Pielke has recently analysed the economics of this controversial technique and has shown that it compares favourably to other ways of stabilising greenhouse gases. "This surprising result suggests, at a minimum, that air capture should receive the same detailed analysis as other approaches to mitigation," Pielke told environmentalresearchweb.

Climate change is increasingly being viewed as a "planetary emergency", and greenhouse gases, such as carbon dioxide, as the culprits. Many people now agree that action is needed to prevent dangerous levels of warming, but there is little consensus on how this should be done.

Already scientists have predicted that significant levels of global warming are inevitable, because it is impossible to turn our lives around and stop emitting greenhouse gases overnight. A technical fix may be the only way of stabilising the climate in the short to medium term.

Capturing carbon dioxide from the atmosphere and storing it safely is one possible technical fix. The technology to capture carbon dioxide already exists. There are various methods, such as a system that uses sodium hydroxide and lime to react with the carbon dioxide and draw it down from the air. And in theory carbon dioxide can be safely stored for many thousands of years underground – in old oil reservoirs for example.

But is it economical to go to all this effort to reduce the level of greenhouse gases in Earth's atmosphere? Pielke has tried to answer this question using data from the Intergovernmental Panel on Climate Change (IPCC) from 2000 and the Stern Review Report from 2007 to calculate the cost of stabilisation of atmospheric carbon dioxide under a number of different scenarios.

First he estimated how much carbon dioxide needed to be removed from the atmosphere to stabilise levels at either 450 parts per million (ppm) or 550 ppm, by either 2050 or 2100. Then he estimated how much it would cost to remove the necessary amount of carbon dioxide over each time period, based on current technology and current prices.

In each case Pielke calculated the cost as a percentage of global GDP, enabling him to compare his estimates directly with the estimates calculated by the IPCC and the Stern Review for other mitigation methods. For example, to stabilise carbon dioxide at 450 ppm by 2050 using carbon capture Pielke estimates it would cost between 0.5 and 3% of global GDP. His findings are published in Environmental Science & Policy.

Previous estimates from the IPCC report and the Stern Review suggest that other forms of mitigation, such as solar heat deflectors and carbon capture at power stations, would entail similar costs. "If other forms of mitigation are judged to be worth the expense, then air capture deserves more attention than it has received in the past, because its costs are in the same ball park," writes Pielke in his blog.

Pielke stresses that he doesn't view air capture of carbon dioxide as a solution to the problem of global warming, but more as a realistic way of helping us to ride out the immediate crisis. "If climate change is indeed a planetary emergency, how can we afford to ignore air capture?" he asks.