Our directory of things of interest

University Directory

Prehistoric caves provide clues to climate change

Stalagmites provide a clue to historic climate conditions Stalagmites provide a clue to historic climate conditions wjarek
31 Jul
2015
Underground water movement in caves reveals climate action above

When water seeps into the ground it picks up minerals, usually calcium carbonate. This mineral-rich water can drip into caves, leaving mineral deposits behind. These deposits can be dated through radioactive decay.

Variation in the thickness of layers can tell researchers how much precipitation occurred over time. With one more twist, using the ratios of heavy to light isotopes of oxygen present in the layers, researchers can find the temperature at which the water originally condensed.

Researchers have used the technique to examine the Mawmluh Cave in the Indian state of Meghalaya, an area thought to be the rainiest place on Earth. The technique helped to establish a relationship between monsoon rainfall and sea surface temperatures in the Pacific Ocean, known as the El Niño Modoki.

‘Now that we have shown that the Mawmluh cave record agrees with the instrumental record for the last 50 years, we hope to use it to investigate relationships between the Indian monsoon and El Niño during prehistoric times such as the Holocene,’ says Jessica Oster, a researcher who worked on the project.

The Holocene saw a period of global climate warming around 6,000 to 9,000 years ago. Temperatures were four to six degrees higher than today, around the increase predicted if human-caused global warming continues unchecked.

Understanding the historical monsoon patterns could help researchers predict how it will change in the future. The monsoon provides the area with 75 per cent of its annual rainfall.

The researchers used stalagmites with high concentrations of uranium for the analysis, including columns that had probably broken off in an 8.6 magnitude earthquake that hit Assam in 1950. The new stalagmite growth was perfect for analysis.

Related items

Subscribe to Geographical!

geo line break v3

Free eBooks - Geographical Newsletter

Sign up for our weekly newsletter today and get a FREE eBook collection!

geo line break v3

University of Winchester

geo line break v3

EDUCATION PARTNERS

Aberystwyth University University of Greenwich The University of Derby

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

DOSSIERS

Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

  • Natural Capital: Putting a price on nature
    Natural capital is a way to quantify the value of the world that nature provides for us – the air, soils, water, even recreational activity. Advocat...
    The human game – tackling football’s ‘slave trade’
    Few would argue with football’s position as the world’s number one sport. But as Mark Rowe discovers, this global popularity is masking a sinister...
    Essential oil?
    Palm oil is omnipresent in global consumption. But in many circles it is considered the scourge of the natural world, for the deforestation and habita...
    The green dragon awakens
    China has achieved remarkable economic success following the principle of developing first and cleaning up later. But now the country with the world's...
    The air that we breathe
    Cities the world over are struggling to improve air quality as scandals surrounding diesel car emissions come to light and the huge health costs of po...

MORE DOSSIERS

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Wildlife

Bonnethead sharks, the second smallest member of the hammerhead family,…

Nature

There’s more than enough plastic in the world. That’s why,…

Wildlife

The recent discovery of more than 200 million termite mounds…

Geophoto

The new year still remains a popular time to set…

Wildlife

After decades battling environmental crises that threaten to rob the…

Climate

As another new year beckons and the fight to protect…

Geophoto

A half century has passed since the ‘Earthrise’ photograph – widely believed to have…

Wildlife

Are howler monkeys being adversely affected by ingestion of pesticides containing…

Tectonics

Why unprepared tourists are putting themselves at risk in order…

Geophoto

The majestic and mighty polar bear is in danger of…

Wildlife

Exciting news for wildlife and photography enthusiasts alike – the…

Wildlife

A new system of robotic aerial vehicles is revolutionising the…

Wildlife

Technology used in creating safe urban environments is now being…

Climate

Brazil’s shift to the right of the political spectrum could…

Wildlife

Laura Cole travels to Orkney to find out why numbers…

Wildlife

The unprecedented frequency of winter tick epidemics have resulted in…

Oceans

Ocean debris, mostly composed of plastic, reaches remote Atlantic islands…

Geophoto

With motion detectors becoming ever more sophisticated, and clearer, crisper…

Nature

Natural capital is a way to quantify the value of…

Tectonics

The reason for the unusual location of Mount St Helens…