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The tenth IMSC, Beijing, China, 2007 - International Meetings on ...

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Extending attributi<strong>on</strong> studies: postage stamps for the world<br />

Speaker: Dáithí St<strong>on</strong>e<br />

Dáithí St<strong>on</strong>e<br />

Tyndall Centre, Dept. of Physics, University of Oxford<br />

st<strong>on</strong>ed@atm.ox.ac.uk<br />

Studies of the detecti<strong>on</strong> and attributi<strong>on</strong> of climate change are progressing bey<strong>on</strong>d the<br />

questi<strong>on</strong> `Have we influenced the climate?' and starting to address the questi<strong>on</strong> `How does the<br />

current climate differ because of our influence?' <str<strong>on</strong>g>The</str<strong>on</strong>g> subtle but important difference between<br />

these two questi<strong>on</strong>s means that different assumpti<strong>on</strong>s are required when addressing them.<br />

Are these assumpti<strong>on</strong>s c<strong>on</strong>tradictory? This talk will discuss these questi<strong>on</strong>s through a<br />

comparis<strong>on</strong> of observed c<strong>on</strong>tinental surface temperature trends with those from a multi-model<br />

ensemble of historical simulati<strong>on</strong>s including <strong>on</strong>ly natural external forcings and an ensemble<br />

including both anthropogenic and natural forcings.<br />

C<strong>on</strong>sistency of observed winter precipitati<strong>on</strong> trends in northern Europe with regi<strong>on</strong>al climate<br />

change projecti<strong>on</strong>s<br />

Speaker: Hans v<strong>on</strong> Storch<br />

Hans v<strong>on</strong> Storch<br />

Institute for Coastal Research, GKSS<br />

hv<strong>on</strong>storch@web.de<br />

J<strong>on</strong>as Bhend<br />

Institute for Coastal Research, GKSS<br />

Often it is claimed that the recent changes in northern European climate are at least<br />

partly anthropogenic even though a human influence has not yet been successfully detected.<br />

Hence we investigate whether the recent changes are c<strong>on</strong>sistent with regi<strong>on</strong>al climate change<br />

projecti<strong>on</strong>s.<str<strong>on</strong>g>The</str<strong>on</strong>g>refore, trends in winter (DJF) mean precipitati<strong>on</strong> in northern Europe are<br />

compared to human induced changes as predicted by an ensemble of four regi<strong>on</strong>al climate<br />

model simulati<strong>on</strong>s.<br />

<str<strong>on</strong>g>The</str<strong>on</strong>g> patterns of recent trends and predicted changes match reas<strong>on</strong>ably well as indicated<br />

by pattern correlati<strong>on</strong> and the similarity is very likely not random. However, the model<br />

projecti<strong>on</strong>s severely underestimate the recent change in winter precipitati<strong>on</strong> by 50 to 80\%.<br />

That is, the signal-to-noise ratio of the anthropogenic precipitati<strong>on</strong> change is either rather low<br />

or the presently used simulati<strong>on</strong>s are significantly flawed in their ability to project changes into<br />

the future.<br />

47

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