Climate science

A data-based appraisal of the current state of our planet: scientists are becoming incressingly concerned that we are close to multiple tipping points

Johan Rockstrom is Director of the Potsdam Institute for Climate Impact Research and Professor in Earth System Science at the University of Potsdam.

Speed and scale of action on fossil fuels, circular business models, healthy plant based diets and restoration of earth systems is what matters to prevent the earth's climate spinning out of control.

The planet's climate is changing faster than expected.  The estimates by the IPCC of the temperature rise needed to reach climate tipping points have been reduced over the past 23 years from a rise in global mean surface temperatures of 5C (in the 2001 report) to 1.5-2.0C (2022 report).  We are currently at 1.2C, with the 2023 average at 1.45C.  

The Paris Climate Agreement was signed eight years ago.  We are half-way through the decade where our actions over the next five years will determine the future for generations to come.  If we don't act we are on a path to 2.7C at the end of the century.  

The earth has shown a remarkable buffering capacity to absorb changes without significant impact on the earth's climate.  53% of emitted CO2 has been soaked up by the earth's systems such as forests in Canada, Germany, Russia and the Amazon.  The Amazon rainforest has now turned from a carbon sink to being closer to a source.  Oceans have absorbed 90% of the increased hear, but the sea surface temperature is getting warmer and 2023 saw a leap in sea surface temperature, with this acceleration continuing in 2024.   Scientists don't know as it can only partly be explained by El Nino.  

All the pointers are towards higher risk of reaching tipping points, creating irreversible changes, accelerating global warming such as oceans releasing heat and forests emitting CO2 instead of absorbing.  This is likely to move us from a dampening state to an amplifying state.  The consequences?  Massively increased droughts, floods, heatwaves, human-amplified storms, with 2023 seen as a moderate year, despite extreme levels of heat (40-50C in India and the middle east), wildfires and floods., with all its economic and human consequences.  Melting of the two ice sheets (Greenland and West Antarctic), both near their tipping points will cause a 10m sea level rise.

There is time and a pathway to avoid this.  There is four years' carbon budget of 40Gt of CO2 (current levels of emissions) remaining to give us a 50% chance to staying with 1.5C of warming.  We know how we can reach net zero but need the will to get there.  But even if we achieve this there will be an overshoot owing to the warming locked into the system.  We also need to restore the earth's ecosystems in order to recreate the ability to absorb temperature and CO2 to bring ourselves back below 1.5C.