At the new raw edge of climate change, scientists Peter Brewer (Monterey Bay Aquarium Institute) & John Shepherd (University of Southampton) peek into upcoming Royal Society conference on oxygen depletion in warming oceans. Seasoned space specialist James Kasting (Penn State) explains a possible end, with scalding seas & bacteria as the only survivors. Radio Ecoshock 160622

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Scientists worry that oxygen will become depleted in the oceans due to global warming. One organizer of the upcoming Royal Society meeting on that topic is the American expert Peter Brewer. The Royal Society conference of experts, set for September 2016, is titled “Ocean ventilation and deoxygenation in a warming world”.

When it comes to ocean chemistry, Dr. Peter G. Brewer has been a leader for a long time. During his 24 years at the Woods Hole Oceanographic Institution, his period at the National Science Foundation, and now his research position at the Monterey Bay Aquarium Research Institute, Peter Brewer has published over 170 scientific papers and edited several books. He’s been out on countless research ships, and more recently is connecting with scientists in China.

Dr. Peter G. Brewer

Peter’s latest commentary, published May 27, 2016 in the AGU Journal of Geophysical Research “Oceans” – is perfect for our program today. It’s titled “Ocean chemistry, ocean warming, and emerging hypoxia.” (“Hypoxia” means reduced oxygen.)

But in this interview, we also find a couple of minutes for his earlier research into ocean acidification and the emergence of methane from the Arctic. Dr. Brewer joins us from Monterey Bay California.

Essentially, Brewer tells us that ocean scientists and biologists have for 50 years used a formula for oxygen based only on depth. It did not take into account the differences based on increasing ocean temperatures. It’s far past time to correct that error, Brewer says.

Here’s why. In an email, Brewer tells me:

When we run the numbers correctly it is clear that under 2 degrees warming ocean oxygen microbial consumption rates will increase by about 30%. And for 3 degrees warming (quite possible) a disturbing +50%.

The effects of reduced solubility, increased microbial rates, and reduced vertical mixing from increased stratification are all effectively additive. It doesn’t look good.”

Most of us don’t realize the depth factor in the seas. We never see the bottoms as low as mountains are high. I almost wonder if it’s a mistake to think of the ocean as a single entity at all, instead of a series of regions, the way we categorize land.

The other stunning factor is the time gap between mixing at great depths and the surface of the sea, where most life exists. Is it fair to say the very bottoms of the ocean are almost in a different age, not yet part of the Anthropocene? Not quite, says Brewer. For example, some radioactivity from atomic bomb testing has been found in the deepest ocean trenches.

The point is: the seas will lose oxygen as they warm. This will affect one of the basic building blocks of all living systems, the plankton. I plan to have more on that for you in a coming show. The loss of plankton, at least in the tropics, will have serious impacts on the billion or more humans who depend on sea food for their protein, not to mention all the other ocean creatures. There is no indication this poses a direct threat to our oxygen in the atmosphere.

We don’t think this great change to ocean oxygen levels will happen in the near-term. But we really don’t know how fast it is developing. That’s why the Royal Society has called together a group of world experts to study the risk.

During this interview, we take a short detour into work Brewer published in 2013. It was in the journal Nature Geoscience, and the title is “Marine biogeochemistry: Arctic shelf methane sounds alarm“. Peter Brewer was asked to look into alarms raised by Russian and American scientists (including Natalia Shahkova from the University of Alaska) about methane leaking from the Arctic sea bed. Brewer says we don’t have evidence that the methane columns found are new, or that significant amounts are making it into the atmosphere. Again, we don’t know enough about this problem.

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Most of us are just trying to get through another week. So it’s inconvenient when a news story flashes by, another big warning sign of developing climate catastrophe. Apparently the ocean, and all the creatures in it, could end up gasping for oxygen.

The science is so new, the issue so underestimated, this September the Royal Society is hosting a series of presentations on this topic. The title is “Ocean ventilation and deoxygenation in a warming world“. The meeting is organized by Professor John Shepherd and two associates. Shepherd is a British Earth system scientist, a professor at University of Southampton, and a former director of the National Oceanography Centre. He’s a Fellow of the Royal Society.


Dr. John Shepherd

Over the years, I’ve broadcast stories about dead zones appearing in many places, generally off the coasts of continents. The cause is generally given as run-off of agricultural fertilizers, or other land-based pollution. But is it more than that? Is deoxygenation due to warming oceans already at play?

