'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 2.6.2.2 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.