This map was in this morning's Washington Post. The red dots are currently-existing coal-fired power plants. The black dots with the central stars are proposed future coal-fired power plants.

Labels: CO2, coal, dc, environmental, nova

A bunch of articles in today's issue of Nature use precise measurements of the composition of glacial air bubbles to extend the record of atmospheric gases (and airborne dust) back to 800,000 years before present. (Previously, the record "only" went back to 650,000 years before present.) Fully eight glacial cycles are seen in the new, expanded dataset. These new findings are all part of the European Project for Ice Coring in Antarctica (EPICA), and they offer some new insights, as well as additional confirmation of the close link between climate and past fluctuations in CO2 and CH4. Check it out.

Labels: climate change, CO2, global warming, ice

Take the next five minutes of your life, and watch this video about a cool new imaging experiment done by Kevin Gurney's research group at Purdue. They've taken pre-existing data about CO2 emissions and plotted it in a dynamic map. The most striking feature is the pulsating nature of the United States' CO2 emissions: we put out a lot during the day, and not so much at night. The maps really show this -- demonstrating yet again the power of images (over description) to convey information.

It's long been my contention that one of the biggest problems with the global warming issue is that CO2 is invisible. I'll bet that if people actually saw giant clouds the color of liquid Barney wafting off the coast every day, then they would be more inclined to think of carbon dioxide as something tangible.

Labels: art, climate change, CO2, global warming, maps

Juliet Eilperin reports in today's issue of the The Washington Post about the Ken Caldeira study I mentioned a few days ago. She also mentions another recent modeling study by Andreas Schmittner, who wrote (with others) a February 14 article in Global Biogeochemical Cycles that suggests that if global emissions continue on a "business as usual" path for the rest of the century, the Earth will warm by 7.2 degrees Fahrenheit by 2100. Schmittner's study continues: If we don't get to zero emissions until 2300, the temperature rise at that point would be more than 15 degrees Fahrenheit. (FYI: I haven't yet read the Schmittner, et al., study myself.)

Anyhow, the Post article reminds me of something I've been mulling over, and meaning to post since then.

I view climate change from two main perspectives: (1) as an earth scientist, and (2) as a citizen. As a scientist, I find it fascinating to watch how all this plays out. As a scientist, it presents an opportunity for learning, for greater understanding of how the Earth works. You see, geologists are limited scientifically: we often don't have the option of running controlled experiments on our topics of study: continents are too big, the spans of time are too vast. But with global warming, we have a colossal experiment that's being run, even though no one intended it as such. I offered this quote back in January, and I think I'll put it up again to give some context to my "scientist views climate change" perspective:

• "Human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future. Within a few centuries, we are returning to the atmosphere and oceans the concentrated organic carbon stored in sedimentary rocks over hundreds of millions of years."

-- Roger Revelle and Hans Seuss, 1957

In other words: The timescale of carbon storage is ~7 orders of magnitude larger than the timescale of carbon release. That's a large difference. Humans are thus changing the atmosphere's composition; but what effect will it have on the climate? Those who practice science can make some logical predictions based on our understanding of the natural world:

(A) It has been demonstrated for over a century that certain gases, like CO2, absorb energy in certain wavelengths of the electromagnetic spectrum. The gases that absorb in the infrared portion of the spectrum are the ones we call "greenhouse gases," since the majority of the energy re-radiated upwards from the Earth's surface is infrared, and absorption of this energy keeps the planet warmer than it would otherwise be.

(B) It has been demonstrated that in the presence of oxygen, biogenic carbon can be oxidized to release energy. Whether it's a campfire or gasoline (derived from petroleum derived from Paleozoic planktonic photosynthesis), organic carbon burns. When it does, carbon and oxygen combine, and CO2 is a product of the (exothermic) reaction.

(C) At numerous locations around the world, we have measured precisely the rising concentration of CO2 in our atmosphere. We have even measured precisely a corresponding decline in free atmospheric oxygen, as oxygen is consumed through the combustion of fossil carbon.

