Geoengineering: 'Plan B' for the planet

The sun sets in a sky dusted with ash over Màrdalsjškull, 20 km east from Iceland's Eyjafjoell volcano, on May 5, 2010
The sun sets in a sky dusted with ash over Màrdalsjškull, 20 km east from Iceland's Eyjafjoell volcano, on May 5, 2010

Dismissed a decade ago as far-fetched and dangerous, schemes to tame global warming by engineering the climate have migrated from the margins of policy debates towards centre stage.

"Plan A" remains tackling the problem at its source. But the UN's top climate science body has made it clear that slashing carbon pollution won't be enough to keep Earth from overheating.

That has opened the door to a host of geoengineering schemes, and an under-the-radar set of global industry guidelines, currently in review, which could help mainstream them.

Here is a menu of "Plan B" geoengineering solutions, and their potential drawbacks:

Direct CO2 capture

Experiments have shown it is possible to suck planet-warming carbon dioxide directly from the air, converting it into fuel pellets or storing it underground.

A Canadian company backed by Microsoft co-founder Bill Gates launched a pilot facility in Canada in 2015, and another company unveiled one in Iceland last year.

DRAWBACK: The technology is currently prohibitively expensive and may take decades to operate at scale.

Afforestation

Extensive planting of trees could significantly slow the concentration of CO2 in the atmosphere, which currently stands at more than 410 parts per million, 40 percent more than 150 years ago.

DRAWBACK: Even if deforestation could be reversed—more than 100,000 square kilometres of tropical forests have disappeared each year since 2013—the number of trees needed to put a dent in CO2 emissions would clash with food and biofuel crops.

Solar radiation management would slow global warming by reflecting more sunlight away from Earth
Solar radiation management would slow global warming by reflecting more sunlight away from Earth

BECCS

Bioenergy with carbon capture and storage (BECCS) marries a natural process with a high-tech one.

The first step is to plant rapeseed, sugarcane, corn or "2nd-generation" biofuel crops such as switchgrass, which pull CO2 from the air while growing. The second step is while burning the harvested plants for energy to sequester the CO2 produced.

In theory, the result is less CO2 in the atmosphere than when the process started. Virtually all climate change models projecting a future consistent with the Paris Agreement's temperature targets assume a key role for BECCS.

DRAWBACK: Studies calculate that up to twice the area of India would need to be given over to biofuels, putting BECCS in conflict with food crops.

Ocean fertilisation

Microscopic ocean plants called phytoplankton gobble up CO2 and drag it to the bottom of the ocean when they die. Their colony size is limited by a lack of natural iron, but experiments have shown that sowing the ocean with iron sulphate powder creates large blooms.

DRAWBACKS: Scientists worry about unintended impacts. Die-offs of plankton, for example, use up oxygen, which could create massive "dead zones" in the oceans, something already on the rise.

Enhanced weathering

Natural weathering of rocks removes about one billion tonnes of CO2 from the atmosphere every year—about two percent of total man-made C02 emissions.

Spreading a powdered form of a greenish iron silicate called olivine across certain landscapes can mimic that process, experiments have shown.

A picture taken on October 17, 2017 shows the sun rising in Tours
A picture taken on October 17, 2017 shows the sun rising in Tours

DRAWBACKS: It would be expensive to mine and mill enough olivine to make a difference.

Biochar

Biochar is charcoal made by heating plant waste—rice straw, peanut shells, wood scraps—over long periods in low-oxygen conditions. It can store CO2 for long periods, and also enriches soil.

DRAWBACK: The scientific jury is still out on how quickly this method could be scaled up, and on the stability of biochar used as a fertiliser.

Solar radiation management

Unlike other strategies, solar radiation management does not target CO2. The goal is simple: prevent some of the sun's rays from hitting the planet's surface, forcing them back up into space.

One idea is to inject or spray tiny reflective particles into the stratosphere—possibly with balloons, aircraft or through giant tubes.

Nature sometimes does the same: Debris from the 1991 eruption of Mount Pinatubo in the Philippines lowered the planet's average surface temperature for a year or two afterwards.

Scientists have also calculated ways to alter clouds that could help beat the heat.

DRAWBACKS: Even if it works as intended, solar radiation management would do nothing to reduce atmospheric CO2, which is making oceans too acidic. There is also the danger of knock-on consequences, including changes in rainfall patterns, and what scientists call "termination shock"—a sudden warming if the system were to fail.


Explore further

Crisis management: Seven ways to engineer climate

© 2019 AFP

Citation: Geoengineering: 'Plan B' for the planet (2019, August 23) retrieved 16 September 2019 from https://phys.org/news/2019-08-geoengineering-planet.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
275 shares

Feedback to editors

User comments

Aug 24, 2019
Under the 'Solar radiation management' heading the Ice911 project wasn't mentioned.

Overall these proposals are based upon the assumption that the collapse of industrial civilization will not take place within a decade from now and that the tipping point, beyond which it became too late to reverse the trend, occurred over a decade ago.

Aug 24, 2019
These morons will be the end of us all.
Why?
Just to sustain their dogma.

Aug 24, 2019
Dismissed a decade ago as far-fetched and dangerous, schemes to tame global warming by engineering the climate have migrated from the margins of policy debates towards centre stage
Actually no, a decade ago it was dismissed as chemtrail nutbagging conspiracy theoretic tinfoil hattery.

Aug 25, 2019
For years, the connivers with the Democratic Rackets have insisted that chemtrails cannot exist, claiming it is impossible for any operation with such as even commercial sized jets would be able to do anything to affect the atmosphere on a large scale. Now the "scientists" say that scattering "reflective particles" from commercial sized jets could cool the atmosphere. They also say that ships, comparable in size to commercial jets, spraying salt water into the air can "whiten" marine clouds. And, yet, connivers with the Democratic Rackets and the followers of the Democratic Rackets refuse to discuss chemtrails as actually having a deleterious effect on the atmosphere or even being able to. They won't even use the word! The fact is, those who claim to care about "climate change", in reality, don't!

Aug 25, 2019
So maybe Julian Simon was right. Humans, with those meat computers, will always find a solution.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more