Climate change policy makers must incorporate critical climate-carbon cycle feedback information into the decision making process or run the risk of falling well short of what is required to prevent dangerous climate change, according to an academic from The Australian National University. 

Associate Director of the ANU Centre for Climate Law and Policy (CCLP) Andrew Macintosh says that information from coupled climate-carbon cycle models suggests that the emission cuts that are required to prevent the global average surface temperature increasing by more than 2 - 3ºC above pre-industrial levels are far greater than previously believed.

Failure to incorporate this information into policy processes now could close off options to avoid dangerous climate change.

The details of the study are released today in the latest CCLP working paper: Climate Carbon-cycle Feedbacks: The Implications for Australian Climate Policy.

Climate-carbon cycle feedbacks are feedbacks in the climate system that relate to the interaction between temperature change, atmospheric carbon dioxide and the carbon cycle – the biogeochemical cycle by which carbon is exchanged between land, ocean and atmosphere. 

“Global warming could significantly reduce the uptake and storage of carbon by land and ocean sinks,” said Mr Macintosh.

“This risk has profound implications for climate policy. If the uptake and storage of carbon by natural sinks declines, a greater proportion of carbon emissions will remain in the atmosphere. As a result, meeting climate targets based on atmospheric concentration of carbon dioxide will be more difficult, requiring a greater reduction in emissions than would otherwise be necessary. 

“The importance of climate-carbon cycle feedbacks is well known in scientific circles, but often overlooked in the policy process where decision makers often rely on data that do not fully account for this information. That could result in abatement targets being set too low and atmospheric carbon dioxide concentration objectives being exceeded,” he said. 

He added that if the data from models that account for feedbacks is accurate, there is little chance of stabilising the atmospheric concentration of carbon dioxide at levels that are consistent with keeping the increase in global temperature below 2ºC – an often-cited threshold for dangerous climate change. 

“A concerted effort from the international community is required to achieve even an atmospheric concentration target that equates to a best-estimate warming of 3.6ºC. If there is a desire to keep the temperature increase below 3ºC, the results suggest the key abatement dates are likely to be 2020 to 2030, not 2050. 

“A 60 per cent mitigation target for developed countries for 2050 is likely to fall well short of what is required if there is a desire to keep the temperature increase below 3ºC,” he said.