Like the heat waves on land we have all grown familiar with, marine heat waves are being amplified by climate change. These extreme warm water events have ushered in some of the most catastrophic impacts of climate change and are now a major threat to ocean life.

Coral reefs, which are home to a quarter of all life in the ocean, are the most vulnerable.
This is a dire situation, given the vast number of people who depend on coral reefs for their sustenance and livelihoods.

As climate change pushes corals beyond their limits, a key question is why different corals vary in their sensitivity to warm waters.

In our new study in Science Advances, we examined the genetics of hundreds of individual corals during the 2015-16 El Niño-driven heat wave. Our results suggest that heat waves have hidden impacts on the genetic composition of reef-building corals. Understanding this could help scientists bolster reef resilience to future heat waves.

Pushing corals out of their comfort zones

Corals are highly adapted to the temperature of their local waters, with temperatures even 1 C warmer than normal pushing them out of their comfort zone.

Unusually warm water disrupts the vital relationship between stony corals (the reef-builders) and their symbiotic partners, microscopic algae that provide food to the corals. This causes coral bleaching, and in many cases mortality.

The tropical heat wave at our study site in the central Pacific Ocean, Kiritimati (Christmas Island), lasted for ten months, a world record. This led to extensive coral bleaching, presenting an opportunity to determine why some corals died and others survived.

Cryptic diversity within a widespread coral species

We focused on the widespread lobed coral (Porites lobata). This species is amongst the most heat-tolerant corals, and despite almost 90 per cent of all coral cover being lost on Kiritimati, over half of lobed corals survived.

In fact, some Porites colonies didn’t bleach at all.

Why?

Using genomic tools, we identified three distinct types of Porites lobata on Kiritimati. These lineages, which may represent distinct species, are indistinguishable by eye but genetically different.

Such biodiversity is known as “cryptic diversity” or “hidden diversity.” Although cryptic diversity is widespread across corals, its ecological implications remain unclear.

Marine heat waves threaten cryptic diversity

We found that one genetic lineage of Porites was highly sensitive to the heat wave: only 15 per cent of its colonies survived compared to 50-60 per cent in the other lineages. Thus, even in a coral widely considered to be stress tolerant, heat waves can have hidden impacts, threatening diversity that is invisible to the naked eye.

If future marine heat waves continue to have similar effects, eventually sensitive genotypes like this one could be completely lost, reducing the genetic diversity of coral reefs.

Because interbreeding between cryptic lineages and species can offer a potential avenue for future adaptation, losses of genetic diversity could make a bad problem even worse by limiting future adaptation to changing environments.

A forced breakup

So why did Porites lineages on Kiritimati differ in survival?

One hypothesis is that they house symbiotic partners with different heat sensitivities. Using metabarcoding, a technique that attempts to identify everything found living in the coral tissue, we identified which symbionts were partnered with which corals before, during and after the heat wave.

We found that the distinct Porites lineages had different partnerships before the heat wave. Porites species pass on their symbionts from one generation to the next and so these relationships likely arose over many generations.

By the end of the heat wave, however, one of Porites’ unique algal partners had been virtually eliminated. The survivors of all lineages had similar symbionts, suggesting specialized relationships between the partners had been lost under extreme temperatures.

Thus, not only was a cryptic coral lineage left teetering on the edge of local extinction, but its specialized symbiotic relationship had also been forcefully broken up.

Implications for conserving coral reefs

Due to climate change and other threats, we are currently experiencing a biodiversity crisis. Our findings underscore that this crisis extends beyond what the eye can see.

Cryptic species often occupy unique ecological niches and play specific roles within ecosystems. Discovering these hidden differences can enhance our understanding of how ecosystems function. But worryingly, we may be losing this critical diversity before it is even discovered.

Continued study of cryptic diversity could prove essential to building climate resilient ecosystems. Using heat tolerant cryptic lineages in restoration approaches, for example, could help make reefs more tolerant to future warming.

Ultimately, greenhouse gas emissions must be rapidly reduced to curb planetary warming. While targeted efforts to bolster coral reefs against climate change may buy limited time, the current heat waves blanketing the world’s oceans underscore that the ocean is simply becoming too hot for corals and we need to act rapidly to mitigate the damage.

Samuel Starko, Forrest Research Fellow, The University of Western Australia and Julia K. Baum, Professor of Biology, University of Victoria

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Featured image: A healthy reef on Kiritimati (Christmas Island, Republic of Kiribati).
(Danielle Claar), Author provided

The ocean holds 60 times more carbon than the atmosphere and absorbs almost 30% of carbon dioxide (CO₂) emissions from human activities. This means the ocean is key to understanding the global carbon cycle and thus our future climate.

The Intergovernmental Panel on Climate Change (IPCC) uses earth system models to project climate change. These projections inform critical political, social and technological decisions. However, if we can’t accurately model the marine carbon cycle then we cannot truly understand how Earth’s climate will respond to different emission scenarios.

In research published today, we show that zooplankton, tiny animals near the base of the ocean food chain, are likely to be the biggest source of uncertainty in how we model the marine carbon cycle. Getting their impact on the cycle right could add an extra 2 billion tonnes to current models’ assumptions about annual carbon uptake by the ocean. That’s more carbon than the entire global transportation sector emits.

Marine carbon cycling is a $3 trillion thermostat

Roughly 10 billion tonnes of carbon are being released into the atmosphere each year. But the ocean quickly absorbs about 3 billion tonnes of these emissions, leaving our climate cooler and more hospitable. If we price carbon at the rate the IPCC believes is needed to limit warming to 1.5℃, this adds up to over A$3 trillion worth of emission reductions accomplished naturally by the ocean every year.

However, we know the size of the ocean carbon sink has changed in the past, and even small changes can lead to big changes in the atmosphere’s temperature. Thus, we understand the ocean acts as a thermostat for our climate. But what controls the dial?

Extensive geological evidence suggests microscopic marine life could be in control. Phytoplankton photosynthesise and consume as much CO₂ as all land plants.

When phytoplankton die, they sink and trap much of their carbon deep in the ocean. It can remain there for centuries to millennia, locked away safely out of contact with the atmosphere.

Any changes to the strength of this biological carbon pump will be felt in the atmosphere and will change our climate. Some have even proposed enhancing this biological pump by artificially fertilising the ocean with iron to stimulate phytoplankton. It’s possible this could sequester as much as an extra 20% of our annual CO₂ emissions.

Right for the wrong reasons

Despite its importance for the global climate and food production, there are large gaps in our understanding of how the marine carbon cycle is expected to change. Most earth system models differ in how the cycle’s major components will respond to a changing climate. Models simply can’t agree on what will happen to:

• net primary production – the carbon consumed by phytoplankton resulting in growth of marine plants at the base of the food web

• secondary production – zooplankton growth, which is an indicator for fisheries, since fish eat zooplankton

• export production – the biological pump of carbon transferred to the deep sea.

