Welcome to the world's first real-time product to examine whether and how greenhouse gas emissions have contributed to our weather.

The idea
Imagine you could make a seasonal forecast for the next month for a world that might have been if human activities had not emitted greenhouse gases. How would that forecast compare to the actual seasonal forecast for our real world? This is what we do here, compare actual seasonal forecasts against seasonal forecasts that might have been in that non-greenhouse gas world. Specifically, we compare the chances of pre-defined unusual monthly weather events in the two worlds, estimating how much more or less likely they are in our warming world than they might otherwise have been.
Further details are available here.

Issued attribution forecasts
Months
2009 January February March April May June July August September October November December
2010 January February March April May June July August September October November December
2011 January February March April May June July August September October November December
2012 January February March April May June July August September October November December
2013 January February March April May June July August September October November December
2014 January February March April May

Recent news
2014-04-11: The preliminary May 2014 attribution forecast was issued today. The final version will be issued in three months once observed sea surface temperatures become available. The February 2014 attribution forecast was updated today using observed sea surface temperatures (for HadAM3P-N96 only).
2014-03-28: An analysis of the degree to which emissions have affected the chance of high floods in the Okavango Delta has just been published here. UCT and LBNL have also posted press releases on this article: LBNL Computing Sciences' press release, NERSC's press release.
2014-03-27: A technical analysis of the sensitivity to spatial and temporal definitions of events of estimates of the degree to which emissions have affected extreme events has just been published in here.

Last update: 11 April 2014
Contact: Dáithí Stone (dstone@lbl.gov)

Copyright 2009-2014 Contributors to the Weather Risk Attribution Forecast

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Data portal
Much of this data is now available on the NERSC Earth System Grid Federation portal (search for "C20C")

Links
* NOAA's Climate Attribution page
* UCAR's Attribution of Climate Events page
* climateprediction.net's Seasonal attribution experiment