Cattle in a feedlot that sits on the northwestern edge of Garden City, Kansas. Photo: Keith Myers/Kansas City Star/MCT

"If you really need it to be from animal sources, that's still OK," Eshel said." You can still have bacon and eggs and whatever you want. ######

The journal's study looked closely at beef production in the United States. It considered the effects of cows grazing. It also examined growing food for the cattle and water use.

Eshel said the study should make us change our meat choices. ######

He said it's a common problem for people to use resources "poorly and wastefully."

All Livestock Are Contributors

The other study looked at beef production around the world over the last 50 years. The results showed a huge increase in harmful gases linked to livestock such as cows. This study was published in the journal Climate Change. ###### People in these countries have been eating more beef.

Wealthier countries such as the United States have been releasing fewer gases since 1970.

Beef cattle produced more than half the amount of greenhouse gases. Dairy cattle were responsible for 17 percent. ###### The largest increases came in African countries such as Congo, the Central African Republic and Oman, the study found.

"More and more of the developing world is adopting the bad habits of the developed world," said study co-author Ken Caldeira.

The beef industry does not accept the results of these studies. Producing beef is more complicated than the scientists realize, the industry says. ######]]>