Since the start of the 20th century, the global average surface temperature has risen approximately 0.7°C. But this rise has not been continuous. Since 1976, the global average temperature has risen sharply, at 0.18°C per decade. In the northern and southern hemispheres, the period 1997-2006 averaged 0.53°C and 0.27°C above the 1961-1990 mean, respectively.

Regional temperature anomalies. The beginning of 2006 was unusually mild in large parts of North America and the western European Arctic islands, though there were harsh winter conditions in Asia, the Russian Federation and parts of eastern Europe. Canada experienced its mildest winter and spring on record, the USA its warmest January-September on record and the monthly temperatures in the Arctic island of Spitsbergen (Svalbard Lufthavn) for January and April included new highs with anomalies of +12.6°C and +12.2°C, respectively.

Persistent extreme heat affected much of eastern Australia from late December 2005 until early March with many records being set (e.g. second hottest day on record in Sydney with 44.2°C / 111.6°F on 1 January). Spring 2006 (September-November) was Australia’s warmest since seasonal records were first compiled in 1950. Heat waves were also registered in Brazil from January until March (e.g. 44.6°C / 112.3°F in Bom Jesus on 31 January—one of the highest temperatures ever recorded in Brazil).

Several parts of Europe and the USA experienced heat waves with record temperatures in July and August. Air temperatures in many parts of the USA reached 40°C / 104°F or more. The July European-average land-surface air temperature was the warmest on record at 2.7°C above the climatological normal.

Autumn 2006 (September-November) was exceptional in large parts of Europe at more than 3°C warmer than the climatological normal from the north side of the Alps to southern Norway. In many countries it was the warmest autumn since official measurements began: records in central England go back to 1659 (1706 in The Netherlands and 1768 in Denmark).

Prolonged drought in some regions. Long-term drought continued in parts of the Greater Horn of Africa including parts of Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Somalia, and the United Republic of Tanzania. At least 11 million people were affected by food shortages; Somalia was hit by the worst drought in a decade.

For many areas in Australia, the lack of adequate rainfall in 2006 added to significant longer-term dry conditions, with large regions having experienced little recovery from the droughts of 2002-2003 and 1997-1998. Dry conditions have now persisted for 5 to 10 years in some areas and in south-west Western Australia for around 30 years.

Across the USA, moderate-to-exceptional drought persisted throughout parts of the south-west desert and eastward through the southern plains, also developing in areas west of the Great Lakes. Drought and anomalous warmth contributed to a record wildfire season for the USA, with more than 3.8 million hectares burned through early December. Drought in the south of Brazil caused significant damage to agriculture in the early part of the year with losses of about 11 per cent estimated for the soybean crop yield alone.

Severe drought conditions also affected China. Millions of hectares of crops were damaged in Sichuan province during summer and in eastern China in autumn. Significant economic losses as well as severe shortages in drinking water were other consequences.

Heavy precipitation and flooding. As the 2005/2006 rainy season was ending, most countries in southern Africa were experiencing satisfactory rainfall during the first quarter of 2006.

In northern Africa, floods were recorded in Morocco and Algeria during 2006 causing infrastructure damage and some casualties. Rare heavy rainfall in the Sahara Desert region of Tindouf produced severe flooding in February damaging 70% of food stocks and displacing 60,000 people. In Bilma, Niger, the highest rainfall since 1923 affected nearly 50,000 people throughout August.

In the same month, the most extensive precipitation in 50 years brought significant agricultural losses to the region of Zinder, Niger. Heavy rain also caused devastating floods in Ethiopia in August, claiming more than 600 lives. Some of the worst floods occurred in Dire Dawa and along the swollen Omo River. Again in October and November, the Great Horn of Africa countries experienced heavy rainfall associated with severe flooding. The worst hit areas were in Ethiopia, Kenya and Somalia.

Somalia is undergoing its worst flooding in recent history; some places have received more than six times their average monthly rainfall and hundreds of thousands of people have been affected. This year’s floods are said to be the worst in 50 years in the Great Horn of Africa region. The heavy rains followed a period of long-lasting drought and the dry ground was unable to soak up large amounts of rainfall.

Heavy rainfall in Bolivia and Equador in the first months of the year caused severe floods and landslides with tens of thousands of people affected. Torrential rainfall in Suriname during early May produced the country’s worst disaster in recent times.

