The United Nations on Monday launched the Decade for Deserts and the Fight against Desertification, a strong call for action to combat continued land degradation, which threatens the livelihoods of more than 1 billion people.

"Continued land degradation -- whether from climate change, unsustainable agriculture or poor management of water resources -- is a threat to food security, leading to starvation among the most acutely affected communities and robbing the world of productive land," UN Secretary-General Ban Ki-moon said Monday in a message to the launch of the Decade for Deserts and the Fight against Desertification in Fortaleza, Brazil.

Degradation of dryland makes up over 40 percent of the world's land surface, which impacts 2.1 billion people -- one in every three people globally, mostly in developing countries.

One third of crops cultivated originate in drylands, which then supports half of all livestock.

"Land degradation also poses growing social costs," Ban said. " Increased competition for depleted dryland resources can generate localized conflict and broader tensions."

Forced migration of millions of people creates the risk of " social breakdown in the traditional lands," leaving behind instability in the overcrowding urban area "to which they go in search of jobs, shelter and services," he said.

"Let us pledge to intensify our efforts to nurture the land we need for achieving the Millennium Development Goals and guaranteeing human well-being," Ban said.

In 2007, the UN General Assembly designated 2010-2020 as the decade to intensity public awareness of the threat posed by desertification, land degradation and drought to sustainable development.

"These are formidable challenges," Ban noted. "But they are not intractable."

Efforts by local communities can lead to the preservation or recovery of millions of hectares of land, alleviate vulnerability to climate change and reduce hunger and poverty, Ban said.

The UN Convention to Combat Desertification (UNCCD), the UN Environment Program (UNEP), the UN Development Program (UNDP), the UN International Fund for Agricultural Development (IFAD) and the UN Department of Public Information (DPI) -- have been mandated by the General Assembly to undertake initiatives related to the decade.