Any Hope for Doomed Earth's Last Organsims?

Billions of years from now, life on Earth will be extinguished when the dying sun scorches the surface of our planet. New research has aimed to determine what the last life forms on Earth will be, and what kind of abodes they will cling to before the Earth becomes sterilized.

We are fortunate that our planet orbits a star that has a long main-sequence lifetime. However, the sun’s luminosity is gradually increasing, and in about one billion years the effects of this will start to be felt on Earth.

Surface temperatures will start to creep relentlessly upwards over the next few billion years, which will increase the amount of water vapor in the air. This will act to further increase temperatures and will thus signify the beginning of the end for life on Earth.

The rising temperatures will cause excessive amounts of rain and wind, and thus increase the weathering of silicate rocks, which will suck extra carbon from the atmosphere. (Top 10 Ways to Destroy Earth)
Ordinarily, the carbon is replaced via plate tectonics in the carbon-silicate cycle as it is released in volcanic gases.

However, the oceans will start to evaporate as the temperatures continue to rise, which will probably put a stop to plate tectonics as scientists believe that water is an essential lubricant for the motion of tectonic plates on Earth. This will deplete the number of active volcanoes, and the carbon will not be replenished in the atmosphere.

The lack of carbon dioxide will effectively choke plant life on Earth, since plants require atmospheric CO2 for their respiration. The death of oxygen-producing plants will in turn lead to less oxygen in the atmosphere over a few million years. This will spell disaster for the remaining animal life on Earth, with mammals and birds being the first to become extinct. Fish, amphibians and reptiles would survive a little longer, as they need less oxygen and have a greater tolerance to heat.

The last type of animal present on the far-future Earth would likely be invertebrates. Once the insects finally succumb to the increasing temperatures, the Earth will once again be solely populated by microbial life, just as it had been for the first few billion years of our planet’s history. The last lingering life will desperately seek out niches of the planet that are still habitable, but  even extremophile forms of life will find this to be a challenge.

A habitable niche in an inhospitable world
 
As the Earth’s oceans evaporate, the few remaining pools of water could provide a last refuge for some microbes. The present average depth of the oceans is 2.5 miles (4 kilometers), but this extends to 6.8 (11 km) in the Mariana Trench, which is the deepest known ocean trench.

Trenches carved in the sea bed could be among the last places to harbor liquid water, with the looming walls offering some source of shade from the unforgiving sun. However, this potential haven is not quite as inviting as it may first seem. Air moving into the trench will become compressed as it sinks lower, and this pressure will greatly increase the air temperature above the water.

"By the time we get to the point where there's a trench with a small pool of water at the bottom, a large mass of ocean water would have evaporated, so surface temperatures on the planet would be rapidly increasing," said Jack O’Malley-James of the University of St. Andrews, and lead author of the new study. "Therefore, water at the bottom of a trench wouldn't remain cool enough for long enough to make a good refuge for life."
Another potential haven for the last microbial life on Earth could be in underground caves.

Microbes have been found living in caves on the present-day Earth without any need for sunlight. Most caves in the far-future Earth would not be suitable for life, as temperatures increase with depth. However, caves that have large chambers below a narrow entrance might be colder, as the dense cold air is sucked in, but lighter warmer air is barricaded out.

 Ice caves could be a final abode for microbial life in a far-future Earth with horrendous surface temperatures. CREDIT: Einreisenwelt

Such caves are formed from collapsed lava tubes, and the cold air in the caves will cause in-falling snow to compact into ice during the winter, as well as freeze any incoming water. When the outside temperature climbs again, the cold air is still trapped within the cave, along with the ice. However, the ice will melt eventually as heat is conducted through the walls of the cave, so it must be continually replaced and therefore some source of water would still be necessary on the far-future Earth for such a cave to retain its cool climate.

Life could also exist in subsurface environments other than ice caves. Microbial life today has been found at depths of 3.3 miles (5.3 km) below the Earth’s surface. The increase of temperature with depth is around 86 degrees Fahrenheit (48 degrees Celsius) per mile (1.6 km); however, the exact increase depends on the type of rock. Such a subsurface refuge could be one of the last to contain life on Earth.

