There are actually four separate questions to global warming: 1. Are world temperatures rising? 2. Are humans causing it? 3. Can we do anything to stop it? 4. Should we do anything to stop it?

First, you have to get past #1, which you can, because we have indeed measured a gradual increase in temperature over the past 100 years or so. This is not a steady rise, year after year. It is a long-term trend, like the stock market, 2 steps forward, 1 step back.