To diagnose what might be going wrong, we compared the marine carbon cycle in 11 IPCC earth system models. We found the largest source of uncertainty is how fast zooplankton consume their phytoplankton prey, known as grazing pressure.

Models differ hugely in their assumptions about this grazing pressure. Even if zooplankton were exposed to the exact same amount of phytoplankton, the highest assumed grazing rate would be almost 100 times as fast as the slowest rate.

This is because some models effectively assume the ocean is filled entirely with slow-grazing shrimp. Others assume it is teeming exclusively with microscopic, but rapidly grazing ciliates. In reality, neither is true.

Models must make up for such large differences in zooplankton grazing by making additional assumptions about how fast phytoplankton grow and how quickly zooplankton die. Together, these differences can be balanced in a way that allows most models to simulate the present-day amount of carbon consumed by phytoplankton and transferred to the deep sea.

However, that is only because we can observe what those values should be. We can then tune models until we ensure they get the right answer.

Yet, even though our best models can admirably recreate the present-day ocean, they do so for different reasons and with dramatically different assumptions about the role of zooplankton. This means these models are built with fundamentally different machinery. When used to test future emissions scenarios, they will project fundamentally different outcomes.

We cannot know which projections are correct unless we know the true role of zooplankton.

Tiny plankton with a big impact

We ran a sensitivity experiment to show how small changes in zooplankton grazing can dramatically alter marine carbon cycling. We considered two sets of experiments, one control and one in which we increased both zooplankton grazing rates and phytoplankton growth rates, such that both were tuned to the exact same total carbon consumption by phytoplankton.

This increase in how fast zooplankton can graze was only a fraction of the difference between assumed grazing rates seen across IPCC models. Despite this, we found even this small increase led to a huge difference in the percentage of carbon consumed by phytoplankton that was eventually exported to depth and transferred up the food chain.

Ocean carbon storage increased by 2 billion tonnes per year. Zooplankton carbon consumption increased by 5 billion tonnes.

From a climate perspective, that is double the maximum theoretical potential of iron fertilisation. From a fisheries perspective, that leads to a 50% increase in the size of the global zooplankton population on which many fish feed. This matters for global food supply as the ocean feeds 10% of the global population.

This work shows we must improve both our understanding and modelling of zooplankton. With limited resources and an immense ocean, we will never have enough observations to build perfect models. However, new technologies for measuring zooplankton are making it easier to make autonomous, high-resolution measurements of many important variables.

We must make a concerted effort to leverage these new technologies to better understand the role of zooplankton in the marine carbon cycle. We will then be able to reduce uncertainties about future climate states, advance our ability to assess marine-based CO₂ removal, and improve global fisheries projections.

Tyler Rohr, Lecturer in Southern Ocean Biogeochemical Modelling, IMAS, University of Tasmania; Anthony Richardson, Professor, The University of Queensland, and Elizabeth Shadwick, Team Leader, Oceans & Atmosphere, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Featured image: Julian Uribe-Palomino/IMOS-CSIRO, Author provided

Some 37% of the world’s 7.9 billion humans live in coastal communities that depend on the ocean for their livelihood. The Ocean Conference says that marine life “accounts for about 17 per cent of protein at the global level and exceeds 50 per cent in many least-developed countries.

Losing half of marine life would be very, very bad, like millions starving bad.

The oceans also have a limit of how much CO2 they can take in. In about 25 years we will be up against that limit, and all the CO2 we put up after that will stay in the atmosphere for a very long time, perhaps 100,000 years, and it will go on keeping the earth hot. The increase in heat would stop immediately if we stop burning gasoline, methane gas and coal now, precisely because the oceans give us a “carbon budget,” i.e. wriggle room. It isn’t clear that as a species we are smart enough to take advantage of this temporary loophole, however.

The extra acid is only one problem, as noted above. The other is hot water from the greenhouse effect. Hotter water holds less oxygen, but marine creatures that live in hotter waters need more oxygen because their metabolic rate increases. Now, that’s a Catch-22 that makes it difficult for them to catch their breath.

Liana Walt at the Princeton newsletter quotes one of the senior authors, Curtis Deutsch, a professor of geosciences and the High Meadows Environmental Institute at Princeton, as saying,

“Aggressive and rapid reductions in greenhouse gas emissions are critical for avoiding a major mass extinction of ocean species”

She continues, “The study found, however, that reversing greenhouse gas emissions could reduce the risk of extinction by more than 70%.”

So this is a bad news, good news story. We face a catastrophic die-off of one of the world’s major sources of human nutrition. But if we act quickly to stop emitting carbon dioxide, we can reduce the damage to below the level of a mass extinction event.

As the authors note, we have seen this movie before.

A 2019 study settled the question of whether the Chicxulub meteor that polished off the dinosaurs was also responsible for the incredible die-off of 50% of marine life that took place around the same time, 66 million years ago. Some scientists had wondered whether volcanic activity in the previous hundreds of thousands of years had put even more carbon dioxide into the atmosphere and contributed along with the meteor to the mass extinctions.

Michael J. Henehan of Yale and his colleagues were able to show by an examination of fossils of microscopic sea life from the period before and after the K-T (Cretaceous-Tertiary) extinction that there had not been a gradual decrease in the pH of the ocean, that is, there had not been a gradual increase in its acidity. The increase was sudden, and devastating.

Britannica explains,

“The K–T extinction was characterized by the elimination of many lines of animals that were important elements of the Mesozoic Era (251.9 million to 66 million years ago), including nearly all of the dinosaurs and many marine invertebrates.”

The oceans became so acidic so fast that half of marine life couldn’t survive. You can imagine what would happen if you dumped acid into the fish tank of your pet fish. Little Bubbles would go belly up tout de suite.

The meteor generated enormous amounts of carbon dioxide and sulphuric acid in the atmosphere, burning the world’s forests and setting off volcanic eruptions, which CO2 was promptly absorbed by the oceans through diffusion.

When the saltwater ocean bonds with carbon dioxide, it produces carbonic acid, which then breaks down into bicarbonate ions and hydrogen ions. When there are lots of free hydrogen ions in sea water, it is very acidic. Under ordinary circumstances, oceans can buffer acidity with alkalinity from chalky rocks eroded by the rivers that flow into the oceans. But if carbon dioxide suddenly balloons up, such long-term processes can’t offset it and acidity will quickly rise.

