We examine a series of betting strategies on the transient response of greenhouse warming, expressed by changes in 15-year mean global surface temperature from one 15-year period to the next. Over the last century, these bets are increasingly dominated by positive changes (warming), reflecting increasing greenhouse forcing and its rising contribution to temperature changes on this time scale. The greenhouse contribution to 15-year trends is now of a similar magnitude to typical naturally occurring 15-year trends. Negative 15-year changes (decreases) have not occurred since about 1970, and are still possible, but now rely on large, and therefore infrequent, natural variations. Model projections for even intermediate warming scenarios show very low likelihoods of obtaining negative 15-year changes over the coming century. Betting against greenhouse warming, even on these short time scales, is no longer a rational proposition.

Item Type:	Refereed Article
Keywords:	climate futures, decadal trends, transient response
Research Division:	Earth Sciences
Research Group:	Climate change science
Research Field:	Climate change processes
Objective Division:	Environmental Policy, Climate Change and Natural Hazards
Objective Group:	Understanding climate change
Objective Field:	Climate change models
UTAS Author:	Hunter, JR (Dr John Hunter)
ID Code:	106816
Year Published:	2015
Web of Science® Times Cited:	5
Deposited By:	IMAS Research and Education Centre
Deposited On:	2016-02-22
Last Modified:	2018-03-29
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