Unchecked Global Emissions on Course To Trigger Mass Extinction of Marine Life

Ocean Ecosystem

Princeton University researchers reported in a new study that unless greenhouse gas emissions are curbed, marine biodiversity may be on track to plummet to levels not seen since the extinction of the dinosaurs. The scientists modeled future marine biodiversity under projected climate scenarios and found that species such as dolphinfish (shown) would be imperiled as warming oceans decrease the ocean’s oxygen supply while increasing marine life’s metabolic demand for it. Credit: Photo by Evan Davis

As greenhouse gas emissions continue to warm the world’s oceans, marine biodiversity could be on track to plunge within the next few centuries to levels not seen since the extinction of the dinosaurs. This dire forecast is according to a new research study to be published by Princeton University researchers in the journal Science today (April 28, 2022).

The researchers modeled future marine biodiversity under different projected climate scenarios. They discovered that if emissions are not reduced, species losses due to warming and oxygen depletion alone could come to mirror the substantial impact humans already have on marine biodiversity by around 2100. Tropical waters would suffer the greatest loss of biodiversity, while polar species would face the highest risk of extinction, the authors reported.

“Aggressive and rapid reductions in greenhouse gas emissions are critical for avoiding a major mass extinction of ocean species,” said senior author Curtis Deutsch, professor of geosciences and the High Meadows Environmental Institute at Princeton.

Big Five Extinction Timeline

The researchers compared their model to the magnitude of Earth’s “Big Five” mass extinctions. The illustration above indicates the percentage of biodiversity lost during each event (left). At lower right, the loss of marine life from the present to 2300 is projected for high- and low-greenhouse gas emissions scenarios with the accompanying global temperature change. Credit: Data by Justin Penn and Curtis Deutsch with illustrations by Yesenia Román

The study found, however, that reversing greenhouse gas emissions could reduce the risk of extinction by more than 70%. “The silver lining is that the future isn’t written in stone,” said first author Justin Penn, a postdoctoral research associate in the Department of Geosciences. “The extinction magnitude that we found depends strongly on how much carbon dioxide [CO2] we emit moving forward. There’s still enough time to change the trajectory of CO2 emissions and prevent the magnitude of warming that would cause this mass extinction.”

Deutsch and Penn, who initiated the study when both were at the University of Washington, combined existing physiological data on marine species with models of climate change to predict how changes in habitat conditions will affect the survival of sea animals around the globe over the next few centuries. The researchers compared their model to the magnitude of past mass extinctions captured in the fossil record, building on their earlier work that linked the geographic pattern of the End-Permian Extinction more than 250 million years ago — Earth’s deadliest extinction event — to underlying drivers, namely climate warming and oxygen loss from the oceans.

Biodiversity Map

The researchers found that as emissions increase (gray), the loss of biodiversity (red) would be greatest in tropical waters, while polar species are at the highest risk of extinction. The researchers found that reversing greenhouse gas emissions could reduce the risk of extinction for marine life by more than 70%. Credit: Figure by Justin Penn

The researchers found that their model projecting future marine biodiversity, the fossil record of the End-Permian Extinction, and indeed the distribution of species that we see now follow a similar pattern — as ocean temperature increases and oxygen availability drops, there is a pronounced decrease in the abundance of marine life.

Water temperature and oxygen availability are two key factors that will change as the climate warms due to human activity. Warmer water is itself a risk factor for species that are adapted for cooler climates. Warm water also holds less oxygen than cooler water, which leads to more sluggish ocean circulation that reduces the oxygen supply at depth. Paradoxically, species’ metabolic rates increase with water temperature, so the demand for oxygen rises as the supply decreases. “Once oxygen supply falls short of what species need, we expect to see substantial species losses,” Penn said.

Marine animals have physiological mechanisms that allow them to cope with environmental changes, but only up to a point. The researchers found that polar species are more likely to go globally extinct if climate warming occurs because they will have no suitable habitats to move to. Tropical marine species will likely fare better because they have traits that allow them to cope with the warm, low-oxygen waters of the tropics. As waters north and south of the tropics warm, these species may be able to migrate to newly suitable habitats. The equatorial ocean, however, is already so warm and low in oxygen that further increases in temperature — and an accompanying decrease in oxygen — might make it locally uninhabitable for many species.

The researchers report that the pattern of extinction their model projected — with a greater global extinction of species at the poles compared to the tropics — mirrors the pattern of past mass extinctions. A study Deutsch and Penn published in Science in 2018 showed that temperature-dependent increases in metabolic oxygen demand — paired with decreases in oxygen availability caused by volcanic eruptions — can explain the geographic patterns of species loss during the End-Permian Extinction ago, which killed off 81% of marine species.

