(about 250 years ago to 150 years ago, depending on the source). What caused the Little Ice Age to end? For that matter, what caused it to begin? Until we know the answers to questions like that, there's no way to know the impact, if any, of human activities on the climate.

There are a host of things beyond human control that affect the climate, including solar variability, volcanic activity, orbital perturbations, etc. The Earth went through many global warming and cooling cycles long before there were any humans. Until we have a better understanding on what causes these climate variations, all the models and pronouncements are little more than guesses. Sorry, but science done properly takes time and shouldn't be influenced by political agendas. The first guiding principle should be the same as for medicine - first do no harm. Doing the wrong thing can often be worse than doing nothing.