The modern concept of geoengineering is usually taken to mean proposals to deliberately manipulate the Earth's climate to counteract the effects of global warming from greenhouse gas emissions.
To me ESA means the European Space Agency. There is however also an ESA otherwise known as the Ecological Society of America
(Sorry but Europe is closer to me than USA). In a symposium where they (the American ESA, I mean) discussed the viability of geoengineering, they concluded that it is potentially dangerous at the global scale, where the risks outweigh the benefits.
Although geoengineering techniques aim to slow global warming through the use of human-made changes to the Earth's land, seas or atmosphere, new research shows that the use of geoengineering to do environmental good may cause other environmental harm (what a surprise!).
Let us have a look at a few examples of geoengineering:
Atmospheric seeding, that would cool the climate by releasing light-colored sulfur particles or other aerosols into the atmosphere to reflect the sun's rays back into space. This approach mimics what happens naturally when volcanoes erupt. Despite its potential to create overall cooling, atmospheric seeding could cause significant changes in localized temperature and precipitation. Sulphur seeding could destroy atmospheric ozone, leading to increased ultraviolet radiation reaching the Earth's surface.
Fertilising the oceans with iron to increase carbon uptake from the atmosphere could create a rise in iron-limited phytoplankton populations, which by dying and sinking would use enough oxygen to create extensive dead zones in the oceans. In addition the maximum possible rate of ocean iron fertilization could only offset a small fraction of the current rate of carbon burning by humans. Ocean fertilization also does not alleviate the increasing problem of ocean acidification, caused by carbon dioxide from the increasingly carbon-rich atmosphere dissolving into sea-water. Ocean fertilization schemes will likely exacerbate this problem.
On the planetary scale most ecologists are skeptical of climate engineering. Playing with the Earth's climate is a dangerous game with unclear rules. More direct ways to tackle global warming are needed, including energy efficiency, reduced consumption, and investment in renewable energy sources.
Maybe, however, research should continue on safer ways to use geoengineering at a smaller scale. Geologic sequestration, sometimes known as CO2 capture and storage, takes CO2 out of the atmosphere and stores it in underground reservoirs. This solution has the potential to store more than a century's worth of electric power emissions at a relatively low cost. Some potential risks of geologic sequestration, however, include carbon leakage and the potential for interactions with groundwater.
In my post on Hypoxia in the Baltic Sea
I discussed a few proposed geoengineering methods to remediate the oxygen situation in the Baltic Sea. And again the conclusion was that “virtually all engineering methods proposed to date for the Baltic Sea seem unrealistic and/or not viable”.
PS with latest news of 7 August 2009:
Lomborg (yes, that Lomborg, Bjørn Lomborg) is suggesting creating man-made clouds to stop global warming. Global warming can be stopped for as little as 6 billion euros by using an armada of 1900 remote-controlled cloud-making vessels in the world’s oceans – if we dare manipulate the earth’s climate – at least according to the enfant terrible of the climate debate Bjørn Lomborg of the Copenhagen Business School’s Copenhagen Consensus Centre.