We know that carbon dioxide is a greenhouse gas (that is, it traps radiant heat from sunlight). We also know that it is a relatively weak greenhouse gas (methane, for instance, is much stronger), one that is typically consumed in a feedback fashion by a increased-co2-level-caused global proliferation of land and ocean plant life, and we know both that the earth has been much warmer than it is now, and that carbon dioxide and methane levels have been much higher than they are now - just not necessarily at the same times. And therein lies the rub.

While there is no doubt that increased levels of greenhouse gases can contribute to global warming, the mostly-ignored-by-agenda-driven people evidence is that it is primarily a phenomenon born of cyclically variable solar radiation levels, and totally beyond our control. They are ignoring this evidence, because it leaves them much less to do - many fewer products to design and produce and many fewer contracts and grants to win.