All posts tagged mass extinction

Half-way to Catastrophe — Global Hothouse Extinction to be Triggered by or Before 2100 Without Rapid Emissions Cuts

Over recent years, concern about a coming hothouse mass extinction set off by human carbon emissions has been on the rise. Studies of Earth’s deep history reveal that at least 4 out of the 5 major mass extinctions occurred during both hothouse periods and during times when atmospheric and oceanic carbon spiked to much higher than normal ranges. Now a new scientific study reveals that we have already emitted 50 percent of the carbon needed to set off such a major global catastrophe.

Fossil Fuel Burning = Race Toward a 6th Mass Extinction

The primary driver of these events is rising atmospheric CO2 levels — often caused in the past by the emergence of masses of volcanoes or large flood basalt provinces (LIP in image below). In the case of the worst mass extinction — the Permian — the Siberian flood basalts were thought to have injected magma into peat and coal formations which then injected a very large amount of carbon dioxide into the Earth’s atmosphere and oceans.

(In the Earth’s deep past, the worst global mass extinctions were driven by large igneous provinces like the eruptions across Siberia during the Permian. The initial killing mechanism during these extinctions was a result of the upshot ocean anoxia, acidification, and biochemistry change. During the Permian, effects eventually spilled over to land and possibly the upper atmosphere. Today’s human carbon emissions will ultimately produce worse impacts over shorter time scales than the Permian. Image source: Skeptical Science and The History of Seawater Carbonate Chemistry, Atmospheric CO2, and Ocean Acidification.)

Higher atmospheric and ocean carbon drove both environmental and geochemical changes — ultimately setting off hyperthermal temperature spikes and ocean anoxic events that were possibly assisted by methane hydrate releases and other climate and geophysical feedbacks. The net result of these events was major species die-offs in the ocean and, during the worst events, on land.

Considering the fact that present human activities, primarily through fossil fuel burning, are releasing vast quantities of carbon into the Earth’s atmosphere and oceans at a rate never before seen in the geological past, it appears that the world is racing toward another major mass extinction. In the past, the location of this dangerous precipice was a bit murky. But a recent study in Science Advances attempts to better define the threshold at which the worst of the worst mass extinction events — set off by rising ocean and atmospheric carbon — occur.

310 Billion Tons Carbon Entering Ocean = Mass Extinction Threshold

The study used a relatively easy to identify marker — ocean carbon uptake — in an attempt to identify a boundary limit at which such mass extinctions tend to occur. And the study found that when about 310 billion tons of carbon gets taken in by the oceans, a critical boundary is crossed and a global mass extinction event is likely to occur.

Presently, human beings are dumping carbon into the atmosphere at an extremely high rate of around 11 billion tons per year. Today, about 2.6 billion tons per year of this carbon ends up in the ocean. In total, since 1850, humans have added about 155 billion tons of carbon to the Earth’s oceans — leaving us with about another 155 billion tons before Rothman’s (the study author) extinction threshold is crossed.

(Thresholds of Catastrophe in the Earth System finds that present carbon emissions bring us about halfway to the global mass extinction boundary limit. That carbon emissions cuts need to be more aggressive than the most aggressive present international policy scenario to reliably avoid risk of setting off a global mass extinction event.)

At the presently high rate of fossil fuel burning and greenhouse gas emissions from humans, that gives us about 60 years. This is true even if emissions levels remain steady and do not increase. If emissions increase along a business as usual pathway, we could cross that threshold by or before the 2050s. And under all present emissions scenarios identified by international climate policy, the 310 billion ton threshold is either closely approached or greatly exceeded by 2100.

This should set off warning bells for global governments and climate policy advocates alike. What it means is that halting fossil fuel burning and transitioning to renewable energy needs to occur at rather swift rates — with annual global carbon emissions peaking within the next 1-10 years and then rapidly diminishing to zero — if we are to avoid a high risk of setting off another major global mass extinction. Of course, this does not mean that such a response will avoid harmful climate impacts — a number of which have already been locked in. Just that such a major response would be needed to avoid a high risk of setting off a catastrophic global mass extinction event equal to some of the worst in all of Earth’s deep history.

