The earth’s climate is always changing, but those changes have nothing to do with molecular level changes in CO2 produced by human activity. Why did the Sahara dry up 6,000 years ago when human activity at the time added little to the global levels of CO2? The sun, the oceans, variations in the tilt of the earth’s axis and volcanic eruptions have far more to do with alterations in climate than any amount of CO2. The big lie is that human caused increases in CO2 resulting in global warming is the only significant cause of climate change.