This rapid and severe increase in ocean acidity killed off the microscopic sea life, foraminifera, on which other marine animals feed, so that they starved to death.

The K-T boundary die-off ranks third in severity among the 6 major extinction events scientists have discovered in earth’s history.

The point of of the Penn and Deutsch study is that our carbon-based industrial civilization is as bad for marine life as the apocalyptic strike of the Chicxulub meteor was. We are our own catastrophe. But as sentient life we can choose a different path, if we have the will.

Scientists are cautious and usually avoid categorical statements. This year’s report says, “It is unequivocal that human influence has warmed the atmosphere, ocean and land.”

You can say that again. I watch a lot of cable news for my sins and have been gobsmacked at how they are all ignoring how the coast of Turkey burned up recently and now Greece is on fire. Greece, the font of European civilization. I’ve been studying Greek for the past few years and before the pandemic went to Athens for a few weeks every summer. It was mostly very pleasant, though a week or so could be hot. This year, the wildfires are encroaching on the capital, and it is like 118 degrees F. (!!!) Even islands like Evia are in trouble. Mediterranean islands burning up.

Channel 4: “Thousands flee catastrophic wildfires on Greece’s second largest island”

The networks aren’t really covering the Dixie fire in California that much and it is even in America. The US Northwest is still having extreme temperatures. One Canadian town had 108 degrees F. I mean, that is nuts. And it is only the beginning if we don’t stop burning coal and gasoline like yesterday.

The scientists say we need to reduce CO2 emissions by 50 percent in the 2020s to avoid a very challenging set of changes in our climate.

It is important to understand that climate change is on a spectrum. It is a scale, say from 1 to 15. If we swing into action right now globally, we could keep it to a 1 or 2. If we go on fiendishly burning fossil fuels for a while, we’ll go to a 4 or 5. If we just don’t give a shit and really want to burn that coal and drive internal combustion engines for a couple more decades, we’ll go to 7 or 8. And if we just blow off the whole thing we go to 10 or 15 on the scale.

People are always saying we’ve passed the point of no return. On a scale, there really isn’t such a thing. The only question is how high on the scale do you want to go. At any point in the next 30 years we could get really serious and make a big difference in the shape of our future.

But, our children and grandchildren won’t like the world we are currently building for them.

So what does the new report say?

The global average surface temperature in 2000-2021 is about 1 degree C. (1.8 degrees F.) higher than the 1850-1900 average. Although a 1.8 degrees F. increase doesn’t sound like much, remember that this is an average, and that the oceans and the poles are very cold, so that some places, like the U.S. West or the Iranian coast along the Gulf, are much hotter than they used to be, and on their way to being hotter yet.

Even more alarming, some of the heating we have created is being masked by our coal and wood burning, which puts aerosol particles into the atmosphere that reflect sunlight and so have a cooling effect. That smog cooling, however, is temporary, and will go away as we stop burning coal and other fuels, and then the full heat we’ve provoked will hit us in the faces all of a sudden.

Humans have almost certainly caused each of the last four decades to be hotter than its predecessor. We have caused precipitation (and flooding as this year in Germany) to increase. We have sent the glaciers into retreat and cause an accelerated melting of Greenland’s ice sheet.

We have warmed up the upper ocean, and made it much more acidic, both with the potential to kill a great deal of marine life on which we depend.

We have caused the seas to rise on average nearly 8 inches during the past century. That may not sound like much, but it is only the beginning, and the rise could be 4 to 6 feet by the end of this century. That would polish off Miami and New Orleans.

We’ve raised the parts per million of carbon dioxide in the atmosphere from 270 in 1750 to over 410 now. The last time the earth saw 410 ppm of CO2 was 2 million years ago, when the whole world was tropical and there was no surface ice. If we stop producing so much carbon dioxide, the oceans will absorb a lot of what we have put up there, but around 2050 the oceans will be full and if we go on burning fossil fuels past a certain date, all the CO2 will stay up there for tens of thousands of years and the whole world will become tropical and there will be no surface ice.

The scientists use that “certain” word again when they say that since 1950 heat waves have become more intense and more frequent because we burned coal, gasoline and natural gas.

Hurricanes and cyclones have increased in intensity in the past forty years, though whether they will become more frequent is hard to know.

We are also making the climate more complicated. They write, “Human influence has likely increased the chance of compound extreme events since the 1950s. This includes increases in the frequency of concurrent heatwaves and droughts on the global scale (high confidence); fire weather in some regions of all inhabited continents (medium confidence); and compound flooding in some locations (medium confidence).”

We don’t just have a heatwave here and a drought there any more– we have them both together, and along with wildfires, too.

The scientists conclude that the hotter we make the earth, the more extreme the climate gets. Even just an extra degree Fahrenheit can push those extremes:

“With every additional increment of global warming, changes in extremes continue to become larger. For example, every additional 0.5°C of global warming causes clearly discernible increases in the intensity and frequency of hot extremes, including heatwaves (very likely), and heavy precipitation (high confidence), as well as agricultural and ecological droughts30 in some regions (high confidence). Discernible changes in intensity and frequency of meteorological droughts, with more regions showing increases than decreases, are seen in some regions for every additional 0.5°C of global warming (medium confidence).”

These extremes won’t be smoothly distributed. The Arctic and the South American monsoon region will heat up 2-3 times more than other places.

They add that precipitation will be heavier in some places, and “The proportion of intense tropical cyclones (categories 4-5) and peak wind speeds of the most intense tropical cyclones are projected to increase at the global scale with increasing global warming (high confidence).”

Me, I vote for green candidates, put solar panels on my roof, and leased an electric car for a while before just biking to work in the good weather. We can keep this thing low on the scale, still. If we all act together now.

—-

Bonus Video:

Michael Mann on the IPPC 6th report on Climate Change – MSNBC Live with Katy Tur

( The Conversation) – The Chagos Archipelago is one of the most remote, seemingly idyllic places on Earth. Coconut-covered sandy beaches with incredible bird life rim tropical islands in the Indian Ocean, hundreds of miles from any continent. Just below the waves, coral reefs stretch for miles along an underwater mountain chain.

It’s a paradise. At least it was before the heat wave.

When I first explored the Chagos Archipelago 15 years ago, the underwater view was incredible. Schools of brilliantly colored fish in blues, yellows and oranges darted among the corals of a vast, healthy reef system. Sharks and other large predators swam overhead. Because the archipelago is so remote and sits in one of the largest marine protected areas on the planet, it has been sheltered from industrial fishing fleets and other activities that can harm the coastal environment.

But it can’t be protected from climate change.

