Natural changes may offset global warming briefly

By Michael Kahn

LONDON (Reuters) - Natural climate changes may offset human-caused global warming over the next decade, keeping ocean temperatures the same or even temporarily cooling them slightly, German researchers said on Wednesday.

However, this short-term situation might create a problem if policymakers regarded it as a sign they could ease efforts to limit greenhouse gases or play down global warming.

"The natural variations change climate on this timescale and policymakers may either think mitigation is working or that there is no global warming at all," said Noel Keenlyside, a climate researcher at the Leibniz Institute of Marine Sciences in Germany who led the study.

Climate researchers have long predicted more greenhouse gases in the atmosphere would spur a general warming trend over the next 100 years. The study in the journal Nature is one of the first to take a shorter-term view.

This is useful because natural changes as opposed to human causes may play a bigger role in the short term, Keenlyside said.

His team made a computer model that takes into account natural phenomena such as sea surface temperatures and ocean circulation patterns.

They checked their work by producing a set of forecasts using data recorded over the past 50 years and found the retrospective forecasts were accurate, Keenlyside said.

"This is important because policies are made in the short term," Keenlyside said. "Our results show we might not have as much change in climate over the next 10 years."