2010 in the top three warmest years

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2010 in the top three warmest years, 2001-2010 warmest 10-year period

Cancun/Geneva (WMO) - The year 2010 is almost certain to rank in the top 3 warmest years since the beginning of instrumental climate records in 1850, according to data sources compiled by the World Meteorological Organization (WMO). The global combined sea surface and land surface air temperature for 2010 (January–October) is currently estimated at 0.55°C ± 0.11°C1 (0.99°F ± 0.20°F) above the 1961–1990 annual average of 14.00°C/57.2°F. At present, 2010’s nominal value is the highest on record, just ahead of 1998 (January-October anomaly +0.53°C) and 2005 (0.52°C)2. The ERA-Interim3 reanalysis data are also indicating that January-October 2010 temperatures are near record levels. The final ranking of 2010 will not become clear until November and December data are analysed in early 2011. Preliminary operational data from 1-25 November indicate that global temperatures from November 2010 are similar to those observed in November 2005, indicating that global temperatures for 2010 are continuing to track near record levels.

Over the ten years from 2001 to 2010, global temperatures have averaged 0.46°C above the 1961-1990 average, 0.03°C above the 2000-09 average and the highest value ever recorded for a 10-year period. Recent warming has been especially strong in Africa, parts of Asia, and parts of the Arctic; the Saharan/Arabian, East African, Central Asian and Greenland/Arctic Canada sub-regions have all had 2001-10 temperatures 1.2 to 1.4°C above the long-term average, and 0.7°C to 0.9°C warmer than any previous decade.

Surface air temperatures over land were above normal across most parts of the world. The most extreme warm anomalies occurred in two major regions. The first extended across most of Canada and Greenland, with mean annual temperatures 3°C or more above normal in parts of west Greenland and the eastern Canadian Arctic and sub-Arctic. The second covered most of the northern half of Africa and south Asia, extending as far east as the western half of China, with annual temperatures 1 to 3°C above normal over most of the region. Many parts of both regions had their warmest year on record, including large parts of northern Africa, the Arabian Peninsula and southwest Asia (with Turkey and Tunisia having their warmest year on record), as well as much of the Canadian Arctic and coastal Greenland. Four of the five sub-regions4 which are wholly or partly in Africa (West and Southern Africa, the Saharan/Arabian region and the Mediterranean) are on course for their warmest year on record, along with South and Central Asia, and Greenland/Arctic Canada. Temperatures averaged over Canada have also been the highest on record.

Only limited land areas had below-normal temperatures in 2010, the most notable being parts of western and central Siberia in Russia, parts of southern South America, interior Australia, parts of northern and western Europe, eastern China and the southeast United States. It was the coolest year since 1996 for the northern European region, and since 1998 for northern Asia, due mainly to below-normal temperatures during the winter. A number of northern European countries are also likely to have their coolest year since 1996, including the United Kingdom, Germany, France and Norway.

Sea surface temperatures were below normal over most of the eastern half of the Pacific Ocean as a result of the La Niña event which developed during the year, but were well above normal over most parts of the Indian and Atlantic Oceans. The tropical North Atlantic was especially warm with temperatures at record levels over most of the area east of longitude 55°W.

Major regional climate events in 2010

Extreme Asian summer monsoon in some regions

Pakistan experienced the worst flooding in its history as a result of exceptionally heavy monsoon rains. The event principally responsible for the floods occurred from 26-29 July, when four-day rainfall totals exceeded 300 millimetres over a large area of northern Pakistan centred on Peshawar. There were additional heavy rains further south from 2-8 August which reinforced the flooding. More than 1500 lives were lost, and over 20 million people were displaced as large parts of Pakistan’s agricultural land were inundated. In terms of the number of people affected, the United Nations rated the flood as the greatest humanitarian crisis in recent history. The total monsoon season rainfall for Pakistan was the fourth-highest on record, and the highest since 1994.

Summer rainfall was also well above normal in western India, and China experienced its most significant monsoon flooding since 1998, with south-eastern China and parts of the northeast most severely affected. The latter floods also extended to the Korean Peninsula. A number of these floods led to significant loss of life, directly as well as through landslides in China, which claimed more than 1400 lives in Gansu Province. However, monsoon season rainfall averaged over India was only 2% above normal, and it was well below normal in north-eastern India and Bangladesh, which had its driest monsoon season since 1994.

