Tell her to turn off the blow-dryer, and stop taking Jet planes as transportation. That, and have her trade all of her cars in for Toyota Prius so she can ride around in comfort in those.
This declaration is so laughable it's not funny. Considering what a prima dona (sp?) Streisand was when she was touring a few years back, I'm sure the amount of wasted electricity just to get the lighting right, or the sound right, or the yards of fabric to hide parts of stages and backdrops and everything else, and what those materials had to have been made of, Streisand is herself probably very responsible for much of the warming that has happened in the last several years.