The Earth is overheating, mostly as a result of carbon emissions and scientists are hoping to replicate nature’s answer to cool it down through a volcanic eruption such as what resulted during the 1991 explosion of Mount Pinatubo in Central Luzon that lowered the planet’s average surface temperature for a year or two afterwards.
Pinatubo’s eruption emitted a cloud of particles that reached over 40 kilometers into the atmosphere and ejected about 17 million tons of sulfur dioxide.
The aerosols circled the globe within three weeks and produced a global cooling effect. The Northern Hemisphere cooled by up to 0.6 degrees centigrade in 1992 and 1993.
Some scientists argue that without the cooling effect of major volcanic eruptions, global warming effects caused by human activities would have been far more substantial.
Now, geoengineers are hoping to copy the effects of the Pinatubo eruption through a process called solar radiation management.
The goal is simple: prevent some of the sun’s rays from hitting the planet’s surface, forcing them back up into space.
The injecting or spraying of tiny reflective particles into the stratosphere, possibly with balloons, aircraft or through giant tubes are being considered.
Scientists have also calculated ways to alter clouds that could help beat the heat.
Even if it works as intended, solar radiation management, however, would do nothing to reduce atmospheric carbon dioxide, 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,” which is a sudden warming if the system were to fail.
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 the center stage.
“Plan A” remains tackling the problem at its source. But the United Nation’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.
Aside from the Pinatubo solution, menu of “Plan B” geoengineering included direct carbon dioxide (CO2) capture, which experiments have shown possible through sucking 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.
The technology, nonetheless, is currently prohibitively expensive and may take decades to operate at scale.
Trees save environment
Afforestation is another option in which extensive planting of trees targets to significantly slow the concentration of carbon dioxide in the atmosphere, which currently stands at more than 410 parts per million, 40 percent more than 150 years ago.
Even if deforestation could be reversed, more than 100,000 square kilometers 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.
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 “second-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.
Studies, however, calculate that up to twice the area of India would need to be given over to biofuels, putting BECCS in conflict with food crops.
Another top candidate for cooling the atmosphere is through ocean fertilization done through microscopic ocean plants called phytoplankton, which is expected to 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.
The main worry of scientists is the 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.