PARIS, FRANCE — Thousands of power plants worldwide face sharp reductions in electricity output by mid-century due to more frequent heatwaves and drought driven by global warming, according to a study published on Monday.

鈥淲e need to be concerned as electricity will become more expensive and less reliable in the future due to climate change,鈥 co-author Keywan Riahi of the International Institute for Applied Systems Analysis in Austria told AFP.

If warming continues unchecked, higher temperatures and water shortages could, by 2050, cut capacity in hydroelectric plants by nearly 4%, and in thermoelectric plants — powered by fossil fuels, nuclear power or biomass — by 12%.

Even if the target embraced at the Paris climate summit in December is met — limiting global temperature rise to less than two degrees Celsius (3.6掳 Fahrenheit) compared to pre-industrial levels — power capacity would still drop significantly, according to the research.

Hydro and thermoelectric plants, which together provide 98% of the global electricity supply, both depend on water to cool machinery or generate power.

Improvements in efficiency and switching types of fuel, however, would be one way to avoid future shortages of water and power, the study said.

Especially vulnerable regions include the United States, southern South America, southern Africa, central and southern Europe, and Southeast Asia.

The study analyzed data from nearly four-fifths of the world鈥檚 hydroelectric plants, and more than a quarter of thermoelectric ones.

鈥淢any of the plants that we couldn鈥檛 include in our analysis will be vulnerable to climate change as well, but we simply didn鈥檛 have the information,鈥 Mr. Riahi said by e-mail.

Water consumption for power generation is expected to double within 40 years, according to the study, published in Nature Climate Change.

In many regions, this vastly expanded consumption will clash head on — particularly in rapidly expanding economies — with increased demands from agriculture and domestic use, neither of which are taken into account in this study.

鈥淐limate change will amplify this competition, reduce reliability of the systems, and increase the risk of water and electric shortages,鈥 Mr. Riahi commented.

鈥淗owever, there is the possibility to adapt鈥 in both types of power plants, he added. AFP