At the other end of the scale, temperatures will decrease by around 18.9 degrees Fahrenheit (10.5 degrees Celsius) per mile above the Earth’s surface. This is because the surface of the Earth re-radiates heat that has been received from the sun, thus heating the lower atmosphere.

The lower temperatures at high altitude would encourage microbial life on the far-future Earth to reach for the skies and seek refuge in the last remaining lakes in the mountains in an attempt to escape the heat. However, as tectonic plates cease to crash into each other, there will no longer be a force to drive mountains upwards. Instead, the mountains will succumb to weathering and eventually there will be fewer regions of high altitude on the planet.

The remaining high-altitude regions would likely be comprised of volcanoes, as convection of molten rock in the mantle of the Earth will still occur even after the cessation of plate movement. The lack of plate tectonics will allow these "hot spot" volcanoes to reach heights that are currently impossible to achieve today.
"Sites around active volcanoes on Earth today host life, so living near an active volcano shouldn't be a challenge for extremophilic microorganisms," said O’Malley-James. "It's likely that volcanic activity would decline as the planet cools, but it may not stop completely during the time period in which planet is still habitable."

Isolated pools from the remnants of the ocean will have high salt concentrations, meaning that bacterial life would have to withstand high saline as well as high temperatures. Such microbes are called thermohalophiles, and they exist today in such conditions around hydrothermal vents. Microbes on the far-future Earth would also have to contend with being bombarded with high doses of ultraviolet radiation, as the ozone layer would have been stripped away when the oxygen in the atmosphere diminished.

Biosignatures of a dying planet

Studying what life will be like on Earth at the end of the habitable era helps scientists narrow down what kind of biosignatures might exist on Earth-like exoplanets orbiting aging stars near the end of their main sequence. So what kind of biosignatures would the last life on Earth exhibit?

Thermohalophiles, such as those found at volcanoes in Chile's Atacama Desert, use carbon monoxide to obtain energy, and the by-products of their metabolic processes include carbon dioxide, hydrogen, and ethanol.

Carbon dioxide could be seen as an indicator of life, considering that the carbon dioxide inherent to the planet would have been severely reduced million of years previously. Carbon dioxide by itself is not a biosignature and its presence, such as on Mars, does not indicate that life exists on a planet. However, biologically produced carbon dioxide would cause a disequilibrium of the CO2 in the atmosphere that could reveal the presence of microbial life.

Similarly, the biological production of hydrogen by the thermohalophiles could create an excess of hydrogen in the atmosphere, which could be used as an indicator of life. However, all of these biosignatures would likely be weak, as biological productivity would be severely diminished in a dying world.

Microbes can adapt to extreme conditions, such as the harsh conditions that existed on the early Earth. The first life to appear on Earth, as far back as 3.8 billion years ago, was unicellular life. Similarly, microbes will be the sole occupants of the Earth during its final days as a habitable planet. Microbial biospheres would exhibit biosignatures that are very dissimilar to what is present on the current Earth, but whether late-type biospheres would appear similar to early-type biospheres is another question.

"It looks like they would be similar to the biosignatures for early-type microbial biospheres, but the strength of the various atmospheric signatures would be much lower for the late-type microbial biospheres," said O'Malley-James. "So it may be possible to distinguish between early and late microbial biospheres purely by looking at the strength of the various biosignature gases in the atmospheric spectra of Earth-like planets."

Future work will seek to refine what these biosignatures could be, and ultimately search for the telltale signs of a dying habitable planet among the Earth-like planets that have been discovered so far.

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My Car Runs on Coffee

An unassuming-looking old car powered not by gas, but by coffee, recently broke the land speed record for a vehicle powered by gasification, clocking in at a cool 66.5 miles per hour on average. Gasification works by introducing oxygen or steam to an organic, carbon-based material (such as coffee beans, in this case) and increasing the temperature until a synthetic gas made of carbon monoxide, carbon dioxide, hydrogen and methane is created and burned up by a regular internal combustion engine.

