Why Looking at Average Temperatures Is a Bad Way to Think About Climate Change: Part 1

Three recent articles remind us that averages can hide more than they reveal

Image laboriously hand-crafted by the author in Powerpoint (public domain clipart from Clipart Library and Clipground).

Remember the old statistician’s joke? If you put your head in the oven and your feet in the freezer, on average you’re comfortable.

This is Part 1 of a two-part post on the topic of extreme vs. average temperatures in our understanding of how climate change is going to impact human civilization. This post considers why we need to be more cognizant of when and where climate change is likely to hit first and most severely. In Part 2, we will look at how asymmetries in climate change effects are likely to trigger crises and ripple effects throughout the global economy and supply chains … assuming we are unable to curtail fossil fuel emissions in a timely manner.

Lately, as I’ve been reading about climate “events” that are now appearing with greater and greater frequency around the world, I’m beginning to think that another way we are lulling ourselves into complacency is by depending too much on “averages” to help us understand what is happening to our world.

Why is this a problem? Because it’s not the average surface temperature that’s going to bring down our global economy, and eventually our fossil-fuel-dependent civilization, it’s the extreme temperatures — and particularly where and when those extreme temperatures appear — that will determine how and at what pace climate change and its partner in crime, resource depletion, will undermine and eventually destroy what we now mistakenly perceive as normalcy.

So our operative question should not be “what’s the average amount of pain we will suffer?” It should be “where will the pain be worst, and when?”

Could our focus on average global warming (e.g., the rapidly receding holy grail of 1.5°C over preindustrial temps) be another way to hide, or at least diminish, the true severity of our situation? Saying that “on average” in 2022 we were “only” 1.06°C warmer than the preindustrial average (source) might even sound a bit comforting, like maybe things aren’t going to be so bad after all.

But, as the graphic at the top of this post implies, our descent into involuntary degrowth isn’t going to start in locations where temperatures are “average” (even if that average is much higher than it is today), it’s going to start in locations where temperatures are “extreme”, overwhelming, and life-threatening. But it’s not going to end there.

Climate change is here. And the planet is not happy with us.

The warnings began in earnest soon after the IPCC was formed in 1988. Climate scientists said we were heating the planet to levels unseen in human history … and they were right. They said fossil fuels were the culprit … and they were right. What they got wrong was the timing (source, source, source). Effects that scientists did not anticipate occurring for decades are happening already, right here and right now in 2023. They’re just not happening everywhere and all at once.

Three recent articles really drove this home for me.

Has 2050 already arrived in 2023?

The first article that hit me between the eyes was this (literal) barn-burner in the Washington Post on June 6, “Extreme heat, wildfires wreaking havoc with hottest months still ahead”. This article lays out in horrific detail what is happening right now, around the world … events that may not be appreciated by those of us who are not directly experiencing it. For example:

• Over the weekend, parts of Siberia soared to highs near 100 degrees (38°C), setting all-time records.
• Parts of China and surrounding East Asian nations including Thailand and Vietnam are in the midst of a several month heat wave that has broken more than a thousand daily, monthly and all-time records. The heat wave in southeast Asia, in its 13th week, has been described as “most brutal never ending heat wave the world has ever seen”.
• At least 8 million acres (3.3 million hectares) of forest have been burned across Canada, which endured its hottest May on record.
• Total burned area in Canada is currently about 1,200 percent normal for the year to date, with several provinces running more than 4,000 percent normal.
• As portions of Antarctica warm five times faster than the global average, the area around Antarctica covered by sea ice is at a record low for this time of year.
• Global ocean temperatures have been running at record highs since the middle of March. Other ocean hotspots include the eastern Pacific Ocean off the coast of Peru and the northern central Pacific.

Meanwhile, back in the good old USA, Texas and Louisiana are experiencing a massive summer heat wave, with temperatures reaching 110°F to 114°F in some places, exceeding wet-bulb thresholds and putting approximately 40 million people under an extreme heat alert that apparently has “no immediate end in sight”. (source)

All of which gets us directly to the point of this piece. As the inimitable William Gibson first put it years ago (although when and where are still in dispute):

“The future is already here — it’s just not evenly distributed.”

How at-risk is the human population, really?

The second article that got my Spidey-sense tingling was a post by Medium’s resident futurologist Will Lockett, titled “The Staggering Human Cost of Climate Change”, in which Will discusses a recent academic study by Tim Lenton and colleagues assessing the potential human mortality costs of reaching various global warming levels over the next several decades.

According to the Lenton study, if we reach an average of 2.7°C above preindustrial temps by 2100 (this is the amount of end-of-century excess warming projected by the IPCC’s “middle of the road” shared socioeconomic pathway, SSP4.5), approximately one-third of the world’s human population (between 1.8 billion and 3.1 billion people) will be exposed to temperatures that, in the words of the authors, are “outside the human climate niche”, which they define as equal to or greater than a mean annual temperature of 29°C (84.2°F for us Yankees).

This is where relying on averages can start to get very misleading. When I first saw that 84.2°F average, I thought “that’s not so bad. I could pretty easily tolerate 84 degrees.” But then Will kindly provides a sobering comparison: In perhaps the hottest place on earth (Death Valley, CA), in the hottest year so far recorded (2022), the average annual temperature was 80.4°F, four degrees (F ) below the average billions of people may be facing by 2100. What was the hottest daily temperature that went into that average? It was 127°F on September 1, 2022 (source).

