Thursday - September 21, 2006

Category Image Global Warming. How do We Know?


There's one thing that always perplexes me about the people claiming there is global warming. No, it's not that the same movement used to claim global cooling. I understand that political agendas make little accommodation for consistency or fact. What I'm flummoxed by is, how do they measure global warming?

I read that the global temperature rises or lowers from time to time. How do you measure this, and how do you compare it to past measurements?

Let's start with the basics. What is the global temperature today? Oh, wait, that's too broad. Let's start with what is the average temperature in Austin, Texas today? How is that measured? Even that is too hard.

Click the drivel link to read more.

So, let's say that we can accurately measure the temperature of a specific point at a specific time. I think we have the technology to do this very reliably, so this is where I'll start.

In Austin, usually we hear of temperatures measured at the airport, at the national guard base in town, and at various other points of the city. I have no doubt that these measurements are correct when they are taken.

But Austin is a pretty big place compared to the number of measurements being taken. Often I will record a temperature several degrees different from what I hear on the radio, because I'm in a higher elevation, I'm on asphalt, or any other number of different reasons. There might be errrors in measurement, but I think it's clear that there are also variations across even one city.

I can't imagine that the people making up the global average temperature for a year take into account the variation across every few hundred meters.

But let's say that they do. In Austin and other large cities, we conceivably can take reliable measurements every few hundred meters in every direction. How do you compile all these measurements into usable data, or an average for the day? How much weight do you give to each reading? What if the peak of a hill is measured and the slopes are not?

Okay, my example is a bit harsh. I suspect that there are reasonable algorithms to get a fairly accurate measurement of areas of cities. But this must be done over a fairly continuous time, to take into account not only highs and lows, but the duration of the highs and lows.

I'm no meteorologist, but I question whether this is done consistently in most cities in the United States, but I've been to too many third world nations to even tolerate the notion that reliable and meaningful data is universally available even in just inhabited places.

Now what about outside the cities? I could be willing to believe that urban areas are saturated with temperature guages all tied into some big megalithic network. But I've been out in the woods often enough to know that there aren't many meteorlogical stations in many parts just outside of most cities. Terrain can vary dramatically, yet there is no systematic collection of temperatures. How can I reasonably believe that we know the variations of temperature?

Sure, we can assume some continuity of temperature between weather fronts (a front being essentially defined as a discontinuity in temperature and pressure, or so I would posit). But within those areas between fronts, the temperature tends to vary as well. We can make assumptions, but remember that they make claims that the global temperature has risen by fractions of a degree from year to year or over decades. The input comes from these measurements in cities and towns which can vary by several degrees easily. There is a statistical fallacy to claiming such trivial global changes based on data that cannot be measured locally to that degree of accuracy.

Now let's look at history. Massive data collection to the scale we see now was available only within the past hundred years, to be very generous. Before then, collection of temperature data was confined to populated areas (even more so than today) and was haphazard in reliability and consistency. How can we extrapolate changes in global temperature based on data from past centuries that is of marginal reliablity at times, and inconsistent coverage?

And before thermometers were invented our only evidence comes from archaeology or from plants and tree growth. This is good for what it can tell us, but I can't believe for a minute that the accuracy needed to define temperature to a degree, let alone tenths of a degree is even remotely possible, and again we have a pretty serious problem with coverage of the entire globe.

And with all these pretty fatal and obvious flaws, I still haven't even addressed how different areas should be weighted. Is the temperature over the ocean more significant than the temperature over a desert, for instance?

Really, what does it even mean to have an average global temperature? It's a nice number for some very coarse uses, but it can't possibly be of real value when splitting the hairs needed to make the wild claims made by people driven by political agendas.

Yes, I'm sure a climatologist can come and explain his algorithms and how his science has come to a complex understanding of weather, but part of good science is to understand the limits of your measurements. Every young student of science learns how important it is to understand the accuracy of your measuring device, be it a beaker or pipette or a yard stick. I am skeptical that anyone making these wild claims about average global temperature changes has taken this basic care, and are either charlatans or have been blinded by their own hubris and believe that their models can be valid.

Next time someone talks about global warming, remember that some of the theories may be plausible, but the state of our science and the need to take accurate measurements over vast areas of the world across vast spans of time, including pre-industrial history and indeed prehistory, are not capable of confirming the theories because they are not capable of measuring the required data.

Global warming may be true, it may be bunk. Since it is driven by politics and since people are making implausible claims about global temperatures, I tend to believe it is bunk.

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