If you are reading or watching the news, winter weather is the current headline. Negative wind chills, feet of lake effect snow in the Great Lakes region, and possibly the coldest New Year's Eve ball drop in almost a half century are on tap...
Forecasts are suggesting that temperatures will be in the teens and wind chills below 0 deg F as the famed ball descends from the New York City skyline. The top 3 coldest temperatures were: 1 degree F in 1917, 11 degrees in 1962, and 15 degrees in 1976/1996, respectively. Like clockwork, you will also start seeing tweets and posts refuting climate change even though 2017 will end as one of the top 3 warmest years on record. It is very common to see statements like"those climate scientists are full of it, I have 30 inches of global warming in my yard." These moments are perfect opportunities to increase science literacy. Here is a template for how I often explain cold weather within the context of a warming climate.
The key thing to convey to that skeptical uncle or vociferous social media friend is that "weather is mood, climate is personality." My University of Georgia colleague Dr. John Knox mentioned this a few years ago, and it has been one of my favorite techniques to use while dealing with this pesky climate communication challenge for the public. Weekly or daily weather patterns tell you nothing about longer-term climate change (and that goes for the warm days too). Climate is defined as the statistical properties of the atmosphere: averages, extremes, frequency of occurrence, deviations from normal, and so forth. The clothes that you have on today do not describe what you have in your closet but rather how you dressed for today's weather. In reality, your closest is likely packed with coats, swimsuits, t-shirts, rain boots, and gloves. In other words, what's in your closet is a representation of "climate." Even my colleagues in the broadcast meteorology world are not immune to the snarky comments about cold weather and global warming. WMAZ-Macon Meteorologist Matt Daniel summed it up this way,
The comment I dislike the most is when people talk about cold weather and people type "So much for global warming..." Not really a joke to me. Also, it proves someone doesn't have the understanding of the definition of weather vs climate. You'll see people type that a lot in the next week or two on professional meteorologists' social media pages.
What we are seeing right now in the United States is just,.........well......wait for it......"winter".....Even as climate warms, we will always have winter (cold weather, snowstorms, blizzards). Winter is related to how the Earth is tilted on its axis as it moves around the Sun. In a previous Forbes piece, I described how the axial tilt of our planet determines our seasons.
Now having said that, our weather is governed by a series of undulations or wave patterns. The "valleys" (troughs) in those waves allow cold, dense air to ooze into the U.S. The "hills" (ridges) in the waves are typically associated with warm conditions. If you search Arctic Amplification on the Internet, there is some evidence that climate change is causing more wavy, high amplitude "valleys" and "hills" in the jet stream pattern. This could be associated with more extreme cold events and more extreme heat/drought events. The science is still emerging on this process, but it should be monitored and not dismissed.
The other thing to point out is that because one part of the world is cold (in that valley), there is likely another part of the world experiencing abnormally warm conditions (in the hill part of the wave pattern). In the temperature map tweeted by long-time weather observer Joe Stepansky, it is clear that on December 28th the United States and parts of Canada are experiencing the anomalously cold weather. If you need a visual of how our three-dimensional atmospheric wave patterns work, consider what happens when you press down on a water bed mattress (for us older folks) or an inflatable bouncy house. One part goes down, another part goes up. The NOAA Weather Prediction Center map of predicted 500 millibar maps for the next several days is a good indicator of atmospheric processes in the middle of our troposphere. They reveal the ridge-trough patterns and where the coldest weather is likely to be entrenched.
For now, the message for this week and the next 7 days (see below) is that winter is reminding us that it still exists and always will even as our climate warms. Prepare accordingly, stay warm, and help others.
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