Satellites – “not good enough to tell us global temperature”, but apparently good enough to tell us global climate sensitivityFirst of all, the paper is about ecosystem sensitivity not climate sensitivity in the temperature sense. That is, how the different ecosystems around the world are responding to climate variability and change, not how much temperature will increase with a doubling of CO2.
Remember that video produced a few weeks ago from the usual suspects that says satellite data is no good for climate data? Others in science don’t seem to think so.
|Figure 1 | Global map of the Vegetation Sensitivity Index (VSI), a new indicator of vegetation sensitivity to climate variability using satellite data. Red colour shows higher ecosystem sensitivity, whereas green indicates lower ecosystem sensitivity. Grey areas are barren land or ice covered. Inland water bodies are mapped in blue. Source: U Bergen|
Secondly, the satellite-derived data is from the imaging spectroradiometer (MODIS), and shows vegetation changes. It's not from the Advanced Microwave Scanning Radiometer (AMSR-E) or other microwave scanning instrument, used to measure "brightness temperature" or the radiance of the microwave radiation of the atmosphere, from which air temperature in different layers of the air is estimated).
I knew that Anthony wasn't too bright, but that opening of his, where he seems to mix up temperature change with vegetation change, takes the cake (one of many cakes). It would be okay if he was just Joe Public, but Anthony pretends his blog is a climate blog. You and I know better. WUWT is a climate conspiracy blog for his scientific illiterati fans.
The paper was authored by a four-person team from the universities of Bergen and Oxford, led by Alistair Seddon. It looks to be a really valuable contribution, even though so far only 14 years of data have been examined. As time goes by, scientists will be able to monitor more of how different vegetation zones are being affected by climate change.
Vegetation Sensitivity Index (VSI)
What the researchers have done is developed what they call a Vegetation Sensistivity Index. It's based on the MODIS Vegetation Index together with three climatic variables that affect plants, being air temperature, water availability and cloud cover. The analysis is based on an autoregressive modeling approach to identify climate drivers on monthly timescales, and to regions with what they call memory effects and reduced response to external forcing. From the press release at ScienceDaily.com:
The metric they have developed, the Vegetation Sensitivity Index (VSI), allows a more quantifiable response to climate change challenges and how sensitive different ecosystems are to short-term climate anomalies; e.g. a warmer June than on average, a cold December, a cloudy September, etc. The index supplements previous methods for monitoring and evaluating the condition of ecosystems.
As I understand it, areas that have high "memory effects" don't respond as much to changed climate conditions. Outback Australia is very very dry (and gets very hot). It will green up after some heavy rain, but the paper signified that it is one of the regions that has a high memory effect. There's an article on the ABC website that elaborates:
Professor Moles said it was also interesting that while there were areas of very high climate sensitivity in the east of Australia, the study showed our inland ecosystems were among the world's least sensitive to climate variability, particularly in terms of rainfall.The regions identified as having a strong memory effect are;
Professor Huete said the researchers suggested this constant level of low productivity was the result of "memory".
"Sometimes when you subject an ecosystem to some kind of disturbance, such as a drought or fire, they behave differently depending on their past," he explained.
The study indicated significant areas of the Australian interior seemed to be having strong memory effects, said Professor Huete, who wrote an opinion piece for Nature to accompany the new study.
"For some reason the vegetation is not responding to the variability in the climate that we are experiencing. Large portions of plants in the interior don't seem to do anything," he said.
Professor Huete said it was possible plants in the Australian outback had "given up".
"They don't care if it is good favourable conditions now, because they know it is temporary and it is not worth investing in growing more at this time because they become bigger and it is a lot more to care of when the drought returns," he said.
- Drylands of the Sahel
- South-west USA
- The Middle East
- Outback Australia.
Features of these regions include:
- Constant and generally stable low productivity conditions despite large climate variability (eg occasional very wet to mostly very dry in inland Australia), or
- Strong cyclical variability with periods of very low and stable Enhanced Vegetation Index or EVI (eg the Sahel). (EVI, among other things, is explained in the MODIS vegetation index user’s guide.)
The low EVI of the Sahel was contrasted with the high mean EVI of the prairies, which have strong seasonal variability but are water-limited. The prairies have an amplified response to climate change.
Amplified response to climate change
There are other regions where there is a substantial response to climate change, what the researchers called an amplified response to changing conditions. These areas include some you'd expect and some you might not have:
- Arctic tundra
- Parts of the boreal forest belt
- Tropical rainforests
- Alpine regions everywhere
- Steppe and prairie regions of central Asia and North and South America
- The Castinga deciduous forest of eastern South America
- Eastern areas of Australia.
As examples, the authors reported enhanced growth in the Arctic tundra and in alpine regions in response to higher temperatures. Tropical rainforests are very sensitive to cloud cover, especially in the Amazon and south-east Asia. These rainforests are likely also very sensitive to temperature, but it's not known whether they are at their thermal limits.
Three key insights
The authors wrote about three key insights into "the patterns and drivers of ecological sensitivity and response to climate forcing at a global scale", being:
- Areas showing amplified responses, such as the Arctic tundra
- An empirical approach to quantifying climate drivers of vegetation productivity, which is a considerable advance on the previous hypothesised ecological limits (with much the same results)
- Areas with strong memory effects. These are the areas which have a low score on the Vegetation Sensitivity Index.
Thresholds and ecological tipping points
The authors also discuss the possibility of some regions being at threshold values of VSI, beyond which they will tip into another ecological state. They mention the Arctic tundra, boreal forests and wet tropical forests in this context. Other high VSI regions, such as the prairies and steppes, they said were not reported to be exhibiting signs that they were at an ecological tipping point (at the global scale).
