No doubt a warmer atmosphere would lead to increased precipitation, but that doesn't necessarily correlate directly to an increase in extreme weather events.
A few points to consider here:
Firstly, global data on extreme weather events pre-1965 is based on local observation; it was only with the Nimbus and Seasat projects that the modern science of remote sensing really took off; and a remote sensing satellite is capable of telling you far more over a far larger area than the previous methods; and to a far greater degree of accuracy.
(The data we got to play with at UCL included stuff from ERS-1; some of my then colleagues were later involved with Envisat.)
As such; the baseline frequency of events pre-1965 is sometimes based on anecdotal rather than exhaustive observation.
Secondly, the IPCC Fourth Assessment Report (AR4) states that there is as yet no firm evidence for a global increase in extreme events, but that there is quite possibly a causal link between the increase in the annual frequency of extreme events in the North Atlantic region in the period 1990-2007 as opposed to the period 1850-1990.
Thirdly, while the frequency of extreme events has not yet shown a clear trend (which may yet manifest under greater warming), there is some correlation between the sea surface temperature (SST) and observed increase in the number of Category 4/5 events in the North Atlantic during the period 1970-2004. There is not currently enough data to make a firm conclusion on this (see the argument between Trenberth/Webster+Holland versus Gray/Landsea on this subject); however, all parties agree that more study is needed.
The IPCC's position is that some degree of causative link between SST and North Atlantic events is probable - it will be interesting to see what AR5 says on the subject.
A single weather event is evidence of nothing, climate-wise; but a measureable trend is a lot more significant.
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branchandroot
no subject
Date: 2010-01-06 10:21 pm (UTC)A few points to consider here:
Firstly, global data on extreme weather events pre-1965 is based on local observation; it was only with the Nimbus and Seasat projects that the modern science of remote sensing really took off; and a remote sensing satellite is capable of telling you far more over a far larger area than the previous methods; and to a far greater degree of accuracy.
(The data we got to play with at UCL included stuff from ERS-1; some of my then colleagues were later involved with Envisat.)
As such; the baseline frequency of events pre-1965 is sometimes based on anecdotal rather than exhaustive observation.
Secondly, the IPCC Fourth Assessment Report (AR4) states that there is as yet no firm evidence for a global increase in extreme events, but that there is quite possibly a causal link between the increase in the annual frequency of extreme events in the North Atlantic region in the period 1990-2007 as opposed to the period 1850-1990.
Thirdly, while the frequency of extreme events has not yet shown a clear trend (which may yet manifest under greater warming), there is some correlation between the sea surface temperature (SST) and observed increase in the number of Category 4/5 events in the North Atlantic during the period 1970-2004. There is not currently enough data to make a firm conclusion on this (see the argument between Trenberth/Webster+Holland versus Gray/Landsea on this subject); however, all parties agree that more study is needed.
The IPCC's position is that some degree of causative link between SST and North Atlantic events is probable - it will be interesting to see what AR5 says on the subject.
A single weather event is evidence of nothing, climate-wise; but a measureable trend is a lot more significant.
(cut for length - part two below!)