e pur si muove

…why not sketch where your recipient lives. If you’re in the UK, that is.

The Sun article about the incident reported:

[Paul Bates], 48, had forgotten the name of the town workmate Peter O’Leary moved to from Neath, South Wales, three years ago.

But he recalled Peter had pointed it out on a map. So he put a dot on a sketch of the South West Peninsula, wrote “somewhere here” and hoped for the best.

Amazingly the card arrived at Peter’s home in Bude, North Cornwall, nine days later

Here’s how the sketch fared with the actual location provided by Google Maps:

That’s a pretty darn good sketch!

This new year brings also a new resolve to write more about Science. Every Thursday, Elia Diodati will bring you a short writeup about science on the bleeding edge, fresh off the presses of the scientific literature. Why Thursday? Because two of the most prominent scientific journals, Science and Nature, roll off new weekly issues on Thursdays.¹

To kick off the inaugural Journal Club Thursday, here’s an article from today’s issue of Nature on how climate change helped destroy the Tang Dynasty. Sound dramatic? Let’s put this in context. Dynastic cycles are often characterized by incompetent governance, with dissent triggered in the immediate wake of natural disasters leading to displaced peasantry and crop failure. The Tang Dynasty collapsed in 907 AD² with the interregnum of the Five Dynasties and Ten Kingdoms.

Now back to the science. Climate scientists at the Geoforschungszentrum (Geosciences Center) in Potsdam, Germany and at the Chinese Academy of Sciences wanted to investigate climate change in China. They basically dug up³ sediment deposits of Lake Huguang Maar⁴ in the Leizhou Peninsula of Guangdong Province and looked at the chemical composition and physical markers of climate change.

The scientists looked at three channels: titanium composition, and two types of magnetic properties.⁵ The titanium levels were used to calibrate their data with previously dated core samples from other parts of the world, which indirectly reflected the levels of wind activity. (Titanium is more common in land soil than lake silt.) The magnetic data allows the direct measurement of wind activity since the level of oxidized minerals from surface soil deposited into the lake by wind would alter the magnetic data.

Their results show that the eighth through tenth centuries AD, winter monsoons were abnormally strong while summer monsoons were weaker than usual. The authors conclude that the climactic anomaly in the physical and chemical data can only be explained by significant climate change. Specifically, they speculate that the position of the Intertropic Convergence Zone, i.e. the doldrums, shifted markedly during this time. Why is this a big deal? Because most of the world’s cyclones/hurricanes are formed in the ITCZ. Imagine if the tropical thunderstorms that used to drop by your part of the world every winter suddenly decided to go somewhere else. Yep: droughts, crop failure, and widespread famine. Sounds like the seeds of peasant rebellion to me, especially when you mix in the growing decline in bureaucratic effectiveness.

It’s always cool to read about this kind of natural skulduggery whereby ancient events can be reconstructed from indirect, yet telltale, evidence.

Here’s the opening paragraph from the Nature website:

The Asian–Australian monsoon is an important component of the Earth’s climate system that influences the societal and economic activity of roughly half the world’s population. The past strength of the rain-bearing East Asian summer monsoon can be reconstructed with archives such as cave deposits, but the winter monsoon has no such signature in the hydrological cycle and has thus proved difficult to reconstruct. Here we present high-resolution records of the magnetic properties and the titanium content of the sediments of Lake Huguang Maar in coastal southeast China over the past 16,000 years, which we use as proxies for the strength of the winter monsoon winds. We find evidence for stronger winter monsoon winds before the Bølling–Allerød warming, during the Younger Dryas episode and during the middle and late Holocene, when cave stalagmites suggest weaker summer monsoons. We conclude that this anticorrelation is best explained by migrations in the intertropical convergence zone. Similar migrations of the intertropical convergence zone have been observed in Central America for the period ad 700 to 900, suggesting global climatic changes at that time. From the coincidence in timing, we suggest that these migrations in the tropical rain belt could have contributed to the declines of both the Tang dynasty in China and the Classic Maya in Central America.

Source: G. Yancheva, N. R. Nowaczyk, J. Mingram, P. Dulski, G. Schettler, J. F. W. Negendank, J. Liu, D. M. Sigman, L. C. Peterson, and G. H. Haug, Influence of the intertropical convergence zone on the East Asian monsoon, Nature, 445 (2007), 74-77.

1. While I will be trying my best to provide references, the unfortunate reality is that most journals will require paid subscription access to the actual articles. If you are a university student or staff member, your university should be able to provide access in one form or other.↩
2. Tang Dynasty: Fall of the Tang Dynastry, Wikipedia↩
3. To be precise, they took core samples of the sediments. But that’s the general idea.↩
4. A reasonable question to ask is, why Lake Huguang Maar? Two reasons. First, it’s the first part of China to be contacted by the winter monsoons, which scientists previously had very little data on. Second, climate data showed that the sediment deposition processes in this lake happens to be almost entirely determined by wind blowing sand and silt into the lake, over and above other natural processes such as decomposing plant matter, etc.↩
5. Specifically, the susceptibility, and something called the S-ratio.↩