Disclaimer: see below. Although I'm no expert on these topics, I've put together some of what I found interesting, including some agricultural snippets (buried in there somewhere).
While I was sleeping (or somewhere else) Anthony Watts put up a post headed up:
An illustration that CO2 won’t roast the Earth in a runaway tipping point…
…because the Earth has experienced massive CO2 pulses and recovered before.
|Source: GeoCO2.png Photo by dhm1353 | Photobucket|
Does Anthony Watts comprehend or even bother to read what he posts?Funny thing is that it was only last night that I made this observation:
I don't think Anthony Watts reads scientific papers and I very much doubt he would understand them if he tried. Notice he writes very little himself on his blog and almost nothing scientific. He relies on guest articles, press releases and other blogs. On the rare occasions he does try his hand at something he usually gets into real strife and gets it all horribly wrong.(This is quite long. If you're on the HotWhopper home page, to read more click here.)
So far I was on the money, because he didn't dream this up himself, he gave a hat tip to Tom Nelson for this particular article of his. However, it looks as if Anthony wrote what little text there is. So let's see how he scores on the message he's sending. I've made up a chart using data from GEOCARB III for CO2 levels, from Rohde and Muller (2005) for biodiversity and Wikipedia for the timing of the major extinction events. Here it is. Click for larger view.
|Data Sources: GEOCARB III, Rohde & Muller (2005), Wikipedia|
The chart shows the CO2 levels for the past 579 million years as columns (left-side scale). It also shows the number of known marine animal genera versus time from Sepkoski’s compendium going back 541 million years as the shaded area in the background (right-side scale), as an indicator of biodiversity. There have been five major extinction events before this current one.
Ordovician-SilurianAt this time, there was only life in the sea, not on land. The extinction took place between about 450 and 440 million years ago. It was actually two events, probably around a million years apart - both from rapid climate change (Finnegan et al 2011). It caused the death of more than 60% of marine invertebrates, including 2/3 of all brachiopod and bryozoan families (Wiki again, with refs). If you look at the chart above, that would have been quite a big deal since there weren't a lot of species to start with, compared to today. According to Finnegan et al (2012) in PNAS, this event is unambiguously linked to climate change. It was related to the glaciation of Gondwana:
The Late Ordovician Mass Extinction (LOME) was the first of the “Big Five” Phanerozoic mass extinctions, and it eliminated an estimated 61% of marine genera globally (1). The LOME stands out among major mass extinctions in being unambiguously linked to climate change. The primary pulse of extinction near the Katian/Hirnantian stage boundary closely coincided with the rapid growth of south polar ice sheets on Gondwana (1⇓⇓–4). Expansion of continental ice sheets was accompanied by substantial cooling of the tropical oceans (5, 6), a major perturbation of the global carbon cycle (7⇓–9) and a large drop in eustatic sea level (2, 5, 10, 11), which drained the vast cratonic seaways that characterized the Late Ordovician world (12).For everyone who thinks they would survive with the high CO2 levels of the early Paleozoic, they might want to think again. AFAIK there was no animal or higher plant life on land at the time so there's no possibility of determining from the past whether or not today's world would survive such conditions. And with the sun the way it is today, and the organisation of the land masses - it would surely get way too hot and kill most of today's species on land and in the oceans if we let CO2 get anywhere close to 4000 ppm.
Late DevonianAfter the big loss of life and diversity in the Ordovician-Silurian event, life took off again. Plants and insects appeared on land. So I guess if Wattsonians went back to the late Devonian, they wouldn't feel as much at a loss on land as they would have some one hundred million years prior during the Ordovician.
In the late Devonian, something like 19% of all families and about half of all genera went extinct in what is known as the Kellwasser Event, which took place at the boundary of the Frasnian-Famennian stage around 374 million years ago. This was followed about 15 million years later by the Hangenberg extinction event. The latter event is linked to climatic changes and, according to Sallan and Coates (2010) was responsible for the "long term losses of over 50% of diversity and the restructuring of vertebrate systems worldwide".