After 500 mm of torrential rainfall during a five-day period in February, a large-scale landslide occurred in Leyte Island, the Philippines with more than 1,000 casualties. Although close to average in total rainfall, the Indian monsoon season brought many heavy rainfall events with the highest rainfall in 24-hours ever recorded in several locations.

Only months after the destructive summer flooding in eastern Europe in 2005, heavy rainfall and snowmelt produced extensive flooding along the River Danube in April and the river reached its highest level in more than a century. Areas of Bulgaria, Hungary, Romania and Serbia were the hardest hit with hundreds of thousands of hectares inundated and tens of thousands of people affected.

Persistent and heavy rainfall during 10-15 May brought historic flooding to New England (USA), described as the worst in 70 years in some areas. Across the US mid-Atlantic and north-east, exceptionally heavy rainfall occurred in June. Numerous daily and monthly records were set and the rainfall caused widespread flooding which forced the evacuation of some 200,000 people. Vancouver in Canada experienced its wettest month ever in November with 351 mm, nearly twice the average monthly accumulation.

Development of moderate El Niño in late 2006. Conditions in the equatorial Pacific from December 2005 until the first quarter of 2006 showed some patterns typically associated with La Niña events. These however, did not lead to a basin-wide La Niña and, during April, even weak La Niña conditions dissipated. Over the second quarter of 2006, the majority of atmospheric and oceanic indicators reflected neutral conditions but, in August, conditions in the central and western equatorial Pacific started resembling typical early stages of an El Niño event.

By the end of the year, positive sea-surface temperature anomalies were established across the tropical Pacific basin. The El Niño event is expected by global consensus to continue at least into the first quarter of 2007.

Deadly typhoons in south-east Asia. In the north-west Pacific, 22 tropical cyclones developed (average 27), 14 of which classified as typhoons. Typhoons Chanchu, Prapiroon, Kaemi, Saomai, Xangsane, Cimaron and tropical storm Bilis brought deaths, casualties and severe damage to the region. Landed tropical cyclones caused more than 1,000 fatalities and economic losses of US $10 billion in China, which made 2006 the severest year in a decade. Typhoon Durian affected some 1.5 million people in the Philippines in November/December 2006, claiming more than 500 lives with hundreds still missing.

During the 2006 Atlantic hurricane season, nine named tropical storms developed (average: ten). Five of the named storms were hurricanes (average six) and two of those were major hurricanes (category three or higher on the Saffir-Simpson scale). In the eastern North Pacific 19 named storms developed, which is well above the average of 16; eleven reached hurricane strength of which six attained major status.

Twelve tropical cyclones developed in the Australian Basin, two more than the long-term average. Tropical cyclone Larry was the most intense at landfall in Queensland since 1918, destroying 80-90 per cent of the Australian banana crop.

Ozone depletion in the Antarctic and Arctic. On 25 September, the maximum area of the 2006 ozone hole over the Antarctic was recorded at 29.5 million km², slightly larger than the previous record area of 29.4 million km² reached in September 2000. These values are so similar that the ozone holes of these two years could be judged of equal size.

The size and persistence of the 2006 ozone hole area with its ozone mass deficit of 40.8 megatonnes (also a record) can be explained by the continuing presence of near-peak levels of ozone-depleting substances in combination with a particularly cold stratospheric winter. Low temperatures in the first part of January prompted a 20% loss in the ozone layer over the Arctic in 2006. Milder temperatures from late January precluded the large ozone loss seen in 2005.

Arctic sea-ice decline continues. The year 2006 continues the pattern of sharply decreasing Arctic sea ice. The average sea-ice extent for the entire month of September was 5.9 million km², the second lowest on record missing the 2005 record by 340 000 km². Including 2006, the September rate of sea ice decline is now approximately -8.59% per decade, or 60 421 km² per year.

Information sources. This preliminary information for 2006 is based on observations up to the end of November from networks of land-based weather stations, ships and buoys. The data are collected and disseminated on a continuing basis by the National Meteorological and Hydrological Services of WMO Members. However, the declining state of some observational platforms in some parts of the world is of concern.

Following established practice, WMO’s global temperature analyses are based on two different datasets. One is the combined dataset maintained by the Hadley Centre of the UK Met Office, and the Climatic Research Unit, University of East Anglia, UK. The other is maintained by the US Department of Commerce's National Oceanic and Atmospheric Administration (NOAA). Results from these two datasets are comparable: both indicate that 2006 is likely to be the sixth-warmest year globally.

More extensive updated information will be made available in the annual WMO Statement on the Status of the Global Climate in 2006, to be published in early March 2007.