title: Betting strategies on fluctuations in the transient response of greenhouse warming.
abstract: 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.
authors.affiliation: CSIRO Oceans and Atmosphere, Hobart, Tasmania 7000, Australia james.risbey@csiro.au.
authors.forename: James S
authors.identifier: http://orcid.org/0000-0003-3202-9142
authors.initials: JS
authors.lastname: Risbey
authors.affiliation: School of Experimental Psychology, University of Bristol, Bristol, UK.
authors.forename: Stephan
authors.identifier: http://orcid.org/0000-0003-1655-2013
authors.initials: S
authors.lastname: Lewandowsky
authors.affiliation: Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: John R
authors.identifier: http://orcid.org/0000-0002-0310-8995
authors.initials: JR
authors.lastname: Hunter
authors.affiliation: CSIRO Oceans and Atmosphere, Hobart, Tasmania 7000, Australia.
authors.forename: Didier P
authors.initials: DP
authors.lastname: Monselesan
keywords: climate futures; decadal trends; transient response