In the world of weather, 1 degree Fahrenheit doesn't mean a lot. When cavorting at the beach, you won't much notice the difference between 80 degrees and 81. When shoveling snow, 26 degrees feels like 27.
But with climate, 1 degree Fahrenheit is a very big deal. It's the margin by which 2012 was the hottest year on record, going back to 1895, in the contiguous United States.
Natural variability certainly played a role, according to climate scientists. Even if the climate were unchanging, there would be hotter and colder years within the normal variance of temperatures. But setting the record by 1 full degree? That's not normal. Exceeding the average annual temperature over the past 117 years by 3 degrees? That's not normal. Setting five times as many daily high-temperature records as cold temperatures records nationally in 12 months? That's not normal. And seeing a 15-year period encompass the 10 hottest years on record, worldwide, as figures to be released this month are expected to show? That's not normal either.
These are huge leaps, and they make a stronger case than ever that the planet is truly warming.
Now, that's not quite the same as saying the Earth is warming as a result of manmade emissions: The planet warmed and cooled long before humans began burning fossil fuels. But the consensus among the top climate scientists has long been that human activity is contributing to these climate changes, and that consensus is only strengthening.
What's more, emissions are the only things we can hope to affect and control in trying to slow global warming and alleviate its effects.
Even if it's not certain that carbon-dioxide emissions are causing the warm-up, reducing them, along with being smarter about what we build and where as we confront rising sea levels, is still the only course of action anyone's advocated that might help.
The planet is warming, and the effort now needs to go toward dealing with that reality, not arguing endlessly over whether reality exists.