More Storms, More Heat Says World Meteorological Association

By Alex Kirby, Climate News Network

This piece first appeared at Climate News Network.

LONDON–If you think the world is warming and the weather getting nastier, you’re right, according to the United Nations agency committed to understanding weather and climate.

The World Meteorological Organization says the planet “experienced unprecedented high-impact climate extremes” in the ten years from 2001 to 2010, the warmest decade since the start of modern measurements in 1850.

Those ten years also continued an extended period of accelerating global warming, with more national temperature records reported broken than in any previous decade. Sea levels rose about twice as fast as the trend in the last century.

A WMO report, The Global Climate 2001-2010, A Decade of Climate Extremes, analyses global and regional temperatures and precipitation, and extreme weather such as the heat waves in Europe and Russia, Hurricane Katrina in the US, tropical cyclone Nargis in Myanmar, droughts in the Amazon basin, Australia and East Africa, and floods in Pakistan.

It says the decade was the warmest for both hemispheres, and for both land and ocean surface temperatures. There was a rapid decline in Arctic sea ice and accelerating loss of net mass from the Greenland and Antarctic ice sheets and from the world’s glaciers.

This melting and the thermal expansion of sea water caused global mean sea levels to rise about three millimetres annually, about double the observed 20th century trend of 1.6 mm per year. Global sea level averaged over the decade was about 20 cm higher than in 1880, the report says.

Global-average atmospheric concentrations of carbon dioxide rose to 389 parts per million in 2010, 39% higher than at the start of the industrial era in 1750. Methane rose to 1,808.0 parts per billion (158%) and nitrous oxide to 323.2 ppb (20%).

The WMO secretary-general, Michel Jarraud, said: “A decade is the minimum possible timeframe for meaningful assessments of climate change.

Clear upward trend

“WMO’s report shows that global warming accelerated in the four decades of 1971 to 2010 and that the decadal rate of increase between 1991-2000 and 2001-2010 was unprecedented.”

He added: “Rising concentrations of heat-trapping greenhouse gases are changing our climate, with far-reaching implications for our environment and our oceans, which are absorbing both carbon dioxide and heat.”

His reference to the oceans’ role as a sink for CO2 and heat is significant in the present debate about the apparent slight slow-down in the pace of atmospheric warming and the likelihood that the heat is going into the oceans instead.

Mr Jarraud said: “Natural climate variability, caused in part by interactions between our atmosphere and oceans — as evidenced by El Niño and La Niña events — means that some years are cooler than others.

“On an annual basis, the global temperature curve is not a smooth one. On a long-term basis the underlying trend is clearly in an upward direction, more so in recent times.”

The report says that between 2001 and 2010, there was no major El Niño event, which normally leads to higher temperatures (as in the then-record warm year of 1998). Much of this last decade experienced either cooling La Niña or neutral conditions, except for the 2009/2010 moderate to strong El Niño.

It says the average land and ocean-surface temperature for 2001-2010 was estimated to be 14.47°C, or 0.47°C above the 1961-1990 global average and +0.21°C above the 1991-2000 global average (with a factor of uncertainty of ± 0.1°C).

The average 1991-2000 decadal temperature was itself +0.14°C warmer than 1981-1990. Every year of this latest decade except 2008 was among the 10 warmest years on record.

Warming Greenland

The warmest year ever recorded was 2010, with a temperature estimated at 0.54°C above the 14.0°C long term average of the 1961-1990 base period, followed closely by 2005.

Greenland recorded the largest decadal temperature anomaly, at +1.71°C above the long-term average and with a temperature in 2010 of +3.2°C above average. Africa experienced warmer than normal conditions in every year of the decade.

When it came to precipitation and floods, the decade was the second wettest since 1901. Globally, 2010 was the wettest year since the start of instrumental records.

Yet the WMO says droughts affect more people than any other kind of natural disaster because of their large scale and long duration. The decade saw droughts across the world, with some of the longest and most severe in Australia (2002 and other years), East Africa (2004 and 2005, resulting in widespread loss of life) and the Amazon basin (2010).

Tropical cyclones were reported to have killed nearly 170,000 people and to have affected more than 250 million, causing economic damage of US$ 380 billion.

More than 370,000 people died during the decade as a result of extreme weather and climate conditions — heat, cold, drought, storms and floods, according to data from the Centre for Research on the Epidemiology of Disasters. This was 20% higher than 1991-2000.

But the WMO says there was a 16% decline in deaths due to storms and a 43% decline in those from floods, thanks mainly to better early warning systems and increased preparedness, and despite an increase in populations in disaster-prone areas.

marc.cappelletti (CC BY-ND 2.0)