(D) These facts predict that the Earth's temperature will rise on average as a result of the greater concentration of greenhouse gases. That too can be measured, with multiple thermometers in multiple locations over a long period of time. What we find is that on average the temperature is going up (it's risen 0.7 of a degree Celsius, or ~1.4 degrees Fahrenheit over the past century), as is logically predicted by (A), (B), and (C).

So, as a scientist, I think it's really interesting: Here you've got some knowns, and some unknowns, and a logical structure linking them. Hypotheses yield predictions, and those predictions are being tested. Wow, scientist-me thinks, it's fascinating to see how the Earth system works when you alter a variable like atmospheric CO2 concentration.

On the other hand, I'm not just a dispassionate observer watching this all play out on an experimental planet: I'm also a person who lives on that planet and will be subject to the consequences of the experiment. It's from that perspective, the "citizen" point-of-view, that global warming scares the hell out of me. The Earth's fate is not in question here: our planet has endured far greater fluctuations in the past (both warmer and colder). The issue is for those of us who live on the surface of the planet Earth (humans and other species): as conditions change, will we be able to adapt? I'm concerned that some of the consequences are potentially too large for ecosystems to maintain their coherency. I'm worried about the huge proportion of my fellow human citizens (of the Earth) who dwell on the low-elevation coastlines of the world. The Earth will endure quite a lot of temperature variation; but I'm not sure about the organisms on its surface (of which I am one).

Last week, one story in the news was about the opening of the "Doomsday" seed vault on Svalbard. I was struck by the scientific parallels between the seed vault story and global warming, yet how very differently people were treating it. Science suggests that biodiversity is declining, and is subject to numerous threats, and we humans depend on viable seeds for our survival as a species. So, we're taking action by making this vault to keep our seed stock safe. It's totally uncontroversial. You don't see any Seed Vault Skeptics publishing editorials or holding conferences. Yet with climate change, there is a substantial voice in public life suggesting that the science is flawed, and thus that no action is required. Obviously, there's a HUGE difference between the relatively simple matter of creating a seed bunker in the Arctic and retooling the world economy's energy source, but those are both matters of political action. The science underlying each issue is strong and compelling. Whether we choose to act on the conclusions of that science is another thing: do we take action only when it's easy? Or do we take action when the science suggests that, for our own benefit as a species, we must?

Perhaps this is the third perspective with which I view climate change: as a "social scientist" intrigued would how people sort out complex issues like this. Will we be able to pull if off, as a society? Maybe it's already too late.

Some quotes from the Post article:

• "People aren't reducing emissions at all, let alone debating whether 88 percent or 99 percent is sufficient. It's like you're starting off on a road trip from New York to California, and before you even start, you're arguing about where you're going to park at the end."

--Gavin Schmidt, NASA Goddard Institute for Space Studies

• "[Global warming] is a classic inter-generational debate, where the short-term benefits of emitting carbon accrue mainly to us and where the dangers of them are largely put off until future generations."

-- Steve Gardiner, University of Washington

• "Each unit of CO2 emissions must be viewed as leading to quantifiable and essentially permanent climate change on centennial timescales."

-- Damon Matthews, Concordia University

Labels: climate change, CO2, global warming, politics

New Scientist gives the full run-down on their findings.

Reference: Matthews, H. D., and K. Caldeira (2008), Stabilizing climate requires near-zero emissions, Geophys. Res. Lett., 35, L04705, doi:10.1029/2007GL032388.

Labels: climate change, CO2, global warming

Just got through watching an episode of the PBS program NOVA (which I like to refer to as the "other" NOVA). The episode was titled "Volcano under the city," and it looks at the volcano Nyiragongo in Congo, central Africa. This was the same volcano that had such a spectacular eruption in 2002, when lava flowed through the city of Goma, on the shore of Lake Kivu. The program follows UN vulcanologist Jacques Durieux on a journey through Goma and into Nyiragongo to evaluate the risk for the ~2 million people who live in the mountain's shadow. The program explores volcanic hazards including lava flows, landslides, lake overturn (a la Lake Nyos), and pockets of CO2 in low-lying areas on land. This last one provided what I found to be the most dramatic footage: Durieux tosses a signal flare into one of the ditches, and the smoke rises and flows on top of the invisible layer of CO2 below: it demonstrates dramatically how there's something invisible pooled in that ditch due to its density. There's also plenty of footage of frothing spewing blobby lava, if that's your thing. As is often the case, the narrator overpitches the dangerous aspects of the situation, and the whole hour-long show feels kind of like a hyped-up movie trailer. Certainly the situation there is dangerous, but I feel like some credibility gets lost when every word is uttered with a sense of looming menace.

