Unsettled science: New study challenges the consensus on CO2 regulation – modeled CO2 projections exaggerated
No, Anthony. Modeled CO2 projections aren't exaggerated.
WUWT conspiracy nutters thrive with high CO2
Anthony's opening line was not only wrong, it was pure conspiracy ideation:
I’m really quite surprised to find this paper in Nature, especially when it makes claims so counter to the consensus that model projections are essentially a map of the future climate.
That's feeding the paranoia of the nutters at WUWT, who think that journals filter out science that doesn't support a consensus. The opposite is true. Journals, particularly high profile journals like Nature, prefer papers that buck the consensus, that make headlines, that help promote the journal. This paper doesn't buck any consensus in any real way. Instead it probes the detail and adds more knowledge.
Fact is, Anthony is getting his (dis)information from another denier website. Not a wise thing to do if you are interested in science, which Anthony isn't. He's a science disinformer so naturally rather than interpret the science, he interprets interpretations of science disinformers :)
Floods led to massive plant growth in semi-arid regions
Anthony got the paper right up to a point. What the large team of researchers found was that the record floods in Australia boosted vegetation so much that it sucked up a lot of carbon from the atmosphere. As the abstract states (my paras and bold italics):
We use a terrestrial biogeochemical model, atmospheric carbon dioxide inversion and global carbon budget accounting methods to investigate the evolution of the terrestrial carbon sink over the past 30 years, with a focus on the underlying mechanisms responsible for the exceptionally large land carbon sink reported in 2011 (ref. 2).
Here we show that our three terrestrial carbon sink estimates are in good agreement and support the finding of a 2011 record land carbon sink. Surprisingly, we find that the global carbon sink anomaly was driven by growth of semi-arid vegetation in the Southern Hemisphere, with almost 60 per cent of carbon uptake attributed to Australian ecosystems, where prevalent La Niña conditions caused up to six consecutive seasons of increased precipitation.
In addition, since 1981, a six per cent expansion of vegetation cover over Australia was associated with a fourfold increase in the sensitivity of continental net carbon uptake to precipitation.
Our findings suggest that the higher turnover rates of carbon pools in semi-arid biomes are an increasingly important driver of global carbon cycle inter-annual variability and that tropical rainforests may become less relevant drivers in the future. More research is needed to identify to what extent the carbon stocks accumulated during wet years are vulnerable to rapid decomposition or loss through fire in subsequent years.
What happened in Australia
Australia's long term average precipitation over the period 1900 to 2009 was 453 mm. In 2010 it was 703 mm and in 2011 it was 708 mm. That's a lot more rain. That made those two years combined the wettest since records began in 1900 and is attributed to La Niña, which also brought above average rain to southern Africa and northern South America. The rain was extra heavy, even for La Niña, because of global warming. The seas are hotter so more water is evaporating. As reported at The Conversation, GRACE satellites estimated a decrease in ocean water mass of 1.8 trillion tonnes, with water shifted from the oceans to land. Sea levels dropped by a massive 5 mm.
Here is an illustration of what happened to the vegetation:
Modelled carbon uptake of the Australian landscape in December 2009 (before) compared with the start of the big wet in December 2010 (after). Adapted from Source: The Conversation.
Semi-arid regions vs tropical rainforests as carbon sinksThing is, conventional wisdom holds that it's tropical rainforests that are the most important carbon sink and will continue to be so. However this new research shows that semi-arid regions may become increasingly important as carbon sinks if events such as those described above occur more often. Semi-arid regions represent around 40% of the world's land surface.
A roller coaster of carbon shifts?
Australia as you know is also prone to drought and bushfires. Australia is the second driest continent on earth, after Antarctica. Any person who lives up the bush will tell you that the worst fire risk comes after a "good season". Lush vegetation dries out and fires take hold. What that does is unleash all that carbon that's been taken up by the extra growth and returns it to the atmosphere.
During the big wet, there weren't so many fires. It wasn't just Queensland that got wet, half of my own home state was under water for much of the 2011 summer. Much of Central Australia was virtually a giant lake. Western Australia had huge floods as well. The authors state that fire emissions were suppressed by about 30%, which "contributed even further to the continent's greening".
The good news of this carbon sink is tempered by the bad. In wet seasons there will probably continue to be a lot more carbon stored in new vegetation and in the soil. However with the projected climate change across much of Australia, it's likely that there will be more droughts and fires, which will result in all that carbon going back into the atmosphere. It won't stay locked up.
The interesting thing buried in the detail of the article at The Conversation, is that Australia has been greening more since the 1980s, not all with a good outcome (note the expansion of invasive species). The authors write:
In addition to the unprecedented vegetation greening of Australia during 2010 and 2011, we also observe a greening trend over the continent since 1980s, particularly during the months of the Australian autumn (March, April, and May).
