Showing posts with label feedback loop. Show all posts
Showing posts with label feedback loop. Show all posts
Monday, June 30, 2014
Wednesday, April 30, 2014
Carbon loss from soil accelerating climate change
Carbon loss from soil accelerating climate change
April 24, 2014 sciencedaily.com
Research published in Science today found that increased levels of carbon dioxide in the atmosphere cause soil microbes to produce more carbon dioxide, accelerating climate change.
Two Northern Arizona University researchers led the study, which challenges previous understanding about how carbon accumulates in soil. Increased levels of CO2 accelerate plant growth, which causes more absorption of CO2through photosynthesis.
Until now, the accepted belief was that carbon is then stored in wood and soil for a long time, slowing climate change. Yet this new research suggests that the extra carbon provides fuel to microorganisms in the soil whose byproducts (such as CO2) are released into the atmosphere, contributing to climate change.
"Our findings mean that nature is not as efficient in slowing global warming as we previously thought," said Kees Jan van Groenigen, research fellow at the Center for Ecosystem Science and Society at NAU and lead author of the study. "By overlooking this effect of increased CO2 on soil microbes, models used by the Intergovernmental Panel on Climate Change may have overestimated the potential of soil to store carbon and mitigate the greenhouse effect."
In order to better understand how soil microbes respond to the changing atmosphere, the study's authors utilized statistical techniques that compare data to models and test for general patterns across studies. They analyzed published results from 53 different experiments in forests, grasslands and agricultural fields around the world. These experiments all measured how extra CO2 in the atmosphere affects plant growth, microbial production of carbon dioxide, and the total amount of soil carbon at the end of the experiment.
"We've long thought soils to be a stable, safe place to store carbon, but our results show soil carbon is not as stable as we previously thought," said Bruce Hungate, director of the Center for Ecosystem Science and Society at NAU and study author. "We should not be complacent about continued subsidies from nature in slowing climate change."
Journal Reference:
Kees Jan van Groenigen, Xuan Qi, Craig W. Osenberg, Yiqi Luo, and Bruce A. Hungate. Faster Decomposition Under Increased Atmospheric CO2 Limits Soil Carbon Storage. Science, 2014 DOI: 10.1126/science.1249534
Friday, April 25, 2014
How Guy McPherson gets it wrong
How Guy McPherson gets it wrong
SCOTT K. JOHNSON, 02/17/2014 fractalplanet.wordpress.com
Recently, a few Ars Technica commenters have been posting references to the work of Guy McPherson on climate articles. McPherson is a retired professor of ecology at the University of Arizona, and he runs a blog called Nature Bats Last. In recent years, he has turned his energies to dire warnings of impending climate catastrophe. Those warnings go far beyond what you’ll find anywhere else: McPherson believes humans will go extinct in as little as two decades.
Now, lots of people run blogs that make wild claims, so why am I spending time on this one? McPherson claims to simply be passing along scientific data to the public— data that most scientists are unwilling to talk about and governments are trying to keep secret. As a result, his followers (I mean to use that term more in the Twitter sense than a religious one) seem confident that they have the weight of science behind them. It takes careful examination of McPherson’s references, and a familiarity with the present state of climate science, to uncover that his claims aren’t scientific at all. I also get the feeling that his internet following might not be insignificant (as noted by climate scientist Michael Tobis) and could be growing, yet I couldn’t find any direct challenges with a web search. This makes one.
Bizarro denial
First, I want to go over general problems with McPherson’s claims and talk about what climate science is really telling us. For those wanting specifics, I’ll post a list of point-by-point corrections of McPherson’s main “Climate Change Summary and Update” post in the third section.
In many ways, McPherson is a photo-negative of the self-proclaimed “climate skeptics” who reject the conclusions of climate science. He may be advocating the opposite conclusion, but he argues his case in the same way. The skeptics often quote snippets of science that, on full examination, doesn’t actually support their claims, and this is McPherson’s modus operandi. The skeptics dismiss science they don’t like by saying that climate researchers lie to keep the grant money coming; McPherson dismisses inconvenient science by claiming that scientists are downplaying risks because they’re too cowardly to speak the truth and flout our corporate overlords. Both malign the IPCC as “political” and therefore not objective. And both will cite nearly any claim that supports their views, regardless of source— putting evidence-free opinions on par with scientific research. (In one example I can’t help but highlight, McPherson cites a survivalist blog warning that Earth’s atmosphere is running out of oxygen.)
McPherson bills himself as a scientist simply passing along the science (even as he dismisses climate scientists and their work), but he cites nearly as many blog posts and newspaper columns as published studies. When he does cite a study, it’s often clear that he hasn’t taken the time to actually read it, depending instead on a news story about it. He frequently gets the information from the study completely wrong, which is a difficult thing for most readers to check given that most papers are behind paywalls (not to mention that scientific papers aren’t easy to understand).
