> I just thought of an indicator species for climatic change that is immune
> to many of the problems that Stuart MacKay and others have outlined:
>
> the thermometer.
>
> Seriously, if the goal is to diagnose global warning, there are more
> straightforward methods than watching birds. If, on the other hand, the
> goal is to discover what effects global warming has on bird populations,
> one would still want to know if global warming were happening before one
> looked for its effects, wouldn't one? I'm not denying that bird
> populations change as the climate varies, nor that the changes are
> uninteresting. But I don't think that looking for indicator species of
> climate change is a subsitute for studying the weather records.

The problem is that changes in weather which might be driven by global
warming aren't as simple as that. What change in that thermometer
are you going to look for? Should it rise or fall to be an indicator
that global warming due to human-caused emissions is occuring?

The answer will likely depend on where you live. The problem is that
climatologists have not reached consensus on predicting local effects.

What does seem to be agreed upon is that some areas will become warmer,
others cooler, some drier, others wetter, etc.

The problem stems from the fact that the world's weather is very much
driven by ocean currents. Global warming (or cooling or any change)
will change how that "heat engine" works - heat sinks within the ocean
may move, currents may meander into different places within the ocean,
etc. At least some models seem to predict (or, did a couple of years
ago when I last did some reading on this stuff) that the ocean system
might be bi-stable, i.e. might absorb a lot of additional heat without
much change in energy transfer between oceans, then reach an unstable
state and "flip" into a new, stable state. Other folks seemed to think
something entirely different would happen.

Some have even argued that global warming will actually drive global
cooling, as more clouds will form which will reflect sunlight which
now warms the earth (that has been debunked, I believe).

The point of all the above - I'm no expert, so ignore the details - is
that the effects of global warming are extremely difficult to predict.

This is one reason why there is a much lower level of consensus
among scientists in relevant fields vs., say, the effect of CFCs
on the ozone layer - a much simpler phenomena to model.

Gee, there's been a lot of non-bird stuff in here recently. Personally,
I'm enjoying it - pestilential plants, pestilential politicians,
potentially pestilential human-produced greenhouse gases, but are others?

Hmmm, perhaps I should add "pestilential posters" to the list!


-Don Baccus-