That has happened for a number of reasons, including increased continental rainfall over the past few decades; plants growing in an atmosphere with increasing carbon dioxide using water more efficiently; and changes in land management such as fire suppression, expansion of invasive species, and changes in livestock grazing that have led to more woodland.
There have been previous studies that show that the increased carbon dioxide in the air is leading to more growth in Australia's native flora (as elsewhere in the world), particular in the arid regions. I wrote about this research on my slumbering Sou from Bundangawoolarangeera blog.
Where Anthony Watts gets it wrong - a short-lived sink
Of course Anthony Watts misrepresents the science. He isn't even aware of the paper itself. He only linked to an article in Nature about the paper calling it "a new paper". And he missed out completely on showing the article in The Conversation by two of the paper's authors.
Anthony wrote (my bold italics):
The authors find links between the land CO2 sink in these semi-arid ecosystems “are currently missing from many major climate models.” In addition, they find that land sinks for CO2 are keeping up with the increase in CO2 emissions, thus modeled projections of exponential increases of CO2 in the future are likely exaggerated.
Obviously Anthony is wrong when he claims that land sinks are keeping up with the increase in CO2 emissions, otherwise atmospheric CO2 wouldn't be above 400 ppm or rising at 3 ppm a year, like it is. It's simple arithmetic. While it is quite possible/probable that some climate models don't provide for CO2 sinks in semi-arid regions during big wets like the recent ones in Australia, I don't know where Anthony got his bit about exaggeration from either. It's not in the page he published from the Nature article about the paper (by Daniel B. Metcalfe). He probably got it from his denier blog source or maybe he just made it up. What the authors say at the Conversation is that the large uptake of carbon in 2011 was likely short-lived, because there was a rapid decline in the sink strength in 2012. So that suggests that Anthony is wrong as usual.
More volatility in CO2 levels
The ramifications of the research are that there is likely to be a lot more volatility in CO2 levels. Vegetation in semi-arid regions isn't like that in tropical rainforests. The latter store carbon in hardwoods, which can lock it up for centuries. By contrast, in semi-arid regions carbon is stored in grasses and shrubs, which are relatively short-lived and prone to fire and drought, which quickly releases the carbon back into the atmosphere. The authors say:
Increasingly, semi-arid regions are driving variability in how much carbon dioxide remains in the Earth’s atmosphere each year. And that has major implications for the long-term, including whether future climate change will slow down or accelerate further.
There's not very much information about the carbon budget in arid and semi-arid regions and I expect this research will lead to more. It could be that climate change will accelerate a lot, or proceed more slowly. I won't be betting on the latter until there's a lot more information.
There is an excellent FAQ on this topic, prepared by the researchers.
From the WUWT comments
As usual, deniers at WUWT only like stuff that they think supports their ideology. Being fake sceptics, they don't check facts for themselves. Also, the greenhouse effect deniers are out in force, suggesting that Anthony is rapidly losing faith with more rational, intelligent fake sceptics (if there is such a beast). Maybe Anthony's readership is shrinking to the utter nutters:
RayG is a greenhouse effect denier who refuses to read science. He stopped reading at the first hurdle, and says:
May 22, 2014 at 11:14 am
I stopped reading at the assertion that in the first sentence that CO2 is the main driver of global climate change. I also note that there are no citations to support this claim.
hunter is another greenhouse effect denier and says:
May 22, 2014 at 11:18 am
While the assertion that CO2 is *the* climate thermostat is dubious, at least this article is exploring one of the significant failings of the current CO2 obsession.
May 22, 2014 at 11:23 am
Well, I mean really….
who was stupid enough in the first place to think an additional 2 ppm/yr would overwhelm the system
May 22, 2014 at 11:41 am
RayG says: I stopped reading at the assertion that in the first sentence that CO2 is the main driver of global climate change. I also note that there are no citations to support this claim.
Obama said it’s a fact. So it’s gotta be true, right?
May 22, 2014 at 11:43 am
“I stopped reading at the assertion that in the first sentence that CO2 is the main driver of global climate change. I also note that there are no citations to support this claim.”
Perhaps that was the price to pay to get the paper through toll gate known as peer review. If there is one unsupported claim that you probably can publish in any climate journal that’s probably it.
Rhoda R says:
May 22, 2014 at 11:44 am
Ray, it may be that that statement was the only way that this study could have been published. I suspect that if the man-made, developed countries driver for C02 is shot down there will be much less interest in government funding of AGW research.
May 22, 2014 at 11:48 am
As many of the actual scientists who have been espousing the “CO2 as Devil” meme walk away from the bad science, this paper tries to reveal that humanity may not even be the cause of higher CO2 concentrations. Those to whom Warmism is a religion will pretend not to notice.
