Environment

Carbon reservoirs in the ocean floor may have ended the last ice age – and could bubble up again

Carbon reservoirs in the ocean...
Researchers have found that deep sea gas reservoirs could be a huge source of carbon dioxide emissions that we aren't yet accounting for in climate change models
Researchers have found that deep sea gas reservoirs could be a huge source of carbon dioxide emissions that we aren't yet accounting for in climate change models
View 1 Image
Researchers have found that deep sea gas reservoirs could be a huge source of carbon dioxide emissions that we aren't yet accounting for in climate change models
1/1
Researchers have found that deep sea gas reservoirs could be a huge source of carbon dioxide emissions that we aren't yet accounting for in climate change models

Current climate models say we're on track for some pretty drastic changes if we don't reduce our carbon footprint. But a new study has found a huge potential source of carbon emissions that are so far not accounted for in climate models: reservoirs of gases trapped at the seafloor, which could be released as the oceans warm up. And it's happened before, with the team suggesting that these gases belched up from the deep thousands of years ago and put an end to the last ice age.

Towards the end of the Pleistocene period, atmospheric greenhouse gas levels shot through the roof, putting an end to the last ice age. But where did all those gases come from? It's long been thought that the ocean's regular carbon cycle might have been responsible, but according to more recent calculations, that process is too slow to account for the sudden uptick.

The next idea was that seafloor reservoirs of carbon dioxide could have been the culprit. These reservoirs tend to build up around hydrothermal vents, where carbon dioxide and methane is released by volcanic activity underground. The gases mix with water and other materials to form a slurry, which hardens into a cap. There they can sit idle for thousands of years, until something comes along and disturbs them.

One such trigger seems to be warming waters – essentially, as the ocean captures more heat from the atmosphere, those caps melt and release the large stores of carbon dioxide. The gases in turn bubble up to the surface and escape into the atmosphere, exacerbating the greenhouse effect.

The new study found evidence that this is may have been what happened at the end of the last ice age. Researchers from the University of Southern California, Australian National University and Lund University examined a region known as the Eastern Equatorial Pacific (EEP). This area is a hotspot for carbon being released from the ocean into the atmosphere.

Studying ancient marine sediments, the researchers found that hydrothermal materials seemed to be deposited in higher amounts around the end of the last ice age. In particular, there was about four times more zinc in the shells of microscopic sea creatures from the time, indicating hydrothermal activity.

The ages of these marine microorganisms were correlated with data on variations in the atmospheric carbon dioxide levels, and the link was clear: the EEP released large amounts of carbon just before the end of the ice age, contributing to increases in the surface temperature.

But the most worrying thing about the study is that the oceans are currently warming again, and our climate models don't account for extra CO2 held in these reservoirs. If it were to be released, the outcomes could be much worse than we had planned for.

"We're using the past as a way to anticipate the future," says Lowell Stott, lead author of the study. "We know there are vast reservoirs of carbon gas at the bottom of the oceans. We know when they were disrupted during the Pleistocene it warmed the planet. We have to know if these carbon reservoirs could be destabilized again. It's a wild card for which we need to account."

The researchers say that much more study is needed to determine the level of the threat. Since so much of the ocean floor remains unexplored, we don't yet know how much carbon dioxide is held in these reservoirs. The oceans also don't warm in a uniform way, so we don't know which reservoirs are most vulnerable.

"This study shows that we've been missing a critical component of the marine carbon budget," says Stott. "It shows these geologic reservoirs can release large amounts of carbon from the oceans. Our paper makes the case that this process has happened before and it could happen again."

The research was published in the journal Environmental Research Letters.

