I thank Jim Angel, the Illinois State Climatologist, for alerting me to this seminar. While most of us cannot attend, the topic is of considerable interest to us.
ANNNOUNCEMENT
The Illinois State Water Survey Presents
Center for Atmospheric Sciences Seminar
A butterfly flaps its wings: The unintended regional and global
consequences of Amazonian deforestation
Peter Snyder
Department of Atmospheric Sciences
University of Illinois at Urbana-Champaign
Tuesday, April 3 2007 2:00 - 3:00 PM
Illinois Room - ISWS Conference Room
Coffee and Cookies at 1:45 PM
ABSTRACT
Although it has been established that the biosphere has an influence on the atmosphere at local and regional scales, there is widespread disagreement over whether the biosphere is capable of influencing the global climate through large-scale changes to the atmospheric general circulation. Numerous studies have already identified the regional climate response to human modification of the landscape through changes to the biophysical exchanges of energy, water, and momentum between the land surface and the atmosphere. However, we still do not understand whether land use and land cover change are capable of influencing remote regions through teleconnection processes. Furthermore, given a specific surface forcing, it is not entirely clear where the response will occur, how strong it will be, or how large a surface forcing is required in order for a climate response to be felt globally. Tropical deforestation is one example of a surface forcing that has the potential to influence the global climate. Several studies have suggested that significant changes to the Northern Hemisphere climate may occur as a result of selective tropical deforestation in the Amazon basin, yet most of these studies have focused on the climate response in the extratropics with little explanation of the mechanisms responsible for propagating the signal out of the tropics. This has led to disagreement over whether these mechanisms are real or are, in fact, artifacts generated by “noise” in climate models.
I will present results from a coupled atmosphere-biosphere model, CCM3-IBIS (Community Climate Model, version 3 - Integrated Biosphere Simulator), to illustrate the potential influence of theoretical land use and land cover change on the global climate by way of atmospheric teleconnections. The results suggest that pan-tropical and Amazonian deforestation can have a strong influence on the Northern Hemisphere general circulation by way of changes to synoptic-scale dynamics and land-atmosphere feedbacks both in the Amazon and in Asia. The result is a large warming across parts of Asia in boreal winter. While theoretical, this approach illustrates the potentially important processes connecting regional land surface changes in the tropics to climate changes in far-removed regions.
You might also ask his take on the meeting at Oxford, March 17 which discussed whether climate change will kill the Amazon. Of course, both seminars assume value to climate modeling. You might want to talk to Prof. Tennekis about that.
Comment by Eli Rabett — March 30, 2007 @ 7:52 pm
I really hope global warming won’t ‘kill’ the amazon cause I really do like piranha, and sometimes even rainforests. Sometimes the rainforests kinda suck though, like Eli said.
Comment by cytochrome_sea — March 31, 2007 @ 8:34 am
Eli,
Apparently, you are caught up in a “chicken or the egg” conundrum.
Dr. Pielke say human activity in the Amazon is causing climate changes; your reference says climate change (ostensibly from a different set of human activities) is causing ecological change in the Amazon.
Before you get too caught up in IPCC methods and predictions or what Dr. Hulme and friends are proposing, you might want to consider the article cited here:
http://www.climateaudit.org/?p=640
This is the problem with long term projections… even by very respected expert scientists.
http://hallofrecord.blogspot.com/2007/04/scientists-and-predictions.html
Comment by Bruce Hall — April 1, 2007 @ 8:50 am
re: #3
For anyone who clicked on the first link, you got a real commentary. I was just having a little fun with the second one. 4/1
Back to the serious stuff later.
Bruce
Comment by Bruce Hall — April 1, 2007 @ 7:32 pm
#3 Bruce: the chicken and egg are chimaerae; the abstract is focussing on the egg; whether tropical rainforest changes have a global impact. There’s no implied discussion of how the rainforest changes come about in the first place. (Last year’s Hadley run on the effects of GW on the Amazon was well covered).
Sometimes I do find myself wondering about the link Roger has been trying to establish between land-use changes and global climate change, but here there’s not likely to be much disagreement; it would be quite surprising if a system as vast and centrally placed as the tropical rainforest didn’t produce a measurable teleconnection somewhere. As always, the issue is going to be the extent of the feedback, and how this helps improve our understanding of the whole system.
