[geo] Re: Just in Time for Hurricane Season

Wed, 03 Jun 2009 08:12:55 -0700


Hi Ken,

Your paper implies that hurricanes can contribute to polar amplification, hence providing positive feedback to global warming (and hence more extreme hurricanes, etc.). Quoting from your paper:

"These results support the hypothesis that tropical cyclones play an active role in the tropical surface ocean heat budget by cooling the tropical upper oceans through enhanced vertical mixing, which likely represents a net warming beneath the oceanic mixed layer. Thus, to the degree that vertical mixing is important for regulating the ocean’s meridional overturning circulation and poleward heat transport, tropical cyclones may be an important contributor to Earth’s climate system. This further confirms the results of Emanuel (2001, 2002) and Sriver and Huber (2007b) that possible future changes in integrated cyclone intensity associated with warmer SST may provide possible climatic feedbacks through enhanced vertical mixing and increased ocean heat transport, thus buffering the tropics to increased temperatures while amplifying the warming at higher latitudes."

Could Katrina, in August 2005, have contributed to warming the Gulf Stream and hence to record Arctic sea ice melt in September 2007?  Anyway it seems that hurricanes probably have a significant and dangerous contribution to polar amplification, thus leading to more rapid Arctic sea ice retreat and raising the threat of massive methane discharge and much enhanced global warming*.

This hurricane effect, combined with the expected warmer sun and next El Nino, could cause the sea ice to retreat much more rapidly than predicted, and make even 2030 seem an optimistic forecast for its seasonal disappearance.

Cheers,

John

* P.S.  Ken, do you still believe that methane is only a small risk, because of paleo records?


Ken Caldeira wrote:
You may find this pdf and the papers cited therein to be relevant to this discussion:

http://web.ics.purdue.edu/~huberm/2007GC001842.pdf

___________________________________________________
Ken Caldeira

Carnegie Institution Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA

[email protected]; [email protected]
http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab
+1 650 704 7212; fax: +1 650 462 5968  



On Tue, Jun 2, 2009 at 10:12 AM, Alvia Gaskill <[email protected]> wrote:
As the article indicates, what hurricanes do is move heat around, not dissipate it.  Whether this actually cools the planet is unknown.  Given the relatively small number of all tropical cyclones and their short lifetimes of around a week or so, I doubt they matter very much on a global scale.  Another theory has them increasing atmospheric CO2 by stirring up surface waters, although they may also reduce it by upwelling nutrients causing phytoplankton blooms.   Global warming didn't stop because of all the storms in 2005 (the year of Katrina) and it didn't get worse in the subsequent years due to fewer storms.  
 
 

Hurricanes' Climate Footprint Felt for Months

Michael Reilly, Discovery News
 

Jan. 29, 2009 -- Just as a changing climate shapes the strength and frequency of hurricanes, the storms may have a huge effect on climate, leaving "footprints" in the atmosphere and ocean.

Watch a video on hurricane-prone coastlines.

Hurricanes are infamous as harbingers of chaos -- flooding cities, ripping houses to shreds, destroying beaches and even whole islands. And concerns are growing that human-induced climate change may lead to stronger storms whose intensity will wreak even more havoc on coastal communities around the world.

But the full interplay between hurricanes and climate remains an enigma.

Robert Hart of Florida State University analyzed two decades of climate data from the tropics, and found that each storm leaves a wake of anomalously cool water and warm air behind it that can persist anywhere from one to two months, depending on the storm's strength.

Scientists have known for years that hurricanes cause cool ocean waters to well up, but Hart was surprised at how long the atmosphere retained a "memory" of each storm.

That got him thinking: if one storm can have such a lasting impact, what does a whole season of storms do to Earth's climate? Would there be a difference in effect between an active hurricane season and a quiet one?

Hart performed a series of calculations and came up with a striking preliminary answer: hurricane seasons that spawned more storms (like 2005, for example) led to quieter winters in the northern hemisphere, and quiet hurricane seasons led to winters with lots of storm activity.

The reason, Hart speculates, is that hurricanes bring large amounts of heat out of the tropics and toward the poles. When a season has more storms, more heat is deposited closer to the poles and the tropics are cooled off more, so that when winter sets in there is less temperature difference between the poles and tropics.

"That's what winter weather is -- movement of heat between the tropics and the poles," Hart said. "So it's possible that hurricanes do more than their fair share of the work during an active season, and there's less work to be done during the winter."

Gabriel Vecchi of the National Oceanic and Atmospheric Association's Geophyscial Fluid Dynamics Laboratory in Princeton, N.J., said Hart's work gets at some of the toughest questions in meteorology today: What are hurricanes? Do they serve a purpose?

"It may sound like a stupid question, but I wonder what tropical cyclones' role in the climate system is," he said.

There are two general theories -- one which states that hurricanes are simply the result of more potent forces, like El Nino pushing vast amounts of heat and moisture around Earth's atmosphere. The other says hurricanes are vital heat engines that transfer energy from the tropics toward the poles. Through their fury, they are in fact bringing balance to the planet's climate.

"The list of results about how they affect climate is getting longer," Vecchi said. "This is all hinting that tropical cyclones do something profound."

----- Original Message -----
From: f.m.maugis
Sent: Tuesday, June 02, 2009 11:30 AM
Subject: RE: [geo] Just in Time for Hurricane Season

Why killing hurricanes, as far as they cool naturally our climate ?
 
François MAUGIS
===============================================
De : [email protected] [mailto:[email protected]] De la part de Alvia Gaskill
Envoyé : mardi 2 juin 2009 01:09
À : [email protected]
Objet : [geo] Just in Time for Hurricane Season

I was admittedly a little drowsy when I saw the promo for this, but it appears to be another incarnation of the ocean pipes idea or perhaps the same one from Atmocean.  One problem for would be hurricane killers is that they seem to be appearing in places where they shouldn't, when they shouldn't and rapidly intensifying, giving little time to react.  Thus, strategies that prevent the conditions that drive hurricane development should probably be considered before filling up the Gulf of Mexico and the Atlantic with plastic pipes.  The cloud ships, the partial desert cover and the stratospheric aerosols all could be part of the first line of defense.
 
 
NextWorld
Future Danger
TV-G

Future Danger enters a world where robots safeguard our cities, massive underwater heating and cooling systems break up hurricanes before they hit land, and advanced rocket interceptors protect the planet from asteroids that could wipe out humanity.
 
Air times in the U.S.: June 7, 9pm, June 8, 12am and June 9, 4 am.  60 minutes.
 
 
 
 
 





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