Source: University of Southern California

11 comments
Fritz
The temperature will not change fast on sea floor. I guess there will be another mechanism: Shock desorbtion. Similar the same way you open spices jars - hit it hard by hand from the bottom and gases desorb from vinegar, oil, sugar water, rising the pressure inside and the jar end can be twisted easily.
Rusty Harris
LOL, they aren't accounting for...YET! And you can bet when they do, they will blame it on the oil/gas industry because of off shore drilling causing it to be released, and, considering the morons that have no education, but believe everything their teachers & professors tell them, they will believe it!
Douglas Bennett Rogers
95% of the greenhouse effect on the Earth is from water vapor. 80% of the AGW is from water vapor. Noncondensibles will leverage this but that is all. Hydrothermal vents are at boiling or hotter. It is hard to believe that much gas would be trapped.
DreadUK
The concept is predicated on the assumption that atmospheric CO2 is somehow heating up the planet. To date, there has not been one single empirical scientific study, accepted by the scientific community, which demonstrates atmospheric CO2 heats the planet up. That's not one study, ever! The next time you read an MSM article/blog posting/scientific paper etc. have that fact planted at the forefront of your mind. Climate change will seem a whole lot less threatening.
Grunchy
There's an easy way to test CO2 warming hypothesis, in your own home and with ordinary materials. What you do is wait for a sunny day, find a sunny window, and set up a couple transparent glass reservoirs. Fill one with atmospheric air (about 400 ppm CO2) and fill up the other one with exhalation (about 5% CO2). You just "breathe" into it. Use a tube or something, there's probably a way. Anyway, once this is accomplished, expose both reservoirs to equal levels of sunshine and measure the resultant temperature increase. One would think the reservoir filled with greater proportion of CO2 would have a higher resultant temperature, with a difference that might even be measurable. Maybe it does, maybe it doesn't. Nobody seems to have 1/2 hr to spare for such a test. Nobody in the world.
Catweazle
There's another way, Grunchy. Go to the Sahara desert where there is very little atmospheric water vapour and measure the temperature through the day and night, you will find it can approach 50deg C during the day and drop to almost freezing point at night. Now go to a rainforest where there is very high atmospheric water vapour and on approximately the same latitude and measure again, you will find that the temperature remains much more constant throughout the 24 hour period, hardly dropping at all at night, even though the CO2 levels are practically identical. So which gas is trapping the heat?
Drew2019
Let's just follow the logic of this paper: Reservoirs of trapped carbon in the seafloor slurry where released into the atmosphere, warming the planet and ending the last ice age. Warming waters caused the resevoir caps to melt. (Ignoring that there's nothing "frozen" at the bottom of the ocean and that a slurry is a a non-newtonian suspension of particles, and that the author seems mixed up). It then goes on to say, ""We're using the past as a way to anticipate the future," says Lowell Stott,". This logic is circular and meaningless: it claims something like this: During the last major ice age (a time when the planet was so cold glaciers hundreds of feet high covered New York) the oceans warmed up and released the CO2 trapped in the ocean, which in turn warmed the planet ending the ice age - and same thing could happen today. Ok, let's say today it IS CO2 that is warming the oceans. And that these warm waters will release the trapped C02 in the seabed - AND that humans started this process. How does that relate to tens of thousands of years? There were not enough people to start the CO2 engine to warm the oceans. So what did? You can't say it was the trapped ocean C02 because you are running your causality backwards. It's trapped remember. Lowell, the trapped CO2 that warmed the planet couldn't have warmed the oceans to "untrap" itself... Because. It. Was. Trapped. And if most of the planet was locked in ice, how could we make any comparisons to that model as a way to anticipate today? I don't doubt that there is/was this slurry. But even a moron like myself can see that you can't say "This is the cause", and then just gloss over the idea that the thing that caused the warming needed a warming to cause it. How's this for an idea (warning sidebar tangent coming): The planet's changing relationship to the massive nuclear heat ball we call the sun is responsible for 99% of climate, and maybe we can alter about 1% of this relationship through carbon emmissions. We are screaming about this 1% like it will kill us all. Lowell, and everyone else panicking - the reality is - we already live on a planet with climate so inhospitable that for one thing, 99% of humanity would be dead. That thing is human-made heat and shelter. (Ok fine, two things). This planet already gets too darn hot and too darn cold every 24hrs for almost everyone on it. I implore anyone who doubts this to grab 3 days food and a sweater and go stand outside. Without our thermostats, roofs, central heating and AC (or a mud hut with a firepit), we would all die from exposure. We don't know exactly what caused the planet to move from one so warm it supported reptiles the size of buses and inland oceans in what is now the Arizona dessert, to then swing to an ice world - but you can't just say carbon dioxide - end of story. There are too many moving parts. If carbon were king we would have gotten stuck in a feedback loop one way or the other. And no matter what, without human inginuity we would all still be huddling together somewhere around the equator. Let's focus on man-made air pollution and the dirty uncombusted metal particulates, that we inhale in our cities. (Something we know kills people and is very impactful on quality of life.) And relax on carbon dioxide, how 'bout. We will of course decrease CO2 in the process - but it's a lot easier to convince people smog is bad for them, than "greenhouse" gas. The most worrying thing about Carbon, isn't that there is more of it in the air than there use to be; but rather, that we've turned it into such a religion, that "scientists" just need to say it's "bad" to get published. Science isn't suppose to make value judgments. And it should be ok to question the validity of the research. And in this case the premise that claimed the cause of the end of the past ice age caused itself? Hurts my brain just thinking about that premise.
midas
Mankind's carbon footprint could never equal close to 1% of the carbon dioxide trapped in these caps, methane deposits, etc. In fact, it's quite arrogant to believe man can change the planet's climate through industrial pollution.....local changes (read smog), yes. Global, no.
Robert in Vancouver
Where is all the global warming and rising oceans happening? I've lived a few metres from the Pacific Ocean for 67 years, there's been no change to the tides marks on rocks, piers, beaches, or seawalls - none. Global warming is just another way for gov'ts to collect more taxes.
piperTom
Author is most worried because "the oceans are currently warming again". Again! Citation needed. A quick search on deep ocean temperature is a clutter, but most often cited as 0-3 °C. That's "warmer"???