Gareth wrote:
> Take a look at Figure SPM-5 in the SPM - AOGCM projections of surface
> temperatures. For the period 2020-29 there is very little difference
> in projected temperature rise (from 1980-99) between the three
> scenarios illustrated (B1, A1B, A2). The SPM says "Best-estimate
> projections from models indicate that decadal-average warming over
> each inhabited continent by 2030 is insensitive to the choice among
> SRES scenarios, and is very likely to be at least twice as large as
> the corresponding model-estimated natural variability during the 20th
> century." My eyeball suggests that the rise is about 0.8C.
The IPCC predicts 0.2C per decade for the global average, so your figure
for land is probably about right. Right now I'm actually trying to do
something a bit more explicit and formal than the IPCC but can't imagine
the answer differing much other than having explicit error bars.
> I'd like to explore some of the implications of this finding. It
> suggests, for instance, that we have in effect got a "forecast" of
> global average temperature change over the next 25 years. We're
> committed to this warming whatever we do. From a policy perspective,
> we therefore have a known challenge to meet (even if we don't/can't
> know the full implications of that 0.8C). Adaptation is required
What adaptation do you think is required?
As Michael says, there isn't really much preparation to do. Few
decisions need to be taken more than a decade out and those that do,
there are probably much larger uncertainties than climate change anyway.
I don't want to downplay it too much - in fact it's an area I'm
increasingly interested in for a number of reasons - but it is hard to
find areas where there is all that much value in adaptation over this
time scale, even if we could forecast the future climate with high
precision.
James
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