Falling sea level caused volcanos to overflow

July 7, 2017
Model of an island volcano. During the last transition to glacial conditions the decreasing pressure at the seafloor could have induced increased lava- and carbon dioxide emissions. Credit: Jörg Hasenclever

Throughout the last 800,000 years, Antarctic temperatures and atmospheric carbon dioxide concentrations have showed a similar evolution. However, they were different during the transition to the last ice age—approximately 80,000 years ago, temperature declined while the carbon dioxide content of the atmosphere remained relatively stable. An international research team led by the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Research has now discovered that a falling sea level may have caused enhanced volcanic activity in the ocean, which can explain the anomaly. The results are published today in the journal Nature Communications.

Climate evolution shows regularities that can be traced throughout long periods of Earth's history. One of them is that the global average temperature and the concentration in the atmosphere usually go hand-in-hand. Generally, if the temperatures decline, the CO2 values also decrease, and vice versa.

However, there are exceptions. An international team of scientists led by the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Research has now discovered a possible cause for such irregularities. An example is the last transition to glacial conditions. At approximately 80,000 years ago, the temperatures declined, but the amount of carbon dioxide in the atmosphere remained relatively stable for several thousand years. The reason could be enhanced volcanic activity in the oceans induced by a falling sea level. The study is being published today in the journal Nature Communications.

During the development of glacial conditions, temperatures decrease and ice sheets form, resulting in the redistribution of water from the to continental regions. Thus, the sea level falls and the pressure on the seabed underlying crust decreases, which enhances magma production.

"To better understand and quantify these processes, we developed a comprehensive computer model that we integrated with geodynamic data. In addition, we analyzed paleo-climate data and carried out simulations with a model of the global carbon cycle," says Dr. Jörg Hasenclever, the lead author of the study. The study investigated the response of mid-ocean ridges and of 43 ocean island volcanoes to glacial sea level changes.

"Our approach has shown that the decreasing pressure at the seafloor could have induced increased lava and . The enhanced volcanic dioxide flux may have stabilized the concentrations during the climate system's descent into the last ice age," says Prof. Dr. Lars Rüpke of GEOMAR.

The investigations suggest that close interactions between the Earth and the climate system exist on relatively short geological time scales of about 5,000 to 15,000 years. Co-author Dr. Gregor Knorr of the Alfred-Wegener-Institute says, "Such interactions could provide a novel component for earth system research to better understand the climate evolution at times of glacial changes."

Explore further: Team takes temperature to determine cause of Ice Age

More information: Jörg Hasenclever et al, Sea level fall during glaciation stabilized atmospheric CO2 by enhanced volcanic degassing, Nature Communications (2017). DOI: 10.1038/NCOMMS15867

Related Stories

Team takes temperature to determine cause of Ice Age

June 13, 2017

New research by Simon Fraser University professor Karen Kohfeld and University of Tasmania professor Zanna Chase, published in the journal Earth and Planetary Science Letters, examines how the ocean pulled carbon dioxide ...

Climate instability over the past 720,000 years

May 3, 2017

A research group formed by 64 researchers from the National Institute of Polar Research, the University of Tokyo, and other organizations has analyzed atmospheric temperatures and dust for the past 720,000 years using an ...

CO2 was hidden in the ocean during the Ice Age: study

March 29, 2012

Why did the atmosphere contain so little carbon dioxide (CO2) during the last Ice Age 20,000 years ago? Why did it rise when the Earth's climate became warmer? Processes in the ocean are responsible for this, says a new study ...

Recommended for you

New Amazon threat? Deforestation from mining

October 18, 2017

Sprawling mining operations in Brazil are destroying much more of the iconic Amazon forest than previously thought, says the first comprehensive study of mining deforestation in the world's largest tropical rainforest.

Scientists determine source of world's largest mud eruption

October 17, 2017

On May 29, 2006, mud started erupting from several sites on the Indonesian island of Java. Boiling mud, water, rocks and gas poured from newly-created vents in the ground, burying entire towns and compelling many Indonesians ...

7 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Nik_2213
3 / 5 (2) Jul 07, 2017
So oceanic volcanism is enhanced by lowered sea-level during ice-ages ? Will this off-set continental volcanism reduced by the pressure of miles-thick ice-caps ? What of transitional phase when ice-caps thaw, massive glacial lakes drain, central isostatic rebound reaches 5~10 cm per century and the peripheral bulge sags at about half that rate ??
https://en.wikipe..._rebound
RealityCheck
1 / 5 (2) Jul 09, 2017
@Nik_2213.

Look up Earth crust subduction boundaries, ie, "Ring of Fire"; and crust spreading boundaries, ie, "Mid-Ocean Ridges". :)

You'll note that these produce eruptions across the undersea 'chains' which straddle huge distances, and combined eruptive contents can greatly dwarf all on-continent' volcanic eruption zones combined!

So imagine the great on-continent ice ages locking a LOT of water on-continents which PRESSED DOWN onto the underlying Earth crust/magma layers! The weight of all that same water was REMOVED from the undersea subduction/spreading zone 'lines'; which then were freed to spew gargantuan amounts of magma and gases, which released huge quantities of CO2 etc, which eventually caused the atmospherically driven warming process that ended each great ice age. This is a simplistic summation, because the process would have been 'stepped'; with transient periodic 'volcanic winter' episodes caused by volcanic dust in atmosphere.

But you get the gist. :)
betterexists
3 / 5 (2) Jul 09, 2017
Currently, too much attention is bestowed on preserving Nature, unnecessarily. Yes, it has to be preserved, but not to the extent it is done today. For example, look at miles & miles of Desert sand over there doing nothing, just erupting into dust storms. Why not make some CHEAP GLUE and spray over at a massive scale. Once, it becomes CAKE, Scoop it and Ship it. Someone somewhere may need it in this modern, industrialized age. Even though following is done already more so in the west, (Forget Colorado Mountains) All Hills should be blasted with Dynamite again at a massive scale, so that current & future generations can use those ready-made stones as and when need for them arises!
ForFreeMinds
2.3 / 5 (3) Jul 09, 2017
"... global average temperature and the carbon dioxide concentration in the atmosphere usually go hand-in-hand."

"Usually" isn't even close. Look at the 2nd chart here:

https://wattsupwi...-levels/
oovarvu
3.7 / 5 (3) Jul 10, 2017
'Generally, if the temperatures decline, the CO2 values also decrease, and vice versa.'

And there was me thinking CO2 drives temperature. Learn something everyday.
CarloC
1.8 / 5 (5) Jul 10, 2017
If the increase in atmospheric CO2 makes temperature to increase why then didn't the glacial period end?
Zzzzzzzz
5 / 5 (1) Jul 10, 2017
If the increase in atmospheric CO2 makes temperature to increase why then didn't the glacial period end?


In case you hadn't noticed, it did...what planet do you live on?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.