All these global temperature records being broken over the past few years might start to sound to you like you're stuck in Groundhog Day...
But this repetition, this slow-motion emergency, must not dull our resolve for action. This is what global warming looks like. Records keep getting broken, the warmest years on record keep clustering in the recent past (15 of the 16 warmest years on record took place since 2001), and over time we move from a climate that is relatively benign for most living creatures on Earth to a climate that is a lot less hospitable.
The latest record to be broken comes from NASA and NOAA's 2015 numbers, which come from measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations: "Earth’s 2015 surface temperatures were the warmest since modern record keeping began in 1880, according to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA)."
And we're not talking about a tiny increase in temperatures. The previous record, which was set the year before in 2014, was left behind by what is considered a wide margin when it comes to global averages (0.23 degrees Fahrenheit or 0.13 Celsius). The planet’s average surface temperature has risen about 1.8 degrees Fahrenheit (1.0 degree Celsius) since the late-19th century. That might not sound like much, but think about how much energy would be required to warm up the surface of the whole planet by 1.8 degrees! That's a lot more energy in the system, potentially fueling droughts, hurricanes, disturbing air and sea currents, etc.
Weather dynamics often affect regional temperatures, so not every region on Earth experienced record average temperatures last year. For example, NASA and NOAA found that the 2015 annual mean temperature for the contiguous 48 United States was the second warmest on record.
NASA has created an animation showing the long-term warming trend over Earth's surface, showing what took place between 1880 and 2015 in just 30 seconds. Check it out, it's a scary half-minute!