What are the extinction risks for species due to climate change?

[pattylou]

In a letter to Nature, several researchers have estimated how many species may be threatened by a changing climate over the next 50 years. The number were higher than even I expected, placing a ballpark estimate of 10 - 30% of species examined, on the road to extinction by 2050.

Nature 427, 145-148 (8 January 2004) |

Extinction risk from climate change
Chris D. Thomas1, Alison Cameron1, Rhys E. Green2, Michel Bakkenes3, Linda J. Beaumont4, Yvonne C. Collingham5, Barend F. N. Erasmus6, Marinez Ferreira de Siqueira7, Alan Grainger8, Lee Hannah9, Lesley Hughes4, Brian Huntley5, Albert S. van Jaarsveld10, Guy F. Midgley11, Lera Miles8,15, Miguel A. Ortega-Huerta12, A. Townsend Peterson13, Oliver L. Phillips8 and Stephen E. Williams14

Climate change over the past 30 years has produced numerous shifts in the distributions and abundances of species1, 2 and has been implicated in one species-level extinction3. Using projections of species' distributions for future climate scenarios, we assess extinction risks for sample regions that cover some 20% of the Earth's terrestrial surface. Exploring three approaches in which the estimated probability of extinction shows a power-law relationship with geographical range size, we predict, on the basis of mid-range climate-warming scenarios for 2050, that 15−37% of species in our sample of regions and taxa will be 'committed to extinction'. When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction (18%) than mid-range (24%) and maximum-change (35%) scenarios. These estimates show the importance of rapid implementation of technologies to decrease greenhouse gas emissions and strategies for carbon sequestration.

Full article with references and methods and assumptions made in modeling:

http://www.nature.com/nature/journal/v427/n6970/full/nature02121.html;jsessionid=3B9E3D847AF2C5D284B0B2160F62DD6D

 

[Andre]

It has come to our attention.

https://www.physicsforums.com/showthread.php?t=12709&page=1
https://www.physicsforums.com/showthread.php?t=60960&page=1

and has led to a jumbo thread http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=9580&start=1

I wonder why we do need the alibi of climate change, whilst we do not need climate at all destroying the habitats and emptying the seas.

 

[pattylou]

Presumably because the systems are all linked? For example, perhaps deforestation represents more of an insult to climate than fussil fuel use.

 

[Andre]

Deforestation most certainly has influence on climate. Forests take up a lot of heat and the evaporation cools the area further. So I most certainly agree that forests are way to precious to waste. Let's reforestate.

Anyway, My best friend has used this article to compare it with the five (actually seven) great extinctions. These were her conclusions:

OVERAL CONCLUSION
There have been multiple extinction events; most, if not all, can be related to catastrophic occurrences. Global cooling has been related to extinctions, global warming has only been observed as a possibly secondary effect in several occasions whereas a more catastrophic event triggered the extinction. The massive clathrate destabilization events appears to be an unexpected new identified catastrophe with clear activity during the Paleocene Eocene Thermal Maximum as well as the Pleistocene extinctions. We propose a secondary effect of the clathrate gun a dramatic precipitation change that changes or destroys biotopes. However, it may be concluded that there appears to be no geologic precedence that links global warming events to extinctions as a direct cause. Consequently the hypothesis of Thomas et al 2004 “Extinction risk from climate change” cannot be sustained. If a great extinction is taking place, humans may blame themselves directly as the main catastrophic event. Secondary effects like global climate changes cannot be held responsible. So if this trend was to be countered, immediate direct measures against the primary causes come into mind, and attempts to dealing with secondary effects like climate changes may be very disappointing

 

[pattylou]

I have the same problems with your friend's approach that I have with yours.

However, it may be concluded that there appears to be no geologic precedence that links global warming events to extinctions as a direct cause. Consequently the hypothesis of Thomas et al 2004 “Extinction risk from climate change” cannot be sustained.

This is somewhat like saying: "A supernova has not caused mass extinction in the past and thus there is no basis to expect our sun to destroy all life on the planet when it supernovas."

The current climate change is different than what has occurred in the past. We have fewer forests, we are putting more and more CO2 into the atmosphere every year, and so on.

It's not the same equation as previous warmings.

 

[Andre]

It appears that Thomas et al have based their three empirical models on several recent detail studies of changing habitats of different species. Then they project these models on future developments. The models have no more status than a prediction aid for testing a hypothesis. But they use another hypothesis predictor (global warming projection) for their claims. I believe that a hypothesis based on a hypothesis is a little overdone. Moreover, both predictors use a linear projection of the past into the future outside the limits of the model parameters. In the old days, when the scientific method still prevailed, the paper might have been rejected for a much too high uncertainty factor like the Drake equation.

One thing that the explores have omitted was integrating the great extinctions and see if climate change was a factor and the other way around, if there were rapid climate changes, would this be accompanied by accelerated extinction rates? This is where my friend made a little survey about.

