The first comprehensive assessment of the climate cooling potential of different geoengineering schemes has been conducted by researchers at the University of East Anglia (UEA). The results are published in the journal Atmospheric Chemistry and Physics Discussions
Among the findings, according to a statement from UEA:
Enhancing carbon sinks will take nearly 100 years to bring atmospheric carbon dioxide levels back to pre-industrial levels and will require sharp cuts in emissions.
Stratospheric aerosol injections and sunshades in space — a concept supported by Paul J. Crutzen, winner of the 1995 Nobel Prize in Chemistry for his work on the hole in the ozone layer — have “by far the greatest potential to cool the climate by 2050” but carry the greatest risk.
Adding phosphorous to the ocean via existing activities may have greater long-term carbon sequestration potential than iron or nitrogen fertilization schemes.
Sequestering carbon by planting forests and as ‘bio-char’ — charcoal added back to the soil — have greater short-term cooling potential than ocean fertilization. Bio-char also offers to potential to boost soil productivity for agriculture.
Increasing the reflectivity of urban areas could reduce urban heat islands but will have minimal global effect. The same goes for schemes involving ocean pipes and stimulating biologically-driven increases in cloud reflectivity.
The beneficial effects of some geo-engineering schemes have been over-estimated and mis-calculated in previous calculations
“The realization that existing efforts to mitigate the effects of human-induced climate change are proving wholly ineffectual has fuelled a resurgence of interest in geo-engineering,” said lead author Tim Lenton of UEA’s School of Environmental Sciences. “This paper provides the first extensive evaluation of their relative merits in terms of their climate cooling potential and should help inform the prioritisation of future research.”
“We found that some geoengineering options could usefully complement mitigation, and together they could cool the climate, but geoengineering alone cannot solve the climate problem,” he added.
CITATION: T. M. Lenton and N. E. Vaughan. The radiative forcing potential of different climate geoengineering options [PDF]. Atmos. Chem. Phys. Discuss., 9, 2559-2608, 2009
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