Labels: africa, CO2, movies, tv, volcano

In this past week's New Yorker, Michael Specter examines the convoluted business of trying to measure a person's (or a product's) carbon footprint. Turns out to be rather complicated. An interesting, thought-provoking article: this is viewed in some sectors as an essential piece of information, but it's amost mind-numbing to try and cover every relevant consideration. I recommend the article.

Labels: climate change, CO2, global warming

The geoblogosphere spawns semi-monthly collections of blog posts on a particular theme, and this time around, Dr. Lemming is hosting with the theme of "things that make you go Hmmmm." The idea here is to write a blog post about something you don't understand in geology -- a mystery. Here's my contribution:

When I was in graduate school at the University of Maryland, I started hearing about a crazy notion that the entire planet had frozen over in the past. Apparently, multiple streams of evidence (chemical, isotopic, geologic, and magnetic) suggested that during the Neoproterozoic era of geologic time, the planet experienced a mega-Ice Age. There were even glacial deposits within a few degrees from the equator. If you've got glaciers operating within a few degrees of the equator, some scientists argued, then that means the Earth would have been entirely sheathed in ice. Its reflectivity ("albedo") would have been so high that most (~85%?) of incoming solar radiation would have been reflected back out into space, and that would have made the planet even colder, promoting more snow and ice. This positive feedback cycle would have reached a tipping point if the planet were covered in ice from the poles to approximately 30 degrees latitude: once it got that white, the "runaway albedo" feedback would have reached a tipping point, and wham, you've got a planet that looks like a great big snowball.

This led Joe Kirschvink (of Cal Tech) to dub this episode of glaciation the "Snowball Earth," which is about as catchy a name as a scientific hypothesis is every likely to get. The idea was then heavily promoted by Paul Hoffman (of Harvard), who was seeing strange stratigraphic patterns during field work in Namibia. Among the evidence Hoffman eventually accumulated for the Snowball were the following: "dropstones" (boulders, presumably dropped by icebergs into fine-grained offshore marine deposits, squishing the layers beneath them); conformable stratigraphy of "tropical" carbonate topped by glacial tillites, topped by more "tropical" carbonate; carbon isotope anomalies in overlying "cap" carbonates indicating a massive inorganic dumping of precipitated CaCO3; delicate crystal fans (some meters tall) precipitated rapidly in the post-Snowball ocean; and the temporary reappearance of banded iron formations (BIFs), which had not been seen since the Paleoproterozoic (and indicated an anoxic ocean, such as one sealed beneath a layer of ice).

When Kirshvink pitched the initial hypothesis, he also proposed how the Snowball could have ended (in a deliciously short, non-peer-reviewed paper): he noted that just because the surface of the planet was frozen, that would have meant diddly to plate tectonics. Radiogenic heat from the Earth's interior would have continued to drive plate tectonic processes, and that meant subduction would have continued, beneath the icy rime. If subduction continued, that meant that volcanoes would have continued to erupt, and as Iceland and Antarctica show us today, volcanoes can erupt underneath glaciers. This is important because volcanic outgassing has a substantial percentage (~15%) of carbon dioxide (CO2), and CO2 absorbs reflected infrared radiation: it's a greenhouse gas.

But with the entire surface of the planet frozen, what would have happened to this degassed CO2? If the planet's surface is frozen solid, that means the hydrologic cycle would be shut down, and the usual means of removing CO2 from the atmosphere (e.g. photosynthesis & also deposition of carbonate sediments like limestones) would be non-functional. Any CO2 emitted by volcanoes would therefore likely linger in the atmosphere, building up in concentration over time. Eventually, Kirshvink suggested, it built up to levels that caused global warming which compensated for the ice albedo effect, and the absorption of all that radiation by the CO2 melted the Snowball.

