Business, government or technology forecasts usually look five or 10 years out, 50 years at most. Among climate scientists, there is some talk of century's end. In reality, carbon dioxide dumped into the atmosphere today will affect Earth hundreds of thousands of years hence.
How will greenhouse gases change the far future? No one can say for sure exactly how Earth will respond, but climate scientists—using mathematical models built from knowledge of past climate systems, as well as the complex web of processes that impact climate and the laws of physics and chemistry—can make predictions about what Earth will look like.