[extropy-chat] Hurricanes and global warming

[Hal Finney]

With all of the hurricanes striking the United States this year,
a question many people are asking is whether the increase is due to
global warming.  Of course this is a controversial issue but still it
is useful to see what is the scientific consensus on the matter.

I found two good pages, a nontechnical one at USA Today from last year,
http://www.usatoday.com/weather/resources/askjack/wfaqhurw.htm,
which points at a technical one by a hurricane researcher at
http://www.aoml.noaa.gov/hrd/tcfaq/G3.html.

The upshot is that no one really knows, but the imperfect modelling
possible today indicates that global warming will have only a small
effect on hurricanes.  Although warmer oceans would superficially lead
to more and stronger hurricanes, actually the strength depends on the
difference between the ocean temperature and that of the upper atmosphere.
With global warming, both will increase, but the precise details are hard
to predict.  At this point it looks like the two effects will largely
cancel each other out.

Why, then, are we getting so many hurricanes now?  It appears that
hurricane activity tends to be cyclic, with a 20-30 year period, and we
are just coming out of a low that lasted from the 60s through the 90s.
This suggests that we will see considerably higher hurricane activity
in the next few decades.

The worst year on record for hurricanes in the United States was 1886,
when 7 hurricanes struck the country.  So far this year there have
been three.

Of course you can't just cherry-pick your science.  If you agree with
this result, you ought to also respect the scientific consensus of a
significant human contribution to global warming (and vice versa).

Hal