McPherson leans heavily on claims from people associated with the “Arctic News” blog about a catastrophic, runaway release of methane that supposedly is already underway in the Arctic. Unfortunately (or, rather, fortunately), the data don’t match their assertions. The latest IPCC and NAS assessment reports, in fact, deemed such a release “very unlikely” this century. One reason for that is that the Arctic has been this warm or warmer a couple times in the last 200,000 years, yet that methane stayed in the ground. Another reason is that scientists actually bother to study and model the processes involved. One thing McPherson and others like to point to is the recent work by Natalia Shakhova’s group observing bubbling plumes of methane coming up from the seafloor on the Siberian Shelf. Since we’ve only been sampling these plumes for a few years, we have no idea whether that release of methane is increasing or if these are long-term features. Similar plumes off Svalbard, for example, appear to be thousands of years old. (More to put this methane in context here.)
That’s exactly the kind of detail and nuance that’s absent from McPherson’s claims. Instead, he’s content to link to YouTube videos or blog posts (some ludicrously unscientific— see below) and run with the idea that catastrophic warming is guaranteed as a result. He just latches onto anything that sounds scary. McPherson is especially fast and loose with timeframes. He likes to point to the magnitude of past climate changes (which took thousands of years or more) as proof that we are about to undergo similar changes in the next couple decades. That’s quite clearly a fallacious argument, but McPherson never concerns himself with the details. All the casual reader learns it that there was a huge change in the past analogous to the present that shows just how screwed we really are.
And that’s McPherson’s thing— despair. We’re absolutely doomed, he tells us, and there’s nothing we can do about it. Everything is lost. He derides any sort of optimism or action as “hopium”. He notes in one recent post that “With an eye to improving my ‘bedside manner’ when I deliver presentations, I’ve recently become a certified grief-recovery counselor.” With such an extraordinary view, you would expect him to make the scientific case for extinction very clearly. But he does not. His argument fundamentally reduces to “positive feedbacks exist, ergo extinction”. That is, he lists examples of positive feedbacks (things that amplify change, like the added sunlight absorption of ocean water that has lost its sea ice cover) for a while, intending to overwhelm you with the number of processes that could add to global warming. And that’s it. There are no numbers explaining how big an effect each could have, no analysis of likely warming impacts, nothing. The fact is that climate scientists know about all these processes. But instead of throwing their hands up and saying “Oh, shit”, they actually do science.
Again, specific examples of these things are given in the last section of this post. If you take a look at some of his mistakes and demonstrably false claims, you’ll have a hard time thinking of him as a credible source of information.
[Update 3-13-14: Michael Tobis has covered some of the points I skipped over—namely, McPherson's discussion of feedbacks— in a new post.]
This is just an excerpt of SJ's article. Read more here
Thursday, April 10, 2014
Global Warming Could Be Accelerated by Microbes
The frozen ground just below the Earth’s surface might hold a hidden danger for the planet’s climate. Permafrost teems with microbes that could be able to accelerate global warming under the right conditions.
Scientists have long known that several mechanisms can contribute to global warming, including carbon dioxide emissions from engines and power plants. The melting of the permafrost in northern latitudes is another source of so-called greenhouse gases. What wasn’t so clear before was the mechanism that released carbon dioxide and methane from the frozen tundra.
Researchers at Florida State University conducted a study of how the permafrost works, and found a simple mechanism involving bacteria, that could contribute in a substantial way to climate change.
What happens depends on organic material being available. Availability depends on whether the soil remains frozen or not. In the Arctic, that permafrost is thawing, making more organic material available to those microbes.
Environmental scientist Jeff Canton, of Florida State University, described the process. Frozen soil starts to thaw. The layer of soil collapses into what used to permafrost and becomes saturated with water. Organic matter in the water is now available to be broken down by anaerobic (able to grow in the absence of oxygen) bacteria to produce carbon dioxide and methane, which can lead to global warming.
Using a sample of Arctic permafrost, the international research team studied soil composition, focusing on what would change the ratio of methane to carbon dioxide produced by bacteria present below the surface.
The amount of carbon dioxide is greater, at first, than the amount of methane. Over time, the organic matter changes in composition, in a way that increases methane production much more than carbon dioxide production. Production of both gases increases, but the ratio changes from 10:1 to 1:1, said Dr. Chanton.
The latest study is part of a world-wide collaborative effort involving scientists from Australia, Europe, and North America. The methane in the soil gets released as new plant species, sphagnum moss then sedges start to grow. Methane is 33 times more powerful a greenhouse gas than is carbon dioxide. As the world gets warmer, additional methane would just add to the problem.
