Headlines calling 2023 the “hottest year on record” mushroomed when 2024 began, and with summer in full swing, the media keep talking about the possibility of a new record in 2024. As usual, though, they exaggerate the significance of such events. A single warm (or cool) year does not constitute evidence of climate change. Nevertheless, in the absence of natural climate variations, we might expect rising atmospheric carbon dioxide levels to make each successive year warmer than the last. But by how much? 

A recent Washington Post headline proclaimed, “A year of record global heat has pushed Earth closer to dangerous threshold,” followed by the claim, “Temperatures surpassed the 1.5-degree Celsius warming threshold over the past year, and scientists warn they will again soon.” But there is no magical “threshold” beyond which something terrible happens. A deep dive into its historical origins has shown that 1.5 deg. C of warming was a somewhat arbitrary number that the 2015 Paris Agreement set for a preferred upper limit to anthropogenic warming (indeed, on some calculations, it was arguably too high). Even the U.N.’s Intergovernmental Panel on Climate Change (IPCC) has admitted that no non-temperature-related changes in weather extremes can yet be distinguished from natural climate variability. 

Regarding records, we must point out the obvious: Record-setting temperatures are relative to the period of recorded thermometer measurements. Even though the U.S. has by far the densest network of thermometers, NOAA uses 1895 as the earliest year with sufficient data to compare later years to. Global averages rely on much more sparse measurements. So, the Post’s claim that 2023 global temperatures were possibly the warmest in the last 100,000 years is highly speculative. 

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Such claims are based on statistical reconstructions of temperatures based on geological data, which is not necessarily comparable to thermometer data and nowhere near as precise. Research has shown that there could easily have been warmer years during the Medieval Warm Period of 1,000 years ago. No one knows for sure. And some of the warming in the last 150 years could well be just a recovery from the “Little Ice Age” that ended during the 19th century. 

Numbers Matter 

Imagine there was no natural source of climate variability or change—no El Niño, La Niña, no Pacific Decadal Oscillation or North Atlantic Oscillation, no changes in the sun, and also no variations resulting from the fact that the climate system is chaotic and varies all by itself. In that imaginary world, increasing CO2 from fossil fuel burning should cause each year to be only about 0.02 or 0.03 degrees C warmer than in the preceding year. That is the average increase in global temperatures over long periods of time in response to increasing CO2 in the atmosphere. 

That is the global-warming signal. Every year would then be the “record warmest.” But so what? Is it enough to notice? Is it dangerous or a crisis? Numbers matter. 

Instead, what we have is a climate system with lots of natural variability. 2023 was a perfect storm of natural and anthropogenic warming influences, including El Niño. It was even a record warm year in the University of Alabama in Huntsville satellite-based dataset that John Christy and I pioneered development of more than 30 years ago. 

And global averages don’t tell us what you or I or our parents or grandparents experienced. In the U.S., 2023 average high temperatures produced only the ninth-warmest year since 1895: 2.2 degrees F above the 20th-century average. 

What about the climate models used to promote changes in U.S. energy policy? What do they expect for summer warming in the U.S.? For the period 1979–2023, the models predicted average warming 59 percent greater than that observed by NOAA’s official thermometer dataset. These models run hot, which would suggest that some caution is required when using them as a base for public policy. 

Today’s Summer Heat Waves Were Yesterday’s Normal Summer Weather 

To add statistical insult to injury, on June 19, the Washington Post followed up with an alarming discussion of warmer-than-normal weather in the U.S. Northeast. Temperatures over 90 degrees F were characterized as some sort of unusual occurrence, which they are not. Individual hot days are weather, not climate. Since 1895, Northeast U.S. high temperatures for June have increased an average of less than 0.1 degree F per decade, which would be nearly impossible for anyone to notice. 

The most egregious claim in the Post story was the statement that “extreme heat is the No. 1 weather-related killer in the United States.” This is false. In a widely cited Lancet report, heat- and cold-related mortality was studied in 13 advanced economy countries. In each one, cold-related deaths far outweighed heat-related deaths. In the U.S., 5.5 percent of deaths were cold-weather related, while only 0.4 percent were heat-related. Thus, over 13 times as many U.S. deaths were attributed to cold versus heat. 

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Finally, keep in mind that most people now live in or near urban population centers. They experience a substantial urban heat island effect that would exist even without global warming. This fact is seldom mentioned by the media when they print summer heat-wave stories about our cities. 

Has All Warming Been Anthropogenic? 

An important issue that is seldom discussed is the fact that warming over the past 150 years is simply assumed to be anthropogenic (human-caused). But increasing CO2 in the atmosphere from fossil-fuel burning has perturbed the energy budget of the climate system by only 1 percent compared with the average 235–245 Watts per square meter in and out of the climate system. That number is smaller than the accuracy with which we know the natural flows of energy in the climate system. Thus, warming since the 1800s could be partly natural, and we would not even know it. This is probably the most important known unknown downplayed by the climate research community. 

Altogether, irresponsible reporting deliberately sensationalizing the weather is not a reason for consternation or concern. People should enjoy their summer and not worry about the sky falling down, because it won’t.