Around the globe, human-caused climate change has affected farming, water supplies, and ecosystems on land and in water, says a new United Nations report.
Compiled by the Intergovernmental Panel on Climate Change (IPCC), the report says melting of permafrost and many glaciers as well as a shift in many species’ geographic ranges is a result of global warming. Climate change thus far has caused more harm than good to crops, it concludes. And the current rate of ocean acidification, caused by uptake of atmospheric carbon dioxide, is unprecedented in the past 65 million years.
The report, released last week, examines the impacts of global warming and societies’ vulnerability to those effects. The document also assesses how societies are adapting to climate change.
“With high levels of warming that result from continued growth in greenhouse gas emissions, risks will be challenging to manage,” says Christopher Field, who cochaired the IPCC working group that prepared the report. “Even serious, sustained investments in adaptation will face limits,” says Field, founding director of the Carnegie Institution’s Department of Global Ecology at Stanford University.
Sen. Barbara Boxer (D-Calif.), who chairs the Senate Environment & Public Works Committee, says the IPCC report “adds a tremendous sense of urgency for Congress to wake up and do everything in its power to reduce dangerous carbon pollution.”
The report also touches briefly on geoengineering—which would involve large-scale efforts to block incoming solar radiation or to strip CO2 from the atmosphere—but does not endorse it. Costs, effectiveness, and side effects of geoengineering techniques are poorly understood, the document says.
The report is the second in a series of three that IPCC is releasing as part of its fifth in-depth assessment of climate change since 1990. The first of these, examining the science of climate change, was released in September 2013. The third IPCC report, on mitigating climate change, is due in mid-April.
The reports are expected to influence international negotiations on a new climate-change treaty, which are due to conclude at the end of 2015.