Geoengineering could disrupt global and regional rainfall patterns

Washington, June 7 (ANI): Tackling climate change by reducing the solar radiation reaching our planet using climate engineering, known also as geoengineering, could result in undesirable effects for the Earth and humankind, a team of European scientists has concluded.

The researchers studied how models of the Earth in a warm, CO2-rich world respond to an artificial reduction in the amount of sunlight reaching the planet's surface.

In particular, the work by the team of German, Norwegian, French, and UK scientists showed that disruption of global and regional rainfall patterns is likely in a geoengineered climate.

"Climate engineering cannot be seen as a substitute for a policy pathway of mitigating climate change through the reduction of greenhouse gas emissions," they said.

Geoengineering techniques to reduce the amount of solar radiation reaching the Earth's surface range from mimicking the effects of large volcanic eruptions by releasing sulphur dioxide into the atmosphere to deploying giant mirrors in space.

Scientists have proposed these sunlight-reflecting solutions as last-ditch attempts to halt global warming.

To find what would such an engineered climate be like, the researchers studied how four Earth models respond to climate engineering under a specific scenario.

This hypothetical scenario assumes a world with a CO2 concentration that is four times higher than preindustrial levels, but where the extra heat caused by such an increase is balanced by a reduction of radiation we receive from the Sun.

"A quadrupling of CO2 is at the upper end, but still in the range of what is considered possible at the end of the 21st century," said Hauke Schmidt, researcher at the Max Planck Institute for Meteorology in Germany and lead author of the paper.

Under the scenario studied, rainfall strongly decreases - by about 15 percent (some 100 millimetres of rain per year) of preindustrial precipitation values - in large areas of North America and northern Eurasia. Over central South America, all models showed a decrease in rainfall that reaches more than 20 percent in parts of the Amazon region.

Other tropical regions see similar changes, both negative and positive. Overall, global rainfall is reduced by about five percent on average in all four models studied.

"The impacts of these changes are yet to be addressed, but the main message is that the climate produced by geoengineering is different to any earlier climate even if the global mean temperature of an earlier climate might be reproduced," Schmid stated.

The researchers noted that the scenario studied is not intended to be realistic for a potential future application of climate engineering. But the experiment allows the researchers to clearly identify and compare basic responses of the Earth's climate to geoengineering, laying the groundwork for more detailed future studies.

The study has been published in Earth System Dynamics, an Open Access journal of the European Geosciences Union (EGU). (ANI)