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 The Coffee Car, originally built by British engineers for the BBC show Bang Goes the Theory, already holds a world record, for longest journey by a coffee-powered car (over 200 miles), and now the second generation has proven itself on the speed front as well. The previous record, held by Americans, was just 47 mph, and the car was fueled by wood chips. In this case, it looks like coffee, the same sweet nectar that gives so many working men and women around the world the energy to go the distance, has proven superior once again.

Get acquainted with the Coffee Car in the video below, or check out the record-breaking drive over at the BBC.

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Snackable Sponge Can Suck Up CO2

Sponges already clean up kitchen spills and soap scum, now they may start cleaning up the atmosphere.

A newly-developed synthetic sponge made of salt, sugar, and alcohol soaks up carbon dioxide. It's non-toxic, reusable, and carbon neutral. In a pinch, you can even make a meal of it.

Northwestern University chemists developed this special sponge, known as a metal-organic framework (MOF). Other MOFs soak up carbon dioxide too, but are usually made from crude oil and contain more toxic heavy metals than Beavis and Butthead's record collection.

 The new sponges don't pollute the environment while cleaning it up. In fact, their manufacture could reduce the amount of greenhouse gas in the air, since they contain sugar made by plants which themselves pull carbon dioxide out of the air.

“We are able to take molecules that are themselves sourced from atmospheric carbon, through photosynthesis, and use them to capture even more carbon dioxide,” said Ross Forgan, a co-author of the sponge study published in Journal of the American Chemical Society, in a press release.

“By preparing our MOFs from naturally derived ingredients, we are not only making materials that are entirely nontoxic, but we are also cutting down on the carbon dioxide emissions associated with their manufacture,” said Forgan.

The main ingredient is gamma-cyclodextrin, a type of sugar derived from corn, held together in a crystalline structure by metals, such as potassium benzoate and rubidium hydroxide, derived from salts.

Despite the intimidating names of its ingredients, the MOF carbon sponge is actually edible.  But don't sit down to a sponge lunch just yet, the carbon-hungry sponges can be cleaned and reused.

“It turns out that a fairly unexpected event occurs when you put that many sugars next to each other in an alkaline environment -- they start reacting with carbon dioxide in a process akin to carbon fixation, which is how sugars are made in the first place,” said Jeremiah J. Gassensmith, lead author of the paper, in a press release.

“The reaction leads to the carbon dioxide being tightly bound inside the crystals, but we can still recover it at a later date very simply,” Gassensmith said.

The MOF sponges suck in the carbon dioxide and converts it to carbonate. But when exposed to an atmosphere with low concentrations of carbon dioxide, the gas is released.

Unlike other methods of carbon capture, little extra energy is needed to release the carbon dioxide.

"In our material, the CO2 is converted into a solid, most likely by reacting with the sugar, but if you blow a stream of nitrogen over the material, the CO2 spontaneously pops off and will go wherever you blow it, and the material is reused and thus recyclable.

"It is thus a very, very green way of trapping CO2," Gassensmith said.

The sponges could be used to scrub emissions or the air itself. The excess carbon can then be used in other industrial processes or stored somewhere.

The sponge even lets people know when it's ready for a cleaning.

The researchers included methyl red, a common chemical pH indicator, in the sponges to let them know when the sponge has soaked up all the carbon it can. A pH shift within the sponge causes the color to change from yellow to red when it is full of carbon.

Since the MOF carbon sponges are cheap and easy to manufacture, not to mention eco-friendly, Northwestern plans to pursue commercialization opportunities.

“I think this is a remarkable demonstration of how simple chemistry can be successfully applied to relevant problems like carbon capture and sensor technology,” said Ronald A. Smaldone, a co-author of the paper.

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Regarding Carbon Dioxide Emissions 2010 Worst Year Ever

“Worst year ever,” the Simpson's comic book guy might say about 2010's carbon dioxide emissions.

A record-setting 36.4 billion tons of carbon dioxide were added to the atmosphere in 2010. That's a 45 percent increase in the global annual release of carbon dioxide by humans since 1990, reports the European Commission's Joint Research Centre and PBL Netherlands Environmental Assessment Agency in the report "Long-term trend in global CO2 emissions."

