AP: Global Warming Cited in Wind Shift

[jasons2k]

Wow, seems like a parade of new articles the last 2 days or so....another one:

Global Warming Cited in Wind Shift
May 03 4:36 PM US/Eastern
By MALCOLM RITTER
AP Science Writer

NEW YORK

An important wind circulation pattern over the Pacific Ocean has begun to weaken because of global warming caused by human activity, something that could alter climate and the marine food chain in the region, new research suggests.

It's not clear what climate changes might arise in the area or possibly beyond, but the long-term effect might resemble some aspects of an El Nino event, a study author said.

El Ninos boost rainfall in the southern United States and western South America and bring dry weather or even drought to Indonesia, Malaysia and elsewhere in the western Pacific.

As for the Pacific food chain near the equator, the slowdown might reduce populations of tiny plants and animals up through the fish that eat them, because of reduced nutrition welling up from the deep, said the author, Gabriel Vecchi.

Vecchi, a visiting scientist at a National Oceanic and Atmospheric Administration lab in Princeton, N.J., and colleagues present their results in Thursday's issue of the journal Nature.

The slowdown was detected in shipboard and land-based data going back to the mid-1800s. It matches an effect predicted by computer climate simulations that trace global warming to a build-up of heat-trapping greenhouse gases, the researchers report. But simulations that consider only natural influences fail to produce the observed slowdown, Vecchi said.

So, it appears the slowdown is largely due to the man-made buildup of greenhouse gases, the researchers concluded. And the result lends more credibility to computer models that trace global warming to greenhouse gases, at least for their ability to forecast what will happen in the tropics, Vecchi said.

The study focused on what scientists call the Walker circulation, a huge wind pattern that covers almost half the circumference of Earth.

The pattern traces a huge loop. Trade winds blow across the Pacific from east to west. The air rises in the western Pacific and then returns eastward at an altitude of a few miles. Then it sinks back to the surface and starts the loop again.

The new study is based on barometric pressure readings, since differences in air pressure drive winds near the equator. Results suggest the average wind speed in the Walker circulation has weakened by about 3.5 percent since the mid-1800s. It has weakened faster since World War II than in the long-term trend since the mid-1800s, Vecchi said.

Computer simulations say the circulation might weaken another 10 percent by 2100, Vecchi said.

Dennis Hartmann, a professor of atmospheric sciences at the University of Washington, said the study makes a strong case that the Walker circulation has slowed. While such an effect had been predicted as a result of global warming, he said, "it's not been demonstrated before as clearly as they've done here."

[Aquawind]

Walker Circulation Explanation

http://www.bom.gov.au/lam/climate/level ... o.htm#four

[Blown Away]

If this scenerio resembles an El Nino pattern then maybe will see less hurricane activity in the Atlantic in the future.

[Hybridstorm_November2001]

If *correct* this would seem to take some wind (pun intended) out of the sails of those saying that GW causes Atlantic TCs

[wxman57]

"... because of global warming caused by human activity" -- that's the part that got my attention. If it's bad, it MUST be OUR fault! Can't be natural.

Beware of scientists with agendas! We probably have very little reliable wind data across the Pacific prior to the 1940s, but that's another issue. Just because a group of modelers can get a similar Walker circulation slowdown (assuming there is such a decreasing trend) by adding CO2 to the atmosphere doesn't prove CO2 is the cause. Many other factors could cause such a slowdown. Did they try adding water vapor to the upper atmosphere to see if it caused a slowdown too? Do they model ocean temperatures? Probably not. And, of course, it's you SUV drivers and big oil that are the cause.

[Hybridstorm_November2001]

Amen

[Audrey2Katrina]

Amen

And AMEN!

A2K

[caribepr]

"... because of global warming caused by human activity" -- that's the part that got my attention. If it's bad, it MUST be OUR fault! Can't be natural.

Beware of scientists with agendas! We probably have very little reliable wind data across the Pacific prior to the 1940s, but that's another issue. Just because a group of modelers can get a similar Walker circulation slowdown (assuming there is such a decreasing trend) by adding CO2 to the atmosphere doesn't prove CO2 is the cause. Many other factors could cause such a slowdown. Did they try adding water vapor to the upper atmosphere to see if it caused a slowdown too? Do they model ocean temperatures? Probably not. And, of course, it's you SUV drivers and big oil that are the cause.

Interesting...I found the above (first quoted) sentence to be an explanation of a measured observation, rather than an agenda.
I think we should also beware interpretations of observations based on opinion, rather than fact.
(Have you found out yet whether they tried adding water vapor to the upper atmosphere which strikes me as pretty darn difficult to do as a controlled experiment, but hey, I am NOT a scientist, nor do I play one on TV). As for the last sentence, generalizing is an interesting thing to do

[sponger]

At least those heralded climate models got SOMETHING right. Their over all ability to hindcast is reminicent of xtrap for the tropics. I would say Bamm as well but even a blind squirrel finds a nut!

[x-y-no]

"... because of global warming caused by human activity" -- that's the part that got my attention. If it's bad, it MUST be OUR fault! Can't be natural.

Ummm ... the point is that climate model runs which include anthropogenic forcings predict this slowdown but climate model runs which exclude anthropogenic forcings do not.

Beware of scientists with agendas!

Guess I should be on the lookout for Dick Lindzen and Bill Gray then ... (OK, that was a cheap shot - I apologize, a little)

We probably have very little reliable wind data across the Pacific prior to the 1940s, but that's another issue. Just because a group of modelers can get a similar Walker circulation slowdown (assuming there is such a decreasing trend) by adding CO2 to the atmosphere doesn't prove CO2 is the cause. Many other factors could cause such a slowdown. Did they try adding water vapor to the upper atmosphere to see if it caused a slowdown too? Do they model ocean temperatures? Probably not. And, of course, it's you SUV drivers and big oil that are the cause.

Water vapor is a feedback, not a forcing. Perturbing water vapor in various ways has been tried in GCMs, and absent some change in forcing it will always return quite rapidly to status quo ante.

And yes, modern GCMs do model ocean-air coupling and ocean temperatures.