IPCC, the World's Top Authority on Climate Science
The UN's Intergovernmental Panel on Climate Change (IPCC), which compiles comprehensive reviews of climate science, meets this week to vet and validate a report on limiting global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit).
Here's a thumbnail profile of the panel.
The IPCC was set up in 1988 by the UN's World Meteorological Organisation (WMO) and Environment Programme (UNEP).
Its mandate is to give policymakers neutral, science-based updates about global warming -- its impacts, and scenarios for bringing the problem under control.
An intergovernmental body, the IPCC currently counts 195 nations as members.
Based in Geneva, the panel is chaired by South Korea's Hoesung Lee, an expert on the economics of climate change.
Its reports are compiled by thousands of atmospheric scientists, climate modellers, oceanographers, ice specialists, economists and public health experts, mostly drawn from universities and research institutes. They work on a volunteer basis.
The IPCC does not conduct new research but trawls through thousands of published studies and summarises key findings, indicating degrees of likelihood and confidence.
"You can think of it as the biggest peer-review exercise in the world," said Jonathan Lynn, IPCC's head of communications.
Every five or six years the IPCC produces vast overviews -- typically 1,500 pages long -- of published climate science. The first came out in 1990, the most recent in 2014.
The next is due in early 2022, ahead of a crucial reevaluation by governments of their greenhouse gas reduction efforts.
Three separate teams, or "working groups", look at the physical science of global warming; climate change impacts; and options for tackling the problem.
SUMMARY FOR POLICYMAKERS
The IPCC concludes each review with a crucial Summary for Policymakers that undergoes multiple rounds of editing, first by scientists and then by government officials.
The last draft is submitted to an IPCC plenary, which vets it line-by-line before approval by consensus.
Governments can seek amendments to the summary, which are approved if the argument is supported by what is in the underlying report written by the scientists.
Beside the special report on 1.5C, the IPCC has two others in the pipeline, both scheduled for completion by September 2019.
The first examines changes in oceans and Earth's frozen regions, known as the cryosphere; and the other looks at deserts, forests, land use and food security.
FAME AND DAMAGED IMAGE
Defenders of the IPCC say that its exhaustive work, and a summary for policymakers endorsed by the world's governments, give it exceptional clout.
Its Fifth Assessment Report, published in 2014, issued the most emphatic warning on global warming yet, and provided the scientific underpinning for the landmark Paris Agreement, inked outside the French capital in 2015.
The previous report earned the IPCC a share of the 2007 Nobel Peace Prize, alongside former US vice president and climate campaigner Al Gore.
The IPCC's image was later dented by several minor errors uncovered in the report that providing ammunition for skeptics who claim the IPCC is flawed or biased.
Some scientists say the panel is too conservative, leading it to underestimate the climate change threat.
The last published report, for example, did not factor in potential sea level rise -- widely recognised today -- from melting ice sheets in West Antarctica and Greenland.
Before Donald Trump gained the White House, the United States consistently covered two-fifths of the IPCC's annual operating budget of about $5 million (4.3 million euros).
Without that money, the panel has had to go cap in hand to other countries, which -- led by Norway and France -- have covered most of the shortfall.