At the United Nations (UN) Climate Summit on Tuesday, efforts to slow deforestation got a major boost when dozens of countries, indigenous groups and companies pledged to halve destructive deforestation by 2020, and completely end losses by 2030.

Backers of the New York Declaration on Forests claim their efforts could save between 4.5 billion and 8.8 billion tons of carbon emissions per year by 2030 - the equivalent of taking all the world's cars off the road.

Deforestation is a significant contributor to climate change, as trees release their stored carbon when they are burned during slash-and-burn land clearing of forests. It accounts for around eight percent of the world's carbon emissions. The new non-legally binding agreement could save more than 350 million hectares of forests and croplands - an area greater than the size of India - while also reducing the amount of carbon released into the atmosphere.

"Forests represent one of the largest, most cost-effective climate solutions available today," the declaration says.

"Action to conserve, sustainably manage and restore forests can contribute to economic growth, poverty alleviation, rule of law, food security, climate resilience and biodiversity conservation."

The move, supported by some of the world's largest palm oil companies, will be an important part of limiting global temperature rises to 2 degrees Celsius (3.6 degrees Fahrenheit) - a goal scientists are worried the world will be unable to meet.

There was also a new commitment to slow the clearing of forests for palm oil plantations. The CEOs of three global food companies that are leaders in palm-oil production - Cargill, Golden Agri-Resources and Wilmar - signed a pledge to work together in Indonesia and elsewhere to reform industry practices and to include third-party suppliers. The UN said commitments to zero deforestation involving palm oil now account for about 60 percent of the global total.

There was also a commitment among 26 governors from Peru and Liberia who presented new forest policies and pledged to cut deforestation by 80 percent.

Despite this progress, Kumi Naidoo of Greenpeace International, which has not signed the declaration, still thinks that the Climate Summit pledges are not ambitious enough, and need to implement binding laws to have any significant effect on halting deforestation.

"While we are celebrating announcements on paper today, forests and forest peoples are facing imminent threats that must be averted if we want the declaration to become reality," he said in a statement.