Although many industrialized nations made cuts in the amount of carbon dioxide pollution they created, the rapid growth of India, China, Brazil and other developing nations resulted in a net increase during the two decades studied in the report.

The good news is that countries which signed on to the Kyoto Protocol seem likely to meet their reduction goal of 5.3 percent from 1990 levels. The European Union-27 and Russia decreased emissions by 7 percent and 28 percent respectively, between 1990 and 2010. Japan's emissions stayed at about the same level.

The United State's annual release of carbon dioxide increased 5 percent between 1990 and 2010.

After the global economy was shaken in 2008, emissions fell. But from 2009 to 2010 carbon dioxide made a serious comeback. Emissions increased 5.8 percent during that period, the fastest ever. Major economies, China (10 percent), India (9 percent), USA (4 percent) and the EU-27 (3 percent) led the pack in increased emissions of carbon dioxide pollution.

 

The record setting increase in emissions between 2009 and 2010 was really more of a return to normal after the economic recovery, and didn't necessarily represent a massive failure in reduction plans. For example, the report notes that the EU-27's emissions were lower in 2010 (4.4 billion tons) than in 2007 (4.6 billion tons).

On a person-by-person basis, the United States is still the world's number one carbon dioxide polluter, although China now releases more. The USA emits 18.6 tons of carbon dioxide per person, compared to China's 7.5 tons and the EU-27's 8.8 tons.

Despite trends towards renewable energy, hybrid cars and other more efficient technologies, power generation (40 percent) and road transportation (15 percent) account for the lion's share of pollution production, in both the industrialized and the developing world.

The European Commission’s report is based on data from the Emissions Database for Global Atmospheric Research as well as country by country statistics.

Carbon dioxide allows ultraviolet radiation from the sun to pass through the Earth's atmosphere. That radiation then heats the surface, producing infrared radiation. But carbon dioxide traps infrared radiation within Earth's atmosphere, and causes average global temperatures to rise.

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Synthetic Trees Better Than Real Ones?

Baobab Trees These baobab trees, native to Africa and Australia, are an important part of the Madagascar deciduous forest. Some baobabs are believed to be thousands of years old, but since the wood does not create annual growth rings, it is difficult to track their growth. The trees are a hardy breed though, with some Madagascar species growing directly out of limestone rock.

Trees are great absorbers of carbon dioxide from the atmosphere, and inhibitors of climate change -- that's why treehuggers hug them so much. But leave it to humanity to engineer a better tree. A synthetic tree, currently being tested as a prototype, ensnares carbon about 1,000 times faster than a real tree.

The "tree" uses plastic leaves that capture the carbon dioxide in a chamber. The carbon dioxide is then compressed into liquid form. The tree captures the carbon without the need for direct sunlight, which means that, unlike traditional trees, the synthetic trees can be stored in enclosed places such as barns, used anywhere, and transported from one site to another regardless of conditions. 

Lackner says the captured CO₂ could be used to create fuel for jet engines and cars, the two most common carbon emitters. In other cases, the CO₂ could be used to enhance current production of vegetable produce.

Klaus Lackner, a professor at Columbia University who is developing the tree, met with U.S. Energy Secretary Steven Chu last month to talk about the concept. In an interview with CNN, Lackner said the synthetic tree is "several hundred times better at collecting CO₂" than windmill generators. 

Lackner says that for every 1,000 kilograms of carbon dioxide collected, the tree emits just 200 kilograms. This ratio is more than enough to warrant the relatively high cost of building the trees (about the same as a new automobile) or retrofitting coal plants.

Each synthetic tree could collect about 90,000 tons of carbon per year.

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Pack Your Suitcase Nuke For Mars

The term “suitcase nuke” hasn’t enjoyed a particularly popular connotation in recent years, but researchers convening at the 242nd National Meeting and Exposition of the American Chemical Society this week think such a concept is the future of interplanetary space travel. 

Scientists supporting a joint NASA/DOE project to develop future power plants for space colonists envision the first such power supplies being suitcase-sized fission reactors that future space explorers could deploy quickly and reliably in the harsh environs of another planet like Mars.

