Keeping global warming to 1.5C

Unless society makes "unprecedented" changes to how it consumes energy, travels and builds to meet a lower limit for global warming, the world risks increases in heat waves, flooding and drought in some regions as well as loss of species, climate scientists said in a flagship U.N. report.

The Intergovernmental Panel on Climate Change, at the behest of governments, published the report October 8 on how to keep global warming to the lowest limit in the Paris climate pact: 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial times.

The report lays out "pathways" to meet that goal, as well as expected impacts at 1.5C of warming compared with 2C, the higher limit in the 2015 Paris Agreement.

Scientists, campaigners and development agencies view the report as ramping up pressure on governments and businesses to speed climate action to bring planet-warming emissions down to "net zero" by 2050 using a range of solutions, from adopting renewable energy to protecting forests.

But there is fierce debate over whether the 1.5C target can be met and what the best policies are to achieve it, given that the planet has already heated up by about 1C and current climate action plans would allow global warming to reach about 3C.