It shows current atmospheric measurements of carbon dioxide in parts per million, as sampled at Mauna Loa, Hawai'i.

Want one? Here's where to pick up the HTML code.

Labels: climate change, CO2, global warming, hawaii

One interesting thing I learned when reading Tyler Volk's CO2 Rising deserves a blog post of its own: It's called the Suess effect, after the Austrian chemist Hans Suess, a fellow who I've quoted here before. The basic idea here is that by burning fossil fuels (oxidizing fossil carbon), we are diluting the amount of ¹⁴C in the atmosphere of our planet. As you may be aware, ¹⁴C is produced continuously in the upper reaches of our atmosphere as nitrogen atoms get bombarded by solar particles (specifically, thermal neutrons). Hydrogen is a byproduct of the reaction. It goes something like this:
This ¹⁴C isn't stable over the geologic long-term: it spontaneously breaks down, via radioactive decay, with a half-life of about 5730 years. This property means that ¹⁴C is really useful for dating organic matter of the relatively recent geologic past, a time of particular interest to us, since that's when our species developed its distinctive cultures. But the short half-life means that by the time 60,000 years or so have gone by, there's so little left that it's no longer useful for radiometric dating.

Of course, most of the fossil fuels we use are far older than 60,000 years [A lot of the coal we use formed during the Carboniferous, about 360-299 million years ago], so their store of ¹⁴C long ago reverted to ¹⁴N. When we burn this carbon, we combine it with oxygen and send it into the atmosphere. Isotopically, this fossil carbon looks different from the rest of the carbon in the biosphere.

So overtime, as we burn low-¹⁴C fossil fuels, we would expect to see the total atmospheric ratio of ¹⁴C to other isotopes of carbon decrease. The carbon in the atomsphere becomes more and more enriched in ¹³C and ¹²C as low-¹⁴C coal, oil, and natural gas get oxidized.

In other words, the abundance ratios of these different isotopes of carbon provide a fingerprint for where all that extra carbon dioxide is coming from: it has to be from ¹⁴C-depleted sources, like old carbonaceous sedimentary deposits. For a nice graph illustrating this, click here.

Last thing: The Suess effect holds up only until the early 1950s because after that extra ¹⁴C produced during nuclear bomb testing starts to build up again, skewing the overall trend.

See also this image. (A high-res slide explaining the phenomenon, and detailing different natural repositories of carbon isotope data.)

References:

P.P. Tans, A.F.M. de Jong, and W.G. Mook. "Natural atmospheric ¹⁴C variation and the Suess effect," Nature 280, 826 - 828 (30 August 1979); doi:10.1038/280826a0

Labels: books, CO2, coal, isotopes, oil

When I started writing this post, I had just finished reading Tyler Volk's book CO2 Rising. Now it's been more than a month, and it's time to get this post up online. The author has kindly granted me permission to reproduce some of the images from the book.

CO2 Rising has got some stuff that sets it apart from other global warming books.

To start with, it's more focused on helping readers understand the carbon cycle rather than outright climate science. To do this, Volk employs a heurisitic device of naming certain carbon atoms. He names one 'Dave' (in tribute to Dave Keeling, who established the atmospheric CO2 observatory on Mauna Loa). Dave gets washed out of limestone and into the sea, he diffuses into the air, he gets sucked into a plant stoma and locked up in plant sugar. He gets fermented in a batch of beer, and drunk by the author, then oxidized and diffuses across the lung membrane and is exhaled back into the atmosphere, and so on. There are three other carbon atoms who also get names, and the reader gets to follow them on their adventures through the biosphere over tens of thousands of years. Some have been locked up in fossil fuel deposits for millions of years.

While I've heard some dismiss this narrative technique as a gimmick, I liked it. It drives home the point that carbon atoms "live" forever, and are simply jumping from carbon reservoir to reservoir through chemical reactions and physical flow. Bonds form and are broken. Energy is absorbed, energy is released. Now Dave is in a coccolithophore, now he's in a tree, now he's being oxidized in a cooking fire. You really get a sense of the complexity and the limits of the carbon cycle.

After these physical pathways are established, the latter half of the book explores the manifestations of accumulating carbon dioxide in the world. The reader, with their new sense of the robust & complicated nature of the carbon cycle, can start looking at the problem of anthropogenic climate change.

