The politics of climate change is far from settled

The latest report from the Intergovernmental Panel on Climate Change, the Sixth Assessment Report, is a valuable update of the scientific thinking on one of the world’s most pressing environmental, economic and geopolitical issues. AR6 confirms the consensus view among climate scientists that the world is warming in response to a build-up of greenhouse gases in the atmosphere. The average global temperature rise since the industrial revolution is calculated at 1.07C. The best estimate of climate sensitivity, the warming that can be expected from a doubling of carbon dioxide in the atmosphere, is 3C. According to AR6, impacts from a warming world already are apparent and will become more pronounced as temperatures continue to rise. This is most pronounced in the number of hot days and increases in rainfall in some areas. But scientists say they are more confident in their model predictions linking some extreme weather events to the impact of climate change. It is possible that annual average global temperatures will exceed 1.5C above pre-industrial levels early next decade but annual temperatures will continue to be determined by a complex interaction of natural forces as well as levels of atmospheric greenhouse gases.

Arguments about a lengthy pause or slowdown in warming that caused so much consternation at the time of the IPCC’s AR5 report in 2014 have largely been resolved. Scientists say natural variability can mask the rate of warming from increased greenhouse gas levels. But they say these natural variations are short-lived when set against a bigger global warming trend that they say has a linear relationship to greenhouse gas levels in the atmosphere.

Some people will continue to question the validity of many of the IPCC findings. The accuracy of climate models is one area of contention. The IPCC report says models are a valuable tool when taken as a group, even if some can give unreliable individual outputs in some areas. It is significant that climate models were not used as a direct line of evidence to calculate the sensitivity of the climate to a doubling of CO2 in the atmosphere. It is also valid to point out that, according to British Met Office data, average global temperatures have returned to the levels they were when the IPCC published its previous report in 2014. Scientists, however, are unequivocal. Human influence has warmed the atmosphere, ocean and land. Human-induced climate change is already affecting many weather and climate extremes in every region across the globe. Global warming of 1.5C and 2C will be exceeded during the 21st century unless deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades. As a body of work, the AR6 report is a valuable tool for policymakers.

The scientific debate, however, is only part of the story. Pressures are building in global financial markets on the issue, which simultaneously threatens to spark a new round of global trade wars. Deep divisions remain between developed and developing nations over past responsibilities and future actions. Even with agreement among climate scientists, the challenge is to build a political consensus among world leaders to act and then to deliver on their promises.

Ultimately, the level of action taken will be determined by the cost involved and political reality. The UN Framework Convention on Climate Change meeting in Glasgow scheduled for November provides an indication of the difficulties involved. British Prime Minister Boris Johnson is under intense pressure domestically over the cost of transitioning to net-zero emissions by 2050 as promised. Similar pressures are evident across Europe, and two of the major emissions nations, China and India, have made it clear they will not support any initiative at the Glasgow meeting to phase out coal globally.

Nonetheless, the Morrison government can expect more pressure to make clear its intention to set a net-zero target for mid-century. As things stand, Australia has pledged to be carbon neutral sometime this century, preferably before 2050. We are leading the world in the take-up of renewable energy and working with major economies on research and development of new technologies that can help reduce global CO2 emissions. Scientists may be in agreement, but the politics of climate change that has already cost a succession of prime ministers and opposition leaders their jobs remains far from settled.