Eliza is hopeful that it's one of the nails in the coffin and figures if climate science gets the chop then the world will magically stop warming. She says:
May 22, 2014 at 12:23 pm
Its probably a discrete “first” way out for NATURE so none of the big AGW shots notice. Its a climb down and we will be seeing more and more of this until the “norm” will in fact be the skeptic position, The whole AGW scam will only completely disappear when the funding dries out. For example, it is highly unlikely that Labor if they win the next election in Australia will pick it up again since Abbot has basically cut off all funding for AGW research and propaganda.
José Tomás says:
May 22, 2014 at 2:43 pm
Nature and other papers have obviously noticed that CAGW has no future (they are not idiots), but you cannot backtrack and save face at the same time.
So, expect lip service paid to CAGW for a long time, even while published articles go in the opposite direction.
May 22, 2014 at 11:10 am
Can’t speak to the particulars, but seemingly excellent news that this paper has seen the light of day in the current repressive atmosphere. Is it possible things are changing a bit?
May 22, 2014 at 12:52 pmThis little curiosity caught my attention, not just because agfosterjr seemed to think that aforesting the tiny percentage of the world's land above 4,000 metres would make a huge difference to CO2, but because of his comment about eucalypts. When I looked it up I came across this article from 1999 that stated: The most abundant tree specie is eucalyptus. Growth and development of eucalyptus in the Altiplano is very slow, due to the adversity of the environment such as constant frost and prolonged period without precipitation. So it looks as if eucalyptus growth is retarded by cold and dry conditions. According to the paper, the trees grow (very slowly) as spindly shrubs. Cold is the main thing stopping trees growing above the treeline generally. (I guess that means the treeline will rise with global warming.) In the Andean Altiplano, lack of water doesn't help either.
We see little mention of the Andean Altiplano, where possibly the growth of some species is limited more by CO2 scarcity (partial pressure) than by temperature or rainfall. Current interpretation of mud cores from Lake Titicaca indicates no certain history of Holocene forestation, but oddly enough, introduced eucalyptus (from Australia, of course) has no trouble growing at 4000 meters. It has been in the region for over a century, and is used for firewood and pole wood. If I were concerned with carbon capture I would plant lots of trees up high.
Of course eucalyptus introduces the potential for forest fires, as we have seen in Oakland and recently in Valparaiso. –AGF
David Ball fails arithmetic
A lot of comments were generated after David Ball failed arithmetic. David Ball, is a chip off the old block, and says:
May 22, 2014 at 11:47 am
As Don Easterbrook pointed out (do not recall the thread), a change from 300ppm to 400ppm is NOT a 30% increase in Co2, as alarmists constantly shout.
No, David, it's a 33% increase. The increase from preindustrial 280 ppm to 400 ppm is a 43% increase in atmospheric CO2. When he's corrected by Scott Scarborough, David doubles down on his arithmetic failure. David Ball says:
May 22, 2014 at 12:28 pmVarious other commenters weighed in, all supporting Scott Scarborough. David Ball retorts with his weird arithmetic, which has nothing to do with his original claim. What he's calculated isn't the amount of increase in CO2 (which has increased by more than 40%), he's talking about the change in CO2 as a percentage of the total atmosphere - going from 0.03% to 0.04%:
Firstly, have the courage to address me directly. Secondly, go back to math class.
The clue is ppm. Get a clue:
May 22, 2014 at 2:41 pm
The difference is 0.0001, which, expressed as a percentage is 0.01%.
What a nutter. Typical of the denialati David Ball is not just very confused about what it is that he's calculating, he's doing a fairly standard version of "how can a trace gas keep the world warm". His dad is a greenhouse effect denier, too, and co-author of the "sky dragon slayers" book - among other things.
Benjamin Poulter, David Frank, Philippe Ciais, Ranga B. Myneni, Niels Andela, Jian Bi, Gregoire Broquet, Josep G. Canadell, Frederic Chevallier, Yi Y. Liu, Steven W. Running, Stephen Sitch & Guido R. van der Werf, "Contribution of semi-arid ecosystems to interannual variability of the global carbon cycle." Nature (2014) doi:10.1038/nature13376
Daniel B. Metcalfe, "Climate science: A sink down under." Nature (2014) doi:10.1038/nature13341
Donohue, R. J., M. L. Roderick, T. R. McVicar, and G. D. Farquhar (2013), "Impact of CO2 fertilization on maximum foliage cover across the globe's warm, arid environments", Geophys. Res. Lett., 40, doi:10.1002/grl.50563.
Roberto Quiroz and Sassan Saatchi, (1999) "Mapping Aquatic and Agricultural Vegetation of Altiplano Using Spaceborne Radar Imagery", from JPL-NASA website.
Roberto Quiroz and Sassan Saatchi, (1999) "Mapping Aquatic and Agricultural Vegetation of Altiplano Using Spaceborne Radar Imagery", from JPL-NASA website.