Air Quote by Greg Benson

“at 378 parts per million, current CO2 levels are unprecedented in recent geological history. (The previous high, of 299 parts per million, was reached…

— Elizabeth Kolbert

“Since about 1850, twice as much atmospheric carbon dioxide has derived from farming practices as from the burning of fossil fuels (the roles crossed…

— Judith D. Schwartz

“CO2 had increased due to human activities, CO2 will continue to increase unless changes are made, and these increases will affect weather, agriculture, and…

— Naomi Oreskes

There is no doubt there is more carbon dioxide in the atmosphere, caused by the burning of fossil fuels. It should have an effect…

— John Christy

About fifty million years ago...geological evidence indicates CO2 levels were several thousand ppm, much higher than now. And life flourished abundantly.

— William Happer

Anything greater than 350 of parts of carbon dioxide per million is more than the planet can safely deal with. It is what's overwhelming…

— Donald Trump

By geo-historical standards, today's atmospheric CO2 levels are remarkably - indeed dangerously - low. We need CO2 in the air to support plant growth…

— Roger Helmer

“It’s] pretty clear that times of high carbon dioxide—and especially times when carbon dioxide levels rapidly rose—coincided with the mass extinctions,” writes University of…

— Peter Brannen

CO2 is the exhaling breath of our civilization, literally... Changing that pattern requires a scope, a scale, a speed of change that is beyond…

— Al Gore

When I was a boy in the 1930s, the carbon dioxide level was still below 300 parts per million. This year, it reached 382,…

— David Attenborough

The warming we've experienced in the late 20th century could just as easily be explained by small decreases in cloud cover - natural changes…

— Willie Soon

The scientists who do climate research understand that much of the ever increasing concentration of CO2 in the atmosphere since 1850 must be attributed…

— John Olver