Today on WUWT Anthony Watts pasted two press releases from Australia's CSIRO.
1. Aerosol influence on ocean circulation
The first one is about this paper (open access) published in Nature's Scientific Reports. It's titled: Forcing of anthropogenic aerosols on temperature trends of the sub-thermocline southern Indian Ocean.
The authors, Tim Cowan et al find support for the hypothesis that aerosols influence ocean circulation trends. Here is the abstract:
In the late twentieth century, the sub-thermocline waters of the southern tropical and subtropical Indian Ocean experienced a sharp cooling. This cooling has been previously attributed to an anthropogenic aerosol-induced strengthening of the global ocean conveyor, which transfers heat from the subtropical gyre latitudes toward the North Atlantic.
From the mid-1990s the sub-thermocline southern Indian Ocean experienced a rapid temperature trend reversal. Here we show, using climate models from phase 5 of the Coupled Model Intercomparison Project, that the late twentieth century sub-thermocline cooling of the southern Indian Ocean was primarily driven by increasing anthropogenic aerosols and greenhouse gases. The models simulate a slow-down in the sub-thermocline cooling followed by a rapid warming towards the mid twenty-first century. The simulated evolution of the Indian Ocean temperature trend is linked with the peak in aerosols and their subsequent decline in the twenty-first century, reinforcing the hypothesis that aerosols influence ocean circulation trends.Anthony Watts comments: From CSIRO, but sadly just with modeling, not empirical analysis:
While it's true that the scientist explored the situation using computer simulations, what they are testing for is an explanation for real world observations. It makes one wonder if Anthony knows what the word "empirical" means. And he's not the only one. From the comments:
Anymoose hasn't read the paper and doesn't know that it's all about explaining "actual measured data" and says:
July 23, 2013 at 6:40 pm Simulation? Model? How about some actual measured data, just like a scientist might provide?The other comments are mainly deniers saying "we know more than those dumb scientists" or "we don't believe you".
2. Carbon exchanges in tropical ecosystems are extremely sensitive to temperature
The second one is an interesting analysis of what happens to photosynthesis and respiration in the tropics, particularly during El Niño years, and how it affects the carbon cycle. In this research, the scientists looked at data on CO2 concentration and global air temperatures for to a fifty-two year time span, from 1959 to 2011. The press release is not the best one I've read. As far as I can make out, the gist of it is as follows.
The focus of the study was on El Niño years when it's hotter and drier in the tropics. What the researchers found was that under those conditions, plants cut down on photosynthesis and increase respiration such that the net effect is an increase in CO2 emissions from the tropical vegetation. And quite a big increase at that. A one degree increase in temperature causes a rise in CO2 equivalent to one third of annual human emissions from fossil fuel burning and deforestation combined. The money quote seems to be this one:
"Our study indicates that carbon exchanges in tropical ecosystems are extremely sensitive to temperature, and they respond with the release of emissions when warmer temperatures occur".
I couldn't find the PNAS paper itself. It doesn't seem to listed at PNAS yet, not even as part of the PNAS early edition. I'd have preferred to read the paper because the press release is not easy to follow. I don't know if there is a net reduction in CO2 during La Nina years, for example. One would presume so, otherwise in the past there would have been an accumulation of CO2 over time. But there wasn't - until recently. But that was from our efforts.
Consistently unstable at WUWT
I notice that Anthony Watts interpreted "consistent" as "stable" - writing a headline "Earth’s self regulation of Carbon Dioxide is remarkably stable". Can't say I got that from the press release. It doesn't match with the "extremely sensitive" quote.
The comments at WUWT are the usual mixed bag of denialist denial, conspiracy theorising, "we know better" and other nonsense. Quite a few comments were debating whether or not a petagram equals a billion tonnes, confusion between tonnes and tons and similar.