 

These mini-reactors would have no cooling towers or billowing steam clouds emanating from them. Rather, they would stand about two feet tall and maybe a foot wide, with a compact uranium fission chamber and power plant tucked inside. 

Unlike the solar panel systems often deployed aboard interplanetary missions--like the Spirit and Opportunity rovers currently on Mars--a small fission system could supply the kind of constant, steady power necessary for human survival on another planet.

That will be key for establishing a beachhead on another planet, as everything from life support systems (oxygen supplies and carbon dioxide scrubbing, for instance) to water treatment to keeping the lights and heat/cooling on will rely on around-the-clock energy. Any lapse in power, and the humans relying on those systems would quickly find themselves in a bad way.

Plus, such suitcase nukes would fit neatly in any future space vehicle’s overhead bins, defraying the cost of checking. The joint NASA/DOE initiative hopes to produce a working demo unit next year.

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Climate Change to Continue to Year 3000

 Scientists have made dire predictions about the effects of climate change. They say the effects will continue until the year 3000 and will cause oceans to rise 13 feet. The calculations are based on a computer model derived from records for more than 300 glaciers.

Global warming may wipe out three-quarters of Europe's alpine glaciers by 2100 and hike sea levels by four meters (13 feet) by the year 3000 through melting the West Antarctic ice sheet, two studies published on Sunday said.

The research places the spotlight on two of the least understood aspects of climate change: how, when and where warming will affect glaciers on which many millions depend for their water, and the problems faced by generations in the far distant future.

The glacier study predicts that mountain glaciers and ice caps will shrink by 15-27 percent in volume terms on average by 2100.

"Ice loss on such a scale may have substantial impacts on regional hydrology and water availability," it warns.
Some regions will be far worse hit than others because of the altitude of their glaciers, the nature of the terrain and their susceptibility to localized warming.

New Zealand could lose 72 percent (between 65 and 79 percent) of its glaciers, and Europe's Alps 75 percent, meaning a range of between 60 and 90 percent. At the other end of the scale, glacial loss in Greenland is predicted at around eight percent and at some 10 percent in high-mountain Asia.
Meltwater will drive up world sea levels by an average of 12 centimeters (five inches) by 2100, says the study.

 This figure -- which does not include expansion by the oceans as they warm -- largely tallies with an estimate in the landmark Fourth Assessment Report by the UN's Intergovernmental Panel on Climate Change (IPCC) in 2007.

Geophysicists Valentina Radic and Regine Hock of the University of Alaska base these calculations on a computer model derived from records for more than 300 glaciers between 1961 and 2004.

The model factors in the middle-of-the-road "A1B" scenario for greenhouse-gas emissions, by which Earth's mean surface temperature would rise by 2.8 degrees Celsius (5.04 degrees Fahrenheit) during the 21st century.
The tool was then applied to 19 regions that contain all the world's glaciers and icecaps.

 But -- importantly -- it does not include the ice sheets of Antarctica and Greenland, where 99 percent of Earth's fresh water is locked up.
If either of these ice sheets were to melt significantly, sea levels could rise by an order of meters (many feet), drowning coastal cities.

That very scenario emerges in the second study, which focuses on the inertial effect of greenhouse gases. Carbon molecules emitted by fossil fuels and deforestation linger for many centuries in the atmosphere before breaking apart.

Even if all these emissions were stopped by 2100, the warming machine would continue to function for centuries to come, says the investigation.
It largely bases its forecast on the "A2" emissions scenario, which sees greater carbon pollution by 2100, stoking Earth's temperature by an average 3.4 C (6.1 F) by century's end.

 Warming of the middle depths of the Southern Ocean could unleash the "widespread collapse" of the West Antarctic ice sheet by the year 3000, it says.

"The inertia in intermediate and deep ocean currents driving into the southern Atlantic means those oceans are only now beginning to warm as a result of CO2 (carbon dioxide) emissions from the last century," said Shawn Marshall, a professor the University of Calgary in Canada.