In 2015, a marine heat wave struck, harming coral reefs worldwide. I’m a marine biologist at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, and I was with a team of researchers on a 10-year global expedition to map the world’s reefs, led by the Khaled bin Sultan Living Oceans Foundation, wrapping up our work in the Chagos Archipelago at the time. Our report on the state of the reefs there was published in spring 2021.

As the water temperature rose, the corals began to bleach. To the untrained eye, the scene would have looked fantastic. When the water heats up, corals become stressed and they expel the tiny algae called dinoflagellates that live in their tissue. Bleaching isn’t as simple as going from a living coral to a bleached white one, though. After they expel the algae, the corals turn fluorescent pinks and blues and yellows as they produce chemicals to protect themselves from the Sun’s harmful rays. The entire reef was turning psychedelic colors.

That explosion of color is rare, and it doesn’t last long. Over the following week, we watched the corals turn white and start to die. It wasn’t just small pieces of the reef that were bleaching – it was happening across hundreds of square miles.

What most people think of as a coral is actually many tiny colonial polyps that build calcium carbonate skeletons. With their algae gone, the coral polyps could still feed by plucking morsels out of the water, but their metabolism slows without the algae, which provide more nutrients through photosynthesis. They were left desperately weakened and more vulnerable to diseases. We could see diseases taking hold, and that’s what finished them off.

We were witnessing the death of a reef.

Rising temperatures increase the heat wave risk

The devastation of the Chagos Reef wasn’t happening in isolation.

Over the past century, sea surface temperatures have risen by an average of about 0.13 degrees Celsius (0.23 F) per decade as the oceans absorb the vast majority of greenhouse gas emissions from human activities, largely from the burning of fossil fuels. The temperature increase and changing ocean chemistry affects sea life of all kinds, from deteriorating the shells of oysters and tiny pteropods, an essential part of the food chain, to causing fish populations to migrate to cooler water.

Corals can become stressed when temperatures around them rise just 1 C (1.8 F) above their tolerance level. With water temperature elevated from global warming, even a minor heat wave can become devastating.

These events and rising global temperatures are why the International Coral Reef Society, which represents thousands of coral scientists, issued an urgent call to governments on July 20, 2021, to do more to protect coral reefs. As part of its report on the state of the world’s reefs, it listed ways to help reefs survive, including investing in conservation, management and restoration; committing to slow climate change, reduce pollution and stop overfishing; and supporting efforts to help corals adapt to warming waters. With swift action to slow climate change, the group writes, about 30% of reefs could survive the century; if global temperatures rise by 2 C (3.6 F) or more, only about 1% will still exist. At stake is an estimated US$10 trillion in annual economic value and coastline protection.

In 2015, the ocean heat from a strong El Niño event triggered the mass bleaching in the Chagos reefs and around the world. It was the third global bleaching on record, following events in 1998 and 2010.

Bleaching doesn’t just affect the corals – entire reef systems and the fish that feed, spawn and live among the coral branches suffer. One study of reefs around Papua New Guinea in the southwest Pacific found that about 75% of the reef fish species declined after the 1998 bleaching, and many of those species declined by more than half.

Research shows marine heat waves are now about 20 times more likely than they were just four decades ago, and they tend to be hotter and last longer. We’re at the point now that some places in the world are anticipating coral bleaching every couple of years.

That increasing frequency of heat waves is a death knell for reefs. They don’t have time to recover before they get hit again.

Where we saw signs of hope

During the Global Reef Expedition, we visited over 1,000 reefs around the world. Our mission was to conduct standardized surveys to assess the state of the reefs and map the reefs in detail so scientists could document and hopefully respond to changes in the future. With that knowledge, countries can plan more effectively to protect the reefs, important national resources, providing hundreds of billions of dollars a year in economic value while also protecting coastlines from waves and storms.

We saw damage almost everywhere, from the Bahamas to the Great Barrier Reef.

Some reefs are able to survive heat waves better than others. Cooler, stronger currents, and even storms and cloudier areas can help prevent heat building up. But the global trend is not promising. The world has already lost 30% to 50% of its reefs in the last 40 years, and scientists have warned that most of the remaining reefs could be gone within decades.

While we see some evidence that certain marine species are moving to cooler waters as the planet warms, a reef takes thousands of years to establish and grow, and it is limited by geography.

In the areas where we saw glimmers of hope, it was mostly due to good management. When a region can control other harmful human factors – such as overfishing, extensive coastal development, pollution and runoff – the reefs are healthier and better able to handle the global pressures from climate change.

Establishing large marine protected areas is one of the most effective ways I’ve seen to protect coral reefs because it limits those other harms.

The Chagos marine protected area covers 640,000 square kilometers (250,000 square miles) with only one island currently inhabited – Diego Garcia, which houses a U.S. military base. The British government, which created the marine protected area in 2010, has been under pressure to turn over control of the region to the country of Mauritius, where former Chagos residents now live and which won a challenge over it in the International Court of Justice in 2020. Whatever happens with jurisdiction, the region would benefit from maintaining a high level of marine protection.

A warning for other ecosystems

The Chagos reefs could potentially recover – if they are spared from more heat waves. Even a 10% recovery would make the reefs stronger for when the next bleaching occurs. But recovery of a reef is measured in decades, not years.

So far, research missions that have returned to the Chagos reefs have found only meager recovery, if any at all.

We knew the reefs weren’t doing well under the insidious march of climate change in 2011, when the global reef expedition started. But it’s nothing like the intensity of worry we have now in 2021.

Coral reefs are the canary in the coal mine. Humans have collapsed other ecosystems before through overfishing, overhunting and development, but this is the first unequivocally tied to climate change. It’s a harbinger of what can happen to other ecosystems as they reach their survival thresholds.

This updates an article published April 29, 2021, to add the International Coral Reef Society report.

Sam Purkis, Professor and Chair of the Department of Marine Sciences, University of Miami

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Featured Illustration: Corals are made of hundreds to thousands of tiny living polyps: Khaled bin Sultan Living Oceans Foundation

The significant increase in CO2 comes as a surprise, since emissions fell 7% last year because of the covid-19 economic slowdown. But it turns out that all the virus did was to slow things down a little, not stop emissions in their tracks. In fact, if it had not been for the pandemic, last year would have see the biggest increase in carbon dioxide ever recorded in a single year!

Methane, which is an even more powerful greenhouse gas than CO2, also jumped up. It doesn’t stay nearly as long in the atmosphere as CO2, but it heats it up a lot while it is around. Rapidly increasing methane is very bad news, 28 times worse than increasing CO2, at least in the short run. Hydraulic fracturing for natural gas production appears to be a major source of methane.

President Biden has suggested capping these wells to stop the leaks.

NOAA points out that we haven’t seen 412 ppm of carbon dioxide in the atmosphere since the mid-Pliocene era, starting 3.6 million years ago.

