The United Nations reports global warming is reducing rainfall and increasing temperatures in most and the world's deserts. A 2006 report suggests the changes are hurting many who farm on desert fringes.

In West Africa, the effects are acute and making food scarce. Those living in farming regions along the Sahel desert have found their arable land shrinking as desert sands encroach. Kari Barber has this report from the Senegal-Mauritania border town of Podor about what desertification means to food production.

No longer a place where grains grow and cattle graze

Where Senegal and Mauritania meet has long been a place where grains grew and cattle grazed. But now, the people who live here say food is becoming harder and harder to come by. The reason is the advancing desert.

Oumar Samba Kane is one of the leaders of his village.  He delivers a bag of grains from a neighboring village to add to his village's nearly empty pantry.

"In years in the past, we had enough food in here to last a year and the surplus we would sell to make money,” Kane said. “Now we do not even have enough for ourselves."

Rivers once used for fishing and watering cattle are drying up. Patches of green land are few and far between.

Cows are a staple food in the area, but now herders must drive their cattle for days to find land they can graze. Crops have also suffered.

And for the most part it is only older farmers, like Moussa Aliou Sow, who stay behind to try to till this soil. "I am 67 years old,” Sow said. “All I know is agriculture, there is nothing else I can do."

He says his hands are tired of working land, which is producing less and less. There used to be rice in these fields just a few years ago.

Scientists blame not only global warming, but also farming practices such as clearing trees, over planting crops and diverting of waterways for irrigation for the desert's advance.

But residents say with a food crisis in the region, halting farming is not an option.