Climate: The "New Normal" Is (Mostly) Warmer Than The Old One

New average temperatures, based on newer data, have
gone up in most of the United States since the last update
a decade ago. The northern Plains have 
cooled off a bit, however. 

 Every decade, what is considered "normal" weather for all the weather stations in the United States get an update. 

The latest update just came through, and for almost everybody, normal is warmer than it used to be.

Normal is calculated by taking an average of what it's been like for the most recent 30-year period. Until this week, "normal" was the average for the period 1981 to 2010.  Now, it's the average of 1991 to 2020.

Climate change is of course in full swing, so these averages for most of us are toastier than they once were.   As the Washington Post reports:

"'We're really seeing the fingerprints of climate change in the new normals,' Michael Palecki, manager of NOAA's effort to update the climate normals said at an April news briefing. 'We're not trying to hide that. We're in fact reflecting that.'" 

TOASTIER UNITED STATES

The average temperature of the United States for a year is now 53.28 degrees. That's 1.7 degrees warmer than in the 1930s and approximates the pace of warming across the rest of the globe due to climate change. 

Most of the United States is warmer than it was under the new definition of normal announced this week. The areas seeing the biggest upward trend are the Southwest, southern and central Rockies, California, and the East Coast east of the Appalachians. 

The Southwest is also quite a bit drier than it used to be. The area was already pretty dry. The combination of higher temperatures and lower precipitation means the worsening droughts they have been suffering through will get even more extreme if these trends continue. 

The Northern Plains and parts of the Upper Midwest are actually a bit cooler under the new averages, especially in the spring for some reason. Scientists are studying why.  It could be a wavier jet stream than in the past that is bringing more frequent cold shots. Increased snow cover or an increasing cloud cover might be holding temperatures down. 

Or it could be changes in farm practices. There's more corn and soybean growing in these areas than in the past. What is known as "corn sweat" - moisture being given off by these plants - the evaporates. The evaporation has a cooling effect. At least in the summer. 

The Northern Plains are also wetter than they once were. So is much of the East Coast. 

WHY THE UPDATE

Members of the World Meteorological Society are required to update their climate averages once per decade.

Not everyone likes these updates every decade.  I'm not a fan of them. People smarter than me, like many climatologists, aren't thrilled by the updates, either. 

Here's some reporting from the Associated Press on that matter:

"Pennsylvania State University climate scientist Michael Mann said he prefers a constant baseline such as 1951 to 1980, which is what NASA uses. Adjusting normal every 10  years 'perverts the meaning of 'normal and 'normalizes' away climate change' he said in an email.

North Carolina's state climatologist Kathie Dello said, 'It seems odd to still call them normals because 1991-2020 was anything but normal climate-wise." 

A (MOSTLY) WARMER VERMONT

Here in Vermont, Burlington's average temperature took a decided swing uphill. The normal annual mean temperature is now 47.6 degrees, up from 46 degrees under the old "normal."

Interestingly, Montpelier's average temperature is marginally down and it's now 42.6 degrees. It had been 43.3 degrees. 

Even more dramatic than the map above is this one,
which shows how much "normal" temperatures in 
the United States have increased since 1901 

Vermont is now a wetter place, too. This is also consistent with climate change, as experts have long said warmer air is more humid, especially in this parts of the country, leading to more potential precipitation. 

This is probably the more worrisome of the new averages. Individual rainfall events have been trending heavier, despite occasionally droughty spells like we've had the first part of this year and much of last year.

This wetter trend means we are becoming more prone to flooding in the Green Mountain State.

Burlington's annual precipitation average is now 37.53 inches, up from 36.82 inches. Montpelier's is up to 38.7 inches, against the old figure of 37.27 inches. 

Burlington is snowier, too. The average for a season is now 87 inches, up from 81.2 inches. I think epic snow years like the winters of `1994, 2001, 2008, 2011 and 2019 really skewed the average. 

This discernible uptick in snowfall might also be related to climate change, believe it or not. Remember a warmer atmosphere can hold more water, which means more precipitation. It still very often gets cold enough to snow, so snowstorms are trending heavier. 

Digging deeper into the new averages, at least for Burlington, it seems every month is more or less equally warmer than the old data, with maybe the pace of warming in March and April a little slower.

Spring and early summer seemed to have gotten wetter the most, but mid to late summer has actually dried out a bit. November has gotten drier too.

There's probably not much rhyme or reason to those subtle changes. Probably natural variability mixed in with the climate change. 

With climate change continuing, all bets are the next update a decade from now will be even warmer than the new "normals" we have just been introduced to.