How many times have you heard someone inform you that global warming “isn’t real” because it’s a cold day, or it’s been an unusually cold winter? Longing to talk back to science deniers? We’ve got you covered — and then some.
Let’s start with some terminology. Scientists are increasingly preferring “climate change” to “global warming” because of its increased accuracy, and because it tends to head off these kinds of conversations at the pass and because global warming is only one aspect of climate change. Yes, the globe is warming overall, but that’s not the only thing going on. The Earth’s climate is changing over time, creating a new trend that appears to be moving more quickly than it would naturally, indicating human involvement. Weather, however, is not climate; it behaves erratically and may appear to be all over the map when viewed in isolation, but when viewed as part of the larger climate trend, certain patterns emerge.
Those patterns are going to include colder winters in some parts of the world, along with warmer summers. Some regions are experiencing drought conditions while others are dealing with flooding and heavy storms. Superstorms, like Sandy, are brewing in some regions, while hurricane seasons are more sustained and ferocious in other areas. Each of these things is part of a bigger network of interacting events, because the Earth’s climate is an extremely complicated place.
What exactly is happening here?
Well, for one thing, a concentration of greenhouse gases in the atmosphere is causing surface temperatures to rise: that’s global warming. As air and ocean temperatures rise, they set off a chain reaction across the Earth, because ocean and air currents are critical to how the climate behaves. A phenomenon known as thermohaline circulation plays an especially key role. Normally, the oceans create a continuous conveyor belt of currents, with air warming at the Equator, floating towards the Poles and getting colder, and gradually sinking. This generates continuous movement, which also drives climate and weather systems.
When this is interrupted — as for example when the ocean heats up too much, or sea ice melts, affecting the density of ocean water — the climate shifts in response. Weather patterns can become disrupted; researchers, for example, have linked melting sea ice with changes in weather patterns in Europe. And warming weather in one place can create cooling weather in another.
The weather on an individual day, or during an individual season, actually doesn’t provide that much information about overall climate trends. However, when researchers pull data from multiple days, seasons, and regions together, looking at it in a historical context, it can start to reveal patterns. These patterns can be collated with other observations, such as measurements of sea ice, increases or decreases in temperature, ocean acidification, and rainfall averages over time, and the intensity of storm systems, to provide information about how the changing climate is affecting the weather.
When someone says “climate change (or global warming) isn’t happening because it’s cold today,” they’re betraying a lack of scientific literacy, and an incomplete understanding of the research and methods behind climate science. The numbers are clear: the globe is warming overall, forcing radical shifts in the climate, and the Earth’s weather is changing with it.
If someone tries to tell you otherwise because it’s a cold day, point out that the Earth’s temperature has increased by 1.4°F over the last 100 years, which is an abnormally fast rate. And make a note of the fact that warming atmospheric temperatures create a range of atmospheric phenomena that can affect the weather, right down to unusually cold days or winters.
Photo credit: NASA Goddard Photo and Video
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