As evidence for this audacious idea, Kirshvink pointed to the cap carbonates: all that limestone ("cap carbonate") deposited on top of the glacial units needed a lot of CO2 to be dissolved in seawater (and a lot of Ca+ too). The cap carbonates, it was suggested, represented the stratigraphic removal of all that built-up CO2 from the atmosphere. Once the levels of CO2 were drawn down to a non-hothouse level, the cycle could repeat itself. Modeling calculations suggest that it would take about 5 million years of CO2 buildup to melt the Snowball.

And this is what I don't get: if you've got an atmosphere full of CO2, I can see how that would melt the Snowball. But wouldn't it then acidify the ocean (with carbonic acid, like we're seeing today), making calcite dissolve, rather than be precipitated? If the ocean is undersaturated with respect to CaCO3, then that ocean should not host accumulations of limestone. How could the voluminous worldwide cap carbonates be deposited in an acidic ocean?

On the Snowball Earth website, a list of suggested reasons why Snowball Earth could not have happened are listed, along with Hoffman, et al.'s scientific rebuttals. But when they come to the question of acid oceans and the deposition of cap carbonates, you can almost see them shrug: "These are serious criticisms," they note. Hmmmmm.

Post-script: The idea is intriguing not merely scientifically, but also in terms of the way science gets done: by people, sometimes people with outsized personalities. Paul Hoffman promoted the idea with an "evangelical zeal" (according to Gabrielle Walker, who wrote a book about the whole idea and the scientists involved). Hoffman's relentless pushing of the idea ruffled a good many feathers. Some scientists fought back, motivated in part by these chafing interpersonal dynamics. There's nothing like a little scientific controversy, and this is what Walker's book focuses on, more than the details of Snowball science.

When I found that Jay Kaufman (of UMD-College Park) was interpreting a local diamictite(near Aldie, VA) as a Snowball Earth tillite (and the overlying marble layer as a cap carbonate), I thought "this could make a great class." Last spring, I applied for and received a grant from the Virginia Community College System to develop a 2-credit class for NOVA utilizing these local rocks as a gateway to understanding the Snowball Earth hypothesis. I offered the class for the first time last summer, and I'll be offering it again this summer in August. We were fortunate to get rock samples from Virginia's two putative Snowball deposits as well as a suite of samples on loan from Gene Domack of Hamilton College. These "Snowball Suite" samples include tillites and dropstones from Namibia, Greenland, Mauritania, and Canada, as well as international BIFs and cap carbonate samples. I have to tip my hat to Dr. Domack and his colleagues: making these samples available is a terrific service in support of geoscience education.

Labels: climate change, CO2, geology, global warming, nova, snow, snowball earth, teaching

While prepping for the Climate Change Symposium on Friday, I came across these excellent old quotes about CO2: One is over a hundred years old. The other is over fifty years old. They both remain totally relevant today:

"If the quantity of carbonic acid (CO2) increases (in the atmosphere) in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression."

Labels: CO2, global warming

A sizable group of researchers (21; all members of the Stratigraphy Commission of the Geological Society of London) has put forward an idea in this month's issue of GSA Today: they suggest that humans have altered the planet enough that it will show up in the geologic record of the future. They suggest, therefore, that we may have already entered a new geologic epoch defined by human alteration. As a result, they've adopted the name originally suggested by Nobel laureate Paul Crutzen: "the Anthropocene." (Crutzen won in 1995, with two other chemists, for his work on the depletion of the ozone layer in the atmosphere.)

The evidence they offer for this assertion is compelling, but it raises a few questions about how we define these stratigraphic breaks in the geologic record.

Here's the only figure from the paper, a temporal comparison between several lines of data (top to bottom): sea level, average global temperature, atmospheric CO2, terrestrial erosion rates, and human population of the planet.

This is a powerful image. The authors note that climate essentially stabilized in the Holocene, the "long summer" of Brian Fagan's phrasing. In a classic display of scientific understatement, they note that this prolonged period of stable climate "has been a significant factor in the development of human civilization."

