new "climate normals"

[frozenintime]

i came across a twitter thread that i thought i'd post in full since it will likely be interesting/sobering/etc to many of us:

"Snow has started to fall in the western mountains. Soon you'll be seeing snowpack reported as a percent of normal/median. But the definition of normal recently changed. Here's what that means.

NOAA, in alignment with international standards, bases its definition of normal temperature and precipitation on a 30-yr period. The 1981-2010 period was replaced earlier this year with 1991-2020. That change matters.

The new "climate normals" drop the 1980s and add the 2010s. For the western states, the current normals are largely warmer and drier than before. (You can see the comparison maps here: https://www.ncei.noaa.gov/products/land ... te-normals)

What does that mean? Snowpack that is 100% of median this winter has less snow than a 100% of median snowpack last year.

Confused? This hypothetical example is another way to look at the numbers.
1981-2010 median: 20 in
1991-2020 median: 18 in
Today, it would take only 18 in to reach normal, whereas last year, when the 1981-2010 period was used, it would take 20 in.

In short, normal ain't what it used to be"

(https://twitter.com/waltonwater/status/ ... 6418087939)

[Wandering Daisy]

Climate (long term) and weather (short term) have never been static- always shifting and trending. "Normal" of a shifting system is based on running average that changes over time. If the climate/weather were to remain static, THAT would be very abnormal! Change is what is normal. A 30-year period is relatively short, and it appears that NOAA adjusts every decade, not annually, so when it does shift it seems like more than it actually is were you to adjust annually . I think the term "normal" is misleading when talking about climate or weather.

Annual weather, which is not climate, does not have a normal distribution. You have wet years and dry years, hot years and colder years. The "average" snowfall may be less likely any given year than either higher than average and lower than average. Personally I do not get to hung up on percent of normal. Just look back at photos of ski areas or mountains in the 1920's or even 1950's and compare to now and it becomes very obvious what is happening and that "normal" is pretty meaningless.

[frozenintime]

“climate normals” is what the NOAA scientists call it — in this instance, it’s a technical term, not a value judgement by me or the quoted author.

i’m no expert, but in our age of relatively rapid anthropogenic climate change, 30 years may be a more meaningful time frame to look at than in the past.

as it relates to snowpack, an increasing amount of mountain precipitation has been falling as rain instead of snow. given the very slow global transition away from co2, it is unlikely that this trend will reverse anytime soon. i thought the downward trend of the new “climate normals” was interesting in this regard.

[Wandering Daisy]

Here is my take on all this. Someone better at statistics than me certainly can chime in. I am not sure I am explaining this very well or if I am completely correct.

To the lay person "normal" is what you would expect most of the years, based on data with a bell-curve normal distribution. The NOAA "normal" is really more of a mean over 30 years. It is like if you have a lot of rich people and similar number of poor people, the mean would be a middle class person, even if the chance that any person is middle class is low. Sierra snowpack, regardless if the underlying trend will jump from high snow years to low snow years and any given year is likely to be quite different (more or less) from NOAA's "normal". NOAA defines their definition very well, but I think most people will think, "Oh, this is what were are supposed to have most years." Then weather does what it does- fluctuates between dry and wet years with very few close to "normal". Underlying the fluctuations is a trend that is slowly going towards less snow. I just think if they called it "mean" instead of "normal" it would be less confusing.

And with computers nowadays I do not see why they do not use a running mean and recalculate every year. It probably gives a better view of the underlying trend.

[gary c.]

Mountain tops that used to be at the bottom of an ocean. Deserts that once were vast jungle forests. Ancient cities under the oceans. Elephants that used to roam the far northern hemisphere. But our conditions today are because of an exact cause or causes that someone can define with such certainty. And they can spend there entire life telling you how to fix it. All while gaining notoriety and fortune.

[rlown]

Basically, live for the moment.. Every eon is different. We could freeze over or turn back to molten rock. Personally, not listening to the politicians. I'll never buy an EV. Look at how many batteries you think you "recycle." An EV car battery pack lasts for 9 years tops.

[c9h13no3]

Mountain tops that used to be at the bottom of an ocean. Deserts that once were vast jungle forests. Ancient cities under the oceans. Elephants that used to roam the far northern hemisphere. But our conditions today are because of an exact cause or causes that someone can define with such certainty. And they can spend there entire life telling you how to fix it. All while gaining notoriety and fortune.

Basically, live for the moment.. Every eon is different. We could freeze over or turn back to molten rock. Personally, not listening to the politicians. I'll never buy an EV. Look at how many batteries you think you "recycle." An EV car battery pack lasts for 9 years tops.

Somehow I knew this thread would end up here...

[frozenintime]

lol that was my fear too, c9.

[c9h13no3]

To sum up this thread:

Frozen: The way we define an average snow year is changing.
Russ: I'M NOT BUYING AN ELECTRIC CAR!!1111

[rlown]

To really sum it up:
We have container ships that run on bunker oil sitting off shore waiting to unload when the truckers are in short supply. Truckers can't afford the increased diesel overhead.
We have a Government that wants to move out of fossil fuel, even though it is necessary to move goods and our companies moved manufacturing offshore to save money.
There isn't enough charging stations so you have to layer the migration from fossil fuels which isn't going to happen.
We were capable of being fossil fuel self-sufficient.

Climate is climate. Changes from year to year. Go figure. We keep offshoring stuff to China and India, and they burn A LOT of fuel.
The US isn't clean in this deal.