- Climate scientists have been monitoring the climate above and within a cave in N Spain for three years.
- The results help to decode stalagmite chemistry and figure out what stalagmites can tell us about climate in the past.
- The scientists are now building a picture of rainfall throughout the last 12,000 years and what this can tell them about climate in West Europe.
Scientists have been decoding the climate information locked away in 12,000-year-old stalagmites from European caves.
These ancient rock formations have formed from rainwater that fell above the cave. This rainwater makes its way down through the soil and limestone bedrock before emerging at the cave ceiling as a drip.
Drip by drip, it falls onto the cave floor, forming a stalagmite and locking away information about the rainfall that fell, many years ago. But climate scientists need to ‘decode’ this information before they can understand what these stalagmites can tell us about climate.
“The monitoring of cave climate and hydrology allows us to understand how cave systems react to changes in climate and how modern cave formations [stalagmites] develop,” says lead-author Andrew Smith, an Isotope Geochemist with the British Geological Survey, UK.
“This knowledge helps us to accurately interpret chemical signatures preserved in stalagmites as they grow and ultimately use these records to deduce the extent of past climate change,” says Smith.
Studying underground to understand ancient climate
If you want to understand what the climate might have been like well before anyone had invented a thermometer or a rain gauge, then you need to look to nature’s own historians: Lakes, bogs, ice, corals, tree rings, all of these contain records of Earth’s past climate, as do stalagmites.
Smith and his colleagues are studying stalagmites that have been growing for the last 12,000 years in Cueva de Asiul, Northern Spain. They want to know if these stalagmites can tell them anything about the climate over this time, and specifically how the North Atlantic Ocean has been affecting western European climate over these long timescales.
To do this, they monitored the climate above (temperature and rainfall), and within the cave (temperature, CO2, humidity, chemistry of drip water) for three years to understand what climate information makes it into the cave as drip water.
Smith saw that the climate inside the cave is relatively stable, with only small variations in temperature and concentrations in the cave air CO2 throughout the three years of monitoring. What’s more, the rainwater took one year to go from the surface above the cave to the cave itself.
“In combination, these microclimatic conditions make this an ideal site for further work,” says Smith, who is now studying the chemistry of two stalagmites from this cave to see how rainfall has changed since 12,000 years ago, at the end of the Last Ice Age.
“These chemical records are very closely related to changes in the North Atlantic Ocean, suggesting a rapid atmospheric response to changes in Ocean conditions [over the last 12,000 years],” says Smith. [wp-svg-icons icon=”mug” wrap=”i”]
Time for a bit more? Read on…
Looking for more reading on this topic? First off, why not try reading the original open-access scientific article.
Check out the lead-scientist Andrew Smith’s research profile.
Feature Photo Credit: Flickr Nick Kenrick
Smith, A., Wynn, P., Barker, P., Leng, M., Noble, S., & Stott, A. (2016). Cave monitoring and the potential for palaeoclimate reconstruction from Cueva de Asiul, Cantabria (N. Spain) International Journal of Speleology, 45 (1), 1-9 DOI: 10.5038/1827-806X.45.1.1928