How will the rise of humanity be remembered by the geologic record? They note that we've accomplished some major changes to the rate of erosion and sedimentation : "directly, through agriculture and construction, and indirectly, by damming most major rivers, that now exceeds natural sediment production by an order of magnitude." I may be missing something here, but it would seem to me that anthropogenic erosion would produce more sediment due to our land use practices, but that less of that sediment would make it to the sea due to the "sediment trap" effect of dammed reservoirs. I mean, the Colorado River doesn't even make it to the ocean anymore.

Then there's temperature. A quote from the paper: "Temperature is predicted to rise by 1.1 °C to 6.4 °C by the end of this century, leading to global temperatures not encountered since the Tertiary." The high end of that estimate is indeed the sort of temperature change that one would think would leave a profound mark in the geologic record. (I find it interesting to note that a cast of 21 stratigraphers persists in using the outmoded and archaic term "Tertiary," by the way. I guess that's as sure a sign as any the Wernerian Chronology still has some kick left in it.)

I think one of the most compelling arguments made in favor of the Anthropocene is the rapid change in the Earth's biosphere. As the authors of the GSA Today paper point out, we've wiped out the majority of the big terrestrial animals, and concomitant wave of extinctions has rippled through the marine realm. Since changes in fossil biota have been the benchmarks of change in the geologic timescale, it seems certain that our tenure will be marked clearly for future paleontologists to see. Not only are species going extinct, those that survive are migrating to new territories as a result of shifting climate.

I'm pleased that the authors also explored changes to ocean chemistry, which will likely be a major source of information to future geologists. They cite Ken Caldiera and Michael Wickett's 2003 study on ocean acidification (which I blogged about last month) which shows that pH in the world's oceans has already dropped by 0.1 unit, and is predicted to continue acidifying so long as there's excess carbon dioxide to absorb from the atmosphere. Of course, add sea level rise to that (as is predicted via accelerated melting of continental ice sheets), and you've got a distinctive stratigraphic signature.

And I guess that brings me to a point that's been on my mind since I started listing these items. Will these changes persist for a long time, or will they be a small but distinct signature, a la the iridium layer at the K/P (formerly known as the "K/T") boundary? Another way of putting this: are we seeing the beginning of the Anthropocene's modus operandi, or are we seeing the environmental catastrophe which paves the way for a new, different, and (at this time) unpredictable Anthropocene status quo? At this point, we don't know what the Anthropocene will really look like in bulk. While it makes a lot of sense to point out the accelerated rates of change unfolding in so many geological realms, what it all portends for an as-yet-unattained future equilibrium remains to be seen.

I think papers like this are important. It's both broad in scope and displays some excellent thinking outside the box. I'm curious to see what reaction it provokes in the scientific community. Certainly it's getting some press.

* A side note: Does anybody else find GSA Today to be a weird journal? It always has one main article and then a bunch of stuff about meetings, awards, and the like, of interest to members of the GSA. But the articles featured each month are all over the map. Some, like this month's, are potentially ground-breaking works of scholarship. Others, just seem a bit... fringe. Like the one in December about how a team has shared Denver's geologic story with the public. Or the one about a historical critique of Lord Kelvin. Don't get me wrong: both topics are well and good, but if you're putting out only a single article each month that gets mailed to the entire GSA membership, why those? Sometimes I'm just left perplexed and scratching my head.

References:

Caldeira K., Wickett M.E. 2003. Anthropogenic carbon and ocean pH. Nature. v. 425. p 365. doi: 10.1038/425365a
Fagan, Brian. (2004) The Long Summer: How Climate Changed Civilization. Basic Books. ISBN 0465022812
Zalasiewicz J, Williams M, Smith A, Barry TL, Coe AL, et al. (2008) "Are we now living in the Anthropocene?" GSA Today: Vol. 18, No. 2 pp. 4–8. doi: 10.1130/GSAT01802A.1

Labels: CO2, environmental, global warming, stratigraphy

On Monday at noon, I went to the Russell Senate Office Building on Capitol Hill to attend a seminar organized by the American Meteorological Society.

