CO2 is a greenhouse gas (read 1.1 The Greenhouse Effect):
https://books.google.com/books?hl=en&lr=&id=ZfoUIfhX3YIC&oi=fnd&pg=PR18&dq=CO2+a+greenhouse+gas&ots=ap5BxikUXY&sig=_2YD01LRu5uiqFz5_qNEA7gevIs#v=onepage&q=CO2%20a%20greenhouse%20gas&f=false
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Man is responsible for a change in atmospheric gasses:
http://www.popline.org/node/378050
"Man's actions are responsible for the rapid atmospheric changes: combustion of fossil fuels, burning of vegetation (biomass), deforestation, and industrial and agricultural practices."
1957 article explaining CO2 as a greenhouse gas:
http://www.tandfonline.com/doi/abs/10.3402/tellusa.v9i1.9075#aHR0cDovL3d3dy50YW5kZm9ubGluZS5jb20vZG9pL3BkZi8xMC4zNDAyL3RlbGx1c2EudjlpMS45MDc1P25lZWRBY2Nlc3M9dHJ1ZUBAQDA=
Human influence on CO2 emissions:
http://www.sciencedirect.com/science/article/pii/S0301421507003126
"Fossil fuel combustion is the single largest human influence on climate, accounting for 80% of anthropogenic greenhouse gas emissions...CO2 emissions of recent years have grown at the highest rates ever recorded, an observed trend incompatible with stabilizing atmospheric concentrations of greenhouse gases and avoiding long-term climate change."