WASHINGTON – Cargill Inc. joined the world's largest makers of palm oil in a pledge to prevent deforestation and vowed to work with Indonesia, the biggest global producer, to implement policies that will protect forests.

Minnetonka-based Cargill announced its action Tuesday at the United Nations summit on climate change with more than 20 producers that account for about half of all palm-oil consumption. Consumers have been pressing the makers of products such as candy and cookies using palm oil to stop clearing forests to plant new palms.

"The last few months have seen a welcome race to the top," Paul Polman, chief executive of Unilever NV, said in a statement announcing the effort. "Consumers have sent companies a clear signal that they do not want their purchasing habits to drive deforestation and companies are responding."

Unilever has pledged forestry protection as part of its sourcing of palm oil, the world's most-consumed vegetable oil, used by Kellogg Co. to make Pop-Tarts, Mondelez International Inc. to produce Oreo cookies and Mars Inc. to make Twix candy bars.

Deforestation contributes to climate change when trees are chopped down to clear forests then are burned, releasing the carbon dioxide that has been absorbed through the leaves.

The effort seeks to cut by half the loss of forests by 2020, and eliminate all deforestation by 2030, a move that environmental groups said could eliminate up to 8.8 billion tons of carbon dioxide each year. The agreement also calls for restoring more than 850 million acres of forests and croplands.

As part of Tuesday's forestry pledges, Norway, the U.K., Germany and others pledged $1 billion to persuade developing countries such as Liberia and Peru to preserve their forests.