Extreme summer heatwaves in Russia and other regions

The Northern Hemisphere summer saw exceptional heatwaves in several parts of Eurasia. The most extreme heat was centred over western Russia, with the peak extending from early July to mid-August, although temperatures were well above normal from May onwards. In Moscow, July mean temperatures were 7.6°C above normal, making it the city’s hottest month on record by more than 2°C, and similar anomalies continued until cooler conditions developed in the last 10 days of August. A new record high temperature for the city of 38.2°C was set on 29 July, and it reached 30°C or above on 33 consecutive days (in comparison, there were no days at all above 30°C in the summer of 2009). About 11,000 excess deaths during the summer were attributed to the extreme heat in Moscow alone5. Some parts of central European Russia had average temperatures more than 5°C above normal for the summer. The heat was accompanied by destructive forest fires, while severe drought, especially in the Volga region, led to widespread crop failures. Neighbouring countries were also affected, with extreme high maximum temperatures recorded in Finland, Ukraine and Belarus, and record high numbers of extreme warm nights in parts of south-eastern Europe, including Serbia.

It was also a very hot summer in many other parts of Eurasia and northern Africa. The Russian Far East had temperatures well above normal, which combined with the extreme heat in the west to result in the hottest summer on record averaged over Russia as a whole. Japan and China also had their hottest summers on record. Earlier in the year, there was exceptional pre-monsoon heat in southern Asia, which included a temperature of 53.5°C at MohenjoDaro on 26 May, a national record for Pakistan and the highest temperature in Asia since at least 1942. Extreme heat affected northern Africa and the Arabian Peninsula at times during the summer, with notable readings including 52.0°C at Jeddah (Saudi Arabia), 50.4°C at Doha (Qatar) and 47.7°C at Taroudant (Morocco).

An abnormal winter in many parts of the Northern Hemisphere

The normal mid-latitude westerly flow was unusually weak during the 2009-10 northern hemisphere winter, which resulted in many substantial climate anomalies in various parts of the hemisphere. In particular, it was a rather cold winter over most of Europe (except the Mediterranean region), the Asian part of Russia (except for the Far East) and Mongolia. The peak winter temperature anomalies (below 4°C) were in central Russia, but in a historical context the most unusual conditions were on the western periphery of Europe, with Ireland and Scotland both experiencing their coldest winter since 1962-63. Many other parts of northern and central Europe had their coldest winter since 1978-79, 1986-87 or 1995-96, although the temperatures were generally not exceptional in a long-term historical context. The lack of the normal winter westerlies also resulted in dry conditions in normally high-rainfall coastal areas, with western Norway having its driest winter on record (72% below normal). While strong westerly winds were infrequent for most of the winter, a severe winter storm (Xynthia) crossed northwestern Europe at the end of February, causing widespread wind and storm surge damage, especially in France where wind speeds exceeded 150 km/h on the west coast. Further south in Europe, it was a very wet winter, with precipitation widely 100% or more above normal over Spain, Portugal, Italy and south-eastern Europe.

Northern Africa recorded warm conditions during winter. February temperatures averaged 3.7°C above the long-term average over the Saharan/Arabian region, the largest anomaly on record for any month. In late February temperatures reached between 30 and 36 °C in northern Algeria, the highest for February since 1980. Winter temperatures were also well above normal over Turkey and the Middle East.

In North America the normal north-south gradient of temperature was much weaker than normal. Canada had its warmest winter on record, with national temperatures +4.0°C above the long-term average; winter temperatures were 6°C or more above normal in parts of the country’s north. (It went on also to have its warmest spring on record, with temperatures +4.1°C above the long-term average). The warm conditions extended further east in the Arctic to cover Greenland and Spitsbergen. Canada also had its driest winter on record, with especially abnormal dry conditions in British Columbia (which combined with unusually high temperatures to cause poor snow conditions for some events at the Winter Olympics in Vancouver). In contrast, most of the continental United States (except for the far northwest and northeast) was colder than normal. For the United States as a whole it was the coldest winter since 1984-85, and most southern areas from Texas eastwards had one of their 10 coldest winters on record. These cold conditions were accompanied by unusually extensive snow cover, and very heavy seasonal snowfall amounts in some eastern cities, including a record seasonal total in Washington D.C.

