Peer Reviewed: Droughts have not increased since the 1950s
According to a commonly used model of drought patterns, researchers had previously assumed that higher global temperatures were causing greater evaporation of water, and therefore more droughts.
But a more detailed analysis of weather data, including wind speed, humidity and radiation levels, found that in fact there has been “little change” in drought over the past 60 years.
Researchers from Princeton University and the Australian National University said drought was “expected to increase in frequency and severity” in the future, but added that currently used prediction methods are inaccurate.
Overestimating the influence of temperature on evaporation could skew estimates of the likely impacts of climate change over the coming decades, they reported in the Nature journal.
The Intergovernmental Panel on Climate Change (IPCC) estimates that global temperatures have risen by about 0.13C per decade for the last 50 years – nearly twice the rate of increase for the last 100 years.
In a report published in 2007, the IPCC claimed that “more intense and longer droughts have been observed over wider areas since the 1970s”, adding that “increased drying linked with higher temperatures and decreased precipitation has contributed to changes in drought”.
In a recent review, however, the statement was significantly revised to recognise that over-reliance on temperature recordings to predict evaporation may have inflated estimates of drought at regional and global scales.
Now in their new study, the American and Australian scientists have outlined “more realistic calculations” which suggest major uncertainty over drought trends since 1950, and little sign of an increase in the overall area affected by droughts.
They added that droughts may cause hot weather, and not the other way around, because there is less of a cooling effect from evaporation due to lower rainfall levels.
In a linked comment article Prof Sonia Seneviratne of the ETH science university in Zurich wrote: “The authors’ results confirm the complexity of the processes that lead to changes in drought conditions.
“The findings imply that there is no necessary correlation between temperature changes and long-term drought variations, which should warn us against using any simplifications regarding their relationship.”
Prof Piers Forster, Professor of Physical Climate Change at the University of Leeds, said: “This study is an important contribution highlighting the complexity of drought prediction but it does not make me downgrade the substantial threat to harvests posed by climate change.
“In terms of staple harvests of wheat and maize, high temperatures at certain times of the growing season, for example temperatures above 35C at the time of wheat flowering, can kill off crops.”
but..the science is settled???
sciene by its very nature is NEVER settled..and anyone who says it is is telling a lie for a reason..one again the doomsters and warmists are wrong..but you wont hear them retract their previous accusations..they just ignore it and wait for “good news”