The most important assessment of climate change ever prepared, which was published yesterday in Copenhagen, should place enormous pressure on the Australian prime minister, Tony Abbott, to make it a major agenda item at the G20 summit later this month, instead of shunting it to the sidelines.
The Synthesis of the Fifth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) lays out the evidence that climate change is already having an impact around the world through rising temperatures, shifts in extreme weather, disappearing glaciers and ice sheets, and advancing sea levels.
With each successive decade being warmer than the last globally, and this year shaping up to be the hottest ever recorded, the reality of climate change is undeniable, and cannot be simply wished away by politicians who lack the courage to confront the scientific evidence.
The IPCC report makes clear that without strong and urgent cuts in greenhouse gas emissions, the world risks impacts from global warming of more than 2 degrees celsius that will threaten the lives and livelihoods of hundreds of millions of people over the coming decades and centuries.
The report should be high on the agenda for the leaders of the world’s 20 most powerful nations, responsible for the majority of the world’s greenhouse gas emissions, when they meet in Brisbane on 15 November.
The G20 is the most effective forum for the discussion of the growth story of the future, the transition to the low-carbon economy.
Yet the local politics of a country of less than 25 million is being allowed to prevent essential strategic discussions of an issue that is of fundamental importance to the prosperity and well-being of the world’s population of 7 billion people.
While Turkey, which will host the G20 next year, is likely to adopt a more enlightened approach to the issue, its summit in late 2015 will be rather late to have the same influence as Brisbane on the outcome of the crucial climate change meeting in Paris in December 2015, at which countries must sign a new international agreement.
In September, the United Nations Secretary-General, Ban Ki-moon, gathered more than 120 leaders at a special summit in New York to ensure that governments are focused on hammering out a new treaty.
As the IPCC report points out, the world can avoid the worst impacts of climate change and the associated instability by cutting annual emissions sharply to avoid global average temperature climbing by more than 2 centigrade degrees above its pre-industrial level.
To have at least 50% chance of staying below the threshold warming of 2 degrees, annual emissions will need to be reduced by about half by 2050 compared with 2010, so that atmospheric concentrations are no more than 530 parts per million by the end of the century, compared with about 435 parts per million today.
The IPCC calculates that the cost of meeting this target will be a reduction in the annual rate of economic growth by 0.06 percentage points.
This is likely to be an exaggeration of the impact of emissions cuts on growth for many reasons, and, indeed, action on climate change could accelerate growth, particularly where there are low interest rates and unemployed resources.
It does not take into account the enormous economic damage that would be caused by unmanaged climate change.
It also has not been able to take into account the most recent evidence of the falling costs of new low-carbon technologies, such as solar panels.
And it leaves out the major economic advantages of policies that would, for instance, improve local air quality by curbing pollution from fossil fuels such as coal and diesel.
A report in September by the Global Commission on the Economy and Climate, which I co-chaired, found that the health impacts of tiny particles of pollution from fossil fuels are the equivalent of reducing GDP by 5 to 10 per cent in some major countries
The Commission showed that the investments required by national economies to transform energy systems, cities and land, as part of the profound structural change and renewal going on around the world, would, if carried through well, yield at least half the emissions reductions required by 2030 to be on track for the 2 degree threshold target.
These investments would carry with them great benefits from reducing air pollution and traffic congestion, as well as promoting energy efficiency and security.
The commission’s report showed that the investments involved in reducing greenhouse gas emissions would create other powerful returns for national economies by transforming energy systems, urban planning and land use.
The IPCC report makes plain that further delays in tackling climate change would be dangerous, and ‘wait and see’ would be a profoundly irrational policy.
World leaders must show that they have understood the evidence presented by the IPCC, by acting decisively to ensure the world avoids catastrophic climate change.
