Global warming is the reality that the world lives with today, with temperatures hitting new records every passing year.
2016 went down in history as the hottest year on record, with all-time highs of 42.7°C in Pretoria, South Africa to 54°C in Mitribah, Kuwait. Overall, the World Meteorological Organisation recorded a 1.2 degree rise in temperatures in 2016, warmer than pre-industrial levels. With 2017 set for a new climate record, the world is desperate for a solution. Can global warming be reversed?
A lot of proposals have been put on the table on how to mitigate the effects of climate change, mostly by cutting carbon emissions. Under the current carbon emission cut proposals from the Paris Agreement, each country made pledges to decarbonise over a certain period.
Kenya, for example, has an eight-page plan that is pegged on the Climate Change Act to reduce its emissions by 30 per cent by the year 2030. These plans seek to slow down the rate of warming, as opposed to reversing the effects of climate change.
However, the problem with decarbonising, as some scientists argue, is that it will take decades to achieve global cooling.
Therefore, researchers are considering another option – solar radiation geoengineering – which focuses on reducing the risks of climate change by blocking out some sunlight to elicit global cooling.
The argument is that while cutting carbon dioxide and other greenhouse gas emissions would slow down or halt their rising concentrations in the atmosphere, a lot of the carbon dioxide released through past emissions will remain in the atmosphere for 100 years or more. Additionally, any inertia in the climate system means that global temperatures will continue to rise, thus calling for a new, cheaper and faster means to deal with climate change.
Granger Morgan and Katherine Ricke of the Department of Engineering and Public Policy at the Carnegie Mellon University, explain the solar radiation management process: “The mass of fine particles needed to counteract the radiative effects of a doubling of atmospheric carbon dioxide concentrations is approximately 2.6 million tonnes of aerosol per day injected into marine stratus clouds or 13,000 tonnes per day of sulphate aerosol injected into the stratosphere. By comparison, to achieve the same radiative effect we would need to remove 225 million tonnes per day of carbon dioxide from the atmosphere for 25 years straight.”
Still a theoretical proposal, solar radiation management mimics the volcano effect. When a volcano erupts, millions of tonnes of ash and sulphur dioxide are sprayed into the atmosphere, creating a blanket between the earth and the sun.
The sulphur dioxide is converted into sulphate particles that reflect sunlight back into space, thereby keeping the earth’s surface cool. In 1991, for example, the eruption of Mt Pinatubo in the Philippines resulted in global cooling of 0.5 degrees.
Researchers propose recreating this by shooting sulphur dioxide particles directly into the stratosphere to achieve cooling within days.
Although this concept was first floated in the 1960s, research hasn’t yet gone beyond the lab. It is only in recent years that discussions about it have picked up, even though it remains very controversial.
The African Academy of Sciences is now bringing this conversation to Africa, a continent that has proved vulnerable to the impacts of climate change.
“Solar radiation management is a threat because we don’t know if it will make our situation worse. At the same time, it is an opportunity because if it works, imagine the things it could do for us. It would mean no more severe droughts and floods,” says Sam Ogallah, the co-ordinator of the Pan African Climate Justice Alliance.
Professor Asfawossen Asarat of Addis Ababa University adds that Africa’s concern about solar radiation geoengineering is not the temperature but the precipitation: “Will there be more rain? More drought? These questions must be answered before we can support this proposal. After all, East Africa has at least 80 volcanic mountains that can be used to study this subject further.”
Professor Asarat concerns are valid, given that this method hasn’t actually been tested. What is the impact of pumping sulphur dioxide into the air? Will it harm the ozone layer? How will it impact human health, given the possibility of acid rain?
Might the side effects outweigh the benefits and should the world try it?
There are many promising possibilities, but a lot of scientists insist that tampering with the complex natural climate system that is not yet fully understood can lead to consequences that are even more disastrous than climate change itself.