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Wednesday, December 3, 2008

Global Climate Weirdness Matches Predictions


Deadly floods in Asia, a cyclone in the Middle East, tornadoes in Brooklyn, and extreme temperatures around the globe since the start of the year have borne out warnings made by a key climate change report, an expert with the U.N. weather agency said Tuesday.

In May the Intergovernmental Panel on Climate Change released its fourth report, warning that global warming would increase the number of extreme weather events and cause more natural disasters, which will hit the poor hardest.

Global surface temperatures in January — when Europe experienced an unusually mild winter — were the highest since records began. According to data compiled by WMO measurements were 1.89 degrees Celsius (3.4 Fahrenheit) above the 127-year average.

WMO, the Geneva-based agency said April temperatures around the world rose 1.37 degrees Celsius (2.46 Fahrenheit) above the historical average since 1880. Record storms, floods and heat waves have since occurred in Africa, Asia, Europe and South America.


Hundreds have died and thousands have lost their livelihoods in floods since the start of the year in China, South Asia, Mozambique, Sudan and Uruguay, while the period from May to July was the wettest in England and Wales since records began in 1766, WMO said.

It said two heat waves in southeastern Europe in June and July broke previous records, with temperatures in Bulgaria hitting 45 degrees Celsius (113 Fahrenheit) on July 23. Other extreme events this year include rare snowfall in South Africa and Argentina, and the first cyclone ever documented in the Arabian Sea.

Climate scientists had reached a consensus that weather extremes have increased over the past 50 years and that this trend would likely continue.

The most accurate measures of European daily temperatures ever indicate that the length of heat waves on the continent has doubled and the frequency of extremely hot days has nearly tripled in the past century. The new data shows that many previous assessments of daily summer temperature change underestimated heat wave events in western Europe by approximately 30 percent.


The study adds evidence that heat waves, such as the devastating 2003 event in western Europe, are a likely sign of global warming; one that perhaps began as early as the 1950s, when their study showed some of the highest trends in summer mean temperature and summer temperature variance.


In the U.S., about twice as many Atlantic hurricanes form each year on average than a century ago, according to a new statistical analysis of hurricanes and tropical storms in the north Atlantic. The study concludes that warmer sea surface temperatures (SSTs) and altered wind patterns associated with global climate change are fueling much of the increase.


The study, by Greg Holland of the National Center for Atmospheric Research (NCAR) and Peter Webster of Georgia Institute of Technology, will be published online July 30 in Philosophical Transactions of the Royal Society of London.


"These numbers are a strong indication that climate change is a major factor in the increasing number of Atlantic hurricanes," says Holland.


The authors note that other studies indicate that most of the rise in Atlantic SSTs can be attributed to global warming.


The unusually active hurricane seasons of 2004 and 2005 have spurred considerable research into the question of whether more intense tropical cyclones are correlated with natural cycles, global warming, or some other cause. The new study indicates that natural cycles are probably not the entire cause because the increase has happened across the last century rather than oscillating in tandem with a natural cycle.


The study also finds that enhanced observations in recent decades cannot account for all of the increase. To observe storms in the Atlantic more systematically, meteorologists began relying on data from aircraft flights in 1944 and satellites about 1970. The distinct transitions in hurricane activity noted by Holland and Webster occurred around both 1930 and 1995.


New research shows that industrial development in North America between 1850 and 1950 greatly increased the amount of black carbon--commonly known as soot-- that fell on Greenland's glaciers and ice sheets. The soot impacted the ability of the snow and ice to reflect sunlight, which contributed to increased melting and higher temperatures in the region during those years. This discovery may help scientists better understand the impact of human activities on polar climates.


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