Geoengineering won't curb sea-level rise

Unless they involve extreme measures, geoengineering approaches to offset the effects of human-driven climate changes won't do much to combat rising sea levels, an international team of scientists reports in the Proceedings of the National Academy of Sciences1.

That is because sea levels respond slowly to changes in Earth's temperature, says John Moore, a palaeoclimatologist at Beijing Normal University and lead author of the study.

"We've got this 150-year legacy of fossil-fuel [burning], land-use changes, et cetera," he says. "You can't just slam on the brakes instantaneously."

Moore and his team examined two proposed geoengineering schemes: mirrors orbiting in space to reduce incoming sunlight, and sulphates being shot into the upper atmosphere to create a bright, sunlight-reflecting haze — similar to the one produced naturally by the 1991 eruption of Mount Pinatubo in the Philippines. Either scheme could reduce incoming solar energy by about 1–4 watts per square metre, enough to offset the atmospheric warming caused by carbon dioxide build-up until at least 2070.

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