The new paper used a similar model to show that anthropogenic warming could drive extinctions from the same physiological mechanism at a comparable scale if warming becomes great enough, Penn said. “The latitude pattern in the fossil record reveals the fingerprints of the predicted extinction driven by changes in temperature and oxygen,” he said.

The model also helps resolve an ongoing puzzle in the geographic pattern of marine biodiversity. Marine biodiversity increases steadily from the poles towards the tropics, but drops off at the equator. This equatorial dip has long been a mystery — researchers have been unsure about what causes it and some have even wondered whether it is real. Deutsch and Penn’s model provides a plausible explanation for the drop in equatorial marine biodiversity — the oxygen supply is too low in these warm waters for some species to tolerate.

The big concern is that climate change will make large swathes of the ocean similarly uninhabitable, Penn said. To quantify the relative importance of climate in driving extinctions, he and Deutsch compared future extinction risks from climate warming to data from the International Union for Conservation of Nature (IUCN) on current threats to various marine animals. They found that climate change currently affects 45% of the marine species at risk of extinction, but is only the fifth-most important stressor after overfishing, transportation, urban development, and pollution.

However, Penn said, climate change could soon eclipse all of these stressors in importance: “Extreme warming would lead to climate-driven extinctions that, near the end of the century, will rival all current human stressors combined.”

Reference “Avoiding ocean mass extinction from climate warming” by Justin L. Penn and Curtis Deutsch, 28 April 2022, Science.
DOI: 10.1126/science.abe9039

The work was supported by grants from the National Science Foundation (OCE-1737282), the National Oceanic and Atmospheric Administration (NA18NOS4780167), California SeaGrant and Ocean Protection Council, and the UW Program on Climate Change.

14 Comments on "Unchecked Global Emissions on Course To Trigger Mass Extinction of Marine Life"

  1. To bad for the oxygen depletion scenario all those Rivers and streams just keep following and oxygenating the water anywhere there are rapids and they just keep dumping all that fresh oxygenated water into the ocean. We have to put a stop to that if you want your Extinction scenario to pan out and not end up looking like a liar

    • Denying Reality will not change a thing and will not prevent your death in the near term from abrupt, exponential climate change. 28 tipping points have now been breached and methane is pouring out of the permafrost as the poles get warmer and melt. The very situation we are now in was predicted and presented to the US Congress in 1987 by top NASA Scientist James Hansen and by renowned scientist Carl Sagan. They warned…no one listened. Now every living Being on Earth faces certain extinction in the near term…this is happening now and will continue to accelerate until there is not another human standing by 2028. Climate Change does not care about your errant egoic opinions. Only Reality matters. The sooner you learn what the Reality is, the sooner you can prepare.

      • Exactly. Climate systems are chaotic. They don’t react to perterbations linearly or even exponentially. They absorb perterbations without reacting up to a point, then they shift quickly and violently to a new configuration with new limits.

    • Instead of beating the same old drum, why not step up pressure on governments that already have the solution that will eliminate the world’s need for fossil fuels?

      When you stop wasting my time with all your “models” and start demanding disclosure, I will begin to listen.

  2. Unacceptable Kanuck | April 28, 2022 at 11:27 am | Reply

    Got off the fossil fuel Trex , do some research, can you comprehend Solar particle forcing or maybe ; ITS CYCLICAL, we have been through this before!!! Oh and how about Mag Pole shift, or the FACT that we are heading into a mini Ice age. We still have a lot of devastation coming during the cyclical nature of our sun ” SOLAR MAXIMIM 2025. Now I see why they named the ECO HIPROCRAT ~ LEONARDO DiCrapprio’s move DONT LOOK UP. Simply because you obviously don’t 🙄.
    In no way shape or form am I for staying with fossil fuels we need to move forward, and clean up our act..IE : plastics, human greed and waste
    But I am a proud 35÷ year oil and gas well drilling professional, After all where else could I make double the yearly income with NO EDUCATION (grade 7 completed) than 99.9 % of you who slam us with this LEFT winged Narrative ! I say to you sir or madam GOOD LUCK with your NARRATIVE and your life in the next 5 yrs. I will check back then, I truly thought you where about REAL SCIENCE.
    PS, SUSPICIOUS OBSERVERS,SKY WATCH MEDIA NEWS maybe you will learn important information on space, planetary, cyclical nature of our solar system as well as earth. Let’s not forget solar forcing 🤔

    • And regardless of what industry you work in, abrupt exponential climate change does not care what you do or who you think you are. The objective data and science, and the conclusions of tens of thousands of the world’s most educated and experienced climate scientists, do not care about your opinions.

      You will go extinct like everyone else in the near term. Extinction does not care whether you believe in it or not…and neither does Reality. Called or not called, karma comes.