The NOAA observations are disheartening because we have a relatively short time window, maybe 30 years, to get down to net carbon zero if we are going to avoid squandering our oceanic carbon budget.

See, the oceans absorb carbon dioxide, and if we stop putting it up in the atmosphere, they will take in everything we’ve produced since 1750. It will take them a while, and it will make them acidic, killing off maybe half of marine life. But gradually the parts per million of CO2 will come back down.

The catch is that the oceans only have so much absorptive capacity. If we exceed it, any further carbon dioxide we put into the atmosphere will stay there for a very long time, and will wreck the earth’s climate for a very long time.

So we want to see the PPM of carbon dioxide level off, not jump up.

I’ll revise what wrote earlier:

From about 10,000 years ago after the last ice age, there were typically between 260 and 280 parts per million of carbon dioxide in the atmosphere. This era is known as the Holocene. Then from about 1750, humankind starting turning the turbines of steam engines by burning, first wood, but then coal, in very large amounts. Then in the late 19th century the internal combustion engine was invented, which used petroleum to spark small explosions that drove pistons. By 1960 there were about 300 parts per million of CO2 up there. We had entered the Anthropocene, in which human beings are driving the climate. And driving it fast and furious.

Now it is 412.5 ppm. Never before in the whole history of planet earth has so much CO2 been put into the atmosphere so quickly. CO2 did increase from time to time in the past, but over millions of years and because of volcanoes.

And here is the bad news. The last time it was 412 ppm was the middle Pliocene warm period, stretching from 3.6 and 2.85 million years ago.

Temperatures in the middle Pliocene were on average as much as 5-7 degrees F. higher than today. The Arctic was 10 degrees C. hotter than today’s and it was covered in forests, not tundra. Seas were roughly 75- 90 feet higher. Some places now wet were desert-like. Here is what would happen to five cities under this scenario.

This 90 feet sea level rise is therefore almost certainly baked in and will occur, over the next few hundred years (oceans are huge and cold and take time to warm up). I wouldn’t buy real estate in Miami or lower Manhattan with an idea of passing it on to your grandchildren. Any beachfront property is ephemeral.

Folks, we are going in the wrong direction.

——

Bonus Video:

Grantham Imperial: “The Pliocene: The Last Time Earth had over 400 ppm of Atmospheric CO2”

Most of us growing up along Canada’s East Coast never worried about hurricane season. Except for those working at sea, we viewed hurricanes as extreme events in remote tropical regions, seen only through blurred footage of flailing palm trees on the six o’clock news.

Today, a warming ocean spins hurricanes faster, makes them wetter and drives them towards Atlantic Canada and even further inland. Hurricanes, winter storms and rising sea levels will continue to worsen unless we slow climate change.

The lifeblood of coastal economies and societies has always been the connection between land and sea, and that’s become more evident with climate change. But this isn’t just a coastal story anymore.

The oceans moderate the world’s climate through the absorption of heat and carbon. And just how much carbon the ocean will continue to absorb for us remains an open question. Whatever we do, it must be grounded in our growing wisdom of the deep connections between life on land and in the sea.

As Canada commits to a net-zero future and plans its post-COVID economic recovery, innovations and investments could backfire if they reduce the ocean’s ability to absorb our excesses.

Links between land and sea

The ocean has always directly affected the climate on land. The well-being of communities across the globe is directly linked to the ocean’s capacity to continue its regulating role of heat and carbon cycles.

Drought in the Prairies is tied to water temperatures in the Atlantic and Pacific oceans. When temperatures are most extreme, they signal the possible arrival of a “megadrought.”

In Australia, the occurrence of below-average rainfall, lasting several years, can be predicted by high Indian Ocean temperatures. This dries soils and lowers river flows, resulting in major community impacts such as water restrictions, declines in agricultural production and increased frequency of bushfires.

The success of Canada’s climate policies will therefore hinge on understanding how ocean processes are changing and society responds. The opportunity is at hand: Canada has committed to net-zero carbon in 2050, and to economic recovery once the COVID-19 pandemic has passed.

The federal government’s throne speech in September highlighted the oceans as critical to economic recovery post-COVID. The “blue economy,” mentioned in the throne speech, includes fisheries, aquaculture and offshore wind energy.

These two commitments are fundamentally linked: economic recovery and carbon neutrality both depend on the ocean’s ability to continue to regulate climate through heat and carbon absorption.

But the development of national policies on climate change, both in Canada and internationally, has generally ignored the ocean in climate calculations. Scientists lobbied intensely before the Paris Climate Agreement just to make sure the ocean was mentioned.

Changes to the ‘carbon sink’

We dare not further neglect the most important global storage depot on Earth: the ocean stores hundreds of times the heat and 50 times more carbon than the atmosphere, and takes up more carbon than all the rainforests combined.

Ocean carbon and heat absorption also provide a critical natural timescale against which we can measure our effectiveness in battling climate change. Fluctuations in the ocean “carbon sink” — the amount of carbon the ocean can remove from the atmosphere — will change the urgency with which we need to act.

For example, a waning carbon sink shrinks our window to curb land-based carbon emissions. But a growing sink might give us more time to enact difficult but necessary carbon policies that will have disruptive economic consequences.

There is no time for delay, and rewards come quickly; strong scientific evidence demonstrates that ocean processes controlling this absorption can either weaken or strengthen measurably in just a few decades.

Heat is absorbed physically from the atmosphere and mixed through the ocean on the scales of millennia. But carbon is absorbed through a complex network of chemical and biological processes, including coastal ecosystems such as kelp, mangroves and seagrasses that sustain local economies. Plankton (the tiny plants and animals that feed everything from mussels to whales) store carbon, so their behaviour and biology become a critical factor in the climate discussion.

We urgently need better observations of the ocean’s continued role as our heat and carbon sink.

Shifting carbon sink

The North Atlantic Ocean is the most intense carbon sink in the world: 30 per cent of the global ocean’s carbon dioxide removal occurs right in Canada’s backyard. If we extend Canada’s net-zero calculation to our exclusive economic zone (waters within 200 nautical miles of our coast), our net carbon emissions could change significantly.

Current estimates suggest including the oceans would reduce net emissions and help us get to net zero faster, but what happens if that changes? We must understand fully the processes controlling the “sink” to make the right climate policy choices.

This recalculation could shift our thinking on how to rejuvenate the Canadian economy. Investment in controversial industries such as deep-sea mining, which can supply materials needed for renewable ocean-based energy technologies like those used in offshore wind, can at the same threaten the very ocean ecosystems and food systems on which we depend. Formulating effective policies in the face of these uncertainties is a major challenge. Our path forward must build on our growing understanding of the deep connections between societal and ocean well-being.

