Fast climate response differs over land and sea

Liz Kalaugher in Environmental Research Web: On a scale of days, climate response is distinctly different between land and ocean, and to carbon dioxide versus solar forcing. That is according to a team from China, India and the US that has completed the first study to investigate responses to these factors in a coupled atmosphere-ocean climate system on a timescale from days to weeks.

"Recently, a number of studies have shown that climate response on timescales shorter than one month, the so called 'fast climate adjustment' has great implication for climate response on longer timescales of decades to centuries," Long Cao of Zhejiang University, China, told environmentalresearchweb. "However, there are very few studies on the actual climate evolution and associated physical mechanisms on timescales from days to weeks."

Together with Govindasamy Bala of the Indian Institute of Science and Ken Caldeira of the Carnegie Institution, US, Cao conducted large ensemble simulations using the UK Met Office Hadley Centre global climate model HadCM3L. The researchers employed a step-change quadrupling of atmospheric carbon-dioxide concentration or a 4% rise in solar irradiation, chosen because it yields a similar long-term change in global-mean surface temperature to the carbon-dioxide increase. The control conditions were 280 ppm of carbon dioxide and a solar constant of 1354 W/sq. m.

"Previous studies investigated fast climate adjustment under the idealized situations of either zero global-mean surface temperature change or fixed sea-surface temperature," said Cao. "We investigate the actual development of fast climate adjustment without imposing any constraints on the atmosphere–ocean climate system."...

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