Northern Hemisphere temperature just reached a terrifying milestone – ‘The old normal is gone’

By Eric Holthaus
1 March 2016 (Slate) – Update, 3 March 2016: Since this post was originally published, the heat wave has continued. As of Thursday morning, it appears that average temperatures across the Northern Hemisphere have breached the 2 degrees Celsius above “normal” mark for the first time in recorded history, and likely the first time since human civilization began thousands of years ago. That mark has long been held (somewhat arbitrarily) as the point above which climate change may begin to become “dangerous” to humanity. It’s now arrived—though very briefly—much more quickly than anticipated. This is a milestone moment for our species. Climate change deserves our greatest possible attention. Original post, 1 March 2016: Our planet’s preliminary February temperature data are in, and it’s now abundantly clear: Global warming is going into overdrive. There are dozens of global temperature datasets, and usually I (and my climate journalist colleagues) wait until the official ones are released about the middle of the following month to announce a record-warm month at the global level. But this month’s data is so extraordinary that there’s no need to wait: February obliterated the all-time global temperature record set just last month. Using unofficial data and adjusting for different base-line temperatures, it appears that February 2016 was likely somewhere between 1.15 and 1.4 degrees warmer than the long-term average, and about 0.2 degrees above last month—good enough for the most above-average month ever measured. (Since the globe had already warmed by about +0.45 degrees above pre-industrial levels during the 1981-2010 base-line meteorologists commonly use, that amount has been added to the data released today.) Keep in mind that it took from the dawn of the industrial age until last October to reach the first 1.0 degree Celsius, and we’ve come as much as an extra 0.4 degrees further in just the last five months. Even accounting for the margin of error associated with these preliminary datasets, that means it’s virtually certain that February handily beat the record set just last month for the most anomalously warm month ever recorded. That’s stunning. It also means that for many parts of the planet, there basically wasn’t a winter. Parts of the Arctic were more than 16 degrees Celsius (29 degrees Fahrenheit) warmer than “normal” for the month of February, bringing them a few degrees above freezing, on par with typical June levels, in what is typically the coldest month of the year. In the United States, the winter was record-warm in cities coast to coast. In Europe and Asia, dozens of countries set or tied their all-time temperature records for February. In the tropics, the record-warmth is prolonging the longest-lasting coral bleaching episode ever seen. […] Numbers like this amount to a step-change in our planet’s climate system. Peter Gleick, a climate scientist at the Pacific Institute in Oakland, California, said it’s difficult to compare the current temperature spike: “The old assumptions about what was normal are being tossed out the window … The old normal is gone.” Almost overnight, the world has moved within arm’s reach of the climate goals negotiated just last December in Paris. [more]