It was recently brought to my attention that an article has been published which merits a response and discussion in our blog, because it relates to a concept which I regularly discussed with my community college classes: careful reading. Especially when considering a hot-button topic such as climate change, it is so important to read behind the articles that circulate on the internet and social media. I hope that this blog post illustrates the need for deep thought and discussion about topics, much of which cannot be condensed into a tweet, social media post, or even a short article. So, are you ready to dive in?
Too hot for humans?
A recent article in The Hill, published in their ‘Environment’ section, opened with the following headline:
Given the black background, and the content, most of us would read something like this and feel like it is time to prepare for the coming apocalypse. Scientists are in a race? Are we losing? Spontaneous killing of humans? This sounds like something out of a movie. The wording of the title itself is intended to draw people in and read the article as if their very life depended on it.
Further, the next thing I scrolled down to is this picture, showing a thermometer reading 120 degrees Fahrenheit!
However…dark pavement areas can regularly reach these high temperatures on hot summer days, even when the air temperature is in ‘normal’ summertime temperature ranges. It is for this very reason that standard measuring equipment which is used by meteorologists is mounted a 2 meter (about 6 foot) elevation above the ground, in a white, ventilated shelter to prevent effects such as what is shown in this image.
Next, I scrolled down to see the following ‘Story at a glance’ synopsis:
As I dug into the article, I found that it was actually intended to discuss finding published in a recent study by scientists affiliated with Columbia University in New York, NASA’s Jet Propulsion Lab, and others. I was confused! The affiliations of the authors in this article are from some highly respected scientific institutions which are well known for their work in the area of climate change. Are they really shouting from the rooftops that we are going to be subject to spontaneous death by heat?
Tip: Always go to the source
My first course of action whenever I come across an article such as this one is to go to the original source. The author did take time to contact the authors of the original article and link to the publication itself, but there are many errors in what ultimately ended up in the article, so I preferred to read what the scientists had to say in their own words.
What does the science say?
This is an important question to ask! What did these scientists do? Did they use appropriate methods? Was their research reviewed by peers? If you are not a scientist, these questions may be more difficult to answer, but it’s always a good idea to try and understand what the original research says if you can.
In this case, the authors of the scientific publication looked at a parameter called wet bulb temperature as a means of assessing the ability of humans to cool their body temperatures via sweating. The basic principle is this:
Evaporation (converting liquid water to vapor, or gas form) is a process which requires energy, which is taken from your body when you sweat. Thus, evaporation of sweat off your skin cools your body temperature.
Digging a little deeper, the saturation point refers to the maximum amount of water vapor that can be contained in air at a specific temperature. If the air has very little vapor compared to its amount at saturation (in a desert, for example, where it is very dry), evaporation happens very efficiently and thus sweat evaporates off of your skin quickly. In high heat and humidity conditions, when the air is much closer to its saturation point, evaporation happens at a slower rate. This is why heatstroke and other heat-related illnesses are very likely to happen in high heat AND humidity conditions, while dehydration is always a real risk (even at not-so-hot temperatures!) in desert climates.
What is the wet bulb temperature?
The article in ‘The Hill’ states that “”Wet bulb” temperature is when “the emergence of heat and humidity [is] too severe for human tolerance,” according to a study published in Science Advances, as reported by Vice.”
This is factually incorrect!
The wet bulb temperature is a parameter used by meteorologists every day, and can be measured at all temperature and humidity levels. Simply put, wet bulb temperature is how cold the air would get due to evaporation, given the measured temperature and humidity levels. The wet bulb temperature always lies somewhere between the actual air temperature and the dew point.
This effect of evaporational cooling can actually change rain over to snow during winter storms when precipitation intensity increases and there is a lot of evaporation going on as precipitation falls from the cloud to the ground. When you see rain falling, changing to heavy wet snow and back again to rain at lighter intensity, you are seeing the effect of cooling of the atmosphere by evaporation.
The article goes on to state that “Wet bulb temperature occurs when the human body can no longer sweat to cool itself down at humidity above 95 percent and temperatures are at least 88 degrees F, according to the study.”.
Wet bulb temperature is not some measure of human cooling capability, but a construct which helps us assess humidity in the atmosphere!
To his credit, the author does try to clarify these statements by adding in quotes from the authors of the original article, but it does little to explain the errors in the statements above.
What do the scientists say about wet bulb temperature?
In the original article, the scientists point out that there is a theoretical ‘upper limit’ of the wet bulb temperature, above which humans are no longer able to physically use sweating to cool their body temperature, for the general reasons I discussed above related to evaporation rates. This theoretical limit is estimated to be about 35 degrees Celsius, or 95 degrees Fahrenheit.
The authors use surface observations to assess exceedance of this wet bulb temperature, as well as frequency at which the wet bulb approaches this level, reaching 31 and 33 degrees Celsius (and thus still causing problems for humans). The authors noted an increase of extreme wet bulb temperatures at certain stations, particularly at coastal subtropical locations, since 1979. They note that “the most extreme humid heat is highly localized in space and time” and thus numerical models may not fully capture some of these events.
The bottom line: read carefully
The scientific article referenced does seem to conclude that there has been a measurable increase of extreme humid heat conditions since 1979, but that there are regional and seasonal variations to consider. The authors note that their results do suggest that this issue is becoming increasingly severe and intense with time.
The ‘The Hill’ article leads with an inflammatory headline, an unrepresentative photo, and factually incorrect bullets in order to draw readers into thinking that this ‘wet bulb temperature’ is an imminent threat to their very existence.
In reality, the scientists correctly discuss that the overlap of population-dense areas with more frequent observations of extreme humid heat conditions will create global societal impacts in the coming years which will need to be addressed via further research and policy development. The scientists note that these areas of primary concern are located in the southern Persian Gulf and northern South Asia, not in the Pacific Northwest United States as the author of The Hill article tries to suggest. While the Northwest did just experience a record-smashing heat wave which resulted in numerous illnesses and fatalities, it is scientifically inaccurate to link the results of this study directly to that weather event in the Pacific Northwest.
So, what is a reader to do?
Here are my recommendations:
- Any time you see a lead to an article such as the one I’ve discussed above, complete with frightening headlines, text and pictures, ALWAYS look for a link to the original source.
- If you don’t see a link to the original source, run away! Find another article discussing the same topic which does link to the original source!
- If you do see a link to the original source, give it a try! A lot of times the abstract and conclusions of scientific articles have some information which can be understood by lay people.
- Research the journalist. If the journalist is not one who regularly writes about scientific topics…give some serious thought to accepting their explanations and interpretations of scientific work.
- Find a scientist! Ask around- go to the library, contact your local universities, reach out to your favorite TV meteorologist! TV meteorologists are seen in our field as the ‘front line’ communicators to the general public on issues related to climate change, and thus many of them are well trained and will be able to answer your questions accurately, honestly, and clearly.