Global warming to surge in next 5 years as El Niño and sun add to greenhouse gases' impact -- study

(Temperature chart from the UK's Climate Research Unit. It was uploaded to Flickr by T. Raftery.)


Beware. This coming fall and winter could be unusually warm. And that fast-warming phase is likely to continue for 5 years and be worse than previously forecast, a new study predicts.

A combination of natural forces have masked the full impact of rising CO2 emissions on average global temperatures over the past decade, but now they are entering a new phase where they will work in tandem with greenhouse gases to heat the planet, according to scientists from NASA and the U.S. Naval Research Laboratory.

Relatively stable average world temperatures since 1999 are the result of a downward cycle in sunspots and flares and a period of weak El Niños, the study says.

But now the 11-year cycle of solar activity is about to go on the upswing and El Niño effects in the Pacific Ocean are expected to produce more extreme heat, says the study. This is the first look at the impact of all four factors on global temperatures: human actions (greenhouse gases), El Niño, solar activity and volcanic eruptions.

The hottest year on record was 1998, in part because of a strong El Niño episode. The extreme heat that year led to droughts, flooding, severe heat waves and the death of 16% of the world’s coral.

(By contrast, 1601 was the coldest year of the millennium, following the giant eruption of a Peruvian volcano that spewed ash that blocked out sunlight. Among the results was a famine in Russia that killed one-third its population.)

The researchers are quick to point out that while these natural forces have an impact, they do not negate the importance of the steady rise of CO2 emissions and their baseline effect on temperatures.

While 1998 was the hottest year and the 1990s the warmest decade on record, 13 of the 14 warmest years were between 1995 and 2008, according to the UK’s Climate Research Unit. And 8 of the top 9 came after 2000.

“We're seeing a long-term warming trend driven by human activity, with natural factors affecting the precise shape of that temperature rise," said Judith Lean, one of the authors.

The study is to be published in Geophysical Research Letters.

(Sources: The Guardian, Climate Research Unit, UK’s Met Office and Greenwire)


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