A Solution to Global Warming?
If the reports on the greenhouse effect issued by the United Nations, environmental organizations and academic institutions are to be believed, then virtually every year since 1999, the Earth has reached a global tipping point whereby changes in average global temperatures, ocean currents, atmospheric circulation and the like become irreversible. The reports emphasise the urgency of the situation and the criticality of putting into action programmes that reduce carbon emissions to manageable levels before a target year is reached. Their objective is to forestall the deleterious effects of global warming, some of which include the destruction of marine resources due to acidification of the oceans, coastal flooding and crop failures, extinction of animal organisms, disappearing islands due to rising sea levels, and political and economic chaos brought on by increasing numbers of ecological refugees.
The United Nations issued its first warning on tipping points in 1982, and in a recent meeting with government officials and top climate scientists, presented a draft report containing the usual warning: the world is running out of time to stop global warming. The response from most governments around the world has been solid. For example, at a summit in 2010, nearly 200 countries signed a resolution indicating their intent to take part in a programme to reduce carbon dioxide emissions. The United Nations Environment Programme (UNEP) urged participants not to exceed 44 gigatonnes in carbon dioxide emissions annually until 2020. In reality, though, most pledges fell short by 6 to 12 gigatonnes.
Assuming that these countries had been able to meet the UNEP requirement, the world would have hypothetically prevented the average world temperature from increasing 2 degrees Celsius above that of pre-industrial times. The UN report noted that scientists had deduced that global temperatures have risen about 0.8 degrees Celsius since the early 1900s.
The 2 degrees Celsius limit, however, is merely a short-term goal. The UN’s actual aim is to buy enough time to reach the long-term goal—that of reducing atmospheric CO2 to pre-industrial levels. This would require a persistent and concerted global effort, and although several measures have been put into place over the past few decades, in the preceding ten years alone, carbon emissions have risen to their highest levels in recorded history.
Generating electricity without emitting CO2 entails shunning non-renewable sources such as coal, petroleum and other fossil fuels. The use of renewable, low-carbon energies such as wind power, hydropower, nuclear power, geothermal power and solar power are advocated as well as measures promoting energy efficiency in homes and factories, green cities and drastic transport emission reductions. The shift to low-carbon sources has not been as rapid or as widespread as desired by the UN, however, and unless renewable sources are made continuously available, the emission savings generated by using these energies could very well be cancelled out, more so if total energy consumption continues to increase.
As such, scientists have been toying with the idea of allowing average temperatures to rise by 2 or 3 or even 4 degrees Celsius, and then cooling the planet by extracting the carbon dioxide from the atmosphere. The technology, which is called BECCS or Bio-Energy with Carbon Capture and Storage, has already been developed and is based on the idea of negative carbon dioxide emission or the permanent removal of greenhouse gases from the atmosphere. BECCS requires planting trees and crops that suck carbon dioxide from the air, burning the extracted gas to generate electricity, and then burying the resulting CO2.
Another similar method include direct air capture, which utilizes a closed-loop industrial process that deliberately captures carbon dioxide from the air to be used in industrial applications or stored in geological formations underground. Finally, there is enhanced weathering, which uses ultramafic silicate rock flour spread. When the silicate dissolves in the oceans, it draws carbon dioxide from the atmosphere into the solution, which calcifying organisms then use to form carbonates. Ultimately, these redissolve when they sink to the bottom of the ocean. These processes should stabilize the Earth’s climate, but there is no way of telling whether they actually will because eons pass before the evidence becomes recordable.
Some scientists think that these methods—BECCS, direct air capture and enhanced weathering—are drastic and even dangerous. The US National Research Council or NRC says that carbon and storage schemes are as risky as hydraulic fracturing or fracking. In the latter, rock is fractured by a pressurized liquid to stimulate the formation of wells. These wells provide access to underground water, gas and oil. But the chemicals used in the pressurized liquids are toxic and half of the water released by fracking makes its way back to the water supply. With carbon storage, billions of cubic metres of CO2 infused liquid are injected below ground, so BECCS and other processes are likely to trigger earthquakes and unseal repositories of carbon, resulting in the release of the gas back into the atmosphere.