Monday, July 24, 2017

Airbrushing Climate History

This day in 1935 saw the peak of the "Dust Bowl" years, at least as far as temperature was concerned. Chicago and Milwaukee set temperature records that have not been surpassed in the intervening 82 years.

Of course, all you read in the daily fish wrap is that each year is the HOTTEST EVER!  How does this happen?  Adjustments are made to the historical temperature databases:
There are two parts to the GHCN data: the raw temperature readings, and adjustments to the readings. The raw numbers are easy - they're just the instrument reported temperature for the weather station. Look outside your house at your thermometer - that's the raw data. Here Chez Borepatch, my thermometer says that it's 39°.

Adjustments are modifications to the readings, to "remove inhomogeneities" in the raw data. You (like me) may look at that and say Whiskey Tango Foxtrot are inhomogeneities? CRU helpfully provides an answer:
Most long-term climate stations have undergone changes that make a time series of their observations inhomogeneous. There are many causes for the discontinuities, including changes in instruments, shelters, the environment around the shelter, the location of the station, the time of observation, and the method used to calculate mean temperature. Often several of these occur at the same time, as is often the case with the introduction of automatic weather stations that is occurring in many parts of the world. Before one can reliably use such climate data for analysis of longterm climate change, adjustments are needed to compensate for the nonclimatic discontinuities.
OK, we don't want a jump in the historical record if you move a station or replace a thermometer with a better one.

But. All the Climatologists in the world will look at this data. How much do the adjustments change the results?

We don't know, but people are starting to look. They're starting to find that adjustments change the data a lot. They change the data so much that they show that the earth is warming when the raw data may show that it's cooling.

Let me say that again: Thermometers may be showing that the Earth is cooling, but adjustments to this data show a rapid temperature rise.
What don't get changed are the records.  Consider these:
Chicago - 1934
Milwaukee - 1934
New York State - 1926
Boston - 1911
St. Louis - 1954
USA lower 48 states - 1913
In fact, with all of this year after year of the HOTTEST YEAR EVER, no state has set a highest temperature record is more than 20 years.  In fact, most (39 out of 50) state highest temperature records were set quite long ago - over 50 years ago, sometimes as long ago as 1888 (!).

Stop and think about that - if the science were as settled as people say, wouldn't there be at least one state that set an all time high record recently?  What a strange warming that raises average temperatures but not record high temperatures.

In any case, if you look at unadjusted temperatures, the 1930s were considerably hotter than today.


William Newman said...

"What a strange warming that raises average temperatures but not record high temperatures."

FWIW, that is less strange than you might think. Pure greenhouse effect actually has a tendency like that --- a disproportionate amount of the warming is expected to show up at the coldest times. If I understand correctly this is most of what's going on the common experience in places with very low humidity and no cloud cover, where without the usual level of greenhouse, midnight tends to be surprisingly chilly compared to noon.

That said, I don't think it's a large enough tendency to explain away your observation about record temperatures, and I don't think the point you are making is off the mark. (Many things about CAGW advocates and historical temperatures --- not just the last century or so of actual thermometers and modern ad hoc undocumented adjustments and cherry picking of data from them, but fancy statistically insane motivated reasoning about what can be inferred from temperature proxies reaching back more centuries than that, and waving away what's known about historical fluctuations over similar periods --- make this chemistry Ph. D. tempted to bang his head against the wall until the pain stops.) I also don't know how many of the huge feedback terms that are used to make models with enormous CO2 sensitivity have the same show-up-at-the-coldest-times tendency as the basic first-order CO2 greenhouse term does. (But I think at least one such feedback term does seem to have that tendency --- CO2 warming is supposed to increase H2O content in the air, causing a secondary greenhouse effect.)

Borepatch said...

William, what I find unimpressive abut the greenhouse theory is that warming in colder seasons (or at night) is probably explained as well by Urban Heat Island effects from poor station siting. But UHI gets waved over (or worse, the adjustments to the historical data make UHI worse in older times than today).