A groundbreaking study published today in the European Geosciences Union (EGU) journal Earth System Dynamics provides a critical and previously underestimated connection between Antarctic sea ice, cloud cover, and global warming.
A groundbreaking study published today in the European Geosciences Union (EGU) journal Earth System Dynamics provides a critical and previously underestimated connection between Antarctic sea ice, cloud cover, and global warming. This research is important because it shows that a greater extent of Antarctic sea ice today, compared to climate model predictions, means we can expect more significant global warming in the coming decades.
The study, led by Linus Vogt from Sorbonne University, utilized an emergent constraint based on data from 28 Earth system models and satellite observations from 1980 to 2020. This constraint allowed the team to reduce uncertainty in climate projections and provide improved estimates of key climate variables. Their findings indicate that ocean heat uptake and the resulting thermal sea level rise by the year 2100 are projected to be 3–14% higher than the average from CMIP6, a leading collection of climate models. Furthermore, the projected cloud feedback is 19–31% stronger, which enhances climate sensitivity, and global surface warming is estimated to be 3–7% greater than previously thought.
The study found that the extent of Antarctic summer sea ice, which has been considered stable and only weakly connected to human-caused climate change, is a crucial indicator of the Southern Hemisphere’s climate. Models that start with a higher, more accurate representation of pre-industrial sea ice levels simulate colder surface waters, colder deep ocean temperatures, and thicker cloud cover in the mid-latitudes. These initial conditions then amplify warming responses under greenhouse gas forcing, meaning they lead to a more severe and accelerated warming effect than what was previously estimated. Essentially, the climate system's starting point makes it more sensitive to the impact of greenhouse gases.
Read More: European Geosciences Union
Image: Figure 1 Left: a strong relationship was found between historical Antarctic sea ice extent and future global ocean heat uptake across climate models. Figure 2 Right: combining this relationship with sea ice observations from satellites results in increased estimates of future ocean heat uptake by up to 14%. (Credit: Linus Vogt)
