The problem with the climate change issue is like asking a coworker if they smell A LOT of smoke.... like the building is on fire smoke.

Climate change has occurred naturally: ice ages and rain forests impinging on North America either of which will cause huge changes to food supply. We KNOW these events will happen again, and they may be aggravated by human activity. We need to act on the assumption IT WILL HAPPEN and develop plans to grow wet and drought resistant plants. At the same time, we do need to determine which human activities cause the most change (in North America forests converted to pasture or grain farms are high on the list and something we need to feed the peopl) and decide how to modify them.

Something is happening. What is the extent? Unknown. But to argue that we may be at the threshold of radical climate change is like arguing who drop the match that set the home we stand in ablaze.