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gathering data to test global warming |
a briefing document |
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tracking and measuring global warming is not as easy as cribbageAlmost every day, articles and claims are made that this proves or disproves global warming, written or made by people who have not the slightest idea of how complex the studies are. Below, in sections 3 and 4, I refer to two local studies which, as you will see, are being widely confused with ‘global warming’, pro or con. What is particularly amazing is the incredible dogmatism of the ignorant writers of these items. Yet more examples of the arrogance of ignorance. The next section gives some idea of the complexity of these studies, both parts being taken from today. Then we have a claim for a localised study in America, this week’s extreme example of the “it ain’t happening” tendency purporting to be global. Next there is an Asia-local example, which makes the contrary claim with the same error. the complexity of global warming studies
There are also claims around that nitrogen availability will have the reverse effect, and increase carbon uptake by plants.
And here is an example of what modern global measurement can do:
confusing local and global dataThe nonsensically titled “Revised Temp Data Reduces Global Warming Fever” is a particularly egregious example from an extremist site. Note that, in this article, the corrections referred to are only corrections to a USA limited, land level-based series. This is not global. (The USA is 1/50th of the world’s area, so is a ‘local’ planet area.) Also note that the article is describing how one lot of fudge factors have been replaced by another set, this time called ‘adjustments’.
The error was picked up by observing the discontinuity in the data, always a red flag that something needs careful checking. In this case, a Y2K error was identified. Despite widespread exaggeration, not only was this an extremely local and not very reliable data series, the correction amounted to approximately one one-hundredth of a degree over the most recent years! Such corrections are very common. For example, there was an earlier problem where deniers claimed that satellite measurements were not consistent with warming. These claims were found to be in error because the changes in satellite distance had been incorrectly assessed. This is not ‘exact’ science, but we are gathering better data from year to year, including such corrections as reported here. The consensus remains there is AGW.
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james hansen on jesters (useful fools) and irresponsible ceos This 5-page .pdf includes details on NASA US data adjustment and global
warming maps.
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on temperature and statisticsanother step to understanding antarctica
The map and text in the above item are unclear to the point of sloppy. Here is a more secure link from NASA Earth Observatory.
related material measuring temperatures - differences in method led to differences in temperature
related material
on temperature and statistics - commentaryIt is useful to recognise that there is no such thing as temperature outside of a real-world context. In general, if you put a thermometer into a glass of water, it will register a reading. That reading is due to the amount of emergy in the molecules of water bouncing around. If the water is heated, the molecules bounce around more quickly and the increased energy is registered as a ‘rise in temperature’. Now consider the glass of water. Despite appearances, it does not have a single temperature, but the temperature varies somewhat from place to place in the glass. As the temperature rises, this becomes more apparent, as can be seen in a pan of water roiling as it is boiling. Any temperature measuring device is, in fact, integrating an average measurement over time. This measurement, you may register as accurately as your eyes or measuring devices can discern. Measuring global temperature is a far more complex process, requiring measurements from all around the world and at many depths - from the top of the atmosphere to deep in the oceans, and even into the Earth. Even this is complicated by the fact that the interior of the Earth also generates heat [see comment at geothermal briefing document]. Choosing the definition for global temperature is no simple task. What statistical weight to do you give to land, to the atmosphere, or to the seas? Almost every day, I see reports confusing global with local temperatures which are, of course, also averages.
Recently, I have seen several reports suggesting that La Nina will cause a hiatus in the rises of global temperatures [black line]. However, if you look at the longer-term temperature predictions, you will see that the hiatus [green line] returns to trend line over a few years. In other words, it is not a slowing in global temperature rise, but merely an artifact of the way in which that particular temperature average is being calculated. Note, our measuring sophistication is growing rapidly, as are our technical means of obtaining local temperature samples (in this case, a sample means a single measurement). We now have satellites, ever-improving instrumentation and the means to put sensors in remote places. It is important to realise that our historic data and temperature surrogates are not as usefuly reliable as the latest satellite measurements. There, millions of readings can be taken daily, and the data (and the processing of that data by ever more powerful computers) is of a far higher order than the recordings made by some enthusiast. Such an enthusiast may have lived fifty or a hundred years ago in a city heat island, in a more advanced country, and without having available measurements from the poles, the broad oceans, or darkest Africa. It is critical to understand that today’s average does not necessarily correspond to an average designed and defined fifty years ago. Notice above, the contrast between the sloppy definitions in the first item, and compare them with the rather better definitions in the second item. related material
end notes
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© abelard, 2007,26 march the address for this document is http://www.abelard.org/briefings/gathering_data_to_test_global_warming.php 2500 words |
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