Suzanne Hodgkins, doctoral student at Florida State University and lead author of the study, said that we have known about the thawing permafrost. The new study shows that changes in plants growing in the far north could lead to far more greenhouse gases being released into the atmosphere.
The paper was published in Proceedings of the National Academy of Sciences.
Permafrost covers approximately 24 percent of the exposed land in the northern hemisphere, with most being in Siberia, northern Canada, and Alaska. Some alpine permafrost exists further south in the mountains.
Another study on the connection between greenhouse gases and the landscape indicated that deserts could trap more carbon dioxide than previously thought. That study was published April 6 in the online science journal Nature Climate Change.
Now that scientists know how changes in tundra permafrost can release greenhouse gases, the challenge remains to actually do something about it. Knowing that global warming could be accelerated by microbes under the tundra adds another mechanism of climate change to cope with.
Scientists have long known that several mechanisms can contribute to global warming, including carbon dioxide emissions from engines and power plants. The melting of the permafrost in northern latitudes is another source of so-called greenhouse gases. What wasn’t so clear before was the mechanism that released carbon dioxide and methane from the frozen tundra.
Researchers at Florida State University conducted a study of how the permafrost works, and found a simple mechanism involving bacteria, that could contribute in a substantial way to climate change.
What happens depends on organic material being available. Availability depends on whether the soil remains frozen or not. In the Arctic, that permafrost is thawing, making more organic material available to those microbes.
Environmental scientist Jeff Canton, of Florida State University, described the process. Frozen soil starts to thaw. The layer of soil collapses into what used to permafrost and becomes saturated with water. Organic matter in the water is now available to be broken down by anaerobic (able to grow in the absence of oxygen) bacteria to produce carbon dioxide and methane, which can lead to global warming.
Using a sample of Arctic permafrost, the international research team studied soil composition, focusing on what would change the ratio of methane to carbon dioxide produced by bacteria present below the surface.
The amount of carbon dioxide is greater, at first, than the amount of methane. Over time, the organic matter changes in composition, in a way that increases methane production much more than carbon dioxide production. Production of both gases increases, but the ratio changes from 10:1 to 1:1, said Dr. Chanton.
The latest study is part of a world-wide collaborative effort involving scientists from Australia, Europe, and North America. The methane in the soil gets released as new plant species, sphagnum moss then sedges start to grow. Methane is 33 times more powerful a greenhouse gas than is carbon dioxide. As the world gets warmer, additional methane would just add to the problem.
Suzanne Hodgkins, doctoral student at Florida State University and lead author of the study, said that we have known about the thawing permafrost. The new study shows that changes in plants growing in the far north could lead to far more greenhouse gases being released into the atmosphere.
The paper was published in Proceedings of the National Academy of Sciences.
Permafrost covers approximately 24 percent of the exposed land in the northern hemisphere, with most being in Siberia, northern Canada, and Alaska. Some alpine permafrost exists further south in the mountains.
Another study on the connection between greenhouse gases and the landscape indicated that deserts could trap more carbon dioxide than previously thought. That study was published April 6 in the online science journal Nature Climate Change.
Now that scientists know how changes in tundra permafrost can release greenhouse gases, the challenge remains to actually do something about it. Knowing that global warming could be accelerated by microbes under the tundra adds another mechanism of climate change to cope with.
Monday, April 7, 2014
Sunday, March 16, 2014
Study Says Climate Change Accelerating Greenland’s Ice Loss
Part of the glacial ice sheet that covers about 80 percent of the country is seen on July 17, 2013 on the Glacial Ice Sheet, Greenland.Joe Raedle—Getty ImagesNew research is upending scientists' long-held belief that Greenland's ice sheets are stable, showing instead that global climate change is melting the country's ice at a much faster rate than once believed, leading to an increase in the world's sea levels
Greenland’s ice sheet is rapidly melting in areas previously believed to be stable, leading to accelerated rises in global sea levels, according to a study published Sunday.
While scientists have been aware that climate change has caused Greenland’s ice sheet to thin for decades, melting in the sheet’s northeast region has been discovered for the first time, USA Todayreports. Ice loss in the northeast region of Greenland has nearly tripled since 2003, with the ice sheet retreating 12.4 miles over the past decade and losing 10 billion tons of ice per year from April 2003 to April 2012, according to the new study
The rapid change in the northeast region “surprised everyone,” said study co-author Michael Bevis, a professor of earth sciences at Ohio State University.
The loss of Greenland’s ice sheet has been a major contributor to global sea level rise over the past 20 years, accounting for one-sixth of the annual rise. As humans emit increasing quantities of carbon into the atmosphere, the atmosphere more readily absorbs sunlight, warming the planet and causing sea levels to rise. Ice deflects most sunlight from the earth’s surface, but water absorbs heat from the sun. This causes a positive feedback loop: as temperatures rise, more ice becomes water, causing the temperature to rise further and ice sheets like the one in Greenland to melt at an increasing pace.
