Sunday, 16 December 2012

'Extreme climate may wipe out mammals from Earth' - or maybe not

The Business Standard intones dramatically
Mammals could be at greater risk of extinction due to a higher frequency of extreme conditions such as cyclones and droughts spurred by climate change, scientists have warned.
Researchers from the Zoological Society of London (ZSL) have mapped out land mammal populations, and overlapped this with information of where droughts and cyclones are most likely to occur. This allowed them to identify species at high risk of exposure to extreme weather.
The study describes the results of assessing almost six thousand species of land mammals in this way.
Bear in mind that land mammals have been exposed over millions of years, to more than one ice age with "extreme weather" (of the cold-induced variety) and at least one interglacial period during which temperatures were several degrees above those of today with "extreme weather" (of the heat-induced variety).
"Approximately a third of the species assessed have at least a quarter of their range exposed to cyclones, droughts or a combination of both," lead author of research, Eric Ameca y Juarez said.
"If these species are found to be highly susceptible to these conditions, it will lead to a substantial increase in the number of mammals classified as threatened by the IUCN under the category 'climate change and severe weather'," said Juarez in a statement.
In particular, primates - already among the most endangered mammals in the world - are highlighted as being especially at risk.
Just a minute though - "If these species are found to be highly susceptible to these conditions" implies, nay states, that the zoologists haven't actually assessed the vulnerability of land mammals to "extreme weather". Neither it seems, have they assessed the actual probability of the extremes they "predict", nor the extent or intensity of the extremes, nor specified the timescales over which those extremes might occur.
"This is the first study of its kind to look at which species are at risk from extreme climatic events. There are a number of factors which influence how an animal copes with exposure to natural disasters.
"It is essential we identify species at greatest risk so that we can better inform conservation management in the face of global environmental change," ZSL's research fellow Dr Nathalie Pettorelli said.
What does AR5 draft have to say about cyclones? Ch2 FAQ 2.2 says
Considering other extremes, such as tropical cyclones, the latest assessments show low confidence that any reported long-term increases in tropical cyclone activity are robust, after accounting for past changes in observing capabilities. There is some evidence, however, of an intensification of the most extreme storms, but records are currently very short.  
Over periods of a century or more, evidence suggests slight decreases in the frequency of tropical cyclones making landfall in the North Atlantic and the South Pacific, once uncertainties in observing methods have been considered. Little evidence exists of any longer-term trend in other ocean basins.
So much for the "increase in hurricanes/cyclones" meme touted as fact lately. What about droughts? Section Floods, Droughts and Severe Local Weather Events:
On the whole the annual maximum number of consecutive dry days appears to be declining in most regions since the 1950s (Figure 2.33b). Using a measure which combines both dry spell length and precipitation intensity Giorgi et al. (2011) indicate that ‘hydroclimatic intensity’ (Chapter 7) has increased over the latter part of the 20th Century in response to a warming climate. They show that positive trends are most marked in Europe, India, parts of South America and East Asia although trends appear to have decreased in Australia and northern South America (Figure 2.33c). Data availability, quality and length of record remain issues in drawing conclusions on a global scale, however.
So where there are trends in tropical cyclones (includes hurricanes) they show decreased frequency - something many sceptics have been saying for years - based on the data. With regards to drought, "On the whole the annual maximum number of consecutive dry days appears to be declining in most regions since the 1950s".

Every so often, more often year on year it seems, I read of some "research" or other that produces an immediate reaction of "what a load of crap". This study is one such.


  1. This is what I call the Numberwatch School of Scientific Endeavour; there's probably a counterbalancing study somewhere which suggests that climate change will bring about too many mammals - of the wrong sort, naturally. It's a contender, surely, to be added to that long list, along with the shrinking polar bears and the extinction of coffee beans.

    Googling for information about the authors "Eric Isai Ameca y Juarez" and "Nathalie Pettorelli" reveals more of the same - "Wildlife under unprecedented threat from natural disasters", "Life In An Age Of Unnatural Disasters", "Long-term memory may help elephants survive climate change", and so forth.

    What I find striking is that by beating the climate change drum, the authors seem to be discounting real threats to species, such as hunting and habitat loss, in favour of the phantom menace of extreme weather. In other words, they appear to be placing more emphasis on a nebulous future danger than on a real here-and-now danger, e.g., men with high-powered rifles.

    1. I didn't bother to look up the authors' credentials or "previous" - I can only take so much in one go. I didn't realise polar bears were shrinking as well as declining (can't resist a little dig now and again hehe). I have a draft post on coffee - might resurrect it with current data on crop yields - at an all time record high it seems. in the meantime I'll totally switch to tea from coffee to reduce my "coffee footprint". Every little bit helps, ya know.

      Apart from the ignored, rather than just discounted threats as you mention, my great brain was musing on the "pending disaster" meme last evening. Why is it (apparently) assumed by so many biologists and zoologists (and anthropologists too it seems) that virtually all Earth's species from phytoplankton to elk are teetering on the brink of extinction?

      Why do we never hear that the "long-eared, short-tailed bat" (alright, I know bat's haven't got tails) is doing just fine, thanks, and could probably withstand drought and a couple of extra degrees? Is there no money in such research (rhetorical question)? Do we as a species thrive on bad news? I'm not answering here but keeping my powder dry (future post maybe?).