* Report most comprehensive yet on land and climate change
* "Unprecedented rates" of land and freshwater use-IPCC
* Climate change will exacerbate food security risks(Adds comments from press conference, more detail)
By Nina Chestney and Stephanie Nebehay
LONDON/GENEVA, Aug 8 (Reuters) - Global meat consumptionmust fall to curb global warming, reduce growing strains on landand water and improve food security, health and biodiversity, aUnited Nations report on the effects of climate changeconcluded.
Although the report stopped short of explicitly advocatinggoing meat free, it called for big changes to farming and eatinghabits to limit the impact of population growth and changingconsumption patterns on stretched land and water resources.
Plant-based foods and sustainable animal-sourced food couldfree up several million square kilometres of land by 2050 andcut 0.7-8.0 gigatonnes a year of carbon dioxide equivalent, theU.N.'s Intergovernmental Panel on Climate Change (IPCC) said.
"There are certain kinds of diets that have a lower carbonfootprint and put less pressure on land," Jim Skea, professor atLondon's Imperial College, said on Thursday.
The IPCC met this week in Geneva, Switzerland to finaliseits report which should help to guide governments meeting thisyear in Chile on ways to implement the 2015 Paris Agreement.
"The IPCC does not recommend people's diets ... Dietarychoices are very often shaped or influenced by local productionpractices and cultural habits," Skea, who is one of the report'sauthors, told reporters in Geneva.
Land can be both a source and sink of carbon dioxide, themain greenhouse gas blamed for global warming, and better landmanagement can help to tackle climate change, the IPCC said.
But it is not the only solution and cutting emissions fromall sectors is essential to quickly curtail global warming.
"The window for making these changes is closing fast. Ifthere is further delay in reducing emissions, we will miss theopportunity to successfully manage the climate change transitionin the land sector," it said.
Since the pre-industrial era, land surface air temperaturehas risen by 1.53 degrees Celsius, twice as much as the globalaverage temperature (0.87C), causing more heatwaves, droughtsand heavy rain, as well as land degradation and desertification.
Human use directly affects more than 70% of the global,ice-free land surface and agriculture accounts for 70% offreshwater use, the IPCC added in the report.
Agriculture, forestry and other land use activitiesaccounted for 23% of total net man-made greenhouse gas emissionsduring 2007-2016. When pre- and post-production activity in thefood system are included, that rises to up to 37%.
Last year the IPCC's first special report warned thatkeeping the Earth's temperature rise to 1.5 degrees Celsius (2.7degrees Fahrenheit), rather than the 2C target agreed under theParis accord, required rapid change across society.
The IPCC warned of more disruption to global food chains asextreme weather becomes more frequent due to climate change andsaid environmental costs should be factored into food.
It projects a median increase of 7.6% in cereal prices by2050, meaning higher food prices and an increased risk ofhunger.
While an estimated 821 million people are undernourished,changing consumption habits have already contributed to about 2billion adults being overweight or obese.
Per capita supply of vegetable oils and meat has more thandoubled based on data since 1961 but 25-30% of total foodproduced is still lost or wasted.
Yields of crops such as maize and wheat have declined insome regions, while those of maize, wheat and sugar beets haveincreased in others in recent decades.
While forests can soak up heat-trapping gases from theatmosphere, desertification and deforestation can amplifywarming due to the loss of vegetation cover and soil erosion.
Measures to cut emissions, such as the production ofbiofuels, biochar - made from biomass - as well as plantingtrees, will also increase demand for land conversion.
Reducing deforestation and forest degradation could resultin a reduction of 0.4-5.8 gigatonnes of CO2 equivalent, thereport said.
The Amazon, about 60% of which lies in Brazil, is sometimescalled the "lungs of the world" due to the amount of CO2 it canabsorb but it was not directly mentioned in the IPCC's summaryfor policymakers.
Brazil's President Jair Bolsonaro has supported opening upprotected areas of the world's largest tropical rainforest tofacilitate agriculture and mining since taking office inJanuary.
The report text is prepared by over 100 scientists but hasto be approved by governments. In those discussions, Brazil andIndia were very active to protect their national agro-industrialinterests, a source familiar with the talks said.
(Reporting by Nina Chestney in London and Stephanie Nebehay inGeneva; Additional reporting by Megan Rowling; Editing by JaneMerriman and Alexander Smith)