Sunday, July 23, 2006



Climate Change: Approaching the tipping point in the Amazon

Tim Flannery's The Weather Makers warned of a number of "tipping points" in the global climate system which could dramatically accelerate climate change. One of these was the Amazon rain forest. While we think of the Amazon as one of the wettest places on Earth, isotope studies have shown that it effectively creates its own rain. Moisture blown over from the Atlantic Ocean is constantly absorbed and effectively transported west by transpiration (and then ultimately flows east again in the rivers). Any disruption in this cycle - either in the amount of moisture input, or in the level of transpiration - could therefore have dramatic effects, and models have predicted that the Amazon could disappear and turn into a desert if we see the sorts of temperature rises and climate shifts we are expecting if CO2 emissions continue unchecked. And this in turn would release vast amounts of carbon from rotting trees and warmer soils.

The models Flannery talked about predicted that this could start happening around 2040, and be complete by 2100. But it might be happening sooner than we think - and the culprit is drought. A story in today's Independent (and syndicated to the Herald) reports that the Amazon is highly sensitive to drought, and could suddenly transform to a desert if severe drought persists for two successive years. Here's the interesting bit:

When Dr Dan Nepstead started the experiment in 2002 - by covering a chunk of rainforest the size of a football pitch with plastic panels to see how it would cope without rain - he surrounded it with sophisticated sensors, expecting to record only minor changes.

The trees managed the first year of drought without difficulty.

In the second year, they sunk their roots deeper to find moisture, but survived.

But in year three, they started dying.

Beginning with the tallest the trees started to come crashing down, exposing the forest floor to the drying sun.

By the end of the year the trees had released more than two-thirds of the carbon dioxide they have stored during their lives, helping to act as a break on global warming.

Instead they began accelerating the climate change.

How much acceleration? According to the article, the Amazon is estimated to contain 90 billion tons of CO2 - and that if this was released, it would increase the rate of global warming by 50 per cent.

And now for the worse news: the Amazon looks set to be entering its second consecutive year of severe drought.

What's worrying is that, of the identified tipping points - Greenland melting, the Gulf Stream shutting down, the Amazon drying up, West Antarctica breaking lose, and Siberia emitting its vast amount of stored methane - we're getting strong warning signs from all of them. And any of them will speed up the process even further, making it far more likely that the others will happen.

But what's really worrying is that, while we know that these tipping points exist and that positive feedback is a real possibility, we don't know exactly where the thresholds are - and given the inertia in the climate system, we may already have passed them.

19 comments:

I suggest we GE somthing really tough that sucks up CO2 and methane and spreads like a weed.
you could build a little system in so that it was hard to mutate out the gene.
Stick a few billion into getting it right and we are away!

Posted by Genius : 7/23/2006 06:52:00 PM

It's a myth that the Gulf Stream keeps Europe warm, as this article rather pointedly shows. Does Flannery get this right or not?

Posted by stephen glaister : 7/23/2006 10:38:00 PM

So. Who's willing to risk $10 that the Amazon won't be a vast desert by this time next year? I'll give odds of 3:1 !

Posted by Graeme Edgeler : 7/23/2006 11:50:00 PM

How are we letting this happen?!?

People were shot at protests in the Vietnam era when there was far less at stake....where are the mass protests and civil disobedience to tell the politicians that something needs to be done?

Our generation deserves to inherit this fucked up mess.

Posted by Tane : 7/24/2006 08:05:00 AM

Well, Seager's conclusions aren't really a challenge to the mainstream on this one -
"This moderating influence is indeed what the climate models show for the 21st century and what has been stated in reports of the Intergovernmental Panel on Climate Change. "

The scientists at Woods Hole Oceanographic Institute (the internationally recognised leaders on this issue) also take a pretty conservative approach to their conclusions.

As for the Amazon - I wouldn't say next year, but if this trend continues, we should be extremely worried.

Genius - do you have any idea how hard that proposal is? Or are you just trying to wind up the anti-GE crowd?

Posted by George Darroch : 7/24/2006 09:48:00 AM

Graeme,

No-one was claiming it'd be a desert by this time next year.

They were saying that it might have entered an unstoppable decline within a year.

Me, I'm in two minds. On the one hand the Amazon rainforest is hundreds of thousands of years old and we've plenty of evidence of major historic droughts: Jarrod Diamond's 'Collapse' talks of twenty and fifty year droughts in the Amazon basin that utterly wiped out civilisations there.

On the other hand the things now really are different. The biosphere now is like nothing the planet has seen before - we've largely deforested the most fertile land on most continents, etc. And we've messed with the atmosphere in ways that haven't been seen for tens of millions of years.

Depends what they mean by "severe drought".

Posted by Icehawk : 7/24/2006 10:27:00 AM

" suggest we GE somthing really tough that sucks up CO2 and methane and spreads like a weed."

I'll file that great idea with

"let's import rabbits into NZ for the fur trade"

and

"we need to bring in gorse seedlings for hedges".

