Wednesday, 8 February 2017

Unusually Hot or Cold Days Don’t Say Anything About Climate Change

Anyone who's lived in a cold weather city is familiar with those rare, but glorious one-off days where the temperature suddenly spikes and people on the street start to crack smiles for the first time in months. A 60 degree February day in New York, for example, when disgruntled pedestrians normally looking like ticks about to pop, all bundled up in jackets and scarves, all of sudden start strutting around in jean jackets. The next day or a couple days later, it's back to looking like ticks.

In the late spring or early summer when this phenomenon occurs it is decidedly less pleasant, because it means the temperature is swinging the other way. But it happens all the same. A sudden cold snap, maybe a few snowflakes, and downcast eyes looking at the ground.  

These days, whenever phenomena like these occur, there is always a certain portion of the populace that thinks it's either because of climate change, or is proof that climate change doesn't exist. Well, the answer is neither. (For the record, it will certainly never be "proof climate change doesn't exist," because man-made climate change—as agreed upon by 97 percent of climate scientists—is very much real, and dangerous). The real answer for why these weird days occur is simple: because of weather. And weather is not the same as climate.

"There's an old saying that climate is what you expect and weather is what you get," Elisabeth Gawthrop from the International Research Institute for Climate and Society at Columbia University, told Motherboard. "Weather is the day to day, and climate is the average condition of a region over the long term," she said. "I think most people conflate weather with climate."

In other words, weather describes the conditions on a specific day, in a specific area. It's the stuff that makes you decide whether to put a jacket on, or to carry an umbrella. Climate is what determines where you might live—like the Mediterranean because it's mostly mild, or if you like cross country skiing, Northern Alaska, because it's mostly cold.      

Gawthrop also pointed out that a good way to understand this difference is to look at the different ways in which weather and climate are measured, modeled and described. Weather is measured on a scale of minutes, hours and days, whereas climate is measured on a scale of many years, decades, or more.

Another way to look at this is to picture a graph of stocks over a period of decades. It's going to be a zigzagging line that follows a general trend of up or down. Whether it's going up over time or going down over time, the line still contains individual peaks and valleys where the stocks rose or fell based on the day. That's like weather and climate. Weather is like the rise and fall of stocks day to day, climate is the trend over years.

So next time some joker tries to use a snowstorm or cold snap to say that climate change isn't real, sit them down and gently explain the difference between weather and climate. Don't rip their heart out.



from Unusually Hot or Cold Days Don’t Say Anything About Climate Change

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