The UN’s Intergovernmental Panel on Climate Change (IPCC) outlined options for tackling climate change in a report published last week.
It warns that greenhouse gas emissions will need to peak and begin to fall within the next 15 years. Emissions should more than halve by 2050 if the world is to have any hope of keeping atmospheric concentrations of greenhouse gases between 445 and 535ppm of their carbon dioxide equivalent.
Concentrations would need to be kept below 450ppm to keep temperature rises below 2°C, while 490ppm would offer a reasonable chance of keeping temperature rises below 2.8°C. Current concentrations are 425ppm.
The European Commission has said that any increase above 2°C represents “dangerous” climate change.
Keeping concentrations between 445-535ppm would cut less than 0.12% off annual GDP growth rates. By 2030 GDP would be reduced by less than 3% and by 2050 by less than 5.5%.
Delaying action would make it more difficult – and expensive – to stabilise emissions at this level.
The IPCC is upbeat about the scope for cutting emissions, saying much of the technology already exists. But carbon taxation or a robust carbon price of US$20-80 by 2030 is needed to make it economically viable.
The panel sees major roles for renewable energy, nuclear power and carbon capture and storage to decarbonise energy supplies, along with measures to improve energy efficiency.
Biofuels, more fuel efficient vehicles and shifts away from motor vehicles will be needed in the transport sector.
Buildings offer the biggest and most cost-effective opportunities for delivering emissions reductions, with further potential for cuts through land use change and reforestation.
The IPCC also calls for a behaviour change. “Changes in lifestyle and consumption patterns that emphasise resource conservation can contribute to developing a low carbon economy that is both equitable and sustainable,” it says.