According to the fourth and final volume of the Intergovernmental Panel on Climate Change’s giant climate assessment climate change is happening, it’s almost entirely man’s fault and limiting its impacts may require reducing greenhouse gas emissions to zero this century, for the world to have a decent chance of keeping the temperature rise below a level that many consider dangerous.
The 40-page synthesis, summing up 5,000 pages of work by 800 scientists already published since September 2013, said global warming was now causing more heat extremes, downpours, acidifying the oceans and pushing up sea levels.
The report warns that failure to reduce emissions could lock the world on a trajectory with “irreversible” impacts on people and the environment. Some impacts already being observed included rising sea levels, a warmer and more acidic ocean, melting glaciers and Arctic sea ice and more frequent and intense heat waves.
Amid its grim projections, the report said the tools are there to set the world on a low-emissions path and break the addiction to burning oil, coal and gas which pollute the atmosphere with heat-trapping carbon-dioxide, the chief greenhouse gas.
To cut emissions, the report points to options including energy efficiency, renewable energies from wind to solar power, nuclear energy or coal-fired power plants where carbon dioxide is stripped from the exhaust fumes and buried underground.
But carbon capture and storage (CCS) is expensive and little tested. In October 2014, Canada’s Saskatchewan Power opened the world’s first big CCS unit at a coal-fired power plant after a $1.21 billion retrofit.
The IPCC was set up in 1988 to assess global warming and its impacts. The latest report is a mega-review of 30,000 climate change studies that establishes with 95% certainty that most of the warming seen since the 1950s is man-made.
The reports must be approved both by scientists and governments, which means political issues from UN climate negotiations, which are nearing a 2015 deadline for a global agreement.
The report is meant as a scientific road-map for the UN climate negotiations at Peru. That’s the last major conference before a summit in Paris in 2015, where a global agreement on climate action is to be adopted.
The biggest hurdle is deciding who should do what. Rich countries are calling on China and other major developing countries to set ambitious targets; developing countries saying the rich have a historical responsibility to lead the fight against warming and to help poorer nations cope with its impacts.