26 August 2010 | Luca Del Buono
Biofuel, Carbon, Climate Change, Food and agriculture, Forestry and wood products, Legislation

 

A new report confirms that geoengineering is not a probable solution to anthropogenic climate change. An international research group of scientists from England, China and Denmark just published a report in PNAS showing that all methods but biomass carbon sequestration were unfeasible for preventing climate change. The report may be a positive sign for the biofuel and carbon capture industries.

Although geoenigneering is being examined as a potential solution to climate change by NASA, the Royal Society, the Institute of Mechanical Engineers, and the UK Parliament, very little is known about its practical or financial feasibility. This report examined the effectiveness of five geoengineering methods: sulfur dioxide aerosol injection into the stratosphere, mirrors in space, afforestation, biochar and bioenergy with carbon sequestration.

"We used 300 years of tide gauge measurements to reconstruct how sea level responded historically to changes in the amount of heat reaching the Earth from the Sun, the cooling effects of volcanic eruptions, and past human activities," stated Dr Svetlana Jevrejeva of the National Oceanography Centre. "We then used this information to simulate sea level under geo-engineering schemes over the next 100 years."

One proposed method to decrease the amount of sunlight reaching the Earth's surface is to use jets to spray sulfur dioxide into the air and dim the atmosphere. However, sulfur dioxide injection would have too costly an impact on global GDP, and too risky because its effects on ecosystems and the climate system, particularly upon global rainfall, are poorly understood. It would work to delay sea level rise for 40-80 years.

A mirror system, such as that proposed United States government, could be launched into space to reflect sunlight, reducing atmospheric heat capture and insulation. This would be expensive not because of costs of building but because of the costs of maintenance, the report claims.

Iron fertilization of the ocean to encourage phytoplankton growth which consume carbon and fall to the ocean floor would arguably sequester large amounts of carbon, but it is uncertain how this would affect the ocean's toxicity levels.

"The least risky and most desirable way of limiting sea-level rise is bioenergy with carbon sequestration," Dr Jevrejeva reported.

Carbon sequestration is the only method which actually reduces the carbon dioxide in the atmosphere by using forests or crop plants to capture it and remove it. The crops could be turned into biofuel and biochar. The biomass is then deposited in a reservoir (carbon storage) or re-used as soil fertilizer.

The carbon capture and storage effort would require a large-scale conversion to a biofuel economy. These two methods could decrease atmospheric carbon levels by 180 ppm bringing it to pre-industrial levels.

As a result of conversion to biofuel/biomass and carbon capture, sea level rise would be held at just 10 centimeters by 2100, according to models in the report. However, Dr Jevrejeva stated, "Substituting geoengineering for greenhouse emission control would be to burden future generations with enormous risk."

Author: Cristina Brooks | Climate Action

Image: Alan Vernon | Flickr

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