Heavy rains and flooding

Large parts of Indonesia and Australia experienced heavy rains in 2010 as a La Niña event developed, with particularly unusual rains from May onwards (normally the driest time of the year). In Indonesia, at least double the normal monthly rainfall fell in each of the months from June to October in most of Java, the islands east of Java and southern Sulawesi. The May-October period was the wettest on record for northern Australia with rainfall 152% above normal, while above-normal rains further south contributed to an easing of long-term drought in parts of the southeast. The spring was especially wet, and averaged over Australia was the wettest on record.

Whilst seasonal rainfall was not as persistently above normal further north in southeast Asia, both Thailand and Vietnam experienced major floods in October with significant loss of life and economic damage.

Many other parts of the world were affected by significant floods during 2010. An active wet summer monsoon season in the West African Sahel was accompanied by floods from time to time, with Benin and Niger the countries most severely affected. In Benin, this caused the worst flooding on record in terms of impact, causing severe losses to the agriculture sector and severe disturbances to public services, including cutting access to health centres, although rainfall amounts themselves were mostly not record-breaking.

Central Europe had major floods in May, particularly in eastern Germany, Poland and Slovakia; in late June flooding occurred in Romania, Ukraine and Moldova, and later Germany had its wettest August on record. Bursa (Turkey) had its wettest January-October on record (1152 mm, 132% above normal), while precipitation averaged over Romania for the January-October period was 34% above normal, and the northern Bohemia region (Czech Republic) had its wettest year since 1981.

In South America, Colombia had its most severe floods in more than 30 years in November. More localised flash floods caused severe damage and loss of life in numerous other locations, including Rio de Janeiro, Brazil (April), Madeira (February), Arkansas, United States (June) and southern France (June).

Drought in the Amazon and elsewhere

Parts of the Amazon basin were badly affected by drought during the later part of 2010. An unusually dry July-September period in northwestern Brazil resulted in sharply reduced streamflow in many parts of the Amazon catchment, with the Rio Negro, a major Amazon tributary, falling to its lowest level on record. Earlier in the year, Guyana and the eastern Caribbean islands were badly affected by drought, with rainfall for the period from October 2009 to March 2010 widely in the driest 10% of recorded years.

In Asia, parts of southwestern China experienced severe drought through late 2009 and early 2010. Yunnan and Guizhou provinces both had their lowest rainfalls on record during the period from September 2009 to mid-March 2010 with totals widely 30% to 80% below normal. The dry conditions were also accompanied by above-normal temperatures and numerous forest fires. Conditions there eased with good rains during the summer. Pakistan also experienced drought in the early months of 2010 before the onset of the monsoon. Summer rains also eliminated developing drought conditions in parts of western Europe, where the United Kingdom had its driest January-June period since 1929.

Some other parts of southern Asia, including northeastern India, Bangladesh, and parts of Thailand and Vietnam, were relatively dry during the main monsoon season, although Thailand and Vietnam were then hit by floods in October. Whilst widespread above-normal rains eased long-term drought in many parts of Australia, the southwest was a marked exception, with January-October 2010 being the region’s driest such period on record.

El Niño, La Niña and other major large-scale climate drivers

2010 began with an El Niño event well established in the Pacific Ocean. This broke down quickly in the early months of the year. A rapid transition took place and La Niña conditions were in place by August. By some measures the La Niña event in progress in late 2010 is the strongest since at least the mid-1970s. The atmospheric response has been especially strong, with the Southern Oscillation Index (SOI) reaching its highest monthly value since 1973 in September. The El Niño-to-La Niña transition is similar to that which occurred in 1998, another very warm year, although in 2010 the El Niño was weaker, and the La Niña stronger, than was the case in 1998.

The eastern tropical Indian Ocean was also significantly warmer than normal during the second half of 2010 (negative Indian Ocean Dipole), in contrast with the previous La Niña event in 2007-08 when it was generally cooler than normal. The Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) were in a negative phase for most of the year, exceptionally so in the 2009/10 Northern Hemisphere winter, which on most indicators had the most strongly negative seasonal AO/NAO on record. The Antarctic Oscillation (AAO) (also known as the Southern Annular Mode (SAM)) was in positive mode for most of the year, reaching its highest monthly values since 1989 in July and August.

