In its Synthesis Report, the Intergovernmental Panel on Climate Change says that to limit global warming over the 21st century to below 2 degrees Celsius relative to pre-industrial levels, “our [carbon] emissions should drop by 40 to 70 percent globally between 2010 and 2050, falling to zero or below by 2100. We have that opportunity, and the choice is in our hands.”
Specifically, regarding decarbonization of the energy supply sector, the report says, “In the majority of low-concentration stabilization scenarios… the share of low-carbon electricity supply (comprising renewable energy, nuclear and CCS [carbon dioxide capture and storage], including BECCS [bioenergy with CCS]) increases from the current share of approximately 30% to more than 80% by 2050 and 90% by 2100, and fossil fuel power generation without CCS is phased out almost entirely by 2100.”
Hydropower is included in IPCC’s definition of renewable energy.
The Synthesis Report forms the capstone of the IPCC Fifth Assessment Report, released in three volumes over the past 13 months. The report distills and integrates the findings of this report, produced by more than 800 scientists. IPCC says this is the most comprehensive assessment of climate change ever undertaken.
The report confirms that climate change is being registered around the world and warming of the climate system is unequivocal. It expresses with greater certainty than in previous assessments the fact that emissions of greenhouse gases and other anthropogenic drivers have been the dominant cause of observed warming since the mid-20th century.
IPCC chair R.K. Pachauri says it is possible to limit climate change but “Addressing climate change will not be possible if individual agents advance their own interests independently; it can only be achieved through cooperative responses, including international cooperation.”
There are multiple mitigation pathways to achieve the substantial emissions reductions over the next few decades necessary to limit the warming to 2 C, the goal set by governments, the report says. “It is technically feasible to transition to a low-carbon economy,” says Youba Sokona, co-chair of IPCC Working Group III. “But what is lacking are appropriate policies and institutions.”
The report finds that mitigation cost estimates vary and economic estimates do not account for the benefits of reduced climate change, nor do they account for the numerous co-benefits associated with human health, livelihoods and development.
IPCC is the world body for assessing the science related to climate change. It was set up in 1988 by the World Meteorological Organization and United Nations Environment Programme, endorsed by the United Nations General Assembly.