I have been in touch previously with Steve McIntyre by email, and I think he’s a decent bloke, but on this occesion, I’m not sure how many legs he has left to stand on. I’m not saying that the IPCC’s ultimate response was necessarily fair, but I can’t see where at any point its actions can be said to be improper. If Hegerl or d’Arrigo didn’t want to share their core data, that’s surely their prerogative, given the unpublished status of the papers and the (imagined)likelihood that Steve might want to do a hatchet job on their statistics. On this occesion, I feel he is making a mountain out of a pimple.
Regards,
Comment by Fergus Brown — April 2, 2007 @ 4:09 am
One further point, the egg depends on GCMs to establish teleconnections. The same arguments (wrongheaded IMHO) that are used here often against GCMs apply, so why is this application being endorsed?
Comment by Eli Rabett — April 2, 2007 @ 8:04 am
Fergus, perhaps I am misreading the abstract offered up by Eli (#1 … I’m not referencing the abstract in the main post):
“One of the most profound predicted impacts of climate change into the 21st Century
is being discussed next week at Oxford University’s Oriel College by an
unprecedented gathering of scientists, conservationists and policymakers. The three
day conference starting 20th March explores why dieback from drought might
happen; the likelihood and length of time for significant dieback of the Amazon; and
what it means for local people and biodiversity; and the implications for the global
climate.
An early wake-up call on the potential die-back of the Amazon rainforest due to a
drying climate emerged from the Met Office Hadley Centre climate model five years
ago. The issue of Amazonian dieback then leapt from scientists’ computer
predictions to global environmental concern with the unexpected Amazonian drought
of 2005. Was it a climate change “tipping pointâ€?, a harbinger of things to come?”
I read this to say that climate changes (implied global warming caused by anthropogenic CO2) is killing the Amazon.
Your comment:
“Bruce: the chicken and egg are chimaerae; the abstract is focussing on the egg; whether tropical rainforest changes have a global impact. There’s no implied discussion of how the rainforest changes come about in the first place.”
My comment:
“Dr. Pielke say human activity in the Amazon is causing climate changes; your reference says climate change (ostensibly from a different set of human activities) is causing ecological change in the Amazon.”
What’s the difference? From my viewpoint, deforestation is changing the regional climate which may have a feedback effect (less rain?) that could cause further damage to the system. I’m guessing that the referenced abstract would lead us to the conclusion that global warming is the culprit regardless of the land use changes.
Then again, abstracts are somewhat vague, but if we are talking about different abstract, that confuses the communication even further.
Comment by Bruce Hall — April 2, 2007 @ 9:47 am
#7 Bruce: yep, we got our wires crossed. I was talking about Jim Angel’s abstract, you’re talking about the meeting Eli linked to. Serves us both right for not being more precise. A simple misunderstanding.
I do understand where you are coming from with the chicken/egg comment, now. I’m not properly qualified to ‘pass judgment’ on this, except perhaps to say that, whilst in this case (albeit, as Angel says, theoretical) a trans-global response to a large regional forcing is at the least plausible, it will still be unclear how potent this forcing is likely to be on a global scale in relation to other known forcings. Roger thinks the IPCC land-use forcing estimates are too low. I’ve seen others argue that the scale of most land-use change is simply not big enough; how the heck am I supposed to know who is right?
The Hadley model run I referenced from last year had the Amazon drying up in about eighty years. It was, though, a single model run with fixed parameters. I would be surprised if deforestation and burning were not factored in to the Hadley model, but as it has now been published, access to the paper should be easy enough to check. It would also have used a standard formula for calculating CO2 forcing as well, I presume.
Reading comment #3 again, it strikes me that it would be easy to infer that the two alternatives had roughly equivalent strength (though this is not exactly what you say); my concern with Roger’s general land-use argument is that some people might understand him to be claiming that land-use change is a more potent forcing than CO2. Whilst I might readily accept that the IPCC systematically underestimates the importance of land-use in its calculations of forcings and feedbacks, I think I would struggle to understand how it could be a major contributor.
I know this is throwing a whole other load of issues into the mix, and my apologies for that, not least to Roger, but clarification of issues like this are of great importance, not least to me.
Respectfully,
Comment by Fergus Brown — April 2, 2007 @ 2:39 pm
I think global warming wont happen. Even if it does our world is better a couple degrees warmer than a couple degerees colder
Comment by brett hendrickson — May 11, 2007 @ 10:57 am
I think Brett is right, if the world was colder then crops around the world will die
Comment by Mike Rotch — May 15, 2007 @ 11:00 am
I think global warming is going to happen if we dont take care of the problem. scientists need tocome up with a solution to solve this. if anyone would like to hear more of my opinion mail me at ahallmeyer@yosemite.usd
Comment by Elmer Fudd — May 15, 2007 @ 11:04 am