Cave temperature study could improve climate change predictions

Jun 05, 2014 by Ry Crozier
Cave temperature study could improve climate change predictions
Dr Mark Cuthbert inspects a speleothem in Wellington Caves. Credit: Martin S. Andersen

(Phys.org) —Researchers studying the hydrology of Wellington Caves in central NSW have made a discovery that challenges a key assumption used to reconstruct past climates from cave deposits.

Published in Nature's open access journal Scientific Reports, the research found that there can be a 1.5 degree Celsius difference between the temperature of the air in the and the drip water that forms the stalactite.

Stalactites and other cave formations – collectively known as speleothems – form when rainwater drips from the surface into the cave system, picking up minerals along the way that solidify once exposed to the cave air.

Scientists had previously assumed that speleothems formed at a temperature equal to the average temperature outside the cave and used this assumption to construct records of past climate variations, says lead author Dr Mark Cuthbert, holder of a European Community-funded Marie Curie Research Fellowship at UNSW's Connected Waters Initiative.

"However that assumption had never been tested," he says. "The 1.5 degree difference is very significant if you're looking at past climate change. It is similar to the kind of change in temperature that we've had in the last 12,000 years naturally during the Holocene."

The difference in is attributed to evaporative cooling, which occurs as the water moves along the cave wall before reaching the point at which it drips and forms the speleothem.

"If you were looking at a speleothem formed in that environment and didn't know this process of evaporative cooling was happening, you might jump to the wrong conclusions, in either direction, about what the climate outside the cave was like at the time the speleothem formed," says co-author Monika Markowska, a Research Scientist at the Institute for Environmental Research at the Australian Nuclear Science and Technology Organisation (ANSTO).

ANSTO researchers have developed expertise in modelling climate change using nuclear techniques such as neutron activation soil analysis and carbon 14 dating.

The research team also includes Professor Andy Baker, Director of the Connected Waters Initiative (CWI) and other CWI researchers.

The same researchers recently found that other important evaporative effects occur between the soil and the cave that also need to be taken into account when interpreting speleothems as records of climate change.

"Further experimental work is underway to investigate the influence of the geometry, orientation, the thermal properties of a particular formation, and the water film thicknesses, on the relative cooling rate," the researchers say in their paper.

Dr Cuthbert hopes that ongoing research will lead to numerical models that take into account all the different variables in a cave system that might influence calculations.

Speleothem chemistry is one of several methods used to reconstruct past climates alongside other techniques including sediments, ice cores, trees and corals. Caves can yield particularly high-resolution records going back several hundred thousand years.

Explore further: Long-standing climate paradox resolved

More information: "Evaporative cooling of speleothem drip water." M. O. Cuthbert et al. Scientific Reports 4, Article number: 5162. DOI: 10.1038/srep05162. Received 28 March 2014 Accepted 07 May 2014 Published 04 June 2014

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User comments : 6

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Frank_Lowe
1 / 5 (7) Jun 05, 2014
Earth is getting hotter from the inside.The polar caps is melting from the bottom up the sea is getting hotter from the bottom up.Please take note.
Torbjorn_Larsson_OM
5 / 5 (7) Jun 05, 2014
Nice check, but cave climat are bound to be rather stable. So likely it won't mean much contribution to variation in the data. As always, checks are good!

@Frank_Lowe: Unless you are trolling, I'll have whatever you smoke. No one is going to take your notes:

- Earth is slowly cooling down since its formation, and we know that from known mechanisms and the geological record.

- The current short time (in the geological context) climate models are consistent with a constant average heat flow through the plates.

- The oceans get most of their heat from atmosphere/solar irradiation as the rest of the surface, and observably more so with the GW increase.

- The ocean and water melt heat flow is what melts ice at the bottom, the melt sinks in cracks et cetera. A lot of melting is on top, see e.g. Greenland ices which lies above water surface.

- You don't have data, yet you post a claim.
JoeBlue
1 / 5 (4) Jun 05, 2014
More propaganda from the Climate Change committee eh?
malapropism
5 / 5 (4) Jun 05, 2014
More propaganda from the Climate Change committee eh?

Are you commenting on the comments or the article?

If the article, then no, you are wrong; there is no suggestion in the text that I can find to suggest that the data they are researching influences the climate change debate in a particular direction, in fact quite the reverse, the researchers seem correctly careful to specifically not presuppose an outcome: "... you might jump to the wrong conclusions, in either direction... ".

If you are referring to the comments, well, Frank_Lowe appears to be an idiot and/or a troll and Larsson (like the article researchers) has not proposed a direction for the results in their possible influence on climate change statistics, merely that that influence might be small given the probable relative stability of cave environments.

So what's *your* problem?
JoeBlue
1 / 5 (4) Jun 05, 2014
Hmm, so you are the self-appointed thought police here these days. Not a lot of traffic anymore, wonder why LOL!
malapropism
5 / 5 (2) Jun 12, 2014
Hmm, so you are the self-appointed thought police here these days.

Thought police? No, merely someone who actually thinks about things.
Not a lot of traffic anymore, wonder why LOL!

Don't understand this comment. Traffic where, by whom? This site seems to get it's fair share of traffic as far as I can tell, hence this comment seems not only pointless but also meaningless and incorrect...