While we are not exactly sure how fast or how much the Earth's average temperature will rise, we know that: If people keep adding greenhouse gases into the atmosphere at the current rate, the average temperature around the world could increase by about 4 to 12°F by the year 2100. If we make big changes, like using more renewable resources instead of fossil fuels, the increase will be less – about 2 to 5°F. —“A Student’s Guide to Global Climate Change,” US Environmental Protection Agency What solution does the author offer for reducing greenhouse gases? Which phrase helps readers understand that this is a solution?