Is geoengineering Earth’s last hope?

CORNELL (US) — If action is not taken soon, ocean acidification and greenhouse warming could reach a tipping point that will take more than 1,000 years to reverse.

Scientists warn that to avoid excessive warming, sea level rise, and extreme weather, CO2 in the atmosphere needs to be reduced to 350 parts-per-million (ppm) by the end of this century from the current level of around 390 ppm.

Charles Greene, professor of earth science at Cornell University and lead author of a new study, says time is running out, yet governments have done little to reverse rising carbon dioxide (CO2) levels.

The study, published in the September-October issue of Solutions magazine, suggests one way to reduce atmospheric CO2 is by setting up fields of air-capture devices that absorb it, similar to the carbon capture and storage technology being developed for coal plants.

The devices would use algal bioenergy as a power source to capture, extract, and pipe CO2 for storage or industrial use.

Algae provide a preferred bioenergy source relative to land plants because they are more productive, more efficient in their use of nutrients, and do not need to compete with food crops for prime agricultural land, Greene says.

The price tag for using this technology over the remainder of the century? About $85.5 trillion to remove the 855 gigatons of carbon needed to bring atmospheric CO2 down to 350 ppm.

Although $85.5 trillion seems high, it is comparable to the estimated cost of using carbon emission reduction strategies to reduce atmospheric CO2 down to a lesser goal of 450 ppm.

Corresponding to less than 1 percent of the global GDP for the rest of the century, such a cost is considered affordable compared with the alternative consequences of catastrophic climate change.

Still, it will take decades to develop air capture and algal bioenergy systems, scale up prototypes, prepare underground carbon repositories, and deploy such systems on a global scale.

“In an ideal case, we could have full deployment on a global scale by 2050,” Greene says.

To buy time, another geoengineering strategy being explored involves altering the Earth’s radiation budget by injecting sulfate aerosols into the atmosphere and blocking the sun’s rays, mimicking what happens after a volcanic eruption.

Other strategies involve injecting seawater droplets into clouds and deploying shades or mirrors in space, all to block the sun’s rays from reaching Earth’s surface.

Such solar radiation management strategies “can be done quickly, but should only be considered as a last resort to buy ourselves some time” since they simply “cover up the problem without doing anything about the CO2,” says Greene.

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chat4 Comments


  1. Scott

    Why would we need carbon repositories when it could be used as raw material for graphene and other carbon-based materials? Since some forms of algae are known to build three-dimensional colonial structures, wouldn’t a fruitful avenue of research be to see if we can get the algae to build these carbon structures for us?

  2. Christian Rioux

    This is bullcrap!
    Those scientists only want to make geoengineeering cause there are big buck to be made there. The earth is NOT doomed, this is a fraud. CO2 is not poison, it`s what plants breathe, and what we exhale!

    This is DANGEROUS to try to play god and change the climate when it is not a problem. Climate always change, always has and always will, This is NOT OUR FAULT, as much as the last ice age was not our fault. These are natural cycles.

  3. Diane

    You’re right, the earth will be fine. But humans (and other life forms that we co-exist with) cannot live in the conditions that we are creating. We are already “playing god” by changing the composition of the atmosphere. Thinking otherwise is wishful.

  4. Robert Reed

    Christian Rioux is correct in saying that the climate of the earth has always been changing.
    That’s what natural systems do, they adjust to differing conditions.
    The plague didn’t work, AIDS hasn’t worked, Ebola hasn’t really put a dent in the real problem.
    Even Cancer from the industries causing Climate Change hasn’t put a dent in the real problem.
    For the sake of this jewel in space we call home, I hope Mother Nature finds a way to kill us off before we usher in an era of mass extinction born out of our own arrogance and greed.

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