Thursday, February 20, 2014
Vicious Global Warming Feedback Loop Worse Than Feared
Vicious Global Warming Feedback Loop Worse Than Feared
Vicious cycle: amount of warming involved in Arctic ice loss, now amounts to roughly one-quarter of all warming
Jacob Chamberlain, February 19, 2014 by Common Dreams
Melting Arctic sea ice (Photo: Ian Joughin / Source: LiveScience)One of nature's key defenses against global warming—the reflection of the sun's rays away from Earth by Arctic sea ice—has fallen victim to... global warming. And according to a study published Monday, the vicious feedback loop is worse than previously thought.
The new research, published in the Proceedings of the National Academy of Sciences, shows the ability of the Arctic ice to reflect sunlight—known scientifically as albedo—hasdecreased dramatically since 1979, with the calculations showing the region's ability to reflect sunlight diminished more than twice what previous studies have shown.
As less of the sun's rays are reflected back into space, the open ocean absorbs more heat leading to additional ice melt in the region. The problem is both self-feeding and a source of deep concern for scientists and those concerned about climate change.
"That is big – unexpectedly big," said the study's lead author Ian Eisenman, a climate scientist at the Scripps Institution of Oceanography in California, on the rate of loss. "Arctic sea ice retreat has been an important player in the global warming that we've observed during recent decades."
And Mark Flanner, a climate researcher at the University of Michigan, told the New Scientistthat the study "reaffirms that albedo feedback is a powerful amplifier of climate change, maybe even more so than is simulated by the current crop of climate models."
The report is the first to use satellite measurements dating back to 1979 to gauge decreasing sunlight reflection in the region.
The amount of Arctic warming caused by this phenomenon now amounts to roughly one-quarter of the total warming caused by the greenhouse effect, said the researchers.
"Basically, it means more warming," said Eisenman.
From the study:
The Arctic sea ice retreat has been one of the most dramatic climate changes in recent decades. Nearly 50 years ago it was predicted that a darkening of the Arctic associated with disappearing ice would be a consequence of global warming. Using satellite measurements, this analysis directly quantifies how much the Arctic as viewed from space has darkened in response to the recent sea ice retreat. We find that this decline has caused 6.4 ± 0.9 W/m2 of radiative heating since 1979, considerably larger than expectations from models and recent less direct estimates. Averaged globally, this albedo change is equivalent to 25% of the direct forcing from CO2 during the past 30 years.
Tuesday, February 18, 2014
Global Climate Change Emergency
Global Climate Change Emergency - the Defining Issue for Our Time
moses seenarine, february 18, 2014
This paper argues there is a global climate change emergency. The focus is on increasing public awareness, examining the causes of climate change, and exploring some of its near-term effects. Remediation and possible solutions are not addressed.
Earth is on the inner edge of the habitable zone, and lies within 1% of inhabitability. A minor change in Earth’s atmosphere removes human habitat, and unfortunately, we’ve invoked major changes. Earth has warmed about 1 C since the beginning of the industrial revolution. The northern hemisphere is particularly susceptible to accelerated warming and summers in the northern hemisphere are already hotter than they’ve been for 600 years.
In the past, many human civilizations were ruined and radically transformed as a direct result of ecosystem collapse and catastrophic climate change. From Egypt to Easter Island, rapid habitat destruction and civilization crash have a common thread – male hegemony and patriarchal models of development.
Continuing a tragically misguided patriarchal tradition, modern economic and social development is male dominated, top-down, and dismissive of women and nature. Generating economic growth is paramount, and trumps sustainability and concerns about climate change. As in the past, across the globe, development activities that generate greenhouse gasses are intensifying, even as collapse of ecosystems is fully under way.
Once again, human civilization has reached a turning point in climate change and local and global catastrophic collapses can occur anytime without prior warning. But, in the face of mounting evidence of global warming, most governments, organizations and individuals view the threat of climate change as distant and irrelevant.
What Are Greenhouse Gases?
Even though only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases, they have a huge effect on climate change. There are several different types of greenhouse gases. The major ones are water vapor, carbon dioxide, methane, and nitrous oxide.
All of these have molecules with three or more atoms. The atoms are held together loosely enough that they vibrate when they absorb heat. Eventually, the vibrating molecule will release the radiation. The radiation will likely be absorbed by another greenhouse gas molecule. This process, which keeps heat near the Earth’s surface, is called the greenhouse effect.