I sometimes read climate science deniers talking about the hardiness of corals. Well there were reef building organisms back in the Devonian. However they pretty well all disappeared during the Late Devonian extinction. Modern corals are thought to have evolved in the Mesozoic after the Permian Triassic extinction. If you're interested in the evolution of corals, I came across this paper by George D Stanley (2003) which looks interesting.
Permian-TriassicThis is probably the most famous extinction event. It happened 252.28 million years ago and is the most severe of all the events. It killed up to 96% of all marine species, 70% of all terrestrial vertebrates and is the only known mass extinction of insects. It seems that it took around ten million years before life on earth recovered. From Wikipedia:
Researchers have variously suggested that there were from one to three distinct pulses, or phases, of extinction. There are several proposed mechanisms for the extinctions; the earlier phase was probably due to gradual environmental change, while the latter phase has been argued to be due to a catastrophic event. Suggested mechanisms for the latter include large or multiple bolide impact events, increased volcanism, coal/gas fires and explosions from the Siberian Traps, and sudden release of methane clathrate from the sea floor; gradual changes include sea-level change, anoxia, increasing aridity, and a shift in ocean circulation driven by climate change.
Triassic-JurassicThis event took place 201.3 million years ago. It took out at least half the species living on earth at the time. It was fairly short as these things go, taking only around 10,000 years - just before Pangaea started to break up. No-one is around from that time to tell us what happened but there seem to be a few different theories, including (from Wikipedia):
- Gradual climate change, sea-level fluctuations or a pulse of ocean acidification
- Asteroid impact - though nothing has been found of the size that would explain it
- Massive volcanic eruptions that released CO2 (causing warming) or sulphur dioxide and aerosols (causing cooling).
K-PG (Cretaceous-Paleogene)This is the most recent major extinction, occurring 66 million years ago. It wiped out around 75% of all plant and animal species and took place over a short geological time span (but I didn't find out how short). It was most likely caused by an asteroid and its after-effects, although there are other hypotheses. Afterwards, life took off again with lots of diversification, resulting in the wide range of species we see today (including us).The article in Wikipedia is very extensive and has lots and lots of references.
The sixth major extinctionI don't know if scientists have settled on a name for the current (probable) extinction event. Might be too soon and there may be a thought that if we name it then it's definitely happening. There is a school of thought that it is happening already. In my opinion (notwithstanding my supreme ignorance of such matters), if it is, it could be the fastest extinction event of all given the speed at which we are changing the world. Let's hope that humans survive to document it properly so that our descendants in future millennia can learn about it and from it. Here are a couple of texts:
The New World of the Anthropocene, Zalasiewicz et al (2010)
Has the Earth’s sixth mass extinction already arrived?, Barnosky et al (2011)
and you might find other interesting papers here.
So where does that leave Anthony Watts' original pronouncement? An illustration that CO2 won’t roast the Earth in a runaway tipping point……because the Earth has experienced massive CO2 pulses and recovered before.
If Anthony Watts is prepared to help cause a major extinction event and let earth recover at her leisure over the next several tens of millions of years, then he has a point. If, on the other hand, he is under some delusion that rapid changes to the earth system won't lead to extinctions and probably to a major extinction, they he is very wrong as can be seen by the above.
From the WUWT comments
The WUWT comments section provides fertile soil for anyone wanting to repeat the experiments of Dunning and Kruger, but there are some more thoughtful responses (sort of). Here's a mixed sample:
August 9, 2013 at 12:28 am At 2500 ppm,170 Myears ago, there was in the atmosphere approx 2×1016 Kg CO2. This is 15 times the total quantity emitted by human activity between 1750 (beginning of industrial age) an 2011 (source CDIAC), of which about one third remained in the atmosphere to reach a concentration of 390 ppm. This carbon had to be fixed in the form of hydrocarbons (which we now burn) or of carbonate sediments. And life has gone on.Increase CO2 quickly and see the consequences: Bill Church wants to "bring it on" and writes:
August 9, 2013 at 12:07 am I seem to recall a paper suggesting very high populations of herbivores during the Cretaceous over and above what trees and plants could support. Perhaps CO2 levels up at 2,000ppm might have had something to do with it. If only we could get CO2 up to, say, 1,000ppm we might see some very interesting crop yields! Damn, might have to mow the lawn more often though.