"The simulation showed that warming will continue, rather than stop or reverse, on the thousand-year timescale." The two studies are published online by the journal Nature Geoscience.

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Posted in: air. global warming,carbon dioxide,climate change,earth,glaciers,years

Self-Cleaning Atmosphere

Anyone who's ever used a public restroom appreciates regular and dependable air freshener.

Earth's atmosphere has just that, thankfully, and it's operating better than expected. A critical part of the self-cleaning system is hydroxl, and the chemical maintains a more stable level of activity than previously thought, according to research by the National Oceanic and Atmospheric Administration (NOAA). Considering that recent models indicate greenhouse gasses are going to be a long-term atmospheric issue to clean up after, this news comes as a bresh of fresh air.

“Now we know that the atmosphere’s ability to rid itself of many pollutants is generally well buffered or stable,” said lead author, Stephen Montzka of the National Oceanic and Atmospheric Administration (NOAA).

“This fundamental property of the atmosphere was one we hadn’t been able to confirm before,” said Montzka in a NOAA press release.

The amount of hydroxyl in the atmosphere rises and falls by only a few percentage points a year, according to the results published recently in Science. Earlier studies had suggested it might fluctuate by as much as 25 percent.

Hydroxyl helps break down pollutants like sulfur dioxide, carbon monoxide, hydrocarbons and even the powerful greenhouse gas, methane. Methane is over 20 times more effective than carbon dioxide at trapping heat. However hydroxyl has no effect on carbon dioxide.

“Say we wanted to know how much we’d need to reduce human-derived emissions of methane to cut its climate influence by half,” Montzka said. “That would require an understanding of hydroxyl and its variability. Since the new results suggest that large hydroxyl radical changes are unlikely, such projections become more reliable.”

Previous studies inferred the levels of hydroxyl being produced in the atmosphere by measuring the concentration of methyl chloroform, a long lived pollutant partly responsible for ripping a hole in the ozone layer. But the results varied widely, possibly because of inaccurate estimates of methyl chloroform released by human activities. The gas was banned by the Montreal Protocol, so now, no new methyl chloroform is fouling the data.

Now that the gas is no longer being produced, scientists can more accurately gauge the action of hydroxyl upon methyl chloroform's atmospheric concentration. They took measurements over time of methyl chloride concentrations. By measuring its decay, they could calculate the amount of hydroxyl acting upon it.

With a better understanding of the mechanisms that clean the atmosphere, scientists can better forecast the future.

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Replace Water With CO2

Common geothermal electricity setups generally involve extracting hot water from subterranean rock formations deep inside the Earth’s crust and using that heat to turn turbines. Common carbon sequestration schemes involve pumping carbon dioxide from the surface deep into the ground to prevent it from becoming atmospheric CO₂. I think you can see where we’re going here.

              In any case, two University of Minnesota Earth Sciences researchers were able to pu two and two together. What would happen, they asked, if you replaced the water in conventional geothermal rigs with compressed carbon dioxide? Models suggest that the new CO₂-based method--termed CO₂-plume geothermal, or CPG--should work just as well if not better, with the added benefit of sequestering carbon dioxide in the ground.

              In fact, the researchers think it could work even better than water. For one, carbon dioxide penetrates porous rock more easily than water, so it could potentially be used in areas where conventional water-based geothermal wouldn’t work. Moreover, CO₂ won’t dissolve minerals it comes in contact with as readily as water, so there’s less of a chance of CPG suffering from the mineral blockages that water can cause.

             It’s important to note that this is just an idea at this point--the duo has applied for DOE funding (in addition to that it has already received for studies) to take CPG to the pilot stage. But if it works, it could be big. Grad student Jimmy Randolph, one of the two researchers behind CPG, tells UM News: “This is probably viable in areas you couldn’t even think about doing regular geothermal for electricity production. In areas where you could, it’s perhaps twice as efficient.”

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Posted in: carbon dioxide,krafia,surface,water

More CO2 From Volcanoes Than Humans?

  

 Human activities emit roughly 135 times as much climate-warming carbon dioxide as volcanoes each year.Volcanoes emit less than cars and trucks, and less, even, than cement production. Climate change skeptics have claimed the opposite. 

