Berlin 2014 – scientific programme

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SYKW: Symposium Klimawandel: Gibt es eine Erwärmungspause?

SYKW 1: Symposium - Klimawandel, gibt es eine Erwärmungspause ?

SYKW 1.2: Invited Talk

Tuesday, March 18, 2014, 17:00–17:30, Audimax

The IPCC assessment of the recent hiatus in surface warming — •Jochem Marotzke — Max-Planck-Institut für Meteorologie, Hamburg, Deutschland

I will review what is known about the recent observed reduction in global-mean surface-warming trend and the ability of climate models to simulate this "hiatus". A comprehensive assessment of the published literature on this topic has recently been given in the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). A particular challenge lies in the evaluation of an ensemble of model simulations vis-à-vis internal variability in the observed record. Furthermore, trends in both observations-based and simulated radiative forcing need to be taken into account, as well as the models* responses to these trends.

The AR5 concludes that the observed hiatus in surface warming trend is due in roughly equal measure to a reduced trend in radiative forcing and a cooling contribution from internal variability, which includes a possible redistribution of heat within the ocean. During the surface-warming hiatus, the climate system has continued to increase its heat content, consistent with estimates of anthropogenic forcing. Surface temperature trends over periods as short as 15 years are thus of little relevance for long-term anthropogenic warming.