‘Plan G’ for Reducing Global WarmingIndonesia
Mount Pinatubo in the Philippines exploded in 1991 with terrifying effect. It was the second-largest volcanic eruption of the 20th century and by far the biggest in a densely populated area. The eruption’s ash rose 35 kilometers into the air with a menacing cloud, providing a hint into how geoengineering might stem the effects of climate change. Nearly 20 million metric tons of sulfur dioxide gas was injected into the upper atmosphere where it combined with other materials to form sulfuric acid particles. These sulfate aerosols acted as a giant sunshade, reflecting solar radiation back into space, thus cooling the earth’s surface.
Dispersal of the aerosols around the world in the jet stream caused global temperatures to drop temporarily by 0.5 degrees Celsius for about two years, a level not far short of the increase at that time in the average land and sea surface temperature since the start of the Industrial Revolution.
International climate change negotiations are intended to prevent ever-larger amounts of greenhouse gas emissions, mainly due to burning fossil fuels and clearing forests for agriculture, from spewing into the atmosphere and raising the mean global temperature by 2 degrees Celsius, a threshold for dangerous climate change adopted by the abortive United Nations conference in Copenhagen last December.
But in subsequent negotiations there’s been little progress on a binding agreement to take the costly steps needed to reduce global warming gases by preserving forests and deploying low-carbon energy sources, such as nuclear, hydro, wind and solar power, on a wide scale.
The scientific panel advising the UN has warned that without such cuts, the temperature could rise by as much as another 4 degrees Celsius by the end of the century, increasing the risk of dangerous, even catastrophic climate change because of the long-lasting effects of carbon dioxide, the main global warming gas from human activity, once it reaches the atmosphere.
With an effective accord on cutting greenhouse gases unlikely any time soon, an increasing number of scientists and officials are calling for research into Plan G — geoengineering — to cool the planet.
The technologies fall into two main categories: One would reflect sunlight back into space, an approach known as solar-radiation management.
This mimics the global dimming and cooling associated with major volcanic eruptions.
Another would remove carbon dioxide from the atmosphere on a scale far greater than anything attempted so far.
Solar-radiation management includes using high-flying aircraft or projectiles to spread chemicals to make sulfate aerosols in the stratosphere.
Aircraft can also inject seawater droplets or other cloud-condensation material over the ocean to whiten clouds, thereby reducing incoming solar radiation warming the ocean.
Among the most feasible of the carbon dioxide removal methods is to add iron, nitrogen or phosphate to selected regions of the ocean to increase phytoplankton growth and remove more carbon from air.
These microscopic organisms already soak up huge quantities of carbon dioxide from the atmosphere.
A dust storm from inland Australia that swept across New South Wales and southern Queensland in September 2009, deposited thousands of tons of nitrogen and phosphate in the Tasman Sea between Australia and New Zealand, stimulating phytoplankton growth.
By one estimate, eight million tons of carbon dioxide was captured.
Of course, geoengineering raises thorny environmental, geopolitical and governance issues.
Would it work as planned without dangerous side effects?
Who would decide if and when to deploy geoengineering techniques?
The debate is set to intensify. On Oct. 29, the US Congress received two reports on geoengineering, both calling for more coordinated research.
At about the same time in Nagoya, an intergovernmental conference to protect global biodiversity proposed a moratorium on large-scale geoengineering experiments “until there is an adequate scientific basis on which to justify such activities.”
Meanwhile, the European Union has funded a German research group to study the physics, ethics and geopolitical aspects of manipulating the climate system.
Critics worry about the side-effects. Fertilizing the seas could cause dead zones and toxic blooms that harm aquatic life.
Adding large amounts of sulphate aerosols to the upper atmosphere might also reduce Asian monsoon rainfall, deplete the earth’s protective ozone layer and reduce sunlight for solar power.
In addition, it would blur the skies, erode greenhouse gas reduction measures and do nothing to stop ocean acidification.
Recent studies show that although the average global temperature could be lowered by seeding the stratosphere, wisps of jet stream might leave some regions too warm and others too cool.
Pete Irvine, a climate scientist at Bristol University and lead author of a study on geoengineering impacts, warns of likely disagreements between countries and regions over any future schemes.
Apportioning the burden of cutting greenhouse gases still causes acrimonious debate among governments after years of negotiation. Putting Plan G into effect is also likely to be fraught with contention.
El contenido de las noticias que se presentan en esta sección es responsabilidad directa de las agencias emisoras de noticias y no necesariamente reflejan la posición del Gobierno de México en este u otros temas relacionados.
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