The 1930s are no longer the hottest decade in US

HBS Guy

Head Honcho
Staff member

Zeke Hausfather
@hausfath

·
12h


We often look at monthly or annual climate datasets, but daily data matters a lot for studying extremes. Using
@BerkeleyEarth
daily homogenized gridded data, I took a look at how the number of daily maximum and minimum records has changed over time:
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Zeke Hausfather
@hausfath



Replying to
@hausfath
To calculate how the number of records have changed over time, I looked at when the record low and high daily temperature over the 1880-2019 period was recorded in each grid cell for each day of the year, resulting in 365 days * 5498 gridcell max and min records.

3:35 AM · May 26, 2021·Twitter Web App








Zeke Hausfather
@hausfath

·
12h


Replying to
@hausfath
If we look specifically at the contiguous US (e.g. excluding Alaska and Hawaii), we see a more pronounced set of 1930s daily maximum records corresponding to the dust bowl, but also see that the past decade (2010-2019) has set more daily maximum records.
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We also see what the idiot Booby cannot—there are fewer cold records in the last five decades. This is all for the contiguous states (i.e. excluding Hawaii and Alaska.) The 1930s were hot because they were the dustbowl years—draught and land mismanagement meaning there was no moisture to evaporate, taking up latent heat and so cooling the ground. Now it is AGW causing the heat records to zoom.
 

HBS Guy

Head Honcho
Staff member
More from the above thread:







Zeke Hausfather

@hausfath

·
13h


Replying to
@hausfath
If we look specifically at the contiguous US (e.g. excluding Alaska and Hawaii), we see a more pronounced set of 1930s daily maximum records corresponding to the dust bowl, but also see that the past decade (2010-2019) has set more daily maximum records.


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Zeke Hausfather

@hausfath

·
13h


Daily minimum temperature records have seen a decline in recent decades in both the global and contiguous US datasets.


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Zeke Hausfather

@hausfath

·
13h


If we look at the whole US, including Alaska and Hawaii, we get a slightly different picture. This is in large part due to the fact that Alaska is quite big, and has been warming quite rapidly in recent decades:


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Zeke Hausfather

@hausfath

·
13h


One caveat: this is an initial analysis and there may be bugs (indeed, I quickly deleted an earlier thread when I found one!). It also may be biased by changing availability of gridcells over time, though this will matter a lot more for the global than US analyses.


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Zeke Hausfather

@hausfath

·
13h


The
@BerkeleyEarth
homogenized gridded daily dataset can be found here:


Data Overview - Berkeley Earth
The datasets presented here have been divided into three categories: Output data, Source data, and Intermediate data. The Berkeley Earth averaging process generates a variety of Output data including...
berkeleyearth.org
 
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