The IEA's annual report notes that some of the anticipated changes could occur gradually, such as rising sea levels and water scarcity in some regions. But using data from several other international reports, the IEA notes that if carbon dioxide emissions continue to climb on their present trajectory and the temperature rises accordingly "other impacts of climate change are likely to be more sudden and destructive," including the increased prevalence and strength of extreme weather events, from cyclones to floods to heat waves.

In order to help reduce these effects and keep Earth's rising temperature to the international goal of a 2 C (3.6 F) increase by the end of this century, the IEA lays out four possible strategies, including halving the amount of methane emissions released by oil and gas drilling by 2020, halting the building of almost all new coal power plants, drastically reducing the amount of government tax credits and subsidies for fossil fuel development, and increasing energy efficiency standards for buildings and device. Still, the IEA notes hitting the 2 C goal will be "extremely challenging."

The report also pointed to a 1.4 percent increase in total global carbon dioxide emissions last year, an improvement over the 3.2 percent rise recorded by the agency in 2011. The United States actually continued several years of emissions reduction, and is down another 200 million tons thanks to a major shift from using coal to cleaner-burning natural gas in power plants. China, the world's leading emitter of carbon dioxide, reported slower growth in carbon emissions than last year, too. But despite some encouraging signs, the IEA says that more needs to be done to keep carbon emissions from rising above the international goal of 2 Celsius by 2020.