Rapid Movement Toward Terrible Long-Term Global Consequences

The study notes that past major extinctions like the Permian occurred on 10,000 to 100,000 year time-scales. And that during these events the changes inflicted upon the global environment by major carbon additions to the ocean and atmosphere occurred too swiftly for organisms to adapt. The pace of human carbon addition is presently faster than even during the Permian — the worst mass extinction event. So if this very large carbon spike were to continue it has the potential to set off impacts as bad, or worse than the Permian and over much shorter time horizons.

The study also notes that it takes about 10,000 years for the worst impacts of a mass extinction carbon spike to be fully realized. So hitting the 310 billion ton threshold by or before 2100 runs a high risk of consigning the world to many, many centuries of increasingly worsening climate impacts.

Links:

Thresholds of Catastrophe in the Earth System

History of Seawater Carbonate Chemistry, Atmospheric CO2, and Ocean Acidification

Today’s Climate Change is More Comparable to Earth’s Worst Mass Extinction

Heading Toward a Permian Future

Hat tip to Abel

183 Comments
by robertscribbler on September 22, 2017  •  Permalink
Posted in Climate Change
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Posted by robertscribbler on September 22, 2017

https://robertscribbler.wordpress.com/2017/09/22/half-way-to-catastrophe-sixth-global-mass-extinction-to-be-triggered-by-or-before-2100-without-rapid-emissions-cuts/

It’s Not Just Subtropical Cornwall — Climate Zones Everywhere are on the March Poleward

A few weeks ago, the University of Exeter found that parts of Cornwall, England had become subtropical. The study stated that since average temperatures had risen to above 10 degrees Celsius (50 Fahrenheit) for periods of time longer than seven months, this part of England situated on a latitude line north of most of Newfoundland has become part of a climate zone that during the early 20th century extended as far south as the southern tip of Florida.

Seemingly oblivious to the new oddity and possible peril implied by such a significant climate shift, the study went on to cheerfully observe that:

Parts of Cornwall have become subtropical since 2000 and this could create opportunities to grow new, unusual plants. Sunflowers, maize, grapevines and tea are already grown in the Duchy.

The study also pointed out that the added heat might present a problem or two, instances that might be sorted out simply by getting scientists to work together with farmers:

While sub-tropical conditions may create opportunities to grow exotic crops, the lower frequency of frosts is also making Cornwall more susceptible to invasive species. As the temperatures continue to warm, we need to ensure we manage the risks carefully as well as capitalising on the opportunities. This will require scientists to continue to work hand-in-hand with the horticultural sector.

Subtropical Cornwall — Sahara Desert Marches North as Coastal Zones Flood

Unmentioned, however, was how bizarre the notion of a subtropical Cornwall actually is and what such a major climate shift may mean for the globe, Europe, and Cornwall itself — a shift that may put the odd notion of ‘capitalising on the opportunities’ practically out of reach.

Unfortunately, big climate-zone movements of the kind shown in the Exeter study risk an amazing range of ecological and geophysical damage. A short and incomplete list includes melting glaciers, shrinking sea ice, rising sea levels (a very real worry for the numerous coastal communities near or within Cornwall, including places like Falmouth, Penzance, St Ives, and Exeter itself), stratifying and increasingly anoxic oceans, mass coral bleaching, and habitat loss for species on a global scale risking mass extinction. Any such mention of this appropriately worrying context was notably and oddly absent from the Exeter study.

Subtropical climates

(The subtropical climate zones of the world as of the late 20th century. Image source: Commons.)

Of particular interest to Cornwall and regions nearby is that the northward expansion of the subtropical regions of the world has long been a concern among climate scientists due to its ability to enhance desertification in highly-populated regions like Europe. The issue is that as the tropics and subtropics drift poleward, they bring hot, dry weather along with them. Because the subtropical regions support conditions conducive for arid climates, there is a high likelihood that deserts will march northward into more densely-inhabited regions.

