Global Warming on Mars and English Wine
Mar. 6th, 2007 09:19 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
chris_gerribI read a number of blogs, including Jerry Pournelle's blog "Chaos Manor." Now, Jerry is a smart man, with the degrees in aerospace engineering to prove it. On his blog, he asks two questions about global warming. First, he asks "why is the Martian ice cap shrinking?" and second, "didn't they used to make wine in England?" The implications of both of these questions is that at least some global warming is caused by solar or other non man made effects. So I decided to do some research.
First, I Googled "Martian ice caps." A number of hits came up, enough to convince me that there was something to it. Then I dug a little bit deeper. It seems that most if not all of the shrinkage observed was from the southern hemisphere. This is significant. The southern ice cap is almost all CO2, which sublimates, and the ice cap is very shallow there. Also, the terrain in the southern hemisphere is weird, even by Martian standards. The southern ice cap is not centered on the pole, but offset, due to permanent high and low pressure zones caused by the massive elevation changes. In short, the southern ice cap is unstable, and generally will fluctuate wildly. See realclimate.org for a good summary.
Jerry's next question, raising grapes in England, is somewhat more obscure. this site mentions that there were 46 vineyards in England circa 1100, but almost none by 1500. There does appear to be some climatic root to this - all the vineyards listed were no more then 50 kilometers north of London. 1500 is about when Henry VIII abolished the monasteries (which were major wine producers) but it is also towards the middle of the Little Ice Age. Realclimate's article on this subject is rather snippy, but generally doesn't dispute the fact of wine production.
What does this all mean? Well, I don't think we can rely on Martian glaciation to get clues as to Terran climate. The "wine in England" data point seems suggestive that the Medieval Warm Period was real. What it doesn't tell us is what's causing this warm period.
First, I Googled "Martian ice caps." A number of hits came up, enough to convince me that there was something to it. Then I dug a little bit deeper. It seems that most if not all of the shrinkage observed was from the southern hemisphere. This is significant. The southern ice cap is almost all CO2, which sublimates, and the ice cap is very shallow there. Also, the terrain in the southern hemisphere is weird, even by Martian standards. The southern ice cap is not centered on the pole, but offset, due to permanent high and low pressure zones caused by the massive elevation changes. In short, the southern ice cap is unstable, and generally will fluctuate wildly. See realclimate.org for a good summary.
Jerry's next question, raising grapes in England, is somewhat more obscure. this site mentions that there were 46 vineyards in England circa 1100, but almost none by 1500. There does appear to be some climatic root to this - all the vineyards listed were no more then 50 kilometers north of London. 1500 is about when Henry VIII abolished the monasteries (which were major wine producers) but it is also towards the middle of the Little Ice Age. Realclimate's article on this subject is rather snippy, but generally doesn't dispute the fact of wine production.
What does this all mean? Well, I don't think we can rely on Martian glaciation to get clues as to Terran climate. The "wine in England" data point seems suggestive that the Medieval Warm Period was real. What it doesn't tell us is what's causing this warm period.
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no subject
Date: 2007-03-08 01:51 am (UTC)Depends on what is causing Martian glaciation. I think the general thrust of that argument is that the sun may (or may not) have a great deal to do with the global warming/cooling cycle.
no subject
Date: 2007-03-08 02:51 pm (UTC)no subject
Date: 2007-03-11 05:23 pm (UTC)1. Glastonbury Abbey used to be surrounded by water. It isn't anymore.
2. Norwich (England) was a seaport circa 1200.
I'm no expert, and I don't have good data, but if true, these suggest sea levels at least 20-30 feet higher than they are now. And again, I don't have good data, but I'm guessing that that would require the melting of most or all of the Greenland and Antarctic ice. (Sea ice does not affect global sea levels.)
Much opportunity for research here, though I am extremely dubious. One would think that in ancient coastal cities we'd have some record of the rising and falling of average sea levels of that magnitude. Venice would be an excellent benchmark, but I see nothing mentioning it.
no subject
Date: 2007-03-11 05:59 pm (UTC)Historical Norwich (http://www.historicalnorwich.co.uk/index.htm) suggests that the river Wensum was and is partially tidal and navigable. At what draft it doesn't say.
Part of the problem with this discussion is alarmism. Al Gore's movie notwithstanding, the official global warming gurus, the Intergovernmental Panel on Climate Change (http://www.ipcc.ch), are only calling for at most half-a-meter of sea level rise by 2100. Although this may screw up some beachfront property, Manhattan will not become the new Venice.
The IPCC's report (http://www.ipcc.ch/SPM2feb07.pdf) (PDF, 18 pages, reasonable facsimile to English) says "If a negative surface mass balance were sustained for millennia, that would lead to virtually complete elimination of the Greenland ice sheet and a resulting contribution to sea level rise of about 7 meters." (Emphasis mine).
One key factor in sea level change (and probably a reason we didn't see much during the Medieval climate shifts) is that it takes a long time to melt or freeze enough water to make a big change.
Why wine and martian polar ice caps matter
Date: 2007-04-07 08:16 pm (UTC)The southern ice cap of mars may be unstable but so are our ice caps in certain respects. The fluctuations in pack ice from winter to summer at both poles are large (huge in fact). This visual instability is similar to the instability of the southern pole on Mars. Both have been very consistent in their instability. If we see a coincident change in two very weakly coupled systems whose only common component is their input from the rest of the solar system and this input is vastly dominated by solar radiation, then it is very likely that this input is causing both changes as opposed to independant changes within each system. Martian glaciation gives us clues as to the source of most energy within the Terran climate.
The Medieval Warm Period, MWP, is supported by ice cores, tree rings, historical context, you name it, as well as "wine in England" (and Greenland). The MWP is not really in debate, what is is the global temperature at this time. The MWP also coincides with the flourishing of many cultures from Aztec and Mayan to Mediterranean and Norse.
Sea level rise using any specific site is weighted heavily by geology as opposed to actual water in the ocean basins. New Orleans and Venice would otherwise imply that the sea levels have been rising throughout the history of the cities. The land that these cities rest on is sinking. These and other cities actually go to show how well mankind has always dealt with changes in sea level, actual or apparent.
The modern doomsday cult of global warming alarmists has spun possible trends in climate into "compelling reasons" to pay more taxes and except more totalitarian regulations in our daily lives.
The world is becoming more conducive to life as we know it, oh no we're all going to die!
Re: Why wine and martian polar ice caps matter
Date: 2007-04-08 04:41 pm (UTC)