Agriculture of all types produces greenhouse gases that warm the planet, but meat production is especially harmful – and beef is the most environmentally damaging form of meat.
Some methods of cattle production demand a lot of land, contributing to destruction of forests; the trees are typically burned, releasing carbon dioxide into the atmosphere. Other methods require huge amounts of water and fertilizer to grow food for the cows.
The cows themselves produce emissions of methane, a potent greenhouse gas that causes short-term warming. Meat consumption is rising worldwide as the population grows, and as economic development makes people richer and better able to afford meat.
This is worrisome: Studies have found that if the whole world were to start eating beef at the rate Americans eat it, produced by the methods typically used in the US that alone might erase any chance of staying below an internationally agreed-upon limit on global warming.
Pork production creates somewhat lower emissions than beef production, and chicken is lower still. So reducing your meat consumption, or switching from beef and pork to chicken in your diet, are both moves in the right direction. Of course, as with any kind of behavioral change meant to benefit the climate, this will only make a difference if lots of other people do it, too, reducing the overall demand for meat products.