Canadian researchers, including those at the Ocean Frontier Institute where we are based, are poised to address the fundamental questions about the ongoing role of the ocean in absorbing carbon, and to help develop appropriate policies. These conversations cut across traditional academic boundaries. In the past, ocean research was separated into the natural and applied, the social and human sciences. Now, we all need to work together.

The role of the ocean has been neglected for too long and must be drawn to the centre of the carbon discussion as we plot our trajectory to net-zero carbon in 2050. Canada’s carbon policies can lead the way internationally if they are grounded in strong, and strongly integrated, natural and social sciences. It is time for the research community to step up in their support.

Anya M. Waite, CEO and Scientific Director, Ocean Frontier Institute; Professor and Associate VP Research, Dalhousie University; Brad deYoung, Robert Bartlett Professor of Oceanography, Memorial University of Newfoundland; Chris Milley, Adjunct professor, Marine Affairs, Dalhousie University, and Ian G. Stewart, Associate professor of Humanities, University of King’s College

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Bonus Video added by Informed Comment:

The carbon cycle is key to understanding climate change | The Economist

The Pacific Ocean is the deepest, largest ocean on Earth, covering about a third of the globe’s surface. An ocean that vast may seem invincible. Yet across its reach – from Antarctica in the south to the Arctic in the north, and from Asia to Australia to the Americas – the Pacific Ocean’s delicate ecology is under threat.

In most cases, human activity is to blame. We have systematically pillaged the Pacific of fish. We have used it as a rubbish tip – garbage has been found even in the deepest point on Earth, in the Mariana Trench 11,000 metres below sea level.

And as we pump carbon dioxide into the atmosphere, the Pacific, like other oceans, is becoming more acidic. It means fish are losing their sense of sight and smell, and sea organisms are struggling to build their shells.

Oceans produce most of the oxygen we breathe. They regulate the weather, provide food, and give an income to millions of people. They are places of fun and recreation, solace and spiritual connection. So, healthy, vibrant oceans benefit us all. And by better understanding the threats to the precious Pacific, we can start the long road to protecting it.

This article is part of the Oceans 21 series

The series opens with five profiles delving into ancient Indian Ocean trade networks, Pacific plastic pollution, Arctic light and life, Atlantic fisheries and the Southern Ocean’s impact on global climate. It’s brought to you by The Conversation’s international network.

The ocean plastic scourge

The problem of ocean plastic was scientifically recognised in the 1960s after two scientists saw albatross carcasses littering the beaches of the northwest Hawaiian Islands in the northern Pacific. Almost three in four albatross chicks, who died before they could fledge, had plastic in their stomachs.

Now, plastic debris is found in all major marine habitats around the world, in sizes ranging from nanometers to meters. A small portion of this accumulates into giant floating “garbage patches”, and the Pacific Ocean is famously home to the largest of them all.

Most plastic debris from land is transported into the ocean through rivers. Just 20 rivers contribute two-thirds of the global plastic input into the sea, and ten of these discharge into the northern Pacific Ocean. Each year, for example, the Yangtze River in China – which flows through Shanghai – sends about 1.5 million metric tonnes of debris into the Pacific’s Yellow Sea.

A wildlife killer

Plastic debris in the oceans presents innumerable hazards for marine life. Animals can get tangled in debris such as discarded fishing nets, causing them to be injured or drown.

Some organisms, such as microscopic algae and invertebrates, can also hitch a ride on floating debris, travelling large distances across the oceans. This means they can be dispersed out of their natural range, and can colonise other regions as invasive species.

And of course, wildlife can be badly harmed by ingesting debris, such as microplastics less than five millimetres in size. This plastic can obstruct an animal’s mouth or accumulate in its stomach. Often, the animal dies a slow, painful death.

Seabirds, in particular, often mistake floating plastics for food. A 2019 study found there was a 20% chance seabirds would die after ingesting a single item, rising to 100% after consuming 93 items.

A scourge on small island nations

Plastic is extremely durable, and can float vast distances across the ocean. In 2011, 5 million tonnes of debris entered the Pacific during the Japan tsunami. Some crossed the entire ocean basin, ending up on North American coastlines.

And since floating plastics in the open ocean are transported mainly by ocean surface currents and winds, plastic debris accumulates on island coastlines along their path. Kamilo Beach, on the south-eastern tip of Hawaii’s Big Island, is considered one of the world’s worst for plastic pollution. Up to 20 tonnes of debris wash onto the beach each year.

Similarly, on uninhabited Henderson Island, part of the Pitcairn Island chain in the south Pacific, 18 tonnes of plastic have accumulated on a beach just 2.5km long. Several thousand pieces of plastic wash up each day.

Subtropical garbage patches

Plastic waste can have different fates in the ocean: some sink, some wash up on beaches and some float on the ocean surface, transported by currents, wind and waves.

Around 1% of plastic waste accumulates in five subtropical “garbage patches” in the open ocean. They’re formed as a result of ocean circulation, driven by the changing wind fields and the Earth’s rotation.

There are two subtropical garbage patches in the Pacific: one in the northern and one in the southern hemisphere.

The northern accumulation region is separated into an eastern patch between California and Hawaii, and a western patch, which extends eastwards from Japan.

Our ocean garbage shame

First discovered by Captain Charles Moore in the early 2000s, the eastern patch is better known as the Great Pacific Garbage Patch because it’s the largest by both size (around 1.6 million square kilometers) and amount of plastic. By weight, this garbage patch can hold more than 100 kilograms per square kilometre.

The garbage patch in the southern Pacific is located off Valparaiso, Chile, extending to the west. It has lower concentrations compared to its giant counterpart in the northeast.

Discarded fishing nets make up around 45% of the total plastic weight in the Great Pacific Garbage Patch. Waste from the 2011 Japan tsunami is also a major contributor, making up an estimated 20% of the patch.

With time, larger plastic debris degrades into microplastics. Microplastics form only 8% of the total weight of plastic waste in the Great Pacific Garbage Patch, but make up 94% of the estimated 1.8 trillion pieces of plastic there. In high concentrations, they can make the water “cloudy”.

Each year, up to 15 million tonnes of plastic waste are estimated to make their way into the ocean from coastlines and rivers. This amount is expected to double by 2025 as plastic production continues to increase.

We must act urgently to stem the flow. This includes developing plans to collect and remove the plastics and, vitally, stop producing so much in the first place.

Fisheries on the verge of collapse

As the largest and deepest sea on Earth, the Pacific supports some of the world’s biggest fisheries. For thousands of years, people have relied on these fisheries for their food and livelihoods.