Almost all of the other gases in Earth’s atmosphere are nitrogen and oxygen. The two atoms in these molecules are bound together tightly and unable to vibrate, so they cannot absorb heat and contribute to the greenhouse effect.
Carbon dioxide has unique long-term effects on climate change that are largely "irreversible" for one thousand years after emissions stop even though carbon dioxide tends toward equilibrium with the ocean on a scale of 100 years. The greenhouse gases methane and nitrous oxide do not persist over time in the same way as carbon dioxide.
Carbon Dioxide
Natural sources of atmospheric carbon dioxide include volcanic outgassing, the combustion of organic matter, wildfires and the respiration processes of living aerobic organisms. These natural sources are nearly balanced by natural sinks, physical and biological processes which remove carbon dioxide from the atmosphere.
Ice core reconstructions going back roughly 800,000 years show concentrations of carbon dioxide in the air around 200 ppm during the ice ages. The concentrations were about 280 parts per million, during the last several interglacial periods and from the most recent ice age to the mid-18th century, as the industrial revolution was getting under way in 1750. The records show that CO2 levels were fairly stable for millions of years, but it has been increasing at an increasing rate since 1750.
Although approximately 57% of human-emitted CO2 is removed by the biosphere and oceans, the remainder stays in the atmosphere for a century or longer. How fast carbon enters the atmosphere translates to the how fast temperature increases, but there is a four-decade lag between emissions and temperature rise.
Burning fossil fuels such as coal and petroleum is the leading cause of increased anthropogenic CO2; deforestation is the second major cause. China and the United States each account for over 20% of global CO2 emissions. Russia, India and Japan contribute around 5% each.
In 2013, atmospheric concentrations of CO2 were more than 43% higher above pre-industrial levels, in 1750, with a recent growth rate of between 2 and 4 ppm per year. In the period 1751 to 1900, about 12 gigatonnes of carbon were released as carbon dioxide to the atmosphere from burning of fossil fuels, whereas from 1901 to 2008 the figure was about 334 gigatonnes. Estimated carbon in global terrestrial vegetation increased from approximately 740 billion tons in 1910 to 780 billion tons in 1990. The environmental and societal consequences of warming at such a break-neck speed could be devastating.
Atmospheric carbon levels are current at just below 400 parts per million – a figure last seen during the Pliocene, between 5.3 and 2.6 million years ago. At that time, global temperatures were 2-3°C higher than today, and sea levels were several meters higher, due to partial melting of the Antarctic ice sheet.
Among the other greenhouse gases involved is methane, which has increased dramatically over the last century. Methane stays in the atmosphere for much less time than carbon dioxide (around a decade) and there is much less of it, but molecule for molecule, it is a far more powerful greenhouse gas. Methane release tracks closely with temperature rise throughout Earth history — specifically, Arctic methane release and rapid global temperature rise are interlinked— including a temperature rise up to about 1 C per year over a decade, according to data from ice cores.
Pre-industrial levels of Methane in the atmosphere were around 700 parts per billion. Methane concentrations rose about 1% a year in the 1980s. The concentrations leveled off beginning about 2000, and then began increasing again in 2007, to 1803 parts per billion in 2011. This figure is 1100 ppb higher than pre-industrial peak levels.
Methane rising from the seafloor of the Arctic Ocean entering the atmosphere, reached levels as high as 2662 ppb in 2013. The total methane burden in the atmosphere now is 5Gt, and almost half of all global warming may have resulted from a 3Gt rise in methane since the 1750s.
Sediments underneath the Arctic Ocean hold vast amounts of methane. Just one part of the Arctic Ocean alone, the East Siberian Arctic Shelf holds up to 1700 Gt of methane. Significant quantities of methane are escaping from this shelf and a sudden release of just 3% of this amount could add over 50 Gt of methane to the atmosphere, and could be released at any time. Imagine the warming that will take place if the methane in the atmosphere was suddenly multiplied by 11. A 50-billion-tonne “burst” of methane could warm Earth by 1.3 C.
Seeps are also appearing in numerous locations off the eastern coast of the United States, leading to rapid destabilization of methane hydrates there. This is in addition to anthropogenic emissions of methane.
Other important greenhouse gases include nitrous oxide, near-surface ozone and water vapor, the most prevalent greenhouse gas. As global temperatures increase, more water vapor is released by oceans and lakes, and this in turn helps to increase temperatures further. This is one of many feedback loops that help to reinforce and intensify climate change.
The current global warming is not unprecedented. There evidence of other hyperthermal events in Earth's history, sudden rapid warmings that occurred during periods of more gradual warming.
Nine million years after an asteroid slammed into the Yucatán Peninsula, setting off a cataclysm that most scientists now believe wiped out the dinosaurs, the Earth seems to have undergone another shock to the system. Earth was already much warmer than it is today. But as the Paleocene epoch gave way to the Eocene, it was about to get much warmer still—rapidly, radically warmer.