The speakers were: David Archer of the University of Chicago and Ralph Keeling of Scripps (son of Charles David Keeling, also of Scripps). In two months, the Keeling curve (started by the father, maintained by the son) turns 50 years old. Probably more than any other graph, the Keeling curve is responsible for convincing people of the reality of CO2 buildup in our atmosphere.

Click on the picture at left to get a full-sized PDF of CO2 data from multiple measuring stations (not just Mauna Loa), all showing the same thing. The concentration varies with the seasons (more CO2 is pulled out during the northern- hemisphere summer; less in the northern winter), but overall the amount of this gas is increasing.


The seminar was titled "Natural CO2 Sinks and their Policy Implications: A Closer Look at Where Current CO2 Levels are Headed, in Historical Context." The two scientists gave an outstanding pair of back-to-back presentations, detailing the enormity of climate change we are now committed to.

The image that stuck most in my mind is this one: measurements of atmospheric oxygen (O2) from Cape Grim, Tasmania (Australia).

If volcanoes were the source of all that CO2 building up in our atmosphere, you would expect oxygen measurements to stay static (or at least not to vary beyond normal seasonal variations: the zig zags). But that's not what researchers have found. Instead, the pattern seen in the graph above is clear: oxygen levels are declining in lock-step with CO2's rise. The reason is simple: when we burn fossil fuels, we oxidize hydrocarbons. We can't burn a fossil fuel without oxygen. Oxygen is consumed by the process, and that oxygen is then paired up with carbon to generate CO2. The process is so simple, but the implications are profound. This graph makes clear that human burning of fossil fuels is the source for atmospheric CO2 rise. This is mankind's fingerprint on global warming.

I might also add that it was cool to run into Michelle Arsenault and Linda Rowan at the seminar.

AMS seminar series.

Labels: CO2, global warming, oxygen

This image shows bubbles of liquid carbon dioxide emerging from the seafloor at a hydrothermal vent on Northwest Eifuku Volcano in the western Pacific Ocean. Marine seismologists say that their seismographic data reveal new insights into how the ocean floor's plumbing system works. More information about the new research is at Discovery News. It occurs to me that you don't usually see bubbles at deep sea vents, because in spite of high temperatures, the pressure is also high so that gases are compressed into liquids. The "smoke" emerging from "black smokers" is actually superheated liquid water incredibly saturated with dissolved minerals (and entrained particles). The fact that we see bubbles here suggests this photo was taken at shallow depths in the ocean. The amount of light suffusing the image backs up this interpretation.

Labels: CO2, deep sea vents

Okay, so we all know that carbon dioxide has this property of being selectively transparent, and that it is accumulating at greater concentrations in Earth's atmosphere because the rate that it is being produced by human activities greatly exceeds the rate it is removed by natural processes. That's the global warming issue in a nutshell. But there's another aspect to climate change that hasn't gotten as much press: ocean acidification.

Much of the carbon dioxide produced since the Industrial Revolution has been absorbed by the oceans. Global warming would have been as noticeable as it is today much earlier had the oceans not acted as a "carbon sink" in this fashion. But the oceans can't absorb CO2 forever without consequence. When CO2 dissolves in H2O, it produces H2CO3, also known as carbonic acid. (top image)

Caldeira and Wickett published a study in 2003 in which the explored the consequences of adding all this extra acid to the oceans. The oceans are large, so changes to their pH take place slowly, but it looks like the ocean's pH is dropping (becoming more acidic) as it absorbs the extra CO2 from the atmosphere. They made some predictions (second image) about how projected emissions of CO2 will influence the amount of CO2 in the atmosphere (shown here as pCO2, which translates as the "partial pressure of carbon dioxide in the atmosphere), and then how that would influence the ocean's pH over a range of depths over the next millennium. As you might expect, their model shows surface waters becoming acidic first, because they are in direct contact with the CO2-rich atmosphere. Oceanic mixing propagates the acidic waters to the depths over longer timescales. They predict a maximum reduction of 0.7 pH units in surface waters, starting around the year 2200.

