"Some say, 'Climate is always changing due to natural cycles. So it can't be us doing it.' That's like saying 'People die from natural causes. So there can't be murder!' Any good crime investigator must develop expertise on natural causes of death, so he can distinguish it from foul play. Same with climate scientists." — Dr. Richard Alley
Saying "climate change happened naturally in the past, and therefore human's can't cause it" is like saying "forest fires occurred naturally in the past. So there can't be arson."
Variation: Arson and camper carelessness can't cause fires, because forest fires often occurred naturally before people even existed!
Think of CO2 in the atmosphere as water in a bathtub. If you partly open the drain and run the tap at the same rate, the water level stays level. If you open the tap a bit more, the water level rises until it overflows.As long as we keeping pouring CO2 into the air faster than nature drains it out, the CO2 level rises and the planet warms. Even a small imbalance, over time, makes a big difference.
"What’s more socialist than American taxpayers subsidizing the fossil industry while they fleece our wallets? Perhaps Exxon should be renamed The People’s Oil Company of America." — Richard Whiteford, Environmental Communications Consultant in Downingtown, Pa.
"the climate changed before so we aren't changing it" is like saying "beavers felled trees before mankind, so lumberjacks cannot exist." — Sebastian Sassi
"A wait and see policy may mean waiting until it is too late." — 1979 National Academy of Sciences report, Carbon Dioxide and Climate: A Scientific Assessment.
"Global warming will very probably unleash unstoppable planetary forces. And they will not be gradual. The history of our planet’s climate shows that it does not do gradual change. Under pressure, whether from sunspots or orbital wobbles or the depredations of humans, it lurches – virtually overnight." — Fred Pearce
“I’m not a doctor, but I know not to drink arsenic.” – climate scientist Dr. Michael Mann responding to the “I am not a scientist” line used by top Republican leaders.
“I’m not a scientist either but I can use my brains and I can talk to one.” – former Florida Governor Charlie Crist in July 2014 responding to Florida Gov. Rick Scott's line, “I’m not a scientist.”
"Anyone who hears this: your job for the rest of your life is to make the impossible possible."—Dave Roberts (Grist).
"You don't have to believe in climate change to solve it. Everything we do to raise energy efficiency, will make money, improve security & health, and stabilize climate." - physicist Amory Lovins, chairman of the Rocky Mountain Institute.
"What I’m trying to do is convince people that acknowledging climate change doesn’t make you liberal. It makes you literate." – meteorologist Paul Douglas.