Dessler keeps stepping into it – Growing with that?

Atmospheric Scientist Andrew Dessler of Texas A&M University created an online sensation on Twitter last year when he decided that a chart published by the EPA and quoted by Bjorn Lomborg a year ago “Just doesn’t seem right.”

Science doesn’t follow, “just doesn’t seem right” as a rule of discovery or investigation, and as a scientist, Dessler should know better. Personally, “it just doesn’t look right” is a quick way to confirm bias. Here’s what Dessler said:

However, like many other climate forecasters, Dessler finds it hard to believe that any time in the past could have been worse than the present when it comes to weather. There have been so many fallacies about the times we live in as “hottest ever” and “unprecedented” that some people actually begin to refute the contradictory data that already exist. for several years.

In this case, Dessler would ask us to believe that The “dust bowl” period in US history nothing compared to the devastation of the heat waves and droughts being experienced in the United States today, and he set out to prove his faith with a series of Tweets that you can read here.

Recently, in a discussion with Marc Marano of ClimateDepot, Dessler brought up the topic from last year again.

But what is the truth about the 1930 heat wave? Is it merely a statistical aberration or a “cherry” as Dessler suggests? Or is it real? And if it’s not real, but “Picking cherries” data, like Dessler paintingsWhy did the EPA publish it?

The study presented the following indisputable facts about the 1930s heatwaves, which contradicted Dessler’s view. First, the World Meteorological Organization determined a heat wave like five or more consecutive days in which the daily maximum temperature exceeds the mean maximum temperature by 5°C (9°F) or more.

first. Yes, prolonged heat and drought did indeed hit much of the United States during that period. 1936 was particularly bad. Wikipedia notes this:

July 1936, part of “Dust Bowl”, produced one of the hottest summers on record across the country, particularly over the Plains, Midwest and Great Lakes regions.. Nationwide, about 5,000 people died from the heat.

https://en.wikipedia.org/wiki/1936_North_American_heat_wave

The US National Weather Service said:

… The summer of 1936 featured the most widespread and destructive heatwave to hit the Americas in centuries..

https://www.weather.gov/ilx/july1936heat

2. The heat waves of 1934 and 1936 were caused by natural ocean patterns, according to this peer-reviewed paper from 2015 that says,

Two oceanic hotspots have been found to be potential drivers of the hottest summers on record in the central United States in 1934 and 1936. The study could also help modern forecasters predict particular summers. especially hot in the central United States for many months to come.

Markus G. Donat, Andrew D. King, Jonathan T. Overpeck, Lisa V. Alexander, Imke Durre, David J. Karoly. Unusual heat in the 1930s US Dust Bowl and associated large-scale conditions. Climate dynamics, 2015; DOIs: 10.1007 / s00382-015-2590-5

3. The US Fourth National Climate Assessment (NCA) since 2017 has done a detailed analysis of US heat waves, including cold and warm ones dating back to 1900, and found the same thing the EPA did. Below is figure 6.4 from chapter 6. Notice the bottom panel.

Since the mid-1960s, the warmest daily temperature of the year has seen only a very slight increase (against the large variation between years). Heatwaves (6-day period with maximum temperatures above the 90th percentile for the period 1961–1990) increased in frequency through the mid-1930s, becoming significantly less common in the mid-1990s. 1960, and then increased again (Figure 6.4). As with warm daily temperatures, Heatwave intensity peaked in the 1930s. The frequency of extreme heat waves (4-day events, 1 in 5 years) has generally increased since the 1960s in most areas except the Midwest and Great Plains. ^, Since the early 1980s (Figure 6.4), there is suggestive evidence of a slight increase in the intensity of heatwaves across the country as well as an increase in droughts and heat waves.

https://science2017.globalchange.gov/chapter/6#fig-6-4

The picture below is the result from 671 individuals US Historical Climate Network (USHCN) stations have more than 94 percent data available. This is the number of days in a “heatwave” lasting at least 5 days, where each day is above the 95th percentile of the distribution of daily values ​​for each day.

There are 671 eligible stations for 94 percent of the available data out of the 1218 USHCN stations.

Note that the US West (ID + OR + WA, CA + NV and AZ + CO + NM + UT) has the highest number of Heatwave Days over the past decade, but the rest of the country is near/under national average. There has obviously been some regional variation over the last 110 years, indicating a change in weather patterns, but for the country as a whole (grey bars), the decade 1932-1941 is still prominent as the weather. The warmest.

Interestingly, this is a very different result from Dessler’s claims, especially when it comes to some of the charts he’s posted, such as this one in his Twitter thread:

Dessler’s graph shows that the dataset he’s using (Berkeley Earth) has had some temperature adjustments applied. The difference is not geographical because results from USHCN stations are also calculated by area. We can get Dessler’s results, more or less, if we add 1°F to each daily temperature from 1980 to 2005 and then add 2°F from there to the end of the data. This provides a rough estimate of the magnitude of the adjustments that were applied to the dataset he used.

Bottom line: unless you use adjusted data, you can’t get Dessler’s results.

If Dessler wanted to claim that hundreds of observers who have taken high-temperature measurements over decades should correct for that hard-earned data, he could claim it, but he ends up with one result he claimed was abhorrent, one was “cherry picking” using adjusted data instead of the actual high temperatures recorded in history. The adjusted high temperature data is not the same as the actual measured high temperature, it is not even real.

Imagine if your evening weather report, when reporting high temperatures for your area that day, used adjusted high temperature data to present the results to the viewer. The backlash will be quick and merciless.

You can compare all of the data in points 1-4 above with Dessler’s “doesn’t look right” analysis and make your own judgment about when heatwaves are worse in the United States. You can trust actual data that was actually measured at the time, or data that was statistically adjusted decades later.