So the five + two biggies appeared to have two separate sets of causes, a distinct geography change and extreme continental scale flood basalt volcanism.

The geography change, due to plate tectonics, is causing landmasses to pass the poles or the equator or it is forming the large super continents with probably uninhabitable areas inland due to the lack of close water sources. This seem to apply to the extinctions of the Mid Cambrian (527Mya), Late Ordovician (443 Mya) –(super continent at the South pole), and the Devonian (365Mya).

Colossal trap volcanism has been co-dated with the extinctions of the end Cambrian (490Mya –Antrim) , Perm - Triassic (248Mya– Siberian Traps), Triassic-Jurassic (206 Mya-Mid Atlantic traps) and the Cretaceous-Tertiary, the famous dinosaur event, (65Mya - Deccan Traps). Notably some of the latter show a large bolide (large asteroid) impact almost “simultaneously” or a bit earlier (triggering the volcanism?). All in all, there is little climate change as direct cause in these habitat destroying events.

Concerning the other way around, climate changes and extinctions. The major event here, is the earlier mentioned Paleocene Eocene Thermal Maximum (55My), which did show a high overturn and grow rate of species, apparently filling the niches that the T-J extinction had left behind. So this alleged warming event showed no clear extinctions other than the mentioned large foraminifera extinction which was most likely caused by a major oceanic clathrate decomposition event.

Next, the multiple “Dansgaard Oeschger events or interstadials” are supposed to be short lived major climate excursions of 5-7 degrees C –near global that happened between 120-28Ky ago. However, there are no exceptional extinctions associated with these events. Incidentally, these interstadials have been associated with oceanic clathrate events too (Kennett et al, Science 2000).

Then we come to the “Bolling Allerod” (alleged warm wet), “Younger Dryas” (alleged cold dry) and the “Preboreal” (alleged warm wet), the start of the Holocene. This is the period of the Mammoth megafauna extinction. For the cause of that event, I’d highly recommend this thread again, please do read it sometimes. Bottom line, clathrate strikes again.

After studying all this I think that she had some point in making those conclusions. The main one being: sudden warming in the past appeared to have happened in the past, but no associated mass extinctions.

But what is the overall conclusion? These severe climate chances, that Overpeck likes to refer to so much, the aforementioned Interstadials, the Bolling Allerod and the Preboreal periods are the direct cause of the global warming scare. But it’s totally different, all these indications of warming are the direct immediate result of major oceanic clathrate decomposition events. This is what the proxies are telling us, the isotope ratio changes et al are not warming but fooling around of humid clathrate events. Now, having identified that, it’s easy to see that we do not face sudden climate changes but sudden clathrate events in which CO2 plays no causality role at all.

 

[CobblyWorlds]

Hi PattyLou,

"It's not the same equation as previous warmings."

This is exactly the crux of the issue. Knowing about past climate changes is very important in understanding the reaction of climate to variables that affect it. However for the past we rely on proxy data, whilst feeling peeved that we can’t get real-time and detailed observational data from those past events. At present we have such data, we can monitor the sun, the atmosphere, land and oceans in great detail. Yet we find no viable alternate to the theory that CO2 driven warming is the cause. And we can see pointers to it, such as upper strato. cooling.

I'd suggest another analogy...

You're lying in bed at night and you smell smoke.

1) You decide that it's not unusual to smell smoke, after all when cooking the smoke alarm goes off fairly regularly. So you turn over and go to sleep for good.

2) You decide that as the smoke alarm has gone off whilst cooking regularly in the past month, this is obviously some kind of lingering tail-end effect. So you turn over and go to sleep for good.

3) You decide that the smoke alarm is faulty, the only time you’ve ever smelt smoke before is whilst cooking. So you turn over and go to sleep for good.

4) You decide that it's an illusion, some part of your subconsciousis trying to manipulate you.

Alternatively;

1) This is like those who suggest Milankovitch cycles or variance of solar radiation. Despite the fact that (you were asleep, not cooking) there is no evidence that these are factors that have a current effect.

2) This is like those suggesting some form of rebound from previous climate changes, despite the lack of a mechanism for such a re-bound. The ‘ringing’ alluded to by those supporting this theory does not happen for no reason, such a transient response type effect has to be for physical reasons – what are they?

3) This is like those who deny the observational methods employed without actually taking the time to go and investigate. Were they to do so they’d actually find less room for doubt than they assert. Aside from on sites like JunScience(sic) all of the methods show a warming trend.

4) er OK mate, just don't shoot. ;)

 

[Andre]

You're stealing the thread. This one is about extinctions. I admit a small sidestep in the previous post but at least 90% of it was extinctions. So please refer to the previous discussion for instance by explaining why the alleged coming warming period would lead to extinctions whereas the others have not, or start your analogies in another thread.

 

[CobblyWorlds]

Cool, sorry Andre, got distracted.