Environment Counts | Arctic sea ice extent directly linked to anthropogenic CO2 emissions :
Comparison of the 30-year running mean of monthly mean September Arctic sea-ice area with cumulative anthropogenic CO2 emissions reveals a linear relationship that implies a sustained loss of 3 Â± 0.3 m2 of September sea-ice area per metric ton of CO2 emission.
Relationship between September Arctic sea-ice area and cumulative anthropogenic CO2 emissions. Thick blue line shows the 30-year running mean of observed September sea-ice area. For reference, the annual values of observed September sea-ice area based from 1953-1978 on HadISST (circles) and from 1979 to 2015 on the NSIDC sea-ice index (diamonds).
Based on this simple empirical relationship it is possible to directly estimate that an additional 1000 Gt of CO2 emissions will result in no Arctic summer sea ice. For current emissions of 35 Gt CO2 per year, the limit of 1000 Gt will be reached before mid century. Internal variability causes an uncertainty of around 20 years as to the first year of a near-complete loss of Arctic sea ice.
The results also imply that measures taken to mitigate CO2 emissions will slow down the loss of Arctic summer sea ice. In particular, for cumulative future total emissions corresponding to a 1.5Â°C global warming target, in other words for cumulative future emissions significantly less than 1000 Gt, Arctic summer sea ice has a chance of long-term survival.