warming words

Thursday night, someone on my Twitter timeline retweeted a post by an account called “AP Stylebook,” the Twitter presence of the Associated Press style guide which sets the standard for writing style in American journalism. A screenshot of the tweet is posted below, but it read simply: “The terms global warming and climate change can be used interchangeably.”

My immediate response: “Umm, no they can’t.”

ap style climate

It chagrined me to see this post, and especially an institution with the gravitas of the AP Stylebook making a mistake on this order. But in a way it’s not so surprising, given all the confusion and outright misinformation there is out there in the public about climate change. For what it’s worth, I thought it would be worth a post explaining exactly what is the difference between “climate change” and “global warming,” and why it’s so unhelpful and downright irresponsible to suggest that the terms are synonyms.

Simply put: global warming and climate change are not the same thing. Global warming is a form of climate change, but they’re not equivalent. An Impala is a type of Chevrolet, but not all Chevrolets are Impalas. It’s that simple.

Climate change has been happening throughout human history, and long before humans got here. Whenever there are significant long-term alterations in the planet’s climate, from whatever cause, this qualifies as climate change. The end of the last Ice Age–the last time that woolly mammoths walked the Earth, during the dawn of human history in what we sometimes call prehistory or the Stone Age–is an example of this type of climate change. So too is the much-debated (and much-misunderstood) “Medieval Warm Period,” which may not have been all that warm and which no one agrees was confined to the medieval ages. Climate change likely occurred in Mesoamerica about 900 C.E., and probably was a factor in the collapse of classical Mayan civilization.

woolly mammoths

This picture involves climate change. It also involves global warming, but not the same global warming that we are currently dealing with.

Another period of climate change occurred between 1810 and 1820. This is the “Cold Decade” that is the basis of my own academic research. This period of climate change was caused by several volcanic eruptions, beginning in 1809 and continuing until 1815, which had the effect of causing lower-than-average temperatures worldwide and a series of bizarre weather anomalies, such as snowstorms in June and frost in the dog days of August. This phenomenon is well-known as the “Year Without Summer.” However, although this is a very clear example of climate change, it has absolutely nothing to do with “global warming.”

Global warming is a phenomenon in which, as you might imagine, there are significant increases in temperatures worldwide over a sustained period of time. While episodes of global warming can and have occurred caused by other things, what’s happening to the world right now–an extremely high and very sustained increase in global temperatures–definitely qualifies as global warming, and it is definitely, provably, undoubtedly and undeniably caused mostly by human activities that release greenhouse gases into the atmosphere. This recent period of global warming, manifested since the late 19th century and particularly since 1950, is what most people mean when they use the term “global warming.”

There is a pervasive myth–one that perhaps the editors of the AP Stylebook tacitly or explicitly buy into–that scientists and environmental activists who in the 2000s talked about “global warming” and were frustrated with the lack of traction the issue had in the public, and resistance from politicians, retooled their talking points and decided to change the name of the phenomenon to “climate change.” This isn’t what happened. From a public policy standpoint, the increased use of the term “climate change” as opposed to “global warming,” especially by people who want to do something about it (as opposed to people who deny its existence) reflects an increasing sophistication and accuracy by people in the policy sphere. “Climate change” has always been the predominant term used by scientists and researchers; note that the major international body that advises on climate change issues is called the Intergovernmental Panel on Climate Change, not the “Intergovernmental Panel on Global Warming.” That’s been its name since 1990, thus also belying the misconception that the switch occurred recently.

nasa climate change

This .gif involves climate change. It also involves global warming–the specific instance of global warming that most people refer to when they use either of these terms.

It’s harmful to conflate the terms “climate change” and “global warming” for two reasons, beyond the fact that they refer to different concepts. The first is that using them interchangeably obscures the very real effects of our recent period of greenhouse gas warming. Extreme weather of all kinds, including cold weather like the “Polar Vortex” (another controversial term) or the blizzards on the U.S. East Coast this winter, is linked to global warming, but it requires a lot more explanation to make that case to lay people who aren’t as sophisticated in the scientific terms of art and who may think, just from the name alone, that “global warming” means that everywhere on Earth will always be hot, everywhere, all the time without exception. This unfortunately gives traction to ridiculous and intelligence-insulting arguments, frequently used by conservative politicians, to the effect of “It snowed today! That means global warming isn’t happening!”

The second and related reason is that conflation of “climate change” and “global warming” plays directly into the hands of professional deniers, who like nothing more than to increase the public’s level of confusion about the issue in the hopes that people will conclude it’s not happening. Deniers are fighting a losing battle anyway, but an unfair conflation of the terms, and arguments like “See! Liberals switched the term in the 2000s! I told ya it’s all made up!” certainly don’t help clear the clutter away from what is undoubtedly the single most important issue facing planet Earth today.

Finally, it’s absolutely inexcusable that the AP Stylebook, a source of information whose ostensible mission is to increase accuracy in the communication of words, would commit such a careless error as characterizing “climate change” and “global warming” as synonymous. It’s simply an abrogation of their duty.

Climate change and global warming are not interchangeable. Period.

The picture of woolly mammoths is by the Public Library of Science and is used under Creative Commons 2.5 (Attribution) license.