My wife likes to gamble. She's no high roller or anything, but give her a hundred dollars, a spare weekend and a room full of slot machines and she's happy.
Not me, though. Somewhere along the way, I guess I took one too many math classes and betting against the house just isn't much fun anymore.
But I understand why she likes it. It's the ups and downs of gambling that are fun. You lose, lose, lose and then every once in a while you win a great big jackpot. Maybe you even win enough to make up for the last 30 or 40 bets you lost. But like any game in the casino, the odds are stacked against you. If you play long enough, you will eventually lose.
Global warming and climate change work in much the same way. Wait long enough and odds are, the Earth will be warmer. But will tomorrow be warmer than today? Who knows! There are plenty of things about the atmosphere and ocean that can't be predicted. Over a period of days or weeks, we call these unpredictable changes "the weather."
No one can predict the weather more than a few days in advance, any more than they can predict which slot the roulette ball will land in before the croupier spins it. Weather, like roulette, is essentially random.
But a little randomness doesn't stop casino owners from taking your bet at the roulette table. They know the odds, and they know if enough bets are laid they will eventually come out ahead. Climate scientists know that, too.
Random events happen in the atmosphere and oceans all the time. Not just the weather, but things like El Nino, La Nina and huge volcanic eruptions can make the planet warm up or cool down for years at time. There could even be a few others that we haven't discovered yet.
Still, for all its short-term ups and downs Earth's average temperature has risen dramatically over the last one hundred years. That's no accident. Like the house edge at the roulette table, human-made greenhouse gasses have tilted the odds in favor of a warming planet.
Sometimes it's easy to forget that fact when new science results come out. Like the recreational gambler, we often find it more fun to focus on the ups and downs: a short-term cooling period, a warm year during a big El Nino.
But for climate change and casino owners, it's important to remember the big picture. The roulette player might win three or four bets in a row, but that doesn't change the odds. Eventually the casino will win. Likewise, as long as humans continue to add carbon dioxide to the atmosphere, the planet will continue to warm.
So whenever people ask me about the latest warming or cooling in the climate record, I'm always reminded of my wife and her slot machines. By the end of the weekend her hundred dollars is almost always gone, but the thrill of the ups and downs kept her entertained for the entire time. "Did you win?" people ask. She always flashes her sly smile and says, "Sometimes!"