Plants need CO2, but more isn't better. There is only so much they can process. They cannot absorb all the excess CO2 in the atmosphere. According to the North American Carbon Program (NACP) , since the industrial revolution, CO2 in the atmosphere has increased 30%. We do know nature (volcanoes) will do its course to naturally change the environment and release CO2 into the atmosphere. But this only accounts for 25% of the increased CO2 in the atmosphere. 75% is from humans - mostly fossil fuels. So the only way to reduce it is by changing human activity. So the facts don't support your contention that all tree hugging liberals conservation efforts have been wasted due to volcanoes.