A 2010 study by UCAR found that under continued fossil-fuel burning, the Sahara Desert essentially leaps across the Mediterranean and fully expands into southern and central Europe. In other words, though Cornwall may be able to support subtropical plants now, the northward movement of the arid zone related to the incoming warmth would make growing such plants an increasingly difficult prospect as time moves forward.

Drought Zones Expand under global warming

(A 2010 UCAR study found that drought zones dramatically expand as the tropical and subtropical climate zones march northward due to human-forced warming. Image source: Drought Under Global Warming.)

It’s Not Just Cornwall — Climate Zones are Moving Everywhere

As we consider what the onset of intensified warming may mean for Cornwall — with deserts expanding and seas stratifying as they rise — it’s also worth thinking a little bit about the related warming-forced movement of the world’s isotherms. Isotherm is a meteorological term for a line connecting regions of the same temperature. Averaged over the coldest or warmest months of a year, these lines of temperature also mark the boundaries between climate zones.

The tropics, for example, are bounded in the Northern and Southern Hemispheres by a line of 18 C (64.4 F) average coldest-month temperatures. The edges of the two polar zones are bounded by a line of 10 degrees Celsius (50 F) average temperatures during the hottest months of the year (July in the Boreal region, January in the Austral region).

 

Isotherms

(NOAA global isotherm map. Image source: NOAA Climate Zones.)

Tucked between these two zones are the temperate and subtropical climates. Over the past 40 years, rapid warming has shoved these isotherms poleward. This shift has created a new climate reality for Cornwall and pretty much everywhere else.

At an average decadal march away from the Equator of about 35 miles, these respective climate boundaries have moved by around 140 miles over the last four decades, expanding the total reach of the tropic zone by 280 miles northward and southward. In the Northern Hemisphere, the polar climate zone has shrunken toward the continental edges by about 14o miles, while in the Southern Hemisphere, the polar zone is shrinking off the tip of South America and across the Southern Ocean toward Antarctica by a similar distance.

These changes in the isotherms are rough measures, of course. In some places, like Cornwall, climate zones are moving toward the poles at an even faster rate. And the Arctic climate zone is notably shrinking at a more rapid rate than the Southern Hemisphere polar zone.

Rapid Climate Zone Movement Risks Species Extinction

Movement of these climate zones is driven by a rate of global warming in the range 0.15 to 0.20 degrees C every ten years, a pace of warming about 30 times faster than the warming at the end of the last ice age. As a result, plants and animals are finding that the habitats to which they’ve adapted are swiftly and dramatically changing. Plant and animal ranges have moved behind these climate zones at a rate of only about four miles every decade. Basically, habitats are moving too quickly for the creatures they support to catch up.

Earth_Global_Circulation

(As the globe warms due to fossil-fuel burning, the tropical Hadley cell expands even as the top of the polar and mid-latitude cells rise. This combination results in severe climate shifts and more persistent weather patterns due to a weakened polar jet stream. Such change in climate results in loss of animal habitat and increasingly difficult and extreme weather conditions for human beings. Image source: NASA/Commons.)

Back in 2008, climate scientist James Hansen noted:

If emissions of greenhouse gases continue to increase at the current rate—“business as usual”—then the rate of isotherm movement will double in this century to at least 70 miles per decade. If we continue on this path, a large fraction of the species on Earth, as many as 50 percent or more, may become extinct. The species most at risk are those in polar climates and the biologically diverse slopes of alpine regions. These animals, in effect, will be pushed off the planet—though some like the polar bear may be “rescued” and allowed to survive in zoos.

It is important to also consider that loss of plant habitat due to warming and drying is a primary driver of the mass tree death and increase in wildfire rates we have seen across the globe in recent years. Along with the mass exodus of fish from warming Equatorial oceans and the flipping-on of the global coral bleaching switch during 2014-2016, we can see these species-threatening impacts in heart-wrenching and terrifying effect today.

