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Hi George, This pattern is indeed disturbing. Climate science predicts increasing _frequency_ of extreme events - but on this basis no single event can be attributed to global warming. However one can show that global warming contributes addition _severity_ to some events, at the time they occur. This includes cases where the severity is related to ocean surface temperature, which has typically increased 0.5 degrees C due to global warming. Examples are Katrina and the recent Australian floods. Note that the damage tends to be exponential with severity, so reducing the severity by cooling the relevant part of the ocean surface (e.g. by marine cloud brightening) could save a lot of damage in the future. Note also that this same cooling technology (a form of SRM geoengineering) could be applied to critical parts of the Earth's climate control system, e.g. to save the Arctic sea ice and to save the Amazon rainforest. The higher surface temperature of the Gulf Stream contributes to the speed of retreat of the sea ice. The higher surface temperature of the tropical Atlantic may contribute to the droughts and die-off in the Amazon. Cheers, John --- On 17/02/2011 10:12, George Marshall wrote: > > Here we have one of the central challenges of science communication. > When an extreme weather event happens scientists are invited to make a > connection with climate change. Quite understandably they are > reluctant to do so without full research. This sometimes comes over as > uncertainty- but increasingly I notice the formula “there is a > difference between climate and weather- we cannot ascribe any single > weather event to climate change” and this suggests that the extreme > event is ‘natural variation’ not climate change...see for example the > Met Office explanation of the cold winter which adamantly says that it > is NOT ascribable to climate change > > Then, years later, researchers collect sufficient evidence to > establish a strong contribution in the event from climate change but > this is too late and disconnected to help the public make the > connection in their own minds. > > What I find disturbing is that this pattern keeps happening (eg 2003 > heatwave, Katrina, floods) and very likely will be repeated for the > current record cold in Northern Europe and US. Science communications > has not found a way of conveying this past experience- that, whilst it > cannot be said with confidence without the research, previous extreme > weather events have been found to be strongly influenced by climate > change. > > *From:*Discussion list for the Crisis Forum > [mailto:[log in to unmask]] *On Behalf Of *Jon Barrett > *Sent:* 17 February 2011 07:23 > *To:* [log in to unmask] > *Subject:* Anthropogenic greenhouse gas contribution to flood risk in > England and Wales in autumn 2000 > > Dear all, > > For those of us wanting to be able to communicate evidence of a clear, > present /and/ local CC threat, the Guardian reports today on this > research just published in Nature > > > "Climate change doubled likelihood of devastating UK floods of 2000 > > *Researchers have for the first time quantified the part climate > change played in increasing the risk of a severe flood"* > > *http://www.guardian.co.uk/environment/2011/feb/16/climate-change-risk-uk-floods* > > *http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html* > > Jon > > > Abstract from Nature > > Volume:470, Pages:382–385 Date published:(17 February 2011) > > > Anthropogenic greenhouse gas contribution to flood risk in England > and Wales in autumn 2000 > > *Interest in attributing the risk of damaging weather-related events > to anthropogenic climate change is increasing^1 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref1> > . Yet climate models used to study the attribution problem typically > do not resolve the weather systems associated with damaging events^2 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref2> > such as the UK floods of October and November 2000. Occurring during > the wettest autumn in England and Wales since records began in 1766^3 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref3>, > 4 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref4> > , these floods damaged nearly 10,000 properties across that region, > disrupted services severely, and caused insured losses estimated at > £1.3** **billion (refs 5 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref5>, > 6 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref6>). > Although the flooding was deemed a ‘wake-up call’ to the impacts of > climate change at the time^7 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref7> > , such claims are typically supported only by general thermodynamic > arguments that suggest increased extreme precipitation under global > warming, but fail^8 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref8>, > 9 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref9> > to account fully for the complex hydrometeorology^4 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref4>, > 10 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref10> > associated with flooding. Here we present a multi-step, physically > based ‘probabilistic event attribution’ framework showing that it is > very likely that global anthropogenic greenhouse gas emissions > substantially increased the risk of flood occurrence in England and > Wales in autumn 2000. Using publicly volunteered distributed > computing^11 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref11>, > 12 > <http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html#ref12> > , we generate several thousand seasonal-forecast-resolution climate > model simulations of autumn 2000 weather, both under realistic > conditions, and under conditions as they might have been had these > greenhouse gas emissions and the resulting large-scale warming never > occurred. Results are fed into a precipitation-runoff model that is > used to simulate severe daily river runoff events in England and Wales > (proxy indicators of flood events). The precise magnitude of the > anthropogenic contribution remains uncertain, but in nine out of ten > cases our model results indicate that twentieth-century anthropogenic > greenhouse gas emissions increased the risk of floods occurring in > England and Wales in autumn 2000 by more than 20%, and in two out of > three cases by more than 90%.* > > > > > > -- > > Jon Barrett > Le projet pour une vie durable > Goastelliou > 29620 Guimaec > France > Tel: 00 33 (0)2 98 67 68 87 > > Converging Crises blog: www.jontybarrett.wordpress.com > <http://www.jontybarrett.wordpress.com/> > > Goastelliou website: www.goastelliou.wordpress.com > <http://www.goastelliou.wordpress.com/> >