Monday, July 09, 2012
Bimetal proxy?
A really dumb and half-assed thought, but maybe someone will derive a better idea from it.
Most of the proxies we use for reconstructing past temperatures are dubious. Tree rings are nearly worthless because they respond more to moisture than temperature. Isotope concentrations may be affected by cosmic rays, which also affect temperature.
Seems like it should be possible to find a natural 'recording thermometer'.
I'm imagining something like this:
A natural bimetallic strip, welded in a volcanic upwelling. Two streams of different metals are flowing together, and end up locked together when they cool.
Later, through tectonic movement, the strip ends up in the roof of a cave.
Caves are extreme low-pass filters for temperature, so the bimetal would respond on a seasonal basis.
When it's hotter, the bimetal would bend (let's say) to the left, opening a water channel on its right side slightly more. The water dripping through this channel would precipitate on a right-side stalagmite.
When it's cooler, the bimetal would bend to the right, opening a left channel slightly more, precipitating more on a left-side stalagmite.
By marking years and figuring the difference between the two stalagmites within each year, you could factor out overall wet and dry years.
The key idea is differential deposition. I doubt that a natural bimetal exists, but something else might create a similar effect that could be analyzed and exploited.
Most of the proxies we use for reconstructing past temperatures are dubious. Tree rings are nearly worthless because they respond more to moisture than temperature. Isotope concentrations may be affected by cosmic rays, which also affect temperature.
Seems like it should be possible to find a natural 'recording thermometer'.
I'm imagining something like this:
A natural bimetallic strip, welded in a volcanic upwelling. Two streams of different metals are flowing together, and end up locked together when they cool.
Later, through tectonic movement, the strip ends up in the roof of a cave.
Caves are extreme low-pass filters for temperature, so the bimetal would respond on a seasonal basis.
When it's hotter, the bimetal would bend (let's say) to the left, opening a water channel on its right side slightly more. The water dripping through this channel would precipitate on a right-side stalagmite.
When it's cooler, the bimetal would bend to the right, opening a left channel slightly more, precipitating more on a left-side stalagmite.
By marking years and figuring the difference between the two stalagmites within each year, you could factor out overall wet and dry years.
The key idea is differential deposition. I doubt that a natural bimetal exists, but something else might create a similar effect that could be analyzed and exploited.
Labels: Carbon Cult
¶ 5:45 PM
