As heavy rains and snow return to California, signalling an end to a 5-year drought, it’s worth reminding green alarmists that making climate claims about current droughts is fraught with great risk because when wetter conditions return they look foolish.
Evidence that droughts have become more prevalent on a global scale is hard to come by. Despite this, there have been some heroic attempts to claim otherwise.
In particular, in 2007 the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) declared that droughts had become more common worldwide, although since that time it has resiled from this position. The Fifth Assessment Report of 2013 noted that academic studies in the area were giving conflicting results and concluded that it was very hard to say if there had been any changes in drought levels worldwide at all:
“Confidence is low for a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century, due to lack of direct observations, methodological uncertainties and geographical inconsistencies in the trends.”
There are few signs that any clear picture will be forthcoming in the near future. Since the time of the Fifth Assessment, a new study by scientists at the University of California found, if anything, a slowly declining trend in drought since 1982.
With evidence of any change thin on the ground, the IPCC has found it equally difficult to attribute blame to humankind, concluding that at a global scale it was almost impossible to say anything about an anthropogenic influence: “…there is low confidence in detection and attribution of changes in drought over global land areas since the mid-20th century. “
For those looking for evidence to support positions of climate alarm, the IPCC offered only a few crumbs of comfort, noting that there had been changes in drought levels in particular regions. However, it also suggested that these were not out with the very wide range of natural variability.
These sorts of scientific difficulties have not prevented some groups from trying to make explicit or implicit claims linking drought events to global warming. A 2011 report in the Guardian claimed that ‘Drought in east Africa the result of climate change and conflict’, a position that turned out to be based on the impressions of aid workers in the area.
Droughts in the Amazon are also said to be the result of climate change. The recent drought in California has also been repeatedly linked to man-made climate change, although as other researchers have pointed out, since current conditions in that state don’t appear to be part of a long-term trend it is hard to see the logic in the claims.
Perhaps most notoriously, environmentalists linked persistent drought in parts of Australia to global warming. Led by Australia’s climate commissioner Tim Flannery, they predicted that some Australian cities would need desalination plants within months:
“Over the past 50 years, southern Australia has lost about 20 percent of its rainfall, and one cause is almost certainly global warming… In Adelaide, Sydney and Brisbane, water supplies are so low they need desalinated water urgently, possibly in as little as 18months.”
Unfortunately, some policymakers took these messages seriously and billions of Australian dollars were spent on desalination plants across the country. However, when the rainfall levels returned to normal levels in subsequent years the new plants were mostly mothballed, although taxpayers are still having to underwrite huge annual bills for interest and maintenance costs.
Making claims about current droughts is fraught with difficulty for environmentalists, because of the likelihood that a return to wetter conditions will leave them looking foolish. Attention has understandably started to focus more on the possibility that man-made climate change will bring increased levels of drought in the future.