LONDON - U.N. negotiators will next month put farming onto the radar of climate regulations for the first time, but governments face aggressive lobbies and gaps in the science proving the extent of agricultural emissions.
Farming is both a likely victim of climate changes including more droughts and floods, and a cause, through the release of greenhouse gases from fertilizers and cattle. The sector also has a wide impact through soil management.
Much public focus is on saving the world's forests to slow climate change, but soils hoard three times more carbon than all the world's plants, underlining how farm management can significantly counter or add to manmade carbon emissions.
Farmers can lock up carbon by tilling the soil less and by improving the fertility of the land, for example adding organic matter including dung and crop waste.
A U.N. climate meeting in Copenhagen in December may launch a research program to test low-carbon incentives, possibly targeting the 2 billion poor living on small farms, for roll-out from 2013 under a new global climate treaty.
In industrialized countries, new rules will limit or at least monitor farm carbon from as early as 2012 in the United States and Europe, and from 2015 in Australia and New Zealand. Double-click here for different approaches.
They're lucky to have got away with it this far, it should be included in a U.S. climate bill and in Copenhagen, said Robert Goodland, formerly of the World Bank and co-author of a report which last month caused a stir by estimating that farm livestock account for 51 percent of all global greenhouse gases.
The estimate included carbon emissions from burning trees to clear land for cattle, and cows' respiration as well as their methane-rich burps, and took account of new research suggesting methane is a stronger greenhouse gas than previously thought.
More conventional estimates put agriculture at about 14 percent of global greenhouse gases, rising to a third including deforestation.
Uncertain accounting is a critical obstacle in harnessing the potential of the agricultural sector and especially soils, which in theory could cut annual global greenhouse gas emissions by as much as 10 percent from present levels by 2030.
One example of the scientific fog is no-till, where farmers plough the soil less and so retain more carbon. But in soggy land that can increase emissions of nitrous oxide -- a far more potent greenhouse gas than carbon dioxide, scientists say.
We know farm management has a very significant influence on how much carbon is in the soil, said Cesar Izaurralde, a soil scientist at the U.S. Pacific Northwest National Laboratory. I think in the next two to three years the research community will have the tools ready.
A new U.N. paper proposed last Friday at climate talks in Barcelona a program of work to add farm research to the climate deal to be agreed in Copenhagen, which could pave the way for support for low-carbon incentives in developing nations.
The World Bank's BioCarbon Fund gives a glimpse of how that may unfold, trialing two projects in Kenya to lock carbon into the soil, and so generate offsets for sale to rich polluters in the developed world.
The projects we're working on are real projects, said Johannes Woelcke, the World Bank's team leader for the Kenya trials which will cut carbon dioxide emissions by an estimated 130,000 tonnes annually, involving 90,000 small-scale farmers.
We're demonstrating that this is working. Of course there needs to be further work on accounting methods.
Like other experts, Woelcke hopes the final text from Copenhagen will refer to agriculture -- unlike the existing Kyoto Protocol -- and support more trials and research.
In the developed world, governments have to decide for themselves how to limit farm emissions. Lobbies are wary of steps to embrace the sector in climate change policies.
New Zealand and Australia have plans to limit farm emissions under cap and trade schemes. The European Union and U.S. plan focus on rewards through carbon offsets or direct payments.
We're not happy with an emissions trading scheme full stop, we remain emphatically opposed, said Don Nicolson, president of Federated Farmers of New Zealand. The American Farm Bureau (AFB) opposes draft U.S. climate bills which would cap carbon emissions from industry, but not from agriculture.
We oppose the bills in congress, said Rick Krause, senior director of congressional relations for the AFB, saying the bills would raise fuel and fertilizer costs.
The public must debate what kind of farming they wanted, for example to choose between housed, low-carbon cows, and roaming, less carbon-limited beasts, said Allan Buckwell, policy director at Britain's Country Land and Business Association.
(Editing by Keiron Henderson)