This is why average temperatures do not serve us well in communicating the depths of the climate crisis we are facing. If we dropped 3 billion people into Death Valley in 2022, it would not be the average temp of 80.4°F that would kill them, it would be a single-day (maybe three days in a row would be required) of extreme temps exceeding the human wet-bulb threshold of 35°C (95°F on the “heat index” scale in the US), a combination of heat and humidity that essentially bakes the internal organs of any human exposed to it for more than an hour (source). That’s a physiological limit. It’s the same for every human body, no matter how young or old, fit or frail, rich or poor, that human might be. If a person cannot protect or remove themselves from a wet-bulb level of heat, they die. And if it’s hot enough to kill one person, it’s hot enough to kill every person in the same circumstance. Because it’s simply biology.

I suspect that if climate scientists talked less about 80° averages, and more about 127° extremes, people might find climate change a little more compelling topic to pay attention to. (More on this in Part 2.)

Anybody notice that the Arctic is heating up four times faster than the rest of the planet?

The third article that prompted me to rethink my attitude toward global temperature averages was one of Richard Crim’s recent “living in bomb time” reports on Medium, specifically #32, describing the concept of Arctic amplification (for some academic background, see source).

This is a really helpful article in general, patiently explaining the basics of how the earth climate system operates. It points out some obvious facts for us non-experts. First, most of the sun’s energy hits the planet around the equator, where it proceeds to heat up land, ocean, and air. The heat then migrates north and south to the poles where it either dissipates back into space or accumulates. When the climate system is in equilibrium (that is, when heat out = heat in) it acts like a familiar water-heated internal combustion engine: it can maintain a constant temperature indefinitely. However, if more heat is entering the system than escaping, there is an accumulation effect at the poles, particularly at the North Pole. Since that heat cannot escape to space, each year’s climate cycle adds another increment of heat to the total already there. The net effect is a growing gap between the effects of climate change at the poles versus its effects elsewhere on the planet.

Today, a 1°C increase in average temp at the equator will result in a 4°C to 7°C increase in average temp in the Arctic.

Why does this matter? There are very few people up in the Arctic region, and those who are there would probably welcome “balmier” temperatures. Certainly the Russians are excited about opening new Arctic shipping lanes (source). But the problem with extreme heating in the Arctic is not about the comfort of humans or geopolitical strategies, it’s about ice. Back in 2021, the IPCC was projecting the Arctic would be able to sustain year-around surface ice as long as global average temperatures stayed below 2°C above preindustrial levels. But a new study published this year revises that projection, concluding that even under an IPCC low-emissions scenario (SSP2.6), heat already baked into the system will generate ice-free summers in the Arctic by 2050. Under more realistic IPCC scenarios (i.e., ones that better match current national commitments), the ice-free summers in the Arctic can be expected to become permanent as early as the 2030s (source, source).

Melting ice way up at the North Pole may seem like “out of sight, out of mind”, and in many ways that’s exactly how it has been treated. But melting Arctic sea ice is a significant potential trigger for many other climate tipping points and cascading effects.

• Albedo effects. Melting sea ice lowers a region’s albedo (its ability to reflect light and heat). When ice melts, the water previously under it is exposed to the sun’s heat. Since blue water has a lower albedo than white ice, it heats up faster, causing the remaining ice to melt even faster — a classic runaway positive feedback effect.
• Jet stream effects. As more ice melts at both poles, fresh water pours into the salt-water oceans. In the Arctic, scientists are starting to observe a weakening the atmospheric jet stream, which has contributed to extreme weather events in North America, Europe and Asia (source, source).
• Ocean current effects. As melting ice adds massive amounts of fresh water to the the world’s oceans, critical ocean currents are disrupted by the new mix. In the Arctic, meltwater is slowing down the North Atlantic current (part of which is popularly known as the Gulf Stream). The last time this happened (12,700 years ago), temps in the region plummeted by 5°C (source). A similar slow down is appearing at the South Pole, as meltwater flowing off the Antarctic ice sheets is disrupting currents in the region (source, source).
• Extreme weather effects. Both jet stream and ocean current disruptions are already contributing to extreme weather events — abnormally cold winters — in North America and East Asia (source, source).
• Permafrost melting. Perhaps the greatest mid-term threat from Arctic amplification is the thawing of vast fields of permafrost under the surface of the tundra that covers most of the landmass north of the Arctic Circle. As permafrost melts under amplified Arctic warming, it releases both CO2 and methane into the atmosphere, accelerating global warming and transforming one of the planet’s most important carbon sinks into a massive carbon source (source, source).
• Sea level rise. Ultimately, in addition to changing the temperature and chemical properties of the world’s oceans, increasing ice melt in both the Arctic and Antarctica must inevitably increase the volume of water in the oceans, thus accelerating potentially catastrophic sea level rise in coastal areas far removed from the polar regions. Although both the speed and extent of sea level rise is hard to predict, several countries now appear vulnerable to population displacement due to rising sea levels, including Bangladesh, China, Vietnam, Indonesia, and the Philippines. Without augmented or new protective barriers, coastal communities in these areas (including a number of giant megacities) may face regular flooding or permanent inundation (and possible abandonment) within 30 years (source).

So … extremes matter more than averages. Hidden under a 2°C average global temperature increase is something that may matter much more: a 4–8°C local increase in Arctic temperatures, capable of setting off a cascade of effects: disrupting both atmospheric jet streams and ocean currents, increasing the frequency and severity of extreme weather events, releasing massive carbon and methane deposits from melting permafrost, and triggering catastrophic sea level rise around the world.

It’s extreme temperatures, not averages, that we need to pay attention to. They tell us where and when climate crises are likely to appear first, with what consequences. Initial hotspots are where our political and economic leaders must focus if they want to protect vulnerable human populations, including that subpopulation to which I used to belong, the one filled with people still thinking “Two degrees hotter? I can live with that!”

Thanks for reading! On to Part 2 …