Then there is the insidious prospect that even without dead zones, oxygen levels go somewhat lower, leading to a weakening of species, or even their disappearance. What is the gradient, and expected gradient, between dead zones and let’s say “oxygen-thin zones”?

John Shepherd spent over a decade studying fish population dynamics. We talk about the impacts of lower oxygen levels on sea life like the fisheries.

Are we studying a feedback system? Does ocean deoxygenation drive more loss of oxygen? That’s a difficult question which John tackles, but more research is needed.

Shepherd tell us about some of the scientists presenting at the September meeting at the Royal Society. It’s a power-house group.

Presentations at this event will eventually be published as papers in the world’s first science journal, the Royal Society “Philosophical Transactions“.

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Could human forcing of the climate take us to a new dangerous state of deserts and a drying sea? That worrying look at extreme possibilities arises from a paper published in the journal Nature Communications in February 2016. That paper claims humans can create the largest known climate feedback mechanism, so maybe we need to know what it’s about. But keep reading to find out why this is no reason to panic!

Our guide will be Dr. James Kasting. He the Evan Pugh Professor in the Department of Geosciences at Penn State University. Kasting is an award-winning member of many scientific societies. He’s published countless scientific papers since his first in 1977, including some dead-on for this topic. Jim Kasting has worked for and with NASA all over the place. He’s also been part of NASA groups researching astrobiology and possible life on other planets.

Dr. James Kasting

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To help with research on this paper, I also had a telephone conversation with the lead author Max Popp. Dr. Popp is from the Max Planck Institute for Meteorology, and also Max Popp Princeton University.

We’re looking at a disturbing new study from science titled “Transition to a Moist Greenhouse with CO2 and solar forcing“. It was published in February 2016 in Nature Communications. We need to understand some new things to get the message of this study by Max Popp and his co-authors. To motivate us, the authors conclude:

this study verifies the presence of the largest known feedback mechanism for amplifying anthropogenic climate change.

Find an abstract for this paper Popp study abstract, and the full textPopp study full text.

In fact, here is the abstract:

Water-rich planets such as Earth are expected to become eventually uninhabitable, because liquid water turns unstable at the surface as temperatures increase with solar luminosity. Whether a large increase of atmospheric concentrations of greenhouse gases such as CO2 could also destroy the habitability of water-rich planets has remained unclear. Here we show with three-dimensional aqua-planet simulations that CO2-induced forcing as readily destabilizes the climate as does solar forcing. The climate instability is caused by a positive cloud feedback and leads to a new steady state with global-mean sea-surface temperatures above 330K [57 C 135 F]. The upper atmosphere is considerably moister in this warm state than in the reference climate, implying that the planet would be subject to substantial loss of water to space. For some elevated CO2 or solar forcings, we find both cold and warm equilibrium states, implying that the climate transition cannot be reversed by removing the additional forcing.”

I’d like to move through the introduction to the paper step by step. To start with, we read:

Water-rich planets such as Earth lose water by photo-dissociation of water vapour in the upper atmosphere and the subsequent escape of hydrogen. On present-day Earth, the loss occurs very slowly, because the mixing ratio of water vapour in the upper atmosphere is very low.

This paper by Popper says, quote “But significant loss of water could occur over geological timescales if the surface temperature were around 70 K warmer than it is today.” Unfortunately, most of us only understand temperatures either in Fahrenheit or Celsius. If this is an important trigger point for “significant water loss”, how much warmer is 70 Kelvin from present temperatures, in Centigrade and Fahrenheit? It’s 57 degrees C. hotter, or 135 degrees Fahrenheit. That’s not going to happen any time soon, and there would be no humans left to know if it did.

Is this a sliding scale? – that is, if the Earth warms 8 to 10 degrees C, as seems quite likely on our current path of emissions – would loss of water to space be increased at a noticeable level? James Kasting says probably not. It takes a much, much hotter Earth to lose significant water to space.


The paper by Max Popp predicts a gruesome result. It says “A planet in this state would eventually become uninhabitable as all water is lost to space.”

The IPCC has said that is not possible, where the oceans boil away.

James Kasting published a paper on water vapor escaping from Venus back in 1983. He was not involved directly with James Hansen, as Hansen did his early work on the atmosphere of Venus. But Kasting worked on the same problems.

If you want to know more about the grim final possibilities for Earth, you should read the book “The Life and Death of Planet Earth” by Peter Ward and Donald Brownlee.

