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 yesterday.
However, this short-term situation might create a problem if policy-makers
regard it as a sign they could ease efforts to limit greenhouse gases or
play down global warming.
³The natural variations change climate on this timescale and policy-makers
may either think mitigation is working or that there is no global warming at
all,² 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,
"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."
A United Nations climate panel report this year predicted temperatures would
rise between 1.8 C and 4 C this century, in part because of fossil fuels
that produce carbon dioxide, the main greenhouse gas.