Paleocene-Eocene Thermal Maximum (PETM)
The most studied hyperthermal is the PETM which occurred in the middle of a 10 million year period of gradual warming, 55 million years ago. During the PETM, around 5 billion tons of CO2 was released into the atmosphere per year. The Earth warmed gradually around 6°C - 9°C (11°F - 16°F) over 10,000 -20,000 years, around 0.025°C every 100 years.
However, Schaller and Wright contend that climate change occurred much more rapidly, following a doubling in CO2 levels. The surface of the ocean turned acidic over a period of weeks or months and global temperatures rose by 5 degrees centigrade – all in the space of about 13 years.
In the Paleocene the summer water temperature in the Arctic Ocean was already around 64 degrees Fahrenheit; during the PETM it shot up to around 74. Today the water at the deep seafloor is just above freezing; in the PETM it was in the 60s. Since the PETM occurred in an already warm climate (another thing that sets the PETM apart from modern warming), there was very little sea ice and glacial cover to melt, so sea level did not change dramatically.
Yet, the PETM brought on drought, catastrophic flooding, insect plagues, and a few extinctions. Ocean circulation reversed, oceans acidified, permafrost melted, peat lands, forests burned in wildfires which caused migration of land mammals, extinction of some benthic foraminifera minuscule organisms (forams for short), coral bleaching. Acidified ocean wiped out myriad life-forms, dissolving the shells of corals, clams, and forams.
When CO2 is injected into modern greenhouses, the plants grow more, but their protein content is lower, making their leaves less nutritious. The same may have happened in the hothouse world of the PETM - insects had to eat much more foliage just to fill up. The PETM leaves were also much smaller than those of their Paleocene ancestors, because rainfall had dropped by around 40 percent. When water gets scarcer, plants cut down on water loss by shrinking their leaves. During the PETM itself a strange thing also happened to some mammals - they got dwarfish. Horses shrank to the size of Siamese cats; as the carbon ebbed from the atmosphere, they grew larger again.
The PETM lasted more than 150,000 years, until the excess carbon was reabsorbed. After 56 million years primates, then the size of mice or rabbits, are directing the show. They have tamed other descendants of the PETM—horses, cows, pigs, sheep—and spread with them around the planet.
Tracking Climate Change
Earth's climate is dominated by amplifying feedbacks on time scales of 10-100,000 years and less. For this reason, Earth can be whipsawed between glacial and interglacial conditions by the small climate forcings caused by perturbations of Earth's orbit.
Changes in the Earth’s orbit and axis cooled the world over the past 10,000 years. This cooling would normally be expected to continue for at least another 1,000 years. And yet Arctic palaeoclimate records show that the period 1950-2000 was the warmest 50 year interval for 2,000 years. We should be cool, but we’re not. Why?
In 1960 the carbon dioxide concentration was 315 parts per million and in the 1960’s the concentration was increasing at 0.8 parts per million per year, in the 1980’s at 1.6 parts per million and from 2003 until 2011 inclusive it rose at 2.0 parts per year.
Today, fossil fuel burning is leading to 30 billion tons of carbon released into the atmosphere every year, driving temperature up at an incredible rate. In 2010, fossil fuel burning released 35 billion tons of CO2. By comparison, volcanoes release 0.2 billion tons of CO2 per year.
Atmospheric carbon levels are current at just below 400 parts per million. If the current rate of increase (2 ppm per year) continues, CO2 levels could reach 600 ppm by the end of this century; levels which ‘have not been seen for 24 million years.’ Should the growth rate of atmospheric carbon dioxide be greater than about 3.1 parts per million then the world could probably enter a fast runaway event.
A relatively modest rise in atmospheric CO2 levels and temperature results in significant sea level rise, while oceans become more acidic and less oxygenated. A doubling of atmospheric CO2 levels could result in temperature increases of between 3°C and 4.5°C, due to fast changes such as snow and ice melt, and the behavior of clouds and water vapor.
Feedback Loops
The transient climate response is inherently slow, due to the great inertia of the system, especially the ocean -- and that allows slow feedbacks to begin to operate while the fast ones are still growing. Unfortunately, slow feedbacks are amplifying on time scales that humans care about: decades, centuries, even millennia. Vegetation changes that occur as climate warms from today's situation will also have a significant amplifying effect, as forests move into tundra regions in North America and Eurasia. This feedback contributed to Pliocene warmth.
