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Lignite mining in Hambach near Elsdorf
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If global warming is to be limited to a maximum of 1.5 degrees Celsius, the global community must move away from fossil fuels - that much is certain.
Because when coal, crude oil and natural gas are burned, the climate-damaging greenhouse gas carbon dioxide (CO₂) is produced.
Not all of these valuable resources should be used.
But how much of what is still in the ground can we still burn?
Four British scientists have now calculated this, taking into account the quantities of these reserves that should remain in the ground to achieve the climate target by 2050: 58 percent of crude oil, 59 percent of natural gas and even 89 percent of coal. In the calculation for their study - published in the journal Nature - the team led by Daniel Welsby from University College London refers to the stocks known in 2018, the extraction of which is considered technically feasible and economically viable.
"Fossil fuels continue to dominate the global energy system and their consumption has to fall sharply in order to keep the temperature rise below 1.5 degrees Celsius," the researchers write. An earlier study showed that by 2100 only 580 billion tons of CO₂ may be emitted to achieve this goal. On this basis, Welsby and colleagues used a global energy system model to calculate how much of the fossil fuels should not be extracted.
One of the driving forces behind this is the cost of funding.
Therefore, according to the model calculations, 84 percent of Canada's oil sands should remain in the ground, and the Arctic oil and gas reserves should even remain completely untouched.
This is important news for climate and environmental activists, because the Arctic is a sensitive region in which changes in the environment have global consequences for the climate - especially the melting of the ice in the region is dramatic.
For oil production in the Arab region, the scientists calculated roughly the global average of almost 60 percent.
Overall, according to the scenario, oil and gas production will have to decrease by around three percent every year until 2050.
In a sensitivity analysis, Welsby's team examined how some factors could affect the percentages. These include the rate of carbon capture and storage (CCS) use, the availability of bioenergy, and the growth in future energy needs in the aerospace and chemical sectors, for example for the manufacture of plastics. The researchers found that the effects are quite small. If a lot of biomass were burned and the resulting CO₂ safely stored, the quota of stocks that should remain in the ground could drop by just two to three percentage points.
In their model calculations, Welsby and colleagues use an amount of carbon that can only limit warming to 1.5 degrees Celsius with a probability of 50 percent. Because various uncertainties are not taken into account, for example reactions of the earth system to the increased CO₂ content. "Therefore, more carbon has to remain in the soil in order to ensure more security when stabilizing this temperature," emphasize the researchers. They also assume that around 4.4 billion tonnes of CO₂ will be removed from the atmosphere annually by 2050 and then around 5.9 billion tonnes of CO₂ annually by 2100, for example using techniques that have been put into operation in Iceland this week. There a system called orka stores up to 4,000 tons of carbon dioxide annually and converts it underground into rock.
The authors of the study advocate that prior consumption of fossil fuels should also be taken into account when reducing production quotas have little transition capacity - or those who forego funding activities - need to be supported in order to follow this lead. "
joe / dpa