I venture to suggest that Richard Sadler’s article (Perspective, 28 May) was a bit short on facts as opposed to a heavy dose of alarmism about global climate.
Whereas carbon dioxide in the atmosphere has surpassed the 400 parts per million (ppm) point recently, global atmospheric temperatures have been at a standstill for 15-17 years with even the Met Office admitting this situation may continue until 2017.
The Intergovernmental Panel on Climate Change (IPCC) has through its reports (including AR4, its fourth assessment report) maintained that a doubling of CO2 in the atmosphere (from 280ppm) will lead most likely to an increase in global temperatures of 3C. Several peer reviewed studies have been released lately indicating that most likely this increase is now projected to be 1.5-2C, which is a considerable reduction induced by the temperature standstill referred to above.
The reference to the Oklahoma tornado as an indication of extreme weather is misplaced since the latest National Oceanic and Atmospheric Administration documentation shows that such heavy tornadoes were more prevalent during the cooler 1970s and are caused by the collision of cold and warm weather over the US Mid-west.
Sea levels as measured by University of Colorado are going up by about 3mm a year and there is no evidence that CO2 is causing any acceleration. Without acceleration there is no way that extreme increases in sea levels will be achieved.
There has been a slight melting of ice from the Greenland ice-cap but it would take about 14,000 years for the Greenland ice mass to disappear at the current rate and there is no acceleration. Global sea ice (North and South Pole combined) is at its long-term average with no sign of acceleration of melting either.
None of the major global climate indicators are showing any alarming increases and it is most unlikely that the scenarios painted in the “Driving towards disaster” article are going to materialise in the foreseeable future. More likely is a standstill in global warming and in fact global temperatures have been heading downwards since 2005 (see the Hadley Centre of the UK Met Office and Climactic Research Unit of the University of East Anglia’s fourth report (HadCRUt4). Carbon dioxide is relentlessly increasing in the atmosphere with what appears to be less and less effect on the climate.
ROY Turnbull (Letters, 28 May) takes issue with my letter of 27 May and selectively quotes my position, before going on to say no other climate scientist thinks as I do. Mr Anderegg, a climate scientist (Letters, 23 May) argues that human-emitted greenhouse gases are the dominant driver of climate change.
I do not know which to believe. Natural variation in climate temperature over both long and short periods of time is well known among geologists of all kinds, but was never mentioned to the public when they were bombarded with claims that humans are the sole instrument changing the climate.
The common implication was that the climate had never previously changed.
And natural variation was never mentioned when legislation was introduced to charge us all for decarbonising the economy.
It has only now come to the fore because the climate has not behaved as the Circulation Models predicted.
The apparent back-pedalling will only lead to cynicism among many; if natural variation can exert such influence now, perhaps it has always been responsible for the apparent warming in the late 20th century.
Trust in climate science may disappear.
The climate is complex with numerous interacting factors and control devices that in my experience can give rise to counter-intuitive behaviour. No simple relation of CO2 to climate temperature emerges; think of that next time you pay the additions on your electricity bill to decarbonise electricity.
(Prof) Anthony Trewavas
Scientific Alliance Scotland
North St David Street