How will this effect marine life? Remember that lots of marine creatures make their skeletal material (hard parts) out of the mineral calcite, and calcite dissolves in acid. (In my classes, we put a drop of hydrochloric acid on a rock sample to determine if it is calcite.) Consider the effects on two kinds of plankton: coccolithophores and pteropods. The third and fourth images here show scanning electron micrographs of how skeletal material reacts to acidified conditions. The third image is from a study by Ulf Reibesell of the University of Norway, who grew coccolithophores in a series of model "ocean" tanks that had equilibrated to an "atmosphere" containing 300 ppm and 800 ppm CO2. For reference, pre-Industrial CO2 values were about 280 ppm, and today's CO2 values are about 380 ppm. You can see that the calcareous plates of the coccolithophores are smaller, thinner, and more degraded in the more acidic water. The fourth image shows the results of a similar experiment on a pteropod, by Orr, et al. in 2005. (A pteropod is a kind of planktonic snail.) The pteropod was placed in a tank of water undersaturated with respect to aragonite (a polymorph of calcite) for 48 hours. Sub-images b, c, and d show degradation of the snail's shell in those acid waters, and sub-image e shows a the surface of a normal pteropod shell for comparison.

Here's some model predictions of ocean pH from Scott Doney in a 2006 paper in Scientific American. Note that the northern Pacific Ocean becomes marginally saturated with respect to aragonite by the end of the century, and the Southern Ocean will be undersaturated by then. The skeletons of organisms with calcareous shells in those waters will begin to dissolve! So far, the pH drop has been only about 0.1 pH unit, but it is expected to hit around 0.3 pH units by 2100. It's hard to imagine how fundamental a change this will be to oceanic ecosystems!

Now, a new study in Science by the Coral Reef Targeted Research Group concludes that it's not just these high-latitude ocean water. Global warming kills tropical coral reefs, too. They consider the effects of ocean acidification as well as the effects of "bleaching" (when warm corals eject their symbiotic algae).

Labels: climate change, CO2, ocean acidfication

A well-illustrated article by NASA's Earth Observatory discusses the issue of coal mining in Appalachia. Estimates are that we have 100 years or more coal reserves in the world -- far more than oil. The problem is, coal is dirty. Appalachian coal in particular is high in pyrite (FeS2), so that when it is burned, sulfuric acid is generated.

And then, of course, there is the issue of greenhouse emissions. When we heat or get electrical power from the burning of coal, we are reversing an ancient photosynthetic reaction. In the Carboniferous, great swampy deltas (much like the modern Mississippi Delta) stretched across what is today West Virginia. Great rivers draining the young Appalachians flowed west into a shallow epeiric sea. In these muddy deltas, plants grew in profusion. Those plants did what modern plants do: they sat in the sunlight and used its energy to fuse CO2 and H2O into sugars -- plant food. Before they got a chance to use that constructed food, and before any animals had a chance to eat the plants, they were smothered beneath additional layers of sediment, and the efforts of their photosynthesis were locked away underground. This went on for millions and millions of years. Now, humanity has discovered that coal burns well, releasing energy originally generated by the Sun 300 million years ago. Using coal for energy reverses the ancient photosynthetic reaction. When we burn coal, we are combining the coal's "carbohydrates" with oxygen, and re-producing the initial ingredients (CO2 and H2O) in the process. Of course, when water vapor in the air reaches a high concentration, it condenses and precipitates. Carbon dioxide is also removed from the atmosphere by geologic processes, but at a much slower rate. Hence the rise in atmospheric CO2 levels since the Industrial Revolution (when coal-burning picked up pace).

The Earth Observatory article deals with another issue, though: the question of how best to get at coal, given that it's underground in strata with other rock layers atop them. Every month, it seems like there is an item in the news about how there's been an accident in some underground coal mine somewhere in the world, always with a dozen or more miners killed or trapped. In West Virginia, strip mining is a favored tactic. It's safer to coal miners because it occurs at the surface, but there's the rub: The surface is also where everything else happens, too. When miners strip away the overlying rock layers, they also strip away the forest and everything that lives there. Often, unwanted rock is dumped into neighboring valleys, which causes a lot of stress on the freshwater ecosystems present in streams draining that valley.

Check out the article here. It is illustrated with great maps and satellite photos.

Labels: CO2, coal, global warming, mining, satellite imagery