Given that the rapid poleward progression of the isotherms has continued since Hansen’s 2008 writing, and given that the pace of global warming appears to have accelerated through the 2014 to 2016 period, it appears that his statement is all the more salient today — especially now that we are starting to see some of the mass loss of animal and plant life due to warming that Hansen mentioned. And especially since parts of Cornwall in England are now considered subtropical.

Links:

Subtropical Cornwall Climate Could Mean Exotic New Crops (among other things)

Commons

Drought Under Global Warming

NOAA Climate Zones

Scientist James Hansen, “The 800 Pound Gorilla”

66 Million Trees Dead in California

This Global Coral Bleaching Event Just Won’t End

Tropical Fish Moving Toward Poles

NASA/Commons

Hat tip to Cate

Hat tip to DT Lange

103 Comments
by robertscribbler on August 4, 2016  •  Permalink
Posted in Climate Change
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Posted by robertscribbler on August 4, 2016

https://robertscribbler.wordpress.com/2016/08/04/its-not-just-subtropical-cornwall-climate-zones-everywhere-are-on-the-march-poleward/

Is Human Warming Prodding A Sleeping Methane Monster off Oregon’s Coast?

We’ve talked quite a bit about the Arctic Methane Monster — the potential that a rapidly warming Arctic will force the release of disproportionately large volumes of methane from organic material locked in permafrost and in frozen sea bed hydrates composing volumes of this powerful greenhouse gas large enough to significantly increase the pace of human-forced global warming. But if we consider the globe as a whole, the Arctic isn’t the only place where large methane stores lurk — laying in wait for the heat we’ve already added to the world’s oceans and atmosphere to trigger their release. And a new study out of the University of Washington provides yet another indication that the continental shelf off Oregon and Washington may be one of many emerging methane release hot spots.

For all around the world, and beneath the broad, blue expanse of the world’s seas, rest billions and billions of tons of frozen methane hydrate.

A kind of methane and ice combination, frozen hydrate is one of the world’s most effective natural methods of trapping and sequestering carbon. Over long ages, organic material at the bottom of the oceans decompose into hydrocarbons, often breaking down into methane gas. At high pressure and low temperature, this methane gas can be locked away in a frozen water-ice hydrate lattice, which is then often buried beneath the sea bed where it can safely remain for thousands or even millions of years.

Plume2_nolabels_cropped

(Plume of methane bubbles rising from the sea floor off the Oregon Coast. This image shows methane bubbles originating from the sea bed about 515 meters below the surface before dissolving into the water column at about 180 meters depth. Image source: American Geophysical Union.)

Most of these deposits lay well beneath the sea bed or at extreme ocean depths of one mile or greater. And so far, human forced warming hasn’t been great enough to risk the destabilization of most of these deep ocean carbon stores. But some hydrate deposits rest in the shallower waters of continental slope systems and at depths where current warming may now be causing them to destabilize.

Scientists Think Methane Hydrates May be Destabilizing off Oregon

Enter a new study by University of Washington scientists which found “an unusually high number of bubble plumes at the depth where methane hydrate would decompose if seawater has warmed.” The scientists concluded that these bubble plumes were likely evidence of methane hydrate destabilization due to a human forced warming of the water column in the range of about 500 meters of depth.

The warm waters, ironically, come from a region off Siberia where the deep waters have, over recent decades, been heated to unprecedented temperatures. These waters have, in turn, through ocean current exchange, circulated to the off-shore region of Washington and Oregon where they appear to have gone to work destabilizing methane hydrate in the continental slope zone. A paper published during 2014 hypothesized that these warm waters would have an impact on hydrates. And the new paper is the first potential confirmation of these earlier predictions.

In total about 168 methane plumes are now observed to be bubbling out of the sea bed off the Washington and Oregon coasts. Of these, 14 are located in the 500 meter depth range where ocean warming has pushed temperatures to levels at which hydrate could begin to destabilize. University of Washington researchers noted that the number of plumes at this depth range was disproportionately high, which also served as an indirect indicator that human heating may be causing this methane to release.

