Could geo-engineering turn Europe into a desert?

Nieuws | de redactie
19 juni 2012 | Advocates of geo-engineering want to cool down the Earth artificially. But what impact would this have on the delicate climate balance?

With a political solution to climate change still appearingdistant and unlikely, other solutions, such as reducing the amountof sunlight reaching the Earth’s surface, known as geo-engineering,become tempting. However, a team of European researchers warn, theeffects of geo-engineering might dramatically alter the world’srainfall patterns. The scientists studied the effects of reducingthe amount of sunlight reaching the Earth’s surface in a CO2-richand warm world, resembling one of the Earth’s scenarios for2100.  In this prognosis, desertification might become aserious threat for Europe, North America and the Amazon. Theirresults are published in Earth System Dynamics, an Open Accessjournal of the European Geosciences Union (EGU).

Mimicking volcanoes

Geoengineering mimics the effects of mayor volcanic eruptions bysending sulphur dioxide into the atmosphere and releasing enormousmirrors in space, creating an effect called global dimming.Volcanic eruptions, such as the one of the Krakatau volcano(Indonesia) in 1883, release giant amounts of sulphur dioxide tothe atmosphere, which has a cooling effect. The same effect on asmaller scale can be seen on a daily basis in the clouds created bycommercial airplanes. This is why geo-engineering is being studiedas a potential solution to stop global warming. 

The scientists studied four models of climate engineering undera potential future scenario. Hauke Schmidt, lead author of thepaper, and his team, state that the study is not intended forfuture application, but it helps to identify and compare theresponses of the Earth’s climate to geoengineering and creating afundament for future research. So what would an engineered climatelook like?

In this scenario the CO2 concentration is four times higher thanthe pre-industrial level, a high estimation but certainly possibleat the end of the 21st century, according to Smith. Theheat created from such an increase is balanced by the reduction ofradiation from the Sun through geo-engineering.

Major impact on climate 

In the studied scenario rainfall strongly decreases, up tofifteen percent in large areas in northern Eurasia and NorthAmerica. In the Amazon Basin, the amount of rainfall might evendrop by twenty percent. In other tropical regions similar changescan be seen, both positive and negative. In all four models theglobal rainfall is reduced by five percent.

The implications are still uncertain, but it is clear reducingthe amount of solar radiation that reaches the earth’s surface willlead to a climate different from any in the Earth’s past. Even ifthe global mean temperature is equal to an earlier age, the globalclimate is different from any climate before.

This research is the first study to compare the differentclimate models used in the Fifth IPCC Report and estimate therobustness of their results. In their paper the researchersconclude: “Climate engineering cannot be seen as a substitute for apolicy pathway of mitigating climate change through the reductionof greenhouse gas emissions.”

The scientists used climate models developed by the UK MetOffice’s Hadley Centre, the Institut Pierre Simon Laplace inFrance, and the Max Planck Institute in Germany. Norwegianscientists developed the fourth Earth model used. For direct linkto the article by Smith et. al (2012), click here. 

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