With academics warning that reducing global warming to 1.5 degrees Celsius is rapidly slipping from our grasp, we know it will require a massive effort to achieve. However, the magnitude of emissions reductions necessary has already been accomplished - albeit recently and somewhat by mistake.
According to a recent analysis published in Nature Geoscience, worldwide carbon dioxide (CO2) emissions declined by 6.3 percent, or around 2,200 metric tons (MtCO2), in 2020.
This "is the largest absolute annual decline in emissions, larger than the emissions decrease of the 2009 financial crisis (380 MtCO2) and even larger than the decrease reconstructed at the end of World War II (814 MtCO2)," wrote Tsinghua University Earth system scientist Zhu Liu and colleagues in their paper.
Of course, we all know that this was owing to the huge disruption to our businesses and way of life caused by the fatal and ongoing COVID-19 epidemic, which we do not want to repeat.
However, if we implemented equal adjustments in a focused and controlled manner, we would be able to accomplish these carbon reductions with substantially fewer negative consequences.
For example, the researchers discovered that the largest single driver in cutting emissions, accounting for over a third of the drop, was a significant reduction in ground transportation - automobiles and trucks. Instead of shutting down most of this transportation, we might achieve significant cost savings by powering it with renewable energy.
"It's a great demonstration that it is possible to reduce our emissions, we just need to choose the way we're going to do that," Nerilie Abram, an Australian National University climate scientist who was not part in the study, told the Australian Broadcasting Corporation.
"It's not just individuals doing their part to reduce how much they travel – those sorts of things are not the solutions. We need a planned transition across society to implement the changes that are needed."
It would take a titanic effort, but the rewards would be enormous.
Another research released this week in Climatic Change revealed that limiting warming to 1.5 °C would minimize hazards to people by roughly 40% compared to a 2 °C scenario and up to 85% compared to a 3.66 °C scenario. Rachel Warren, an environmental scientist at the University of East Anglia, and her colleagues utilized 21 different types of climate models to evaluate water shortages, heat stress, illnesses, flooding, drought, and economic repercussions.
They determined that with each level of warming, hundreds of millions more people will be subject to severe drought. However, limiting global warming to 1.5 degrees Celsius might lower global economic repercussions by 20% compared to a 2 degree Celsius future, as well as cut the number of individuals exposed to malaria and dengue illness by 10%.
CO2 emissions have recovered to 2019 levels after the lockdowns, according to Liu and colleagues. They propose directing pandemic recovery stimulus packages toward mitigation initiatives, but note that the funds for such assistance are still dominated by fossil fuel investments.
These are the kinds of structural issues that must be addressed in order to achieve long-term effects, and such changes are already beginning.
Unfortunately, exceeding 2 degrees Celsius would be costly to life on Earth, resulting in "waves of irreversible extinctions and lasting damage to tens of thousands of species", according to University of Cape Town ecologist Joanne Bentley and colleagues in The Conversation. Their new study aims to determine the extent of the harm to the ecosystems on which humans rely.
"The effort to stop temperatures rising isn't an abstract attempt at bending curves on a graph: it's a fight for a livable planet."
Even if the 1.5 °C aim is lost, every fraction of a degree of warming is significant. The 1.5 °C target was always intended to offer something real to strive towards; it is not a magical scientific figure.
Furthermore, we have already averted some of the worst-case scenarios, and analysts say we still have a good chance of keeping warming below 2 degrees Celsius.