But, around the world, including in the Pacific, fishing operations are depleting fish populations faster than they can recover. This overfishing is considered one of the most serious threats to the world’s oceans.

Humans take about 80 million tonnes of wildlife from the sea each year. In 2019, the world’s leading scientists said of all threats to marine biodiversity over the past 50 years, fishing has caused the most harm. They said 33% of fish species were overexploited, 60% were being fished to the maximum level, and just 7% were underfished.

The decline in fish populations is not just a problem for humans. Fish play an important role in marine ecosystems and are a crucial link in the ocean’s complex food webs.

Not plenty of fish in the sea

Overfishing happens when humans extract fish resources beyond the maximum level, known as the “maximum sustainable yield”. Fishing beyond this causes global fish stocks to decline, disrupts food chains, degrades habitats, and creates food scarcity for humans.

The Pacific Ocean is home to huge tuna fisheries, which provide almost 65% of the global tuna catch each year. But the long-term survival of many tuna populations is at risk.

For example, a study released in 2013 found numbers of bluefin tuna – a prized fish used to make sushi – had declined by more than 96% in the Northern Pacific Ocean.

Developing countries, including Indonesia and China, are major overfishers, but so too are developing nations.

Along Canada’s west coast, Pacific salmon populations have declined rapidly since the early 1990s, partly due to overfishing. And Japan was recently heavily criticised for a proposal to increase quotas on Pacific bluefin tuna, a species reportedly at just 4.5% of its historic population size.

Experts say overfishing is also a problem in Australia. For example, research in 2018 showed large fish species were rapidly declining around the nation due to excessive fishing pressure. In areas open to fishing, exploited populations fell by an average of 33% in the decade to 2015.

So what’s driving overfishing?

There are many reasons why overfishing occurs and why it is goes unchecked. The evidence points to:

• poverty among fishers in developing nations

• fishing subsidies that enable large fishing fleets to travel to the waters of developing countries and compete with small-scale fishers and keep ailing industries going

• poor fishery and community management

• weak compliance with fishing regulations due to shortfalls in local government capacity.

Let’s take Indonesia as an example. Indonesia lies between the Pacific and Indian oceans and is the world’s third-biggest producer of wild-capture fish after China and Peru. Some 60% of the catch is made by small-scale fishers. Many hail from poor coastal communities.

Overfishing was first reported in Indonesia in the 1970s. It prompted a presidential decree in 1980, banning trawling off the islands of Java and Sumatra. But overfishing continued into the 1990s, and it persists today. Target species include reef fishes, lobster, prawn, crab, and squid.

Indonesia’s experience shows how there is no easy fix to the overfishing problem. In 2017, the Indonesian government issued a decree that was supposed to keep fishing to a sustainable level – 12.5 million tonnes per year. Yet, in may places, the practice continued – largely because the rules were not clear and local enforcement was inadequate.

Implementation was complicated by the fact that almost all Indonesia’s smaller fishing boats come under the control of provincial governments. This reveals the need for better cooperation between levels of government in cracking down on overfishing.

What else can we do?

To prevent overfishing, governments should address the issue of poverty and poor education in small fishing communities. This may involve finding them a new source of income. For example in the town of Oslob in the Philippines, former fishermen and women have turned to tourism – feeding whale sharks tiny amounts of krill to draw them closer to shore so tourists can snorkel or dive with them.

Tackling overfishing in the Pacific will also require cooperation among nations to monitor fishing practices and enforce the rules.

And the world’s network of marine protected areas should be expanded and strengthened to conserve marine life. Currently, less than 3% of the world’s oceans are highly protected “no take” zones. In Australia, many marine reserves are small and located in areas of little value to commercial fishers.

The collapse of fisheries around the world shows just how vulnerable our marine life is. It’s clear that humans are exploiting the oceans beyond sustainable levels. Billions of people rely on seafood for protein and for their livelihoods. But by allowing overfishing to continue, we harm not just the oceans, but ourselves.

The threat of acidic oceans

The tropical and subtropical waters of the Pacific Ocean are home to more than 75% of the world’s coral reefs. These include the Great Barrier Reef and more remote reefs in the Coral Triangle, such as those in Indonesia and Papua New Guinea.

Coral reefs are bearing the brunt of climate change. We hear a lot about how coral bleaching is damaging coral ecosystems. But another insidious process, ocean acidification, is also threatening reef survival.

Ocean acidification particularly affects shallow waters, and the subarctic Pacific region is particularly vulnerable.

Coral reefs cover less than 0.5% of Earth’s surface, but house an estimated 25% of all marine species. Due to ocean acidification and other threats, these incredibly diverse “underwater rainforests” are among the most threatened ecosystems on the planet.

A chemical reaction

Ocean acidification involves a decrease in the pH of seawater as it absorbs carbon dioxide (CO₂) from the atmosphere.

Each year, humans emit 35 billion tonnes of CO₂ through activities such as burning of fossil fuels and deforestation.

Oceans absorb up to 30% of atmospheric CO₂, setting off a chemical reaction in which concentrations of carbonate ions fall, and hydrogen ion concentrations increase. That change makes the seawater more acidic.

Since the Industrial Revolution, ocean pH has decreased by 0.1 units. This may not seem like much, but it actually means the oceans are now about 28% more acidic than since the mid-1800s. And the Intergovernmental Panel on Climate Change (IPCC) says the rate of acidification is accelerating.

Why is ocean acidification harmful?

Carbonate ions are the building blocks for coral structures and organisms that build shells. So a fall in the concentrations of carbonate ions can spell bad news for marine life.

In more acidic waters, molluscs have been shown to have trouble making and repairing their shells. They also exhibit impaired growth, metabolism, reproduction, immune function, and altered behaviours. For example, researchers exposed sea hares (a type of sea slug) in French Polynesia to simulated ocean acidification and found they had less foraging success and made poorer decisions.

Ocean acidification is also a problem for the fishes. Many studies have revealed elevated CO₂ can disrupt their sense of smell, vision and hearing. It can also impair survival traits, such as a fish’s ability to learn, avoid predators, and select suitable habitat.

Such impairment appears to be the result of changes in neurological, physiological, and molecular functions in fish brains.

Predicting the winners and losers

Of the seven oceans, the Pacific and Indian Oceans have been acidifying at the fastest rates since 1991. This suggests their marine life may also be more vulnerable.

However, ocean acidification does not affect all marine species in the same way, and the effects can vary over the organism’s lifetime. So, more research to predict the future winners and losers is crucial.

This can be done by identifying inherited traits that can increase an organism’s survival and reproductive success under more acidic conditions. Winner populations may start to adapt, while loser populations should be targets for conservation and management.

