climate change · climate science · Politics · Rhetoric

Satellites vs. Thermometers? They Are Both Tools to be Used

I play guitar. Okay, I used to play guitar. The question of “which is best” is a longstanding battle. Les Paul vs. Stratocaster? Humbucker vs. Single Coil? Active vs. Passive pickups? Light versus heavy strings? Tube vs. solid state amp? My standard rig is a Les Paul with dual passive humbuckers playing .11 strings through a solid state amp. This is the best rig setup.

“But Pro,” you say. “The Les Paul is heavy.” Yes, that’s why I like it.  The sound is lush and the resonance maintained. Nigel Tufnel himself marveled at the sustain. “But the neck on the Les Paul is beefy!” Yes. I’m 6’2″ and it’s just right. ” “Single coils give better attack.” I like the full sound of my humbuckers.  “A solid state doesn’t give that distortion at high volume.” Yeah. Stays clean no matter how loud.

What I think is best and what others think is best comes down to opinion. Period.

There are plenty of other topics open for this debate.  Let us take a look.  Aspirin versus ibuprofen.  Screws versus nails. SUVs versus subcompacts. Cleats versus sneakers. Oils versus watercolors. Steel versus wood. Propeller versus jet.

Ah, yes.  Satellite temperature readings versus land-based thermometers. The famed battle ground in the climate war.

Only in Climate Debates do People Try to Dismiss Tools

I’m an outsider looking in for the last decade, but I am actually pretty shocked at way that the climate sides have aligned to disparage either satellite temperatures or thermometer temperatures.  The reason is pretty simple: satellites don’t show the same rate of warming as do thermometer readings.  Thus, the deniers say that thermometers can’t be trusted and should not be used. And the alarmists say that satellites can’t be trusted and should not be used.

Some say that satellite data is the best we have. Others say thermometer readings are the best we have.  I say, “They are both tools, each have their own strengths and weaknesses, and neither should be dismissed off hand.” Each can show their own things and serves different purposes.

Thermometers versus Satellites – Each Have their Positives and Negatives

On one side, there are those proponents of the thermometric readings. People have a natural understanding of thermometer readings, because they are something that pretty much everybody has seen and used. There are thousands of thermometers placed throughout the US and the world. The job of this network of thermometers is to tell the temperature.  Put simply, when I walk into a room, I check a thermometer to discover the temperature.

Thermometers, however, have their limitations. The key limitation is that a thermometer can only measure the temperature where it is. While the temperature may be 60 degrees in one location, it may be 62 degrees a couple of miles away.  Even though it gives a good idea of what is going on in the locality it does not provide total accuracy. With enough thermometers, though, placed closely enough, can give a much more accurate idea of what is going on area-wide by smoothing out the results. Further adjustments are necessary in order to homogenize data for time of measurement and adjustments to changes in thermometer systems.

Add to the equation satellite data. Satellites measure temperature but in a slightly different way: they measure microwave radiance off of O2 in the atmosphere. The temperature is then inferred from those measurements. (Same with ground based thermometers: temperature is measured nowadays by changes in electrical resistance). In some ways, satellite temperatures require more adjustment and factoring than do ground based thermometrics.

On the other hand, satellite data does provide truly global coverage.  Thermometer sites are very sparse in some areas of the world.

ghcn_allstations

The US and Europe have some fairly good coverage, as well as other spots in Asia and Australia.  Despite this, large swaths of sparse data are clearly visible.  This particularly relates to the oceans, the Amazon basin, Central Australia, most of Africa, and the far northern latitudes. Ironically, places like the Greenland and Siberia are the spots where the CO2 signal would be strongest. Antarctica has some decent coverage on the Peninsula but inland temperatures are pretty much unknown to ground-based instruments.

Some data sets deal with these gaps by smoothing.  They take the readings of thermometers and average them out. It’s a sensible approach – if one measured the temperature at Huntington Beach Pier and then measured the temperature at Seal Beach Pier, one would think that in between the two the temperature could be fairly easily gleaned.

The problem comes when smoothing distant stations.  Sure, one can try to smooth the temperature reading between Nord, Greenland and the Petermann ELA.  But the smoothing becomes difficult when attempting to infer what was happening in Gertrud Rask Land. Some data sets do interpolate, such as NASA GISS and NOAA MLOST. Others do not smooth, such as HADCRUT4.

Which is better?  Interpolation or non-interpolation?  The answer is neither. One of the key strengths of HADCRUT4 data is that it does not smooth beyond a grid box average. One of the weaknesses of HADCRUT4 is that is does not smooth beyond a grid box average.

Wait. So what may be viewed as a strength may also be viewed as a weakness?  Sure.  Some may value the GISS data because it smooths and paints more of an overall picture. On the other hand, some may prefer the uncertainties to be explicitly shown, as HADCRUT4 does.

So Which is Better? Thermometers or Satellites?

Neither.  Which is better? A hammer or a screwdriver? Depends on what you want. Want to take a look at temperature data?  All the data sets are tools that can be used to provide a picture.  If a carpenter wants to build a redwood deck, would carpenters argue over whether to use screws or nails?  No, they would not.  They would use BOTH.  They’d use nails for the structural framing. They’d use screws to fasten the deck slats to the framing.

If one dismisses thermometric readings off hand, I’d place money that the readings aren’t showing what you expect. When the thermometers don’t meet a person’s subjective expectations, that person will find whatever is necessary to cast doubt on that data set, right down to accusing the data compilers of fraud. (There is more on that later).

The same is true for satellite data.  Satellite data was fine back in 1999, when both RSS and UAH showed 1998 to be the warmest year on record – by far.  In agreement with land-based instruments.  It was when divergence occurred that the real campaigns started mounting.

I would think it would be preferable to use all tools available to paint the picture.  Whichever is “best” for one might not be “best” for another.  Each person places value on what they think is important and what matches them.

Both satellites and ground-based thermometers show a long-term warming trend.  On this they agree.  Why is that not enough? The reason is because there are politics and rhetoric at work. When something does not show what a person wants to see, it is discounted.  Or attacked.

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