Posted by Icehawk : 7/24/2006 10:51:00 AM

Stephen,

the article you site doesn't prove that: "It's a myth that the Gulf Stream keeps Europe warm"

All it purports to show (one article alone doesn't prove anything) is that the Gulf Stream is not the only thing keeping NW Europe warm.

Posted by terence : 7/24/2006 02:05:00 PM

I'm sure that Genius was being a little frivolous but greenhouse gases are an air pollution problem - carbon capture techniques of all different sorts are going to be tried, and should be tried. That broadly GE is part of that is a certainty.... Broadly GE is also certain to be a huge part of reducing methane emissions.... in fact if I had to predict a single key headline for 2050 it would be: "Who would have thunk it? The Genetic Revolution that was suposed to make us immortal, cure all disease doesn't do any of that, but ends up sacving the planet by changing the way certain key plants and ruminants work?"

Darroch: good, so we are agreed - i/s was taking crap last year here and every time someone talks about temperatures plunging in Europe because of changes in Gulf Stream circulation changes they are just being, at best, naive scare-mongers?

Posted by stephen glaister : 7/24/2006 02:27:00 PM

Terrence: Did you read to the end of the article? There's a bunch of stuff that all fits together so it's not really just one paper as you suggest. I don't claim to be expert in this area at all, but deep down this gulf stream stuff never made sense to me (just as the Bernouilli principle explanation of lift via the aerofoil shape of wings never made sense to me either and it was very relieving to me to find out that *that* was a myth too a few years ago!)... so I'm primed to believe the story here I must admit. We'll see I guess.

Posted by stephen glaister : 7/24/2006 02:44:00 PM

Stephen, I just read I/S's post you linked to. Nothing in either his post, the articles linked to in that post is contradicted by your article.

They all point to the same thing - a slowing of the North Atlantic thermohaline circulation would cause a drop in temperature of several degrees, and a total shutdown even more.

This is probably the best summary -
http://en.wikipedia.org/wiki/Shutdown_of_thermohaline_circulation - and unlike most Wikipedia articles I'd treat it with a high degree of confidence, as it's watchlisted by prominent scientist William M Connelly.

Get a grip, and stop trying to point score - global warming needs to be a consensus issue. Using words like "myth" just makes you look like an idiot to any right minded person.

And Genius - what if you were wrong in 50 years time? Don't you think that we'd better err on the side of caution than rely on as yet non-existent inventions? Get back to real world solutions...

Posted by George Darroch : 7/24/2006 09:36:00 PM

George (if i may): Yes, that may have been a bit point-scoring on my part... but the fact remains that Europe's not looking like a bad place at all to be if things are going to get warm overall, and that's not the picture painted by i/s ("There's an inescapable irony in the prospect of Europe being frozen due to global warming...") or any number of other folks. There's a general willingness to believe the worst and to think precautionarily in this area that I think needs to be resisted. A stupidly panicked consensus is not one I want to form let alone be part of. The _Indepedendent_ article on the Amazon that started this thread didn't convince: the coupling it described between atmosphere and ocean-temperature and -salinity basically is too tight to be plausible I think. So in *that* case too I'd want to take a "wait and see" approach to the relevant research. On that side of things you seem to demand credulousness (and lots of people are prepared to give it: Tane "How could we let this happen?"). Interestingly, however, on the side of possible technological partial solutions to the greenhouse gas problems you're *highly* skeptical. That amounts to quite an agenda that you're expecting consensus to form around - a very specific and I believe optional pattern of credulity and incredulity. Good luck trying to get that consensus, but I prefer to keep a bit of distance from that and I do expect that many right-minded folk will join me there.

Posted by stephen glaister : 7/24/2006 11:03:00 PM

George,

I think
1) There IS global warming.
2) That is a bad thing (in general - at very least we should be in control)
3) Almost all the "tipping point" arguments are scaremongering - deep down they rest on the idea that the costs are so huge you can’t ignore the small but unknown probability of it happening.
4) Kyoto doesn’t stop global warming it just slows it down a tiny bit. (So it is grossly inadequate)

> Don't you think that we'd better err on the side of caution than rely on as yet non-existent inventions?

1) It isn't all that "out of this world". There are already bacteria that could reduce emissions of animals or plants. It is just the problem of doing it in a commercially viable way.

2) I am not saying don’t have damage limitation strategies (e.g. slight slowing of global warming, or possibly "lesser acceleration"), But I am saying "where is the big push towards solutions like GE?"

Where are the billions of dollars and the marches?

Posted by Genius : 7/25/2006 07:14:00 AM

I don't oppose research in this area, all I'm saying is that it's highly speculative. There are a lot of problems with trying to engineer something that takes and then _retains_ greenhouse gases.

Real solutions exist that would easily reduce our emmissions significantly. And avoid many of the possible tipping points which may be fast approaching, such as Amazon collapse, permafrost methane release, ocean methane release etc. The imperative to do something now is incredible. A 'wait and see' approach that you advocate is not a conservative one, but a very dangerous gamble with everyone's future.

You're right, as an environmentalist, I'd rather we took the most conservative approach to the to issue possible when it comes to the possibility of everything not turning out rosy.

