FACTBOX: U.N. climate panel agrees policy guide

(Reuters) - The U.N. climate panel agreed a guide for policymakers on Friday about the rising risks of climate change and a need for quick action to axe greenhouse gas emissions.

The 130-nation group, meeting in Valencia, Spain, will formally present the findings on Saturday:

WHAT IS THE PANEL?

* The Intergovernmental Panel on Climate Change (IPCC) was set up in 1988 by the U.N. Environment Program and the World Meteorological Organization to give governments scientific advice about climate change.

* Run from Geneva, it draws on work by about 2,500 climate scientists from more than 130 nations and has issued three reports so far this year, totaling more than 3,000 pages. The previous set of reports was in 2001.

* The IPCC was awarded the 2007 Nobel Peace Prize with former U.S. Vice President Al Gore.

* WHAT IS THE SUMMARY?

The IPCC condenses the main findings of three reports earlier this year:

1) In February, the IPCC squarely blamed mankind for global warming. It said it was "very likely" or more than 90 percent probable that human activities led by burning fossil fuels had caused most of the warming in the past half century.

-- It said warming was "unequivocal" and projected a "best estimate" that temperatures would rise by 1.8 to 4.0 degrees Celsius (3.2-7.2 degrees Fahrenheit) this century.

2) In April, the IPCC outlined the likely impacts of warming and said rising temperatures could lead to more hunger, water shortages and ever more extinctions of animals and plants.

-- It said crop yields could drop by 50 percent by 2020 in some countries and projected a steady shrinking of Arctic sea ice in summers. By the 2080s, millions of people will be threatened by floods because of rising sea levels, especially around river deltas in Asia and Africa and on small islands.

3) In May, in a third report on confronting climate change, the IPCC said costs of action could be moderate, or less than 0.12 percent of global gross domestic product a year, but that time was running out to avert the worst effects. The toughest scenario would require governments to ensure global greenhouse gas emissions start falling by 2015.

* PAST REPORTS:

-- The IPCC's first report in 1990 outlined risks of warming and played a role in prompting governments to agree a 1992 U.N. climate convention.

-- In 1995, the IPCC concluded that "the balance of evidence suggests a discernible human influence on global climate", the first recognition that it was more than 50 percent likely that people were stoking warming. The report paved the way to the Kyoto Protocol, now the main U.N. plan for curbing warming.

-- A 2001 IPCC study said there was "new and stronger evidence" linking human activities to global warming and that it was "likely", or 66 percent probable, that humans were the main cause of warming in the past half century.

-- For Reuters' latest environment blogs click on: blogs.reuters.com/environment/

(Writing by Alister Doyle in Oslo and David Cutler, London Editorial Reference Unit; Editing by Caroline Drees)