There are dozens of positive feedback loops affecting climate change, including: (1) methane hydrates are bubbling out the Arctic Ocean; (2) Siberian methane vents have increased in size from less than a meter across in the summer of 2010 to about a kilometer across in 2011; (3) methane is being released from the Antarctic, too; (4) warm Atlantic water is defrosting the Arctic as it shoots through the Fram Strait; (5) summer ice in the Antarctic is melting 10 times quicker than it was 600 years ago, with the most rapid melt occurring in the last 50 years; (6) Arctic ice is growing darker, hence less reflective; (7) Greenland ice is darkening; (8) surface meltwater draining through cracks in an ice sheet can warm the sheet from the inside, softening the ice and letting it flow faster; (9) cracking of glaciers accelerates in the presence of increased carbon dioxide; (10) exposure to sunlight increases bacterial conversion of exposed soil carbon, thus accelerating thawing of the permafrost; and (11) breakdown of the thermohaline conveyor belt is happening in the Antarctic as well as the Arctic, thus leading to melting of Antarctic permafrost.
Other feedback loops include: (12) loss of Arctic sea ice is reducing the temperature gradient between the poles and the equator, thus causing the jet stream to slow and meander; (13) ocean acidification leads to release of less dimethyl sulphide (DMS) by plankton. DMS shields Earth from radiation; (14) sea-level rise causes slope collapse, tsunamis, and release of methane; (15) rising ocean temperatures will upset natural cycles of carbon dioxide, nitrogen and phosphorus, hence reducing plankton; (16) earthquakes trigger methane release, and consequent warming of the planet triggers earthquakes; (17) mixing of the jet stream is a catalyst, too. High methane releases follow fracturing of the jet stream, accounting for past global-average temperature rises up to 16 C in a decade or two; (18) droughts, for example, in 2010 one in the Amazon triggered the release of more carbon than the United States; (19) peat in the world’s boreal forests is decomposing at an astonishing rate; (20) forest and bog fires are growing; and (21) invasion of tall shrubs warms the soil, hence destabilizes the permafrost.
Today, the globe is warming fast, anywhere from 1 to 4°C every 100 years, and we may have passed a tipping point in 2007, at about 0.76 C warming. Arctic sea-ice passed its tipping point, with the six lowest September ice extents have occurred in the last six years as the Arctic moves to sea-ice-free conditions in summer by summer 2016. But the Greenland Ice Sheet is not far behind. In 2012 Greenland crossed a threshold where for the first time we saw complete surface melting at the highest elevations in what we used to call the dry snow zone.
An average temperature increase beyond one degree C may elicit rapid, unpredictable and non-linear responses that could lead to extensive ecosystem damage.
Ecosystems Already Affected
There is already significant sea ice decline, extreme drought, more wildfires, increase in glacier melt, more catastrophic floods, ocean acidification, sea level rise, shoreline erosion, etc. Oceans are more acid than they have been for eight million years and the rate of acidification is greater than it has been for 350 million years. Foraminifera have already decreased markedly in some areas, and coral is bleaching at a very rapid rate.
Penguins, polar bears, whales, seals, salmon, and orangutans are just a few of the mammals being impacted by anthropogenic climate change. While it was possible for land mammals to migrate to cooler regions in the PETM, man made infrastructure (roads, railways, cities, etc) will prevent them from doing so this time around.
The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change. In their draft 2014 Report, they reported that there is risk of death and disruption in low-lying coastal zones; dangers of food insecurity, with risks of starvation greatest among the world’s poor; “severe harm” risks of flooding in cities; the collapse of ocean and land ecosystems and the food they provide; and deaths and illnesses caused by heat waves. Hundreds of millions of people will be affected by flooding, with many of them driven from their homes by the end of the century. The majority of those affected will live in Asia.
The biggest impacts from climate change will be felt on farms, which will endure worsening water shortages and will have to deal with shifting growing ranges. That’s going to make it harder to feed the world its staples of wheat, rice, and corn.
Climate change will reduce yields of major crops by up to two per cent each decade for the remainder of this century. (One of the reasons for this is that heat waves, which will become more common as the world warms, depress the yields of staple crops like corn.)
We are losing a major carbon sink as the forests - and indeed, all perennial vegetation on earth - is dying. It is being poisoned by tropospheric ozone. Ozone is invisible so most people don't even realize that the background level is inexorably rising. The persistent concentration is now at or over 40 ppb, in even very remote locations far from precursors - and that is the point at which plantlife becomes damaged when it absorbs ozone through the stomata. Commercial crops are reduced, everything from coffee to bananas to citrus and maple syrup. Annual crop yield and quality loss is measured in the billions of dollars worldwide, including essentials such as wheat, rice, corn, and soybeans.
Since the global population is projected to grow throughout the century—to eight billion by 2025, nine billion by 2050, and almost eleven billion by 2100 - this is obviously rather bad news. At the same time, the incidence of flooding, drought, and general weather-related mayhem will increase, and already-vulnerable populations will be pushed closer to the edge, or, quite possibly, over it. Conflict is bound to ensue. Climate change “will increasingly shape national security policies,” the report warns.
