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Weather and climate are two different things

CAROL LANDIS • Feb 17, 2014 at 9:56 AM

Weather is defined as “the state of the atmosphere at a place and time as regards heat, dryness, sunshine, wind and rain.” It’s a description of the atmosphere at any given moment — a snapshot. The atmosphere moves constantly, changing on the scale of minutes and hours. Its effects can linger, but even floods and droughts are temporary.Climate, though, is defined as “the weather conditions prevailing in an area in general or over a long period.” (Teachers say, “Today’s weather helps you decide what clothes you’ll wear; climate defines what’s in your closet.”) Once again, place and time are critical elements needed to describe trends from weather events. Periods of at least 30 years (which define weather “normals”) may be used, but 50- to 100-year periods, and longer, are more common for climate studies.Jack Van Zandt’s examples (Jan. 26) of ships being stuck in ice are the result of weather, not evidence of climate variations. As an avowed “denier” of climate change, he rejects the overwhelming evidence of warming and the success of climate models to forecast changes we’re already seeing, such as increasing intensity of rainfall events (with less frequency) that result in droughts and floods. More open water in the Arctic Ocean in winter contributed to the recent shift of the “polar vortex” off the Polar Region. Sea level is rising, and more.International climatologists have stated a 2 degrees Celsius increase for average global temperature as the goal for an upper limit of continued warming. With business-as-usual energy choices, we are likely to see more than that.Finally, hurricanes are increasing in strength and intensity (more 4s and 5s), and climate models also predict regional impacts as well. To learn what is predicted for the Southeast, search “USGCRP” and “Regional Impacts.” Are you already seeing these changes?CAROL LANDISJohnson City