme configuration in 145 years of record-keeping. Canada had its warmest and driest winter on record, but the US its coldest winter in 25 years. A series of remarkable snowstorms pounded the eastern US with the "Snowmageddon" blizzard dumping more than two feet of snow on Baltimore and Philadelphia.
Sea ice
Arctic Sea ice volume in 2010 was the lowest on record, with 60% missing in September 2010 compared to the average from 1979-2010.
Corals
Coral reefs took their second-worst beating on record in 2010, thanks to record or near-record high summer water temperatures over much of the planet's tropical oceans.
Wettest
Last year set a new record for the wettest term in Earth's recorded history over land areas. The difference in precipitation from the average in 2010 was about 13% higher than that of the previous record wettest year, 1956. The record wetness over land was counterbalanced by relatively dry conditions over the oceans.
Amazon
The Amazon rainforest experienced its second 100-year drought in five years with the largest northern tributary of the Amazon river - the Rio Negro - dropping to 13 feet (four metres) below its usual dry-season level. This was its lowest level since record-keeping began in 1902.
Cyclones and hurricanes
Each year, the globe has about 92 cyclones - called hurricanes in the Atlantic and eastern Pacific, typhoons in the western Pacific and tropical cyclones in the southern hemisphere. In 2010, we had just 68.
Monsoon
An abnormal summer monsoon helped lead to precipitation 30-80% below normal in northern China and Mongolia, and 30-100% above average across a wide swath of central China. Western China saw summer precipitation of more than double the average.
Heatwaves
A scorching heatwave struck Moscow in late June 2010 and steadily increased in intensity through July, as the jet-stream remained "stuck" in an unusual loop that kept cool air and rain-bearing low-pressure systems far north of the country.