As for the 'freezing of Europe': I/S actually said this - The slowdown so far detected won't be as bad, and is only expected to cool Western Europe by about a degree over the next couple of decades - but even that is bad enough.

And then talked about the negative effects that could have - whether you think that is scaremongering is up to you...

Posted by George Darroch : 7/25/2006 08:18:00 AM

stephen: "at best naive scaremongering"

Unfair.

The article you link to says that the thermohaline warming effect on Europe is real and is "two or three degrees". It also gives a history as to why climatologists thought it was larger.

So people like Flannery who quoted 8 to 10 degrees were wrong, but I don't see why you call them "naive". Their maths adds up: their mistakes seem to be that the current cools slightly faster than they think and that it's only got half the effect they expected on Europe because it warms both sides of the Atlantic significantly rather than just Europe.

The account he gives, whereby it's the rockies on the west coast of America that causes Wester Europe to be much warming than you'd expect is
quite elegant. But it's hardly intuitive.

Or do you think every scientist proved to have made a mistake is "naive"? Will you now lecture us on Newton's naivete in physics? Einstein's naivete in quantum physics?

It's not "naive" for science to develop and improve.

Posted by Icehawk : 7/25/2006 09:03:00 AM

OK... I think we're reaching a higher-level consensus here.... I'm happy to take back (or accept as unnecessarily harsh) calling the earlier work/discussions projecting "frozen Europe" (i/s's title for his piece from last year!) from gulf-stream circulation change.... myths if everyone can agree to dropping talk in anything like catastrophist terms vis-a-vis Europe and the gulf-stream. (The final conclusion of Seager's article remember is that the much smaller drop cooler of Europe might be enough to balance other actually warming effects of global warming on Europe, for possibly net zero effect. My brother tells me that Al Gore's new film talks in pretty seriously catastrophist terms for Europe,....) Sorry if I sound irrtatingly self-satisfied in some of this discussion but, as I mentioned to Terrence, the gulf-stream stuff never made sense to me and in fact when I worked in Seattle I had *exactly* Seager's core thought: "Why aren't *we* the comparison case for Europe not Newfoundland?" I didn't explore it but I just made the relevant mental note that there was something not right. Similarly in high school when I was taught the Bernouilli effect explanation of aerofoil lift I couldn't understand how planes could fly upside down if that were correct. Again, I made a mental note that this could't be right. I'm sure I've made plenty of such notes over the years that haven't panned out but this is one that (apparently) did, and I'm enjoying it! We'll see about the explanation of much of the trade-winds over Brazil as driven by Amazon evaporation/transpiration (I'm skeptical - I tend to think the almost all of the trade wind blows no matter what )and then that that wind differential (i.e., between tradewinds and tradewinds-boosted by Amazon induction) makes a big difference to Atlantic temperatures and salinity (again, I'm skeptical). So, making mental notes....Cheers.

Posted by stephen glaister : 7/25/2006 02:23:00 PM

No, I actually think that we're not reaching consensus, because you appear to only be interested in evidence that points in the direction of less significant climate change. You want me to deny that there is a high likelihood of catastrophic climate change, and I won't do that.

The whole point of the original post about tipping points was that there is still an incredible amount we don't know about the earth's climate system, and and we should thus be very cautious - the current system appears to be working rather fine - we have only a vague idea how bad things could get.

As for An Inconvenient Truth - it pretty much gets full marks as far as accuracy and tone go according to the scientists at realclimate.org

Posted by George Darroch : 7/26/2006 09:22:00 AM

George, I only meant a consensus about frozen Europe/ironic twist possibilities and how to describe their (apparent) reevaluation. Beyond that, differences remain I'm sure. I'm happy to see lots more study of everything about the climate though, and I do consider it prudent to approach greenhouse gas control as a project to be worked on in all sorts of ways over the next 50 years, with technical progress of various sorts being absolutely key as far as I can see... Just want to keep the power of nightmares under control in the meantime... The echo chamber effect of modern life is remarkable: I'm happy that the people at realclimate.org like Gore's film but plenty of knowledgeable people have thought its worst-case-scenario-mongering (frozen Europe/flooded Manhattan etc.) is quite stupid (greg easterbrook's review at slate is one I remember). But if its *your* nightmare....

Posted by stephen glaister : 7/26/2006 03:03:00 PM

The people you refer to are phonies and liars, who distort the truth to support their dogma.

http://mediamatters.org/items/200605260014

They're not knowledgeable at all - the quote in today's Herald by the "Climate Science" Coalition was a classic example of such intellectual dishonesty (or perhaps plain ignorance?).

They claimed the 'hockey stick' graph was discredited and evidence of the need for further investigation. The claims against it were discredited in April, after the journal Science printed a comment pointing out the errors in the research it had published.

http://www.realclimate.org/index.php/archives/2006/04/a-correction-with-repercussions/

As per usual, the Herald published the press release without any comment from real scientists.

Posted by George Darroch : 7/27/2006 11:53:00 PM