I was particularly impressed with Volk's pedagogical style by "zooming out" from a series of graphs of carbon dioxide, granting a tremendous perspective on how out-of-whack our modern CO2 concentrations really are. He does this by starting with the present day and backing out further and further into the past. The saga begins with the familiar Mauna Loa curve:


Then he puts that in perspective by showing CO2 data from Law Dome ice, which overlaps with Mauna Loa:


...But Law Dome's record goes back further than that:


...And where Law Dome's record ends, the ice of Taylor Dome takes over:


...And it takes us back further still:


Finally, we get to Vostok's record, which takes us back (in this graph) 400, 000 years:


I think that's a pretty impressive way of presenting this data -- building it out bit by bit, starting with the familiar and then going waaaaaaaaaayyyy back into the past.

All in all, I really enjoyed the book. I recommend that you read it. Say hi to 'Dave' for me!

Labels: books, climate change, CO2, global warming

Here's the results of a neat little experiment my Environmental Geology students did a couple weeks ago. This is the first time I've run this activity, and I was pleased with the results:

Labels: climate change, CO2, global warming, nova, teaching

Heh! This "clean coal" debunking campaign is directed by the Coen Brothers.

And another:

Behind the scenes:

Labels: climate change, CO2, coal, global warming, humor, politics

Nevada's Yucca Mountain site for a proposed nuclear waste repository has lost much of its funding in President Obama's proposed budget. Personally, I think this is a good call - I never thought that the Yucca Mountain site seemed viable for the geological long-term. For a facility being designed to outlast human civilization (warning signs are not written in English, but in sign language that's predicted to still be useful when potential meddlers show up 10,000 years from now), Yucca Mountain is located in too tectonically-active an area for my liking. Basin and Range extension, with associated earthquakes and volcanism, imperils the facility's security over the long-term.

But then where do we put this nuclear waste? We've got more and more of it every day. I'm a fan of nuclear energy because I feel that in spite of the risks associated with radioactive leaks, it's a proven technology that looks better all the time because it produces no carbon emissions. To me, the relatively short-term (local) risk of radiation leaks is outweighed by CO2's long-term (global) risk of climate change. Provided sufficient security, I think it's a great "halfway house" between fossil fuels and 'alternative' energies like solar, wind, and geothermal.

Yucca Mountain has several advantages in terms of its location: it's dry, and it's not in someone's backyard (far from large populations -- though Los Vegas residents might quibble with the definition of "far"). But Nevada's regular seismic shaking (3rd in rank among the U.S. states, after California and Alaska) and the proximity of some young volcanic extrusions make me think it's not so great a spot if you want the waste to stay put. I'm thinking that the best place for nuclear waste would be in the craton, the stable interior of the continent. I'm thinking: Canadian Shield, maybe in Minnesota or Michigan or Wisconsin. The issue there is water: you would be trading tectonic stability for saturation and precipitation.

I'll readily admit I'm not an expert here -- just a geologist speculating on an issue that's more complex than mere geology. What do you think? Where's the best place to store nuclear waste until radioactive decay makes it reasonably safe? Use 10,000 years as your hypothetical timeline, bearing in mind how different the world is today than it was 10,000 years ago.

Labels: CO2, earthquakes, energy, environmental, michigan, minnesota, nevada, volcano, wisconsin

Last week, I mentioned the impending launch of the Orbiting Carbon Observatory... Well, last night at the launch, things didn't work out so well...

NASA Satellite Fails to Reach Orbit (New York Times)
NASA satellite crashes (Los Angeles Times)
Seven years' work on satellite crashes and burns in 12 minutes (Scotsman)
NASA satellite launch fails (Newsday)
and from NASA themselves, the grim Launch Mishap Ends OCO Mission

What a bummer. All that potential knowledge, snuffed out before we even got a chance to see it.

Labels: climate change, CO2, global warming, news, satellite imagery

Very cool -- I think I want to design an Environmental Geology lab that uses Google Earth to access and evaluate this data. Kudos to the Vulcan Project for putting it together.

You can open these layers in Google Earth by clicking here.

Labels: climate change, CO2, coal, global warming

NASA is launching a new satellite next week to monitor the atmosphere's carbon flux from a outside-the-planet perspective. It's called the Orbiting Carbon Observatory (OCO). Hopefully this will complement and give context to our current ~100 monitoring stations around the world (point measurements) for a truly global picture of our atmosphere's carbon inputs and outputs.

According to the NASA OCO website, the satellite will map the globe "once every 16 days for at least two years. It will do so with the accuracy, resolution and coverage needed to provide the first complete picture of the regional-scale geographic distribution and seasonal variations of both human and natural sources of carbon dioxide emissions and their sinks-the reservoirs that pull carbon dioxide out of the atmosphere and store it."

