Geoengineering may be feasible but is it worthwhile?

News editor

As film scenarios go, this seems pretty hackneyed but might turn a profit. The premise sees Earth warming gradually, threatening mankind with untold catastrophes unless quick, radical solutions can be found. Luckily, a bunch of scientists have seen this coming and have devised a series of interventions to avert said disasters.

It sound feasible and could make for a night out at the cinema save for the fact that many scientists see this situation as very real and in need of some quick and radical solutions.

The National Snow and Ice Data Center reported earlier this week that levels of Arctic sea ice are the lowest since satellite recording began.

They say that the extent of sea ice fell to 4.10 million square kilometres on August 26, which was 70,000 square kilometres below the September 18, 2007 daily extent of 4.17 million square kilometres.

An even larger loss of sea ice is expected in the coming weeks as the Arctic melt season draws to an end from mid-to-late September.

The ever-reliable Science Media Centre (SMC) drew comment from scientists who put this event into context.

‘The consequences are enormous and represent a huge boost to global warming from two sources: the reduction in global albedo caused by the replacement of ice by open water, and an acceleration of methane release into the atmosphere as the warm open water causes seabed permafrost to melt,’ said Prof Peter Wadhams, Professor of Ocean Physics at Cambridge University.

Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment at London School of Economics and Political Science, added: ‘Polar scientists agree that it is the rise in global average temperature, driven by increasing levels of greenhouse gases in the atmosphere, that is driving this rapid loss of Arctic ice.

‘Not only is this having a big impact on Arctic wildlife…but the rapid loss in sea ice is accelerating global warming. Ice reflects more sunlight than sea water, so more heat is being absorbed, increasing the amount of warming.’

Prof Wadhams believes an interim measure to reverse the trend could involve geoengineering, whereby science devises methods of deliberately manipulating an environmental process that affects the earth’s climate. He added that techniques, such as whitening low-level clouds should be ‘investigated with the utmost urgency.’

As recently as August 20 Rob Wood, an atmospheric physicist at the University of Washington, described a possible way to run an experiment to test the concept of marine cloud brightening on a small scale. The clouds would reflect sunlight and, theoretically, counter global warming.

In May this year a SPICE (Stratospheric Particle Injection for Climate Engineering) field study was cancelled, due in part to ‘governance, intellectual property and public engagement’.

SPICE was designed to investigate the feasibility of spraying a shield of sulphate particles into the stratosphere and was inspired by volcanoes and the way they can affect the climate after eruptions.

SPICE has had its problems but a report out today suggests that similar solar radiation management (SRM) projects are feasible and affordable.

Published in Environmental Research Letters, the study has shown that the basic technology currently exists and could be assembled and implemented in a number of different 
forms for less than $5bn a year.

According to a statement from IOP Publishing, researchers from Aurora Flight Sciences, Harvard 
University and Carnegie Mellon University performed an engineering cost analysis on six systems capable of delivering 1-5 million metric tonnes of 
material to altitudes of 18-30 km: existing aircraft, a new airplane designed to perform at altitudes up to 30km, a new hybrid airship, 
rockets, guns and suspended pipes carrying gas or slurry to inject the particles into the atmosphere.

Based on existing research into solar radiation management, the researchers performed their cost analyses for systems that could deliver around one million tonnes of aerosols each year at an altitude between 18 
and 25km and between a latitude range of 30°N and 30°S.

Despite the findings, the researchers point out that reducing sunlight won’t reduce concentrations of greenhouse gasses or the resulting increase in the acid content of the oceans, a line endorsed by Friends of the Earth who concur that injecting aerosols could bring down global temperatures but with ‘very significant unknown risks to global weather systems and food production.’

Wood urges caution too, saying geoengineering is essentially a ‘quick fix’ when a move to a low-carbon economy would be preferable.

The final word goes to Prof John Shepherd FRS, chair of the Royal Society’s Geoengineering the Climate report.

Speaking in response to today’s Cost analysis of stratospheric albedo modification delivery systemsreport he said: ‘Few of us like the idea of taking purposeful action to manipulate the climate of our world, with great uncertainty about the potential side effects.

‘However, it is vital to undertake assessments like this of geoengineering options, given humanity’s current unfettered appetite for burning fossil fuels.’