If meat offends your brother, do not eat it. Because of deforestation to provide grazing land, meat or the raising of cattle is the most destructive to the environment. Second would be dairy products, then vegetables. The only food group which helps in reforestation of the planet is fruit. Every time you eat an apple or a walnut or an avocado, you are voting for orchards.
Slaughterhouses dump billions of gallons of raw sewage and urine into our waterways.
The Sahara was originally caused by the destruction of trees and their replacement with grazing animals. A food yield of 100 to l000 lbs per acre or a food yield of 400,000 lbs. Fruit has time released natural sugar molecules. Recent 1997 flooding in both Arkansas and Ohio is directly related to massive tree cutting both for the money the wood would bring in and to clear land for intensive poultry and pig farming. Much of the hardwood forest of Arkansas was cleared and sold to a multinational lumber corporation.