I can't wait to learn what we don't currently know about the carbon system. This is a tool that's long overdue!

Labels: climate change, CO2, satellite imagery

There's a new study out I read about today in New Scientist which took squid and put them in a tank of ocean water that was equilibrated to simulated atmospheric concentrations of carbon dioxide predicted for the year 2100. The oceans were also warmer in temperature, again simulating predicted future conditions. In these acidic oceans, the squid's metabolic levels dropped by 31%, and the time they spent contracting their muscles dropped by 45%. I didn't get to read the full study, which is behind a Proceedings of the National Academy of Sciences paywall, but the abstract online hints that these mini-oceans were about 0.3 pH units lower than modern ocean values. The abstract doesn't say how much warmer the experimental tanks were, but notes that water's ability to hold oxygen decreases with warmer temperatures. The lack of oxygen may be the prime reason for the squid's diminished activity.
______________________
Journal reference: DOI: 10.1073/pnas.0806886105

Labels: CO2, critters, mollusks, news, ocean acidfication, oceans

What're you doing on Friday? There are two excellent-sounding earth science seminars inside the Beltway: The University of Maryland Geology Department's weekly seminar, and the American Meteorological Society's monthly seminar for policy makers. Both events are free and open to the public. AMS is at 10am, UMD at 11am. You can't do both -- you must choose...

AMS: Friday, September 26, 2008New Time - 10:00 AM - 12:30 PM
Dirksen Senate Office Building, Room G50 Washington, DC

Accelerating Atmospheric CO2 Growth from Economic Activity, Carbon Intensity, and Efficiency of Natural Carbon Sinks

What is the relationship between economic activity and CO2 growth? What is carbon intensity and how does it relate to economic activity? What are the trends in CO2 growth, carbon intensity, and changes in the efficiency of natural reservoirs to store carbon? How does the growth in CO2 compare to the various estimates of CO2 growth contained in the most recent IPCC assessment of climate change? What is permafrost and what is the extent of permafrost thaw in the Arctic? Is permafrost thaw a response to global warming and if so, what is the future likely to hold? Will permafrost thaw result in the release of additional CO2 into the atmosphere from Arctic soils? If so, what is the impact likely to be on global warming? How much carbon is stored in Arctic soils? Assuming that the Arctic continues to warm well above the global average, what is the likely fate of that soil carbon and how might it influence climate in the future?

Public Invited; Buffet Reception Following

Moderator: Dr. Anthony Socci, Senior Science Fellow, American Meteorological Society

Speakers:

• Dr. Josep (Pep) Canadell, Executive Director, Global Carbon Project, Commonwealth Scientific and Industrial Research Organization (CSIRO) Marine and Atmospheric Research, Canberra, Australia
• Dr. Vladimir Romanovsky, Geophysical Institute, University of Alaska, Fairbanks, A
• Dr. Howard E. Epstein, Department of Environmental Sciences, University of Virginia, Charlottesville, VA

Program Summary

How Fast is Atmospheric CO2 Growing and Why, and Does it Suggest Ways to Mitigate Climate Change?

The increase in atmospheric carbon dioxide (CO2) is the single largest human perturbation of the climate system. Its rate of change reflects the balance between human-driven carbon emissions and the dynamics of a number of terrestrial and ocean processes that remove or emit CO2. It is the long term evolution of this balance that will determine to a large extent the speed and magnitude of climate change and the mitigation requirements to stabilize atmospheric CO2 concentrations at any given level. Dr. Canadell will present the most recent trends in global carbon sources and sinks, updated for the first time to the year 2007, with particularly focus on major shifts occurring since 2000. Dr. Canadell’s research indicates that the underlying drivers of changes in atmospheric CO2 growth include: i) increased human-induced carbon emissions, ii) stagnation of the carbon intensity of the global economy, and iii) decreased efficiency of natural carbon sinks.

New Estimates of Carbon Storage in Arctic Soils and Implications in a Changing Environment

The Arctic represents approximately 13% of the total land area of the Earth, and arctic tundra occupies roughly 5 million square kilometers. Arctic tundra soils represent a major storage pool for dead organic carbon, largely due to cold temperatures and saturated soils in many locations that prevent its decomposition. Prior estimates of carbon stored in tundra soils range from 20-29 kg of soil organic carbon (SOC) per square meter. These estimates however, were based on data collected from only the top 20-40 cm of soil, and were sometimes extrapolated to 100 cm. It is our understanding that large quantities of SOC are stored at greater depths, through the annual freezing and thawing motion of the soils (cryoturbation), and potentially frozen in the permafrost.

