Adjusting to Another “New Normal”
Fun fact: When your local TV meteorologist tells you that today’s temperature is “above normal” that’s not just an average temperature for the last forever-number of years. It’s actually based on a thirty-year average from…
wait for it…
If you aren’t surprised by that, you are a bigger weather geek than my spouse. And he watches TV weather and checks the forecast on his phone more often than a nervous parent checks a newborn. We’re talking geeek.
But I digress.
What are Climate Normals?
It turns out that climatologists from the National Oceanic and Atmospheric Administration, National Centers for Environmental Information (NOAA NCEI) are currently compiling the most recent 30 years of weather and climate data from across the U.S. to create the next batch of 30-year Climate Normals, which will cover 1991–2020. These numbers are scheduled to be released in May. Then we’ll use that data for another 10 years.
The 30-year average isn’t a magic formula. In 1935, the International Meteorological Organization (now known as the World Meteorological Organization) set a standard for member nations to calculate climate Normals beginning with 1901–1930.
NOAA’s Normals aren’t simple averages. Rather, they are made up of complicated calculations that make corrections for when individual stations are missing data or discrepancies when stations change locations. they also ensure that daily Normals fit with monthly Normals.
Each decade, the calculations may be slightly tweaked. In the 1991–2020 series, for example, NCEI has made minor changes in how numbers are rounded, percentiles calculated, days over thresholds are counted, and output formatted.
In addition to the 30-year series, other time ranges and data tools are available. With the 30-year release will come a 15-year Normal series for the first time, and high spatial resolution monthly Normals.
Why Climate Normals?
Various economic sectors use the climate Normals to inform their work. For example, utility companies can use the data to plan electric load, and construction companies and agriculture can schedule locations and timing for their work. (It’s like a high-tech Farmer’s Almanac!)
Our local meteorologists use the Normals to put our daily weather forecasts in context. The image below shows my local weather. Today’s low was above the Normal low temperature, but well above the record set in 1985.
The “New Normal” and Climate Change
My big question is, will the “new normal” make climate change a little less visible on a daily basis?
Stay with me here, this is going to take some mathing.
First, we know that U.S. (and world) average temperatures have been rising over the last century. Here’s a lovely graphic from NOAA showing the trend and the mean from 1901–2020:
As you can see, this chart indicates a rise of .16 degrees Fahrenheit per decade. The same data source (I won’t bore you with the graph) shows a 1.55 degree increase over the course of the century.
So, yeah, climate change. But we knew that.
Let’s look at the “new” Normal (1991–2020):
And the “current” Normal (1981–2010):
So, the mean for the new Normal 30-year period is nearly half a degree higher than the old Normal for 1981–2010. That’s no surprise, considering what we know about climate change since the early 1900s.
So, on a daily basis, the change in Normal is going to make our weather look not quite as out of whack in the next few years. To me, anything that normalizes the speed of climate change that we are seeing is alarming.
Does a 30-year average make sense?
If you are using the data for planning, it does make sense. In fact, a set of 15-year averages will also be released this year. With temperatures rising quickly, more recent data will be more predictive than data averaged over a longer time frame.
Research shows that people fairly quickly become accustomed to events associated with climate change. That half-degree difference between the old Normal and the new is hardly noticeable. We are even getting used to increasingly extreme floods, hurricanes, and wildfires. Researchers warn that disasters are going to keep coming more often.
The long-term data is alarming
Increases in temperature are closely linked with the increases in disasters. CO2 increases the temperature, which accelerates the evaporation of water. Water evaporation leads to drought that boosts heat waves and wildfires; in humid places, evaporation increases rain, which causes flooding.
So getting used to the new Normal scares me. I want us to be reminded, daily, of the vast difference between the average temperature in 2021 compared to a century ago. I would like to hear that local average temperature in April 1858 was 52.2 and in 2020, it was 55.6.
But maybe that’s just me. I always think “Normal” is a little bit suspect.