This strikes me as work that can be built upon over time. Perhaps one of HW's resident ecologists can add their thoughts on this :)
From the WUWT comments
February 18, 2016 at 7:51 pm
Climate used to refer to locations, like “California has a Mediterranean climate.” But it’s such a handy, can-mean-anything word that it’s been Orwellified.
Mark from the Midwest wants the researchers to travel from the Arctic tundra to the Australian outback and all places in between, like the Sahel, and the Amazon rainforest, and talk to farmers. There aren't too many farmers in the Australian outback (and not that many pastoralists either), and I doubt that there are a heap of them in the Arctic tundra either (more than before, though):
February 18, 2016 at 5:07 pm
“First of all, the method identifies which climate related variables such as temperature, water availability, and cloudiness are important for controlling productivity in a given location,”
Here’s a thought, just ask a local farmer! Me thinks that the academia of the world needs a visit from Mr. Obvious.
JohnWho got as far as Anthony Watts' headline but couldn't manage to read as far as Anthony's copied and pasted press release and asked for help in translating to English (from English):
February 18, 2016 at 5:30 pm
Which satellites? What data? Why only back to 2000?
Taylor Pohlman asks if the researchers isolated/factored in the increase in atmospheric CO2 over the period from 2000 to 2013. From the paper I don't think they did.
February 18, 2016 at 8:18 pmA lot of people wanted to talk about air temperature, not ecological sensitivity. For example Aphan, who I'm told is one of that rare breed, a WUWT woman, moaned about a video about atmospheric temperatures vs surface temperatures, and apparently only wants to screw over the lives of all the tens of thousands of people who help put together the surface temperature data sets (maybe more), and protect the lives of the four or five people who report upper air temperatures:
Any idea how they factor in rising levels of CO2 and the corresponding greening? Or do they subtract that factor to look at other variables? It would be nice to see a paper that actually gets CO2’s effect right…
February 18, 2016 at 5:58 pm
Like I said when Mann et al released that idiotic video….Do they even realize how many other scientists…and their studies….and their departments….and their LIVES….they just screwed over by insinuating that the satellite data isn’t good enough to use? The absolute arrogance/stupidity of the people who put that video together is still just mind blowing. They just started throwing their own under the bus for no good reason. I hope there is some blow-back from other scientists whose work will now be viewed as less than trustworthy.
ntesdorf wasn't interested in ecology either, and only talked about temperature:
February 18, 2016 at 6:40 pm
It’s not that Satellites are “not good enough to tell us global temperature”, rather it is that they do tell us global temperatures but not the global temperatures that the Warmistas want to hear. If the Satellites had shown higher temperatures they would have been the Bees’ Knees to Warmistas.
RH had a thought and wondered how we got to where we are. Could someone tell him or her what happens when you burn fossil fuels? Then what happens to plants that suffer heat stress, too much or too little water, or pest and disease outbreaks? I don't think there's much point in talking to RH about ecological niches or food webs.
February 18, 2016 at 7:04 pm
How did we end up in a world where more CO2 and slightly higher temperatures are bad for plants? /rhetorical
gymnosperm uses NDVI rather than EVI (see p31 of the MODIS vegetation index user’s guide), but says he or she would prefer to use the temperature of the lower troposphere (TLT) to work out what the plants need, than any vegetation index; which is a bit weird.
February 18, 2016 at 6:09 pm
“First of all, the method identifies which climate related variables such as temperature, water availability, and cloudiness are important for controlling productivity in a given location,” says Seddon.
That would be impressive. We hillbilly farmers have been using NDVI for a while. It tells us what is stressed, but we have to boots on the ground truth soil moisture, soil nutrients, leaf water potential, tissue nutrient levels, etc. to figure out why the plants are stressed. Often the reason is an off the wall nutrient that may be very abundant in the soil but unavailable to the plant due to microbial/soil chemistry.
Personally far more comfortable with satellite TLT.
Mike Jonas thinks they should have looked at some data or other first. I don't know what he's talking about and suspect he doesn't either.
February 18, 2016 at 6:17 pm
First they work out which factors control productivity, then they look at the data. To me, that’s backwards.
Skeptical wonders what he or she is missing. (A working brain?)
February 18, 2016 at 7:42 pm
There has been no global warming this century, but they can measure the effects of it. What am I missing here?
Tony Rohl says - who gives a toss about plants, his son is okay:
February 18, 2016 at 8:33 pm
My son lives in Fairbanks, Alaska. He’s witnessed temperatures from -50 to +85 degrees Fahrenheit, which indicates humans can survive and thrive extreme temperature swings
References and further reading
Alistair W. R. Seddon, Marc Macias-Fauria, Peter R. Long, David Benz, Kathy J. Willis. Sensitivity of global terrestrial ecosystems to climate variability. Nature, 2016; DOI: 10.1038/nature16986 (pdf here)
- Mapping the world for climate sensitivity - press release at ScienceDaily.com, with a headline that confused the WUWT-ers who didn't bother with the body of the article
- Global satellite map highlights sensitivity of Australia's plants to changes in rainfall and temperature - article by Dani Cooper at the ABC
Solano, R., Kamel Didan, A. Jacobson, and A. Huete. "MODIS vegetation index user’s guide (MOD13 series)." Vegetation index and phenology lab (2010). (pdf here)
The Anthropocene Debate: Why is Such a Useful Concept Starting to Fall Apart? - This article by Aaron Vansintjan is not directly related, but I noticed it in the Twitter timeline of the lead author, and it's an interesting perspective.
From the HotWhopper archives