PlumesMap

(Locations of methane plumes in the continental slope zone off Washington and Oregon. The location of a disproportionate number of these plumes in a zone now featuring a warming water column is an indication that the human-forced heating of ocean currents is starting to drive some methane hydrate structures to destabilize. Image source: AGU.)

Lead author H. Paul Johnson, a University of Washington professor of oceanography noted in AGU:

“So it is not likely to be just emitted from the sediments; this appears to be coming from the decomposition of methane that has been frozen for thousands of years… What we’re seeing is possible confirmation of what we predicted from the water temperatures: Methane hydrate appears to be decomposing and releasing a lot of gas. If you look systematically, the location on the margin where you’re getting the largest number of methane plumes per square meter, it is right at that critical depth of 500 meters.””

Implications For Ocean Health, Carbon Cycle

Most methane released at this depth never reaches the atmosphere. Instead, it either oxidizes to CO2 in the water column or is converted by ocean bacteria. That said, expanding zones of methane release can rob the surrounding ocean of vital oxygen even as it can saturate the water column with carbon — increasing ocean acidification and reducing the local ocean’s ability to draw carbon out of the atmosphere. Such a response can indirectly increase the volume of heat trapping gasses in the atmosphere by reducing the overall rate of ocean carbon uptake. In more extreme cases, methane bubbles reach the surface where they then vent directly into the atmosphere, proportionately adding to the human-produced greenhouse gasses that have already put the world into a regime of rapid warming.

It has been hypothesized that large methane releases from ocean hydrate stores contributed to past hothouse warming events and related mass extinctions like the Permian and the PETM (See A Deadly Climb From Glaciation to Hothouse). But the more immediate consequences of smaller scale releases are related to declining ocean health.

According to AGU and Dr. Johnson, the study author:

Marine microbes convert the methane into carbon dioxide, producing lower-oxygen, more-acidic conditions in the deeper offshore water, which eventually wells up along the coast and surges into coastal waterways. “Current environmental changes in Washington and Oregon are already impacting local biology and fisheries, and these changes would be amplified by the further release of methane,” Johnson said.

Instances of mass sea life die-off have already occurred at a very high frequency off the Washington and Oregon Coasts. And many of these instances have been associated with a combination of low oxygen content in the near and off shore waters, increasing ocean acidification, increasing dangerous algae blooms, and an overall warming ocean system. It’s important to note that ocean acidification, though often cited in the media, is just one of many threats to ocean life and health. In many cases, low oxygen dead zones and large microbial blooms can be even more deadly. And in the most extreme low oxygen regions, the water column can start to fill up with deadly hydrogen sulfide gas — a toxic substance that, at high enough concentrations, kills off pretty much all oxygen-based life (See Hydrogen Sulfide in the World’s Warming Oceans).

During recent years, mass sea life deaths have been linked to a ‘hot blob’ forming in nearby waters (See Mass Whale Death in Northeast Pacific — Hot Blob’s Record Algae Bloom to Blame?). However, indicators of low oxygen in the waters near Washington and Oregon have been growing in frequency since the early 2000s. Though the paper does not state this explicitly — increasing rates of methane release in the off-shore waters due to hydrate destabilization may already be contributing to declining ocean health in the region.

Slope Collapse, Conditions in Context

A final risk associated with methane hydrate destabilization in the continental slope zone is an increased prevalence of potential slope collapse. As methane hydrate releases, it can deform the sea bed structures within slope systems. Such systems become less stable, increasing the potential for large underwater landslides. Not only could these large landslides displace significant volumes of water or even set off tsunamis, slope collapse events also risk uncovering and exposing more hydrate systems to the warming ocean in a kind of amplifying feedback.

In context, the total volume of methane being released into the off-shore environment is currently estimated to be about 0.1 million metric tons each year. That’s about the same rate of hydrocarbon release seen from the Deepwater Horizon blowout. A locally large release but still rather small in size compared to the whopping 10+ billion tons of carbon being dumped into the atmosphere each year through human fossil fuel burning. However, this release is widespread, uncontrolled, un-cappable and, if scientists are correct in their indications of a human warming influence, likely to continue to increase as the oceans warm further.

