From growing forests the size of a continent to calling for rain, scientists have begun to propose, test, and even deploy large-scale geoengineering projects to radically transform the planet. These projects are designed to tackle problems such as overgrown deserts, droughts or excess carbon dioxide in the atmosphere - all in the name of fighting climate change. After all, if not us, then who? Nature will take her own and destroy us.
Why is geoengineering dangerous?
The impact of uncontrolled climate change is costing countries hundreds of billions of dollars a year as the frequency of extreme weather increases and yields decline, among other impacts. All this leads to the need to introduce radical solutions. However, geoengineering in particular has faced significant resistance.
Opponents argue that humans do not sufficiently understand the complexity of global natural cycles, and trying to change them will cause more problems than it will solve.
Large green walls
One of the projects already underway in some is the creation of green walls over large areas of the planet. They are composed of native vegetation and are planted at the edge of deserts to stop the desertification of the surrounding areas. The fact is that the land at the edge of the deserts is already prone to drought and overwhelmed by the communities living there, creating a vicious circle and forcing residents to struggle to survive. Green walls and supportive conditions are designed to rejuvenate the earth by making large areas of the planet more livable.
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The two largest walls are China's Shelter in Three Northern Forests program, which is 4,500 km long, aimed at stopping the spread of the Gobi Desert, and the 8,000 km African Great Green Wall to reduce the Sahara.
The success of these walls depends on tracking long-term changes in vegetation, and to that end, scientists will rely on ten-year satellite imagery and augmented visual interpretation algorithms to analyze images. Collect Earth, a joint project between Google and the UN Agriculture Division, has created an open source interface that allows researchers to access all of this data.
Blocking the sun
Last year, Harvard scientists conducted a test that involved sending trace amounts of aerosol - not enough to have any significant effect - into the Earth's stratosphere, at an altitude of about 20 km. The aerosols contained sulfate compounds that can reflect incoming sunlight and lower global temperatures.
An article published in 2017 in the journal Atmospheric Chemistry and Physics argues that injecting aerosol into the atmosphere, in fact, mimics the ash plume from a volcanic eruption. And like the ash plume, when introduced into the atmosphere, the aerosol quickly spreads and affects large areas of the planet.
Scientists are also exploring the possibility of launching a giant umbrella into space to control the amount of solar radiation reaching Earth. This idea has been afloat for decades, but only recently received a boost.
For example, a 2018 paper from the Journal of Aerospace Technology and Management describes the launch of the so-called HSS, or Huge Space Shield. The plan is to place a thin, wide sheet of carbon fiber at the Lagrange point, which is a relatively stable point in the complex system of gravitational pulls of the Earth, Moon, and Sun. This sheet will block only a small portion of the sun's radiation, but it may be enough to bring global temperatures below the 1.5 degrees Celsius limit set by the International Climate Change Panel.
Others want to block the sun by stimulating cloud formation - a process known as cloud seeding. In order for it to rain, the moisture in the air must condense, which means that an interesting concept of nucleation (nucleation) is required for a drop in temperature and condensation. In nature, water droplets form around particles of dust, pollen, sea salt, or even bacteria, but scientists have confirmed that compounds like silver iodide or dry ice can also work. The plan is to inject these substances into the atmosphere over drought-prone areas, thereby increasing cloud cover and rainfall.
Removing CO2 from the atmosphere
Direct Air Capture (DAC) is a cocktail of chemicals that bind to CO2 but are inert to other gases. When air is passed through DAC machines, also known as artificial trees, CO2 adheres to the chemicals and is released again as the energy rises, allowing it to be captured, stored and recycled, or reused. The Swiss company Climeworks has built the only commercial plant dedicated to the capture and resale of carbon dioxide. Its goal is to capture one percent of the world's carbon dioxide emissions by 2025.
Removing CO2 from the atmosphere can also be accomplished by seeding the oceans, which are one of the planet's main carbon sinks, responsible for removing about 30% of carbon dioxide. The best two ways to do this include iron and lime. Fertilization with iron is designed to stimulate the growth of phytoplankton, which sucks carbon dioxide out of the atmosphere and helps deposit it on the seabed.
In a Korean article published in 2018, the authors looked at iron seeding experiments over the past 25 years and concluded that this might be a viable solution. However, they admit that much more testing is needed. The addition of lime will react with the carbon dioxide already dissolved in the ocean and convert it into bicarbonate ions, thereby decreasing the acidity of the oceans and making them more susceptible to absorbing more carbon dioxide.
Is the medicine worse than the disease?
While these ideas seem promising, there are a number of potentially harmful consequences. In 2008, 191 countries approved a UN ban on fertilizing oceans over fears of unknown side effects such as altering the food chain or creating regions with low oxygen concentrations. The Rhode Island State Legislature passed the Geoengineering Act 2017, which stated that “geoengineering includes a variety of technologies and practices associated with hazardous activities that can harm the health and safety of people, the environment and the economy of Rhode State. Island.
Despite opposition, some companies are lobbying governments to allow geoengineers to work, and scientists continue to develop and experiment with new ideas. Some of the perceived benefits of such plans are being questioned. A recently published article in the journal Nature argues that reducing the amount of solar radiation reaching the earth's surface will do little to halt the harmful effects of climate change on crops.
The question is, do we know enough to do geoengineering? What if, for example, large-scale cloud seeding changes flow and delays the monsoon season in Southeast Asia? How will this threaten rice crops? Or what if dumping tons of eeze into the ocean wipes out fish populations along the Chilean coast?
No one knows for sure what the consequences will be for such geoengineering projects - but it is also possible that they will be the solutions we were looking for.
Ilya Khel