Meanwhile, as bad as things look for humans, the prognosis for non-humans is, in many ways, worse. A “large fraction” of terrestrial and freshwater species face elevated extinction risks. Under the most likely scenarios, many species “will not be able to move fast enough during the 21st century to track suitable climates”, and there is a chance that some ecosystems, including the Arctic tundra and the Amazon rainforest, will undergo “abrupt and irreversible change.”
Women and Climate Change
Women, as the majority of the world’s poor, are among the most vulnerable to the impacts of climate change. Women are involved in, and dependent on livelihoods and resources that are put most at risk by climate change. Women produce 60 to 80 percent of the household food supply in most developing countries. They carry water, gather wood for fuel, and manage household resources worldwide. They are also the chief caregivers for victims of weather-related and other natural disasters.
As part of the world’s poor, women suffer most from erratic weather and its disruptions because they live in substandard housing in marginal land subject to drought or flood, or in crowded urban areas lacking essential services.
Further, climate change threatens to set back decades of progress and efforts made by women, who lack rights and access to resources and information vital to overcoming the challenges posed by climate change. Women are frequently excluded from processes and decisions relating to the use and management of natural resources, including those impacting on climate change. And male dominance and discrimination means women worldwide are the first to lose their homes and their jobs after weather-related disasters, and the last to receive credit, technical help and education on energy and resource conservation.
Potential Impacts in the Near Future
The rate of climate change clearly has gone beyond linear, as indicated by the presence of the myriad self-reinforcing feedback loops, and now threatens our species with extinction in the near term. Modern ecosystems are already struggling to adapt to their new, warmer environments. Given the rate of warming the globe is experiencing, it is likely that many ecosystems will be totally incapable of adapting.
Some potential impacts include degraded air and water quality, permafrost melting, global ocean circulation changes, more violent winter storms and spring tornado seasons, more intense hurricanes. There is plenty of ice to melt on our modern planet, and sea level may rise anywhere from 0.2 to 0.6 meters (0.7 to 2 feet) by the year 2100. The long-term sea level that corresponds to current CO2 concentration is about 23 meters above today's levels.
The rising carbon dioxide levels will probably lead to rising global temperatures from about 2015 onwards which will cause more climatic disruption, especially severe droughts, and thus more carbon emissions almost certainly before 2020. This is going to occur at a time when the Arctic Ocean will probably become free of sea ice leading to a different set of runaway events which will coalesce with the build-up of carbon dioxide in the atmosphere. This will lead to societal collapse after rising global temperatures have caused severe droughts and a global famine at some time prior to 2040, but probably much sooner in about 2020 or in the 2020’s. Carana expects up to 20 C warming by 2050.
In much of China, India, southern Europe, and the United States, summer temperatures would average well over 100 degrees Fahrenheit, night and day, year after year.
Uninhabitable Earth?
Looking ahead, if the rate of fossil-fuel burning continues to rise on a business-as-usual trajectory, such that humanity exhausts the reserves over the next few centuries, CO2 will continue to rise to levels of order 1500 ppm. The atmosphere will not return to pre-industrial levels even tens of thousands of years into the future.
Is it possible, with the present surface pressure of ~ 1 bar, for Earth's surface to become so hot that that the planet is practically uninhabitable by humans? Earth is not now near a runaway greenhouse effect situation, but studies do not provide a picture of where Earth is headed if all fossil fuels are burned.
If we should "succeed" in digging up and burning all fossil fuels, some parts of the planet would become literally uninhabitable, with some time in the year having wet bulb temperature exceeding 35°C. At such temperatures, for reasons of physiology and physics, humans cannot survive, because even under ideal conditions of rest and ventilation, it is physically impossible for the environment to carry away the 100 W of metabolic heat that a human body generates when it is at rest. Thus even a person lying quietly naked in hurricane force winds would be unable to survive. Temperatures even several degrees below this extreme limit would be sufficient to make a region practically uninhabitable for living and working. Burning all fossil fuels could result in the planet being not only ice-free but human-free.
Conclusion
Just like prior episodes of ecosystem collapse, rapid climate change, and global warming, we are likely catapulting ourselves into a new geologic era, the post-Anthropocene. A male modern development paradigm is causing the sixth extinction, and we need to change this 10,000 year-old tradition of male dominance of women and nature in order to halt ecosystems decline and start to turn things around. Tens of millions of years from now, whatever becomes of humanity, the whole pattern of life on Earth may be radically different from what it would otherwise have been – as a direct result of patriarchal development and the way men desired to power their lives for a few centuries.
By moses seenarine, educator and activist
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