Based on the above graph, the concentration of Carbon Dioxide in our atmosphere began to increase exponentially around 1860. Today, CO2 is at the highest concentration is has ever been. What do scientists attribute this exponential increase around the 1860s to? (1 point) Responses Increased agriculture and farm animal reproduction Increased agriculture and farm animal reproduction Deforestation by humans Deforestation by humans Glaciers melting and causing ocean acidification Glaciers melting and causing ocean acidification Combustion of fossil fuels by humans