  3. “… earlier work that linked the geographic pattern of the End-Permian Extinction more than 250 million years ago … to underlying drivers, namely climate warming and oxygen loss from the oceans.”

    The myopic authors left out that most paleontologists now think that the cause of the End-Permian was magma intruding under coal beds. This baked the coal, giving off not only carbon dioxide, but poisonous carbon monoxide, sulfur dioxide, and a witch’s cauldron of volatile coal tars. The oceans likely became truly acidic from sulfuric acid, and when everything started dying, bacteria decomposed them, removing oxygen.

    They base their ‘could happen’ on a model of unknown veracity and apparently unexamined confounding factors such the effect of truly toxic emissions from coal beds. The article is behind a paywall so I couldn’t read it for details. However, I strongly suspect they used an extreme scenario (RCP8.5) that has been discredited as being impossible. Such scary ‘campfire stories’ may serve to promote the ‘humans are bad’ meme, but are supported by a one-legged stool called a model. Computer models of things that are well known, such as the behavior of airplanes, are useful for designing new planes. However, before human lives are put at risk, physical models are tested in a wind tunnel. There is far too much reliance today on speculative computer models without any means of being validated.

  4. More sudo science. They base all their projections on theories or other projections. Just look at the planets history. Scientists routinely find that when the earth was warmer there were more varieties and larger populations of animals and plants on land and in the water. The planet has easily been 9 degrees warmer on average and life was doing great then. Keep beating a dead horse for 40 years with none of the projections having come true.

    Should we find a better way to power our lives, sure. But until we can we are stuck with what works. Not to mention all the other products we use on a daily basis being made from oil like plastics etc…

    • You are clearly uninformed and posting what you wish was true. Perhaps you don’t have the courage to face your own near term extinction. It takes a strong person to face their own death head on. With the ice now rapidly melting in Arctic and Antarctica, with forest fires burning out of control all around the world, with the oceans dying, the ocean currents dying, water becoming increasingly scarce, food becoming scarce, species going extinct by the day, we are clearly finished…and very soon…much sooner than the scientists predicted. Forget 2050 or 2100…there won’t be another human standing by 2028. It is too late and deniers like you did humanity a disservice with your cowardice and inability to understand the dire predicament we are in.

      • Clyde Spencer | April 28, 2022 at 4:18 pm | Reply

        “… With the ice now rapidly melting in Arctic and Antarctica, with forest fires burning out of control all around the world, …”

        I guess that you haven’t been keeping up. There has been no statistically significant trend in temperatures for over 7 years. The Arctic reached the lowest coverage in 2012 and there has been no trend for the last decade. It is only the western part of Antarctica — over a volcanic hot spot — that is showing any significant melting. It is you who is uniformed. Only you don’t know it. It is easy to make dire predictions based on ‘facts’ that you make up.

        Well, it is distinctly possible that there may be no one around in six years. However, the risk isn’t climate change, it is nuclear weapons exchange.

        Do you walk around with a sandwich board advertising “The end is nigh!”?

  5. This is way too optimistic. We and all other species are going extinct in the near term and no amount of emissions reductions will save us. It is too late. When one considers the aggregate of peer reviewed scientific literature on climate change, the precise magnitude of the catastrophe we face comes into full view. When all the tipping points are considered together, it is clear that there won’t be another human being standing by 2028.

    • Clyde Spencer | April 28, 2022 at 4:20 pm | Reply

      “When one considers the aggregate of peer reviewed scientific literature on climate change, …

      It doesn’t matter how much is published if it can’t be supported by evidence. Some people will believe anything, especially if they don’t understand the science behind the claims.

  6. Christopher William Aurand | April 28, 2022 at 3:02 pm | Reply

    All major extentions in history were caused by either volcanic eruptions or a massive meteorite, all in all causing an ice age of sorts or making the environment to poisonous for life to survive, we’ve all ready reached peak oil and are on the downhill slope now, two things to look at, the environment after the use of all that fossil fuel is still okay life is continuing, next is the availability is going to start becoming unfortunate so less will be use and another form of fuel will have to be made. One thing to also look at is human population didn’t start to rise until combustion engine started to become available. It made life easier more food was able to be made and work in general became easier. This all comes from using oil, my opinion is now we need to use oil as a lubrican and not burn it and start using hydrogen as a fuel, the earth is 70% water, start separating H2o, put more oxygen in the air and burn clean hydrogen

    • Clyde Spencer | April 28, 2022 at 4:30 pm | Reply

      If you actually think that hydrogen is without problems, then you are showing how much you don’t know. Not all oil is suitable for use as a lubricant.

      There have been five major extinctions and lots of smaller ones, with the average being about every 27 million years. One can be attributed to an asteroid. One or two to volcanic events. What about the other dozen-plus extinctions? There are none so certain about reality as those who know nothing.

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