One such winner may be the epaulette shark, a shallow water reef species endemic to the Great Barrier Reef. Research suggests simulated ocean acidification conditions do not impact early growth, development, and survival of embryos and neonates, nor do they affect foraging behaviours or metabolic performance of adults.

But ocean acidification is also likely to create losers on the Great Barrier Reef. For example, researchers studying the orange clownfish – a species made famous by Disney’s animated Nemo character – found they suffered multiple sensory impairments under simulated ocean acidification conditions. These ranged from difficulties smelling and hearing their way home, to distinguishing friend from foe.

It’s not too late

More than half a billion people depend on coral reefs for food, income, and protection from storms and coastal erosion. Reefs provide jobs – such as in tourism and fishing – and places for recreation. Globally, coral reefs represent an industry worth US$11.9 trillion per year. And importantly, they’re a place of deep cultural and spiritual connection for Indigenous people around the world.

Ocean acidification is not the only threat to coral reefs. Under climate change, the rate of ocean warming has doubled since the 1990s. The Great Barrier Reef, for example, has warmed by 0.8℃ since the Industrial Revolution. Over the past five years this has caused devastating back-to-back coral bleaching events. The effects of warmer seas are magnified by ocean acidification.

Cutting greenhouse gas emissions must become a global mission. COVID-19 has slowed our movements across the planet, showing it’s possible to radically slash our production of CO₂. If the world meets the most ambitious goals of the Paris Agreement and keeps global temperature increases below 1.5℃, the Pacific will experience far less severe decreases in oceanic pH.

We will, however, have to curb emissions by a lot more – 45% over the next decade – to keep global warming below 1.5℃. This would give some hope that coral reefs in the Pacific, and worldwide, are not completely lost.

Clearly, the decisions we make today will affect what our oceans look like tomorrow.

Jodie L. Rummer, Associate Professor & Principal Research Fellow, James Cook University; Bridie JM Allan, Lecturer/researcher, University of Otago; Charitha Pattiaratchi, Professor of Coastal Oceanography, University of Western Australia; Ian A. Bouyoucos, Postdoctoral fellow, James Cook University; Irfan Yulianto, Lecturer of Fisheries Resources Utilization, IPB University, and Mirjam van der Mheen, Fellow, University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Although the governments of the world talk a nice game, actually none of them is significantly reducing their annual emissions. Temporary falls in emissions from events like Covid-19 don’t count because all signs point to a ramping back up of emissions as soon as the crisis passes. In 2019, you, I, and everyone else on earth put nearly 37 billion tons of the dangerous heat-trapping gas, carbon dioxide, into the atmosphere, the third year in a row the number increased. We’ve been going in the wrong direction.

The way we put CO2 into the atmosphere is to drive our gasoline cars, to burn coal to make electricity or heat our homes, to burn natural gas for the same purposes, etc. That is, the innocent little things we do every day to get around and turn on our lights and to control the temperature in our buildings — those quotidian little things are wrecking the earth, raising the seas, burning the forests, turbo-charging hurricanes and cyclones, and beginning the process of destroying up to $563 trillion in value throughout the world.

In the second presidential debate, Joe Biden said he wanted to transition away from US government subsidies for petroleum. Biden has also urged an end to fracking on public land. Trump jumped on these statements and twisted them, because he knows that western Pennsylvania has a lot of people in it who depend on fracking and on the production of oil and gas. Trump probably cannot win the presidency without Pennsylvania.

While I sympathize with people who might lose their jobs because of technological change, people in western Pennsylvania should look around for alternatives to fracking and fossil fuels as ways to make money. Because they are wiping out the value all the wealth in their communities over time and beggaring their grandchildren and great-grandchildren. New York state has banned fracking and it is still rich. Solar is now the cheapest form of energy, with wind turbines just behind, and oil, coal and gas are doomed over the next two decades. But we can’t wait for the markets and technology to make fossil fuels even more uneconomical than they are.

A couple of years ago, this site estimated the value of all the immoveable property in the world at $217 trillion. Stocks and securities come to $55 trillion. Money, i.e. cash, bank deposits, etc., comes to about $37 trillion. Then you have almost $100 trillion in securitized debt.

That is, its seems likely that the $563 trillion that the Nature Communications article found was the upper range of climate emergency damage comes to more wealth than currently exists in the entire world. It would all be wiped out, and we’d all be in the stone age or dead.

The world has what is called a “carbon budget.” This results from the ability of the oceans to absorb carbon dioxide. It isn’t actually a really good thing, since it makes the oceans more acidic and will kill off a lot of fish. But at least large amounts of this dangerous gas won’t still be trapping heat in the upper atmosphere. It will be in the ocean.

Here’s the problem. The oceans can only absorb so much CO2. There is also evidence that a warm layer of ocean water at the surface, which is intermixed with freshwater ice melt, actually has less CO2 absorptive capacity, so as the earth heats this oceanic offset may diminish.

When the ocean has taken in all the CO2 it can, whatever petroleum, gas and coal we burn beyond that will produce carbon dioxide that just hangs in the air and overheats the earth. There are still things that will scrub it from the atmosphere, like igneous rock, to which it binds. But one estimate I read said that it would take 100,000 years for those processes to take back out all the CO2 humans have put up there.

So, really, there is only one thing to do if we want to preserve our jobs and our wealth. That is to invest in getting off fossil fuels as soon as humanly possible. That task will require governments to intervene– it can’t be accomplished solely by individual effort. It is admirable for people to get electric cars and put solar panels up on their roofs, but those changes won’t come in sufficient numbers or quickly enough. We need the government.

Economist Robert Pollin has estimated that if we spend 2% of GDP annually from now to 2050, we could get to net carbon zero for $18 trillion over those 30 years. That is $600 billion a year, or less than the cost of the Department of Defense (which has not actually defended us from the most dire threats we’ve faced recently, like Covid-19 and the climate emergency).

Personally, I think such estimates don’t take account of how steeply and quickly the cost of solar and wind power generation is falling. We would already save money by closing all coal and natural gas plants and replacing them with wind and solar. Imagine what it will be like in 2030.

But what the Nature Communications paper demonstrates is that it is absolutely crazy *not* to invest that $18 trillion in moving quickly to keep the increase in global heating down to about 2 degrees F. (1.5 degrees C.).

Because the worst case scenario of not doing anything is that we lose everything.

*Calel, R., Chapman, S.C., Stainforth, D.A. et al. Temperature variability implies greater economic damages from climate change. Nat Commun 11, 5028 (2020). https://doi.org/10.1038/s41467-020-18797-8

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Bonus video:

Thom Hartmann: “The Real Cost Of Climate Change (w/ Dr. Michael Mann)”