On the 24th of July, 2012, Murry Salby gave a talk at the Sydney Institute. He makes a large number of claims in the talk, some of which are even true, while some merely misrepresent the science. Of these, one the worst is his discussion of the relative contribution of CO2 (and other long lived greenhouse gases) to the greenhouse effect. Another is his continued misunderstanding of what has caused the modern increase in CO2 concentrations. I will be ignoring these, and other, errors. In this post I focus only on a misrepresentation that cannot be explained by inadequate knowledge, or simple misunderstanding.
Friday, April 5, 2013
Reposted from Skeptical Science.
The human-caused origin (anthropogenic) of the measured increase in atmospheric concentrations of CO2 is a cornerstone of predictions of future temperature rises. As such, it has come under frequent attack by people who challenge the science of global warming. One thing noteworthy about those attacks is that the full range of evidence supporting the anthropogenic nature of the CO2 increase seems to slip from sight. So what is the full range of supporting evidence? There are ten main lines of evidence to be considered:
- The start of the growth in CO2 concentration coincides with the start of the industrial revolution, hence anthropogenic;
- Increase in CO2 concentration over the long term almost exactly correlates with cumulative anthropogenic emissions, hence anthropogenic;
- Annual CO2 concentration growth is less than Annual CO2 emissions, hence anthropogenic;
- Declining C14 ratio indicates the source is very old, hence fossil fuel or volcanic (ie, not oceanic outgassing or a recent biological source);
- Declining C13 ratio indicates a biological source, hence not volcanic;
- Declining O2 concentration indicate combustion, hence not volcanic;
- Partial pressure of CO2 in the ocean is increasing, hence not oceanic outgassing;
- Measured CO2 emissions from all (surface and beneath the sea) volcanoes are one-hundredth of anthropogenic CO2 emissions; hence not volcanic;
- Known changes in biomass too small by a factor of 10, hence not deforestation; and
- Known changes of CO2 concentration with temperature are too small by a factor of 10, hence not ocean outgassing.
Reposted from Skeptical Science.
Heating and Heat Flow
Some physics, everyone knows. In our daily lives we encounter the effects of physics all the time, and as a result, we know what physics predicts in those circumstances at a gut level. We may not be able to put it into numbers. We may not be able to apply it in novel situations. But we know it all the same.
One example is as simple as putting on a blanket. We know that if we want warm something up, we can increase the supply of heat - or we can reduce the escape of heat. Either is effective. If you have a pot that is simmering and you want to bring it to the boil, you can turn the heat up, or you can put on the lid. If we put on the lid, the pot will go nicely from simmering to boiling, and we don't need to turn up the heat even slightly. Indeed, if we are not careful to turn down the heat, the pot may well boil over.
Likewise, if you have two identical motors running with an identical load and speed (Revolutions Per Minute), one with the water pump working and one without, we are all physicist enough to say that the second one will run hotter. It does not matter that the energy supplied as fuel is identical in both cases. The fact that heat escapes more easilly with water circulating through the radiator will keep the first cooler. The consequence is that stopping the the water from circulating will lead second motor to disaster.
Nor do we find people who doubt this. Suppose somebody told us their water pump was broken, but that the Second Law of Thermodynamics prohibited transfer of heat from a cooler place (the water) to a hotter place (the engine block), so they'ld be fine so long as they didn't rev any faster than normal, we'ld look at them in complete disbelief. Or we would if we were too polite to burst out laughing. And if they set out cross country confident in their belief, it doesn't matter what destination they claim they're heading for. Rather, as we all know, they're really heading for a breakdown!