Climate scientists are warning that even with moderate emissions of greenhouse gases, there is a 1-in-10 chance of the planet warming by 7°C in around 200 years. This alarming prediction comes from a climate model developed by Andrey Ganopolski at the Potsdam Institute for Climate Impact Research in Germany. Ganopolski emphasizes that a 7°C increase in temperature would have catastrophic consequences, far worse than a 3°C increase.
The model also indicates that even if emissions were to cease immediately, there is still a 1-in-10 chance of the planet warming by more than 3°C. The amount of warming is influenced by the amount of CO2 and other greenhouse gases in the atmosphere, as well as the sensitivity of the climate to these increases. The equilibrium climate sensitivity, which is the amount of warming that would occur after a doubling of CO2 levels, is estimated to be around 3°C in most models beyond 2100.
Ganopolski and his team decided to explore what would happen if the equilibrium climate sensitivity differs from this expectation. They incorporated additional carbon feedback effects, such as the release of CO2 and methane from permafrost and wetlands, which previous models haven’t accounted for. Including these feedback effects can lead to a significant increase in warming, especially for higher assumed sensitivities.
The uncertainty surrounding the equilibrium climate sensitivity is due to aerosol emissions counteracting the warming effect of greenhouse gases. The recent rapid warming is believed to be partially caused by a reduction in shipping emissions. Ganopolski explains that aerosol effects are complex and challenging to quantify, making it difficult to predict future warming scenarios accurately.
Andy Wiltshire from the Met Office in the UK agrees that there is a high level of uncertainty in predicting future warming. He appreciates the way Ganopolski’s research presents this information in a different light, highlighting the potential for significant warming if climate sensitivity is high and emissions continue unabated.
Ganopolski remains hopeful that if emissions are limited and climate sensitivity is on the lower side, warming of 3°C can still be avoided. However, he believes it is already too late to limit warming to under 2°C. With the 23rd century not too far off in terms of human generations, the urgency to address climate change and reduce emissions is more crucial than ever.
