"Climate change has an impact on prosperity. If climate change is not mitigated or understood early enough, the ability of a country to generate a livelihood may be impacted by increased disease, new pest patterns, diseases that plants weren't accustomed to in northern regions," Spellman said.

"It's a profound re-engineering of the entire agricultural system," he said.

Most scientists have linked the buildup of greenhouse gases like carbon dioxide to global warming. The Intergovernmental Panel on Climate Change (IPCC), a UN body, said last month that rising world temperatures were already affecting plants and animals, water supplies, growing seasons, and fisheries.

Use of soils, forests and the ocean are key to climate change since they act to break down carbon dioxide from the atmosphere. Industrial agriculture also puts large amounts of greenhouse gases like methane into the atmosphere.

Experts noted myriad efforts now going on in agriculture to adapt to and mitigate climate change from waste use and tillage to biofuels, carbon markets and drought-resistant crops.

"Farm practices like no-till capture CO2. Livestock producers are converting animal waste to fuel. Carbon exchanges like the Chicago Climate Exchange are paying producers for agricultural offsets," said Carole Brookins, managing partner of Public Capital Advisors and a former World Bank official.

But as the IPCC report said: "There is no universally applicable list of mitigation practices; practices need to be evaluated for individual agriculture systems and settings."

EVERYONE ON THE SAME PAGE?

One theme that emerged at this week's agriculture leaders' conference was a need for more coordination and analysis of the effects on agriculture and food production from the world's scramble to cut fossil-fuel use, the major source of CO2 and of other greenhouse gases.

The European Union wants to derive 20 percent of its energy from renewable sources by 2020. Green fuels are part of the mix but energy would also come from other renewable sources such as solar, wind, hydropower and conservation technology.

"Energy and climate change are linked together and therefore it has been very high on the agenda of the European Commission since last year," said Mariann Fischer Boel, EU commissioner for agricultural and rural development.

Europe's goal is to cut greenhouse gas emissions by 20 percent by 2020 compared with 1990, she said.

"If we can be joined by other big players like the United States, then we would go up to a 30 percent reduction of greenhouse gas emissions," Fischer Boel told the conference.

The current massive push toward biofuels made from corn, soybeans, sugar and other crops also raised a red flag to some who said food supplies and prices for both rich and poor could be affected as energy demand seized agriculture.

"We can't allow this to be thought of strictly as an economic or technological problem. We really have to think hard ... of what kind of role we want our agriculture to play in the future," said Paul Thompson, W.K. Kellogg chair in agriculture, food and community ethics at Michigan State University.

Regional climate change effects on land and water also mean conflicts will be complex and have to be negotiated, resolved and debated within a regional and global context.