IPCC 2021 report on climate change – just limited time to avert catastrophe

Posted: January 2023

Image license: Guenter Albers/Shutterstock.com

Indeed even the most avid climate change sceptic must have moved their position somewhat in the light of the devastating weather events we have experienced over the last few years. Record-breaking rainfall and temperatures do not in themselves prove the climate is changing, yet they are a good indication that something quite frightening is happening to our weather.

The latest report from the Intergovernmental Panel on Climate Change (IPCC) examines the physical changes that are happening to the climate right now due to human activity and how these are likely to manifest as devastating floods, destructive wildfires, rising sea levels and other adversities in the future.

The current report looks at the projected impact of five possible emission scenarios, while reports the IPCC plan to publish in 2022 will discuss possible ways to adapt to these changes and suggest how we might ameliorate them. However, the message couldn't be more precise – we must take "immediate and large scale" action to avoid climate catastrophe.

Unless we act now, by 2030, the world will breach the Paris Agreement target to keep global warming below 1.5 0C. It is now unequivocal that this is the result of human activity. Every increment of warming will exacerbate natural disasters. Some of the report's key findings include

Temperatures rising

Under all three emission scenarios, surface warming will each 1.5 0C by 2040 and or 1.6 0C by 2060. To avoid this, we must show a drastic reduction in CO2 emissions this decade and reduce emissions to net-zero by 2050.

Irreversible changes

Even if we achieve the above, we can't turn back the clock. Many impacts of climate change will remain for hundreds or thousands of years. Such changes include rises in sea levels, ocean acidification and glacial melting. Even if we could reduce emissions drastically, we are likely to see sea levels rise by half a metre by the end of the century. However, the worst scenario will result in rises of almost two metres.

Tipping points

Tipping points are thresholds where small increases can trigger systems into new states. Once they occur, tipping points rarely move in the reverse direction. Some of these highlighted in the report include: rising temperatures could cause forests to die back and consequently be less able to capture CO2; already, parts of the amazon are emitting more CO2 than they absorb. In addition, antarctic ice sheets could break free, resulting in rapidly rising sea levels.

It is all our fault

The 1990 report attributed just a proportion of the warming was caused by humanity. The latest report now states that human influence is evident and the dominant cause of climate change. It is now unequivocal that greenhouse gas emissions and temperature rises are driven by human activity,

Regional impacts

The science of climate change has advanced considerably and can now analyse the data at a regional level. We now know that the arctic temperatures are rising faster and that at high northern latitudes, temperatures could rise by up to four times higher than average global warming. Additionally, the Gulf Stream will weaken, and it could collapse entirely with devastating effects, including reduced African and Asian rainfall and increased European dry spells.

Limiting global warming

The good news is that we still have an opportunity to reduce these consequences. In IPCC's worst-case scenario, we would see a warming of up to 4 0C from 2075 to 2094. The table below shows when various temperature thresholds would be reached if we take no action and if we drastically reduce emissions.