claim: This growth stimulation occurs because CO2 is one of the two raw materials (the other being water) that are required for photosynthesis.
evidence: The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations that is dedicated to providing the world with objective, scientific information relevant to understanding the scientific basis of the risk of human-induced climate change, its natural, political, and economic impacts and risks, and possible response options.