Record highs and drought
Although the 2009/2010 European winter saw some exceptionally cold and snowy periods, the Arctic polar regions and Canada experienced unusually mild winter conditions. Northern Europe experienced its coldest winter for nearly 30 years, while temperatures in some places in the Arctic and Canada reached +6°C above the long-term average and Canada experienced its mildest winter on record.
Despite a very few cold places, above average winter temperatures were also experienced in most parts of China, South Asia, the Middle East and Africa. Although Europe experienced a very cold winter, the period December 2009 to February 2010 saw temperatures across the whole of the northern hemisphere to be an estimated half a degree over the long-term average. The southern hemisphere also saw above average temperatures during its summer, with Australia experiencing an extended drought and forest fires.
The northern hemisphere summer continued the trend of above average temperatures; Russia suffered under its longest known heatwave with record temperatures experienced in several parts of the country and contributing to a prolonged and expensive drought. The Russian heatwave is an unprecedented weather event that caused more than 4,000 deaths, wrecked a quarter of Russia's grain crop and may eventually see $14 billion cut from the country's gross domestic product. Predictions that global warming may benefit crop yields in the northern hemisphere are appearing to be far from accurate, with one of the world's bread baskets severely hit by drought. Grain prices in Europe are expected to soar as a result. Records continued to tumble in the autumn, with Russia experiencing record November temperatures.
Drought has been felt harshly elsewhere around the globe: as the Amazon basin experienced its worse drought for 40 years, the Rio Negro, an important tributary of the Amazon, fell to a record low. Rafael Cruz, a Greenpeace activist in Manaus, Brazil, told The Guardian that recent years had seen both extreme droughts and flooding become worryingly frequent.
2010 has seen a year of record breaking temperatures around the globe. In July, the Peruvian government declared a state of emergency in many of Peru's regions due to cold weather. In areas in the south of the country, temperatures dropped as low as -24°C and Lima recorded its lowest temperatures in 46 years at 8°C. In the south, hundreds of people, the majority of them very young children, died of cold-related diseases such as pneumonia.
However, the trend in 2010 has been for record breaking highs, with several countries experiencing their highest ever temperatures: 49.6°C in Dongola, Sudan (June); 52°C in Basra, Iraq (June); 44°C in Yashkul, Russia (July); 50.4°C in Doha, Qatar (July); 37.2°C in Joensuu, Finland (July) and 53.5°C in Mohenjo-daro, Pakistan (June), the fourth highest temperature ever recorded. While we expect to see the odd record breaking high each year, this year has been unusual in that we've seen record after record broken.
National Oceanic and Atmospheric Administration (NOAA) figures show that the combined global land and ocean average surface temperature for March, April , May and June all reached their highest ever level this year. The June figure continued another trend by being the 304th consecutive month with a global temperature above the 20th century average.
Perhaps unsurprisingly, 2010 has also seen the largest calving from Greenland's ice sheet in the past 50 years of observations and data. The MODIS sensor on NASA's Aqua satellite detected a large chunk of ice measuring around 260km2 breaking from the Petermann Glacier. The WMO reports that although ""tens of thousands of icebergs calve yearly from the glaciers of Greenland... this one is very large and because of its size more typically resembles icebergs in the Antarctic"".
Exceptional rainfall and flooding
2010 has seen extremely heavy rainfall in many countries around the world that has caused unprecedented flooding, often of a severity not witnessed since records began. The flooding in Pakistan in July was precipitated by phenomenal monsoon rainfall: in two days 400mm fell in mountain areas in the far north of Pakistan flooding the Indus River along a 1,000km stretch, the worst flooding in over a 100 years. Twenty million people were affected, tens of thousands of villages were swept away, hundreds of thousands of livestock perished and millions of acres of crops were destroyed. It is a catastrophe greater in size than the 2004 Indian Ocean Tsunami, the 2005 Pakistan earthquake and the Haitian earthquake combined.
The rainy season in West Africa has resulted in flooding in almost every country in the region with the worst hit being Benin, where two thirds of the country was inundated, destroying 300,000 acres of crops and affecting half a million people. The flooding is the worst to hit the country in 50 years, and was caused by extremely heavy rain (twice the normal amount) bursting the Niger River's banks in the north of the country. The most serious problem Benin's population now faces is the outbreak of water-borne diseases, especially cholera, with nearly 1,000 cases reported by the end of October.
Flooding over the summer also caused major problems in southeast Europe and a disaster in China, where mudslides destroyed villages and killed over 1,000 people in August. The mudslides were undoubtedly precipitated by unusually heavy rainfall, but the cause can also be attributed to man-made events; in the worst hit province, Gansu, deforestation has reduced the forested area by nearly a third. The Gansu mudslide contained up to 1,800,000m3 of mud and covered an area 5km long and 300m wide in a surge reported to be five storeys high.
The intense rainfall in Asia can partly be attributed to the movement south of the jet stream, with evidence suggesting that heavy rainfall in the region has increased significantly over the past 20 years.
Intense tropical cyclones
The WMO Expert Team on Climate Change Impacts on Tropical Cyclones early this year concluded that, if global warming continues, there will likely be an increase, on average worldwide, in the strength and intensity of tropical cyclones while the total number of worldwide cyclones will either decrease or remain the same.
This year has not been notable for a large increase in the number of tropical cyclones, but we have witnessed extreme events such as Super-typhoon Megi that hit northern Philippines in October, with sustained one-minute winds of 190mph and gusts of up to 220mph. With surface pressure as low as 885mb, Megi is one of the 10 most intense tropical cyclones ever recorded. While the human cost of this event was relatively small, thanks in part to accurate predictions and storm warnings, the destruction wrought on farm lands by this type of weather event impacts on worldwide food prices, with potentially repercussions.
Are the unprecedented weather events experienced this year, especially the extreme temperatures, evidence that global warming is taking place?
According to the World Meteorological Organization (WMO), 2010 appears on track to be the world's warmest year since reliable temperature records began in the mid-19th century, beating the previous record set in 1998, a fact that appears consistent with the general pattern of climate change. ""We will always have climate extremes. But it looks like climate change is exacerbating the intensity of the extremes,"" said Omar Baddour, chief of climate data management applications at WMO headquarters in Geneva.
The WMO's August 2010 report on extreme weather states that although individual climate extremes have always existed, the events this year ""exceed in intensity, duration or geographical extent, the previous largest historical events"". It also suggests that the weather events of 2010 can possibly be linked to the predicted increase in intensity and frequency of extreme events; quoting the Intergovernmental Panel on Climate Change: ""The type, frequency and intensity of extreme events are expected to change as Earth's climate changes, and these changes could occur even with relatively small mean climate changes. Changes in some types of extreme events have already been observed, for example, increases in the frequency and intensity of heatwaves and heavy precipitation events.""
The cause of this climate change? Omar Baddour told theWeather: ""Currently we are recording more than a 38% increase in COí¢äó_äó_ concentration in the atmosphere compared to the pre-industrial period. It is well established that global warming has likely increased the intensity and frequency of extreme weather and climate events, such as heat waves and extreme precipitation events.""