evidence: CLAIM "Natural variation explains a substantial part of global warming observed since 1850;" no statistical evidence that global warming is intensifying natural disasters, or making them more frequent. [...] Human additions of CO2 are in the margin of error of current measurements and the gradual increase in CO2 is mainly from oceans degassing as the planet slowly emerges from the last ice age. [...] CO2 can increase plant growth in greenhouses while also negatively affecting ecosystems and human societies