With his background in space studies, James Kasting finds one of the best uses of the theories in this paper by Popp et al. is to help assess other planets. In our phone conversation, Max Popp agreed that one way to test or verify this theory (without cooking the Earth) is to see if we can find other planets in a moist-greenhouse state, or in an advanced stage of heating. Max told me “The paper wasn’t meant for the context of climate change.”

Note that the study by Popp et all did not use Earth as it’s model. They assumed a fully water-covered planet (no land) which was six degrees C warmer than Earth is. There were no seasons on this model planet. It’s definitely not Earth!


As described in this paper by Max Popp et al in Nature Communications, various models have tested the relationship of water vapor, as a potent greenhouse gas, and global warming. The results have been conflicting or inconclusive, or models cannot do it. However, the introduction to this paper by Popp et al says:

However, if clouds are considered, these arguments may not apply, because clouds themselves can contribute to the climate becoming unstable.”

How can clouds contribute to a climate become unstable? James Kasting explains it.


We know that more than a billion years in the future, the sun will get hotter as it expands. Eventually this hotter sun will make Earth uninhabitable for life, perhaps three billion years from now. One key question investigated in this paper is whether human-forced warming can mimic or duplicate the role of a warming sun. The authors find that warming by CO2 could create the same effect as changes to the Sun.

The Popp paper says, quote:

Thus we show that cloud-radiative effects (CRE) destabilize a present-day Earth climate as readily with CO2 as with solar forcing.”

The authors say these cloud effects come due to a “weakening of the large-scale circulation with increasing global-mean surface temperature“.


The authors of the study describe an ocean which is literally scalding hot. For reference, Wikipedia says the long-term global average surface temperature of the oceans is 16.1 °C or 60.9 °Fahrenheit.

The paper by Popp et all says, quote: “The climate instability … leads to a new steady state with global-mean sea-surface temperatures above 330K.”

That works out to a new global ocean temperature of about 57 C or 135 Fahrenheit. In the model, the new steady state for the ocean is 41 degrees C hotter, or 74 degrees F hotter.

So the average ocean temperature would be 20 degrees C higher, or 38 degrees F hotter than the human body. According to the Burn Foundation, oceans at 135 degrees F or 57 C would be scalding (that is, cause burns) in 15 seconds.

Please remember: the scientists are not talking about the ocean in your lifetime, or even in the next century or two! The sea will not become scalding hot any time soon. In fact, the Earth would need to go through such extreme changes to reach that stage, that humans and all mammals would be long, long gone before this state happens.


The paper says, “Hence a planet in such a state would lose water at a fast rate to space.”

According to the paper, “a Moist Greenhouse would be attained if the mixing ratio in the upper atmosphere exceeds [about] ~0.1 %. For comparison, the mixing ratio in Earth’s stratosphere is presently around two orders of magnitude smaller.


Perhaps the most worrying sentence in this paper by Popper et al, like a death sentence really, occurs at the end of the paper’s abstract. Max Popp and his group write:

Furthermore, there is hysteresis in the warm regime and removing the imposed forcing does therefore not necessarily cause a transition back to an Earth-like climate.

For listeners, Wikipedia describes “hysteresis” as: “the time-based dependence of a system’s output on present and past inputs.” For a short-cut here, lets call it a kind of memory that can drive further action. We could say that the memory of the heating continues to prevent a transition back to our current climate.



The over-all risks and conclusions of this paper are projected so far into a theoretical future that James Kasting tells us “This paper is not about climate change”. About the claimed “largest known feedback mechanism”, Jim Kasting tells us:

I wouldn’t say it verifies the feedback mechanism, what they’re talking about is cloud feedback, and that’s actually very controversial. It varies from one model to another.”

There is a certain Professor who claims humans will all go extinct before the middle of this century due to a rapidly escalation of global warming. In a recent talk, he cites this paper by Max Popp as a further indication of that rapidly approaching extinction. According to other scientists, including the lead author Max Popp, and here James Kasting, this theoretical research has nothing to do with our current threat of climate change, at least not in human terms and time-frames.

THE harsh truth is this “largest known feedback mechanism” is so far away that the public doesn’t really need to know right now, while scientists continue to hash it out.

Here as a decent article in the Guardian newspaper about this study.

You can also check out the Scripps Oxygen Project.

Thank you for listening, and caring about our world. Please listen again next week as Radio Ecoshock pushes the edge.

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