What are tipping points?
Climate tipping occurs when warming temperatures push parts of the Earth system past critical thresholds, triggering self-reinforcing changes that become difficult or impossible to reverse. Crossing these thresholds will lead to major changes in sea level, ocean circulation, and weather patterns, changes that governments and international agencies need to anticipate and plan for. That’s why monitoring for early warning signs of tipping is crucial.
Tipping points in the news
Recent headlines have focused on the first major climate system to tip into irreversible decline– coral reefs. Scientists confirmed in research published this year that warm-water coral reefs have crossed their thermal tipping point and are experiencing unprecedented, widespread decline.
Other tipping points currently making headlines include:
- AMOC/Gulf Stream collapse – a shutdown of this ocean circulation system would cause changes to global weather patterns, potentially causing northwest Europe to experience more severe winters while disrupting monsoons and food security worldwide.
- Weakening carbon sinks – forests and oceans that normally absorb some of the human-made CO2 emissions are becoming less effective, accelerating atmospheric warming.
- Greenland and Antarctic ice sheet collapse – an irreversible retreat, which, when initiated, would cause metres of additional sea level rise
Focus on the ice sheets
The collapse of the Greenland and Antarctic ice sheets presents a serious threat. Their collapse would commit us to metres of sea level rise affecting hundreds of millions globally.
But what are the key instabilities scientists are concerned about?
In this article in The Conversation, CPOM Co-Director for Science Dr Inès Otosaka (Northumbria University) explores the three ice sheet instabilities that could trigger collapse and rapid melting:
- Marine Ice Sheet Instability (MISI)
- Marine Ice Cliff Instability (MICI)
- Surface Elevation Melt Instability (SEMI)
Inès leads the ESA CryoTipping project with Earth Observation experts from ESA’s Antarctic CCI+ Project and ice sheet modelling experts from Northumbria’s Future of Ice on Earth Peak of Research Excellence, PIK (Potsdam Institute for Climate Impact Research) and MPI-GEA (Max Planck Institute of Geoanthropology) combining satellite observations with ice sheet modelling to detect marine ice sheet instability at Thwaites glacier in Antarctica’s Amundsen Sea Sector. By feeding satellite data on grounding line location, ice velocity, and surface elevation into ice sheet models, the team aims to detect early warning signs of tipping points and investigate potential irreversibility of the retreat of the Thwaites glacier.