             Colossal, mind-bogglingly hot and capable of spewing billowing clouds of flight-grounding smoke and searing, molten lava, volcanoes are spectacular displays of the massive forces at work inside our planet. Yet they are dwarfed by humans in at least one respect: their carbon dioxide emissions. 

             Despite statements made by climate change deniers, volcanoes release a tiny fraction of the amount of carbon dioxide emitted by human activities every year. 

        In fact, humans release roughly 135 times more carbon dioxide annually than volcanoes do, on average, according a new analysis. Put another way, humans emit in under three days the amount that volcanoes typically release in a year, according to the best estimates of volcanic emissions. 

       "The question of whether or not volcanoes emit more CO2 than human activity is one I get more than any question in my email from the general public.' said Terrence Gerlach, a retired volcanologist, formerly with the Cascades Volcano Observatory, part of the US Geological Survey in Vancouver, Wash. Even earth scientists who work in other areas often pose him the question, he said. 

                   To lay out a clear answer, Gerlach compiled the available estimates of CO2 emissions from all global volcanic activity on land and undersea and compared them with estimates for human emissions. He published the compilation in Eos, a publication of the American Geophysical Union. 

                   Researchers estimate the amounts of carbon dioxide released by terrestrial volcanic eruptions by methods including remote sensing or flying through clouds of erupting volcanic gas, and by measuring certain isotope concentrations near undersea volcanoes. Carbon dioxide is dissolved in magma at great depths and is released as the magma rises to the surface. 

    "A lot of climate skeptics claim that volcanoes emit more CO2 than humans do," Gerlach said. "They never give any numbers, but the fact is you will never be able to find the volcanic gas scientist that will agree to that," he said. 

      One example of these skeptic's claims is the 2009 book, "Heaven and Earth: Global Warming, the Missing Science" by Ian Plimer of the University of Adelaide, who did not respond to Discovery News' requests for comment.

       "The main reason, I think, that this myth persists," Gerlach said: "First of all, the emissions are extremely spectacular. When people see volcanic eruptions on television and it's awesome, and it's very easy for people to imagine that huge amounts of CO2 are being emitted to the atmosphere." 

                     "However, these spectacular volcanic explosions that are so stunning on TV last only a few hours," he added. "They are ephemeral. In contrast, the sources of anthropogenic CO2 (smokestacks, exhaust pipes, etc) are comparatively unspectacular, commonplace, and familiar, and in addition they are ubiquitous, ceaseless, and relentless. They emit CO2 24/7." 

                     While there is uncertainty in the measurements--researchers estimate between 0.13 and 0.44 billion metric tons per year, with their best estimates between 0.15 and 0.26 billion tons--even the highest end of the range is dwarfed by anthropogenic emissions of 35 billion metric tons in 2010. 

                     

            Gerlach noted that human land-use changes alone, which include deforestation, release 3.5 billion metric tons per year. Cars and light-duty trucks produce 2 billion metric tons; even cement production produces 1.5 billion tons. Any of these by itself is still several times higher than the annual emissions of all of the world's volcanoes . 

           

           Pakistan or Kazakhstan each produce about the amount of CO2 as volcanoes do each year, Gerlach noted in the article. 

           In yet another comparison, Gerlach reported that in order for volcanic emissions to match those made by humans, the May 18, 1980, Mount St. Helens eruption would need to happen every 2.5 hours. The June 15, 1991, Mount Pinatubo eruption would need to occur every 12.5 hours.

          "There is no way you can escape the fact that volcanoes are releasing a tiny amount of emissions right now," said Bernard Marty of the Centre de Recherches Petrographiques et Geochimiques in Nancy, France. "There is no doubt about this." 

  

            "Even if you do the reverse and you compute how much volcanism should happen to match atmospheric levels, you end up with completely unrealistic eruption rates," he said.

             Marie Edmonds, a volcanologist at Cambridge University agreed. While volcanoes are the most important natural source of atmospheric CO2, she noted, "The results show clearly that the amount is 100-150 times less than anthropogenic amounts."

               

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