Most life doesn't adapt: Aidan Donnelly thinks that evolution will happen much more quickly than it did in the past and that "all life adapts". As can be seen above, in a major extinction the vast majority of life doesn't adapt, it becomes extinct.
August 9, 2013 at 12:04 am I am still confused as to how the alarmist crowd can get away with continually ‘denying’ evolution. More particularly the one part of Darwin’s theory that is (almost) universally accepted and completely non-controversial. I refer of course to Natural Selection, by which all life adapts, either to survive a changed ecology or to take advantage of that change (or both) It appears to be incontrovertible that plants thrive with much higher Co2 rates than have been naturally present for many years.I am no scientist but then I don’t have to be as it is easy to find the information on this. Plants starve under 180 ppmv and thrive best at 1-3000 ppmv. Those plants must have experienced CO2 levels at least as high as the amount they can make best use of. So for them to say higher amounts (than the ~260ppmv which was the baseline for all the alarmism) are harmful, while most plants are still limited by Co2 much lower than optimum is to invalidate ‘Micro’ evolution, without which ‘Macro’ evolution is also invalidated. So why are eminent persons like Richard Dawkins not screaming foul on these ‘scientist’s'?Does Aiden like his bread, sugar, rice or noodles? It was probably only about 35 million years ago that grasses evolved from their ancestors that emerged after the K-PG event. At that time CO2 was probably between about 400 and 600 ppm. A long way short of his 3,000 ppm. And it was only about ten thousand years ago that humans started domesticating plants, including some of the wheats (bread wheat around 8,000 years ago) and rice (about 6,500 years ago). CO2 was considerably lower then than it is today. (Here is a short paper on the evolution of grasses including C4 plants, and their antecedents).
August 8, 2013 at 7:55 pm I wonder what happened to ocean acidification when CO2 content was more than 1000ppm. Did all the coral reef vanish then? AGW is not only global surface temperature rise.Acidification is considered one of the causes of the Late Devonian extinction event, causing the demise of the then reef building organisms. Similarly, ocean acidification is thought to have contributed to the Permian Triassic extinction event. CO2 was much higher leading up to both of those, however (2,000 - 3,000 ppm). CO2 was falling leading up to the K-PG extinction. However this article suggests that nitric acid following the asteroid impact may have caused ocean acidification and contributed to some extinctions.
Mind-boggling: Gary Pearse says lets bring on the :
August 8, 2013 at 5:49 pm Interesting that the Mississippian and Pennsylvanian, aka “Carboniferous” is very low in CO2 but this was the era when almost all global coal seams were laid down! This means that the very high CO2 previously created these enormous tropical swamps which died down in the Carboniferous sequestering all the C as coal without any help from us. It is just mind boggling that we have spent $2 trillion because of the pathetic CO2 problem illustrated in this graph. It seems as if the Climategate scandal, which put CAGW into a downward spiral, allowed shackled, closeted scientists to come out of the woodwork and release a pent up store of scientific papers.Gary seems perplexed that biology, chemistry and physics still worked the same way even when humans weren't around. I don't know where he gets his $2 trillion figure from or to what it relates. What is mind-boggling to me is that he doesn't seem interested in limiting the destabilisation of earth systems when it's us who are causing the destabilisation at present. In the Carboniferous period, it wasn't just CO2 that changed, it was oxygen as well. Does he really want that? (I'm not suggesting we are going to bring about marked changes in atmospheric oxygen, although of course we are causing minute changes in its concentration.)
I think that's enough. I'll repeat my earlier caution. I've learnt quite a bit from writing this article but I'm not even a beginner on the subject. So don't go quoting me. I've provided references for most things but there's no guarantee I got it all correct. Feel free to point out any errors.