Tropical cyclone activity well below normal, except in the North Atlantic

Global tropical cyclone activity was well below normal in 2010, except in the North Atlantic. A total of 65 tropical cyclones have been observed so far in 2010, of which 35 have reached hurricane/typhoon intensity as of 30 November. These are both well short of the long-term averages of 85 and 44 respectively. It is likely that the final total for the year will be the lowest since at least 1979.

Tropical cyclone activity was especially sparse in the North Pacific Ocean. Only 7 cyclones occurred in the Northeast Pacific and 14 in the Northwest Pacific (long-term averages 17 and 26 respectively). Both the Northeast and Northwest Pacific totals were the lowest on record for January-November. In contrast, the North Atlantic had a very active season with 19 named storms and 12 hurricanes, which is equal second highest behind the record of 15 set in 2005 (long-term averages 10 and 5 respectively).

The strongest tropical cyclone of the year was Supertyphoon Megi, which crossed the northern Philippines in October after reaching a minimum central pressure of 885 hPa, making it the strongest tropical cyclone in the world since 2005 and the strongest in the Northwest Pacific since 1984. Megi caused widespread damage to infrastructure and agriculture in the northern Philippines, Taiwan and Fujian province in China, but only limited casualties. Tomas (North Atlantic, November) reached category 2 intensity, but its associated rains contributed to the spread of a cholera epidemic in Haiti.

Polar regions: third-lowest Arctic summer sea ice minimum on record

Arctic sea-ice extent was again well below normal in 2010. The minimum extent of Arctic sea ice was reached on 19 September with an area of 4.60 million square kilometres, the third-lowest seasonal minimum in the satellite record after 2007 and 2008, and more than 2 million square kilometres below the long-term average. The autumn 2010 freeze-up has also been abnormally slow, with the ice cover as of 28 November being the lowest on record for the time of year. The Canadian sector had its lowest summer ice extent on record. The low ice cover was consistent with well above normal temperatures over most of the Arctic, with numerous stations in Greenland, as well as the Greenland/Arctic Canada region as a whole, having their warmest year on record with annual mean temperatures 3-4°C above normal.

In contrast, Antarctic sea ice extent was generally slightly above normal in 2010, with the lowest monthly average being 3.16 million square kilometres in February, 0.22 million square kilometres above the long-term average. Temperatures averaged over the Antarctic region were also slightly above normal.

Background to data used in this statement

This preliminary information for 2010 is based on climate data from networks of land-based weather and climate stations, ships and buoys, as well as satellites. The data are continuously collected and disseminated by the National Meteorological and Hydrological Services (NMHSs) of the 189 Members of WMO and several collaborating research institutions. The data continuously feed three main depository global climate data and analysis centres, which develop and maintain homogeneous global climate datasets based on peer-reviewed methodologies. The WMO global temperature analysis is thus principally based on three complementary datasets. One is the combined dataset maintained by both the Hadley Centre of the UK Met Office and the Climatic Research Unit, University of East Anglia, United Kingdom. Another dataset is maintained by the National Oceanic and Atmospheric Administration (NOAA) under the United States Department of Commerce, and the third one is from the Goddard Institute of Space Studies (GISS) operated by the National Aeronautics and Space Administration (NASA). Preliminary November 2010 information is drawn from the ERA-Interim reanalysis-based data set maintained by the European Centre for Medium-Range Weather Forecasts (ECMWF). The content of the WMO statement is verified and peer-reviewed by leading experts from other international, regional and national climate institutions and centres before its publication.

Final updates and figures for 2010 will be published in March 2011 in the annual WMO Statement on the Status of the Global Climate.

1. The +/- 0.11°C uncertainty has been calculated from the HadCRU data set only. It is likely that the uncertainty for the three data sets combined is marginally lower than this but this has not been quantified.

2. Uncertainty margins for 2005 and 1998 are +/- 0.10 C

3. The ERA-Interim reanalysis is produced by the European Centre for Medium-Range Weather Forecasts (ECMWF),

4. The sub-regions used in this report are those defined by the IPCC (available at http://www.ipcc.ch/ipccreports/tar/wg1/fig10-1.htm), with some regional names slightly modified. Sub-regional temperature anomalies are drawn from the HadCRU data set.

5. According to a Moscow city health official quoted by the AFP news agency (http://www.terradaily.com/reports/Russian_heatwave_caused_11000_deaths_in_Moscow_official_999.html)

The World Meteorological Organization is the United Nations System’s authoritative voice on Weather, Climate and Water

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