Links:

Bubble Plumes off Washington and Oregon Suggest Warmer Ocean May be Releasing Frozen Methane

Geochemistry, Geophysics, Geosystems

Warming Oceans May be Spewing Methane off US West Coast

Concern Over Catastrophic Methane Release

Hydrogen Sulfide in the World’s Warming Oceans

Mass Whale Death in Northeast Pacific — Hot Blob’s Record Algae Bloom to Blame?

A Deadly Climb From Glaciation to Hothouse

Hat tip to Humortra

233 Comments
by robertscribbler on October 16, 2015  •  Permalink
Posted in Climate Change, Cthulhucene
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Posted by robertscribbler on October 16, 2015

https://robertscribbler.wordpress.com/2015/10/16/is-human-warming-prodding-a-sleeping-methane-monster-off-oregons-coast/

Renewable Energy and The Fierce Urgency of Now: A Second Call For Fossil Fuel Abolition

“We have also come to this hallowed spot to remind America of the fierce urgency of Now.”

Though these words were spoken in the noble pursuit of the most just of causes by Dr. Martin Luther King many years ago, they have lost none of their potency or relevance. For though those facing economic and social oppression have been justly elevated by the actions of the equality movement Dr. King so eloquently spoke for, we are now in the process of consigning ourselves and our progeny to an entirely different but no less brutal kind of oppression. A world where danger, difficulty, severe environmental hazard and poverty will come as a result of our failure to make the right energy decisions now.

It is a brutal kind of generational theft in which the current wealth of some is dependent on the enslavement of our own children to the spite of a barren and violent world. A world that could best be seen as a curse. A world of rising seas, expanding deserts, of scarce water, of ruined and abandoned cities, a world where the oceans themselves vent poison gas.

That we could set ourselves on such a path requires the very worst kind of social blindness. A zombie state of denial in which we have willfully hidden our faces from the ever-more-visible harm we are causing. For we must be in such a state to even consider the continued use of the dirty and harmful fuels. For we must be lost if we do not understand the pain we will surely inflict on future generations and even ourselves as we inflame our world to conditions not seen in 10 million, 55 million, or 250 million years. As we, with each lighting of a fossil fire, invoke the names of past great extinctions: Eocene, Jurrassic, Permian.

Mass extinction events

(Mass Extinction Events. Two of the three major mass extinctions and many more of the minor mass extinctions over the past 250 million years have been linked to greenhouse gas driven hothouse and Stratified/Canfield Ocean events. Image source: Biodiversity Crisis.)

There is no excuse for keeping on this path. No justification for the harm that would surely come from our continued burning. No rationale that could lend credence to ensuring our world becomes a place of Great Dying.

On March 22, 2013, a call was made for Fossil Fuel Abolition. Only a few have listened. Some, like the nation of Scotland, have pledged to pursue a true construction of that enlightened ‘City on a Hill,’ by harnessing the glorious blaze of solar radiance or the whispering winds of our world.

So I ask, why not America? Is Scottland to boldly lead in the turning away from the path of harm? Is it for America to come up with a vile excuse not to follow? To delay and to therefore cause more harm?

Some among us have turned their face from environmental oppression and asked others to follow. James Hansen, Rachel Carson, Bill McKibben, Joe Romm, Chris Hayes and ever so many more. Yet others dissemble, making false claims, providing rationales for escalating violence. So, in this most desperate hour, we are a house divided. Divided into those who serve a future in which humankind can rationally live and those who serve the Destroyers of the Earth.

This is an unconscionable state and it cannot stand. So the call must again go out.

Fossil Fuel Abolition!

52 Comments
by robertscribbler on April 25, 2014  •  Permalink
Posted in Climate Change
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Posted by robertscribbler on April 25, 2014

https://robertscribbler.wordpress.com/2014/04/25/renewable-energy-and-the-fierce-urgency-of-now-a-second-call-for-fossil-fuel-abolition/