Scientists: Risky schemes may be only hope for cooling planet

the report.

  • The other category is called solar radiation management. Instead of tackling CO2, it would act like a thermostat, turning down the heat that reaches Earth from the Sun. Concepts in this field include deflecting the Sun’s heat away from the Earth through space mirrors, scattering light-colored particles in the high atmosphere to reflect the solar rays and using ships to spray water that would create reflective low-altitude clouds.

    • The advantage of the second approach would be to lower temperatures quickly and could be tempting if global warming suddenly cranked up a gear, the report said. These techniques, however, would not curb CO2 emissions that cause dangerous ocean acidification; their costs are unclear but possibly astronomical; and they may end up generating disasters of their own.

    Even so, they should not be dismissed out of hand, given their potential in an emergency, said Ken Caldeira, a professor of climate modeling at Stanford University, California. “We need to think if Greenland were to be sliding into the sea rapidly, causing rapid sea-level rise, or if methane started to de-gas rapidly from the Siberian permafrost, or if rainfall patterns were to shift in such a way that wide-spread famines were induced,” he said. “We would be remiss if we did not do what we could do to understand the potential of these options as well as their uncertainties and risks ahead of time.”

    Painting roofs white to reflect solar rays — an idea gaining ground in California and other sunny places — would provide only limited, local cooling and not affect the rise in global temperature. “None of the geo-engineering technologies so far suggested is a magic bullet and all have risks and uncertainties associated with them,” Shepherd said.

    The panel called for funding of around $160 million a year to kickstart research into the feasibility of geo-engineering schemes could be feasible — and, if so, in what circumstances they should be applied and how they would be managed.

    Here is a snapshot of the report’s views on the main geo-engineering proposals:

    Carbon removal projects
    These are schemes that remove carbon dioxide (CO2), the principal greenhouse gas, from the atmosphere. Projects that are shown to be “safe, effective, sustainable and affordable” should be deployed alongside cleaner energy and other conventional methods to reduce carbon emissions. Among those highlighted in the report:

    • Planting trees: Afforestation would suck carbon dioxide (CO2) out of the atmosphere through the natural process of photosynthesis. FOR: Safe, easy,