Recent detailed analysis of Arctic soils by Dr. Epstein and his colleagues found that soil organic carbon values averaged 34.8 kg per square meter, representing an increase of approximately 40% over the prior estimates. Additionally, 38% of the total soil organic carbon was found in the permafrost.

A total of 98.2 gigatonnes (1015 grams) of carbon is estimated to be stored in the soils of the North American Arctic tundra. An area-based estimate for the entire Arctic suggests the presence of approximately 160 gigatonnes of carbon. The annual increase in atmospheric carbon dioxide is roughly 2% of this amount, so small changes in Arctic carbon storage could have substantive impacts on atmospheric CO2. The future of this stored carbon is, however, largely uncertain in the face of a changing Arctic environment. Climate change and resulting increasing temperatures in much of the Arctic could increase the decomposition rates of soil organic carbon (producing atmospheric CO2), and increase permafrost thaw, which would expose more soil organic carbon for decomposition. On the other hand, increasing temperatures could also lead to greater sequestration of atmospheric CO2 by tundra vegetation. Actual changes will be the result of complex interactions between processes that sequester carbon and those that release it.

Past, Present and Future Changes in Permafrost and Implications for a Changing Carbon Budget

Presence of permafrost is one of the major factors that turn northern ecosystems into an efficient natural carbon sink. Moreover, a significant amount of carbon is sequestered in the upper several meters to several tens of meters of permafrost. Because of that, the appearance and disappearance of permafrost within the northern landscapes have a direct impact on the efficiency of northern ecosystems to sequester carbon in soil, both near the ground surface and in deeper soil layers. Recent changes in permafrost may potentially transform the northern ecosystems from an effective carbon sink to a significant source of carbon for the Earth’s atmosphere. Additional emissions of carbon from thawing permafrost may be in the form of CO2 or methane depending upon specific local conditions.

Dr. Romanovsky will present information on changes in terrestrial and subsea permafrost in the past during the last glacial-interglacial cycle and on the most recent trends in permafrost in the Northern Hemisphere. He will further discuss the potential impact of these changes in permafrost (including a short discussion on potential changes in methane gas clathrates) on the global carbon cycle. Dr. Romanovsky’s research suggests that permafrost in North America and Northern Eurasia shows a substantial warming during the last 20 to 30 years. The magnitude of warming varied with location, but was typically from 0.5 to 2°C at 15 meters depth. Thawing of the Little Ice Age permafrost is on-going at many locations. There are some indications that the late-Holocene permafrost started to thaw at some specific undisturbed locations in the European Northeast, in the Northwest and East Siberia, and in Alaska. Future projections of possible changes in permafrost during the current century, based on the application of calibrated permafrost models, will be also presented.

The next seminar is tentatively scheduled for October 10, 2008.
Topic: Ecosystem Health in a Rapidly Changing Climate

Please see the AMS web site for seminar summaries, presentations and future
events: http://www.ametsoc.org/seminar

For more information please contact:
Anthony D. Socci, Ph.D. Tel. (202) 737-9006, ext. 412 socci@ametsoc.org

UMD: 11:00am - 12:00pm at 1121 Computer Science Instructional Center

Internal flow and extrusion of the Greater Himalayan Slab, Mount Everest Massif: a tour of the world's highest rocks
Dr. Rick Law from Virginia Polytechnic Institute and State University

If you are interested in meeting with Dr. Law please sign up online. You also may delete an appointment from this page. Please join the faculty and students for refreshments in the Geology Building foyer at 10:30 am.

Seminar series web page for UMD-College Park Geology.

Labels: climate change, CO2, geology, global warming, maryland, meetings

Fellow DC metro area residents -- there are a bunch of geology events coming up in the next couple of months that you may be interested in. Everything* listed here is free and open to the public.

Next Sunday, August 24, I'll be leading an event called "Geology Along the C&O Canal," at the Lock 8 River Center from 10am until 11am. My plan is to give an overview of the Appalachian mountain belt, then focus on the Piedmont "chapter" of that story, using local outcrops to illustrate the rock types produced. I'm not sure if you need to reserve a spot or not; Call Bridget Chapin at the Potomac Conservancy (number at link above) to inquire about details.

Friday, September 5: "Geology Along the Billy Goat Trail," I'll lead this hike along the famous Billy Goat Trail, examining its exquisite display of metamorphic geology and geomorphology. 12:30pm-4:30pm. Reserve a spot through the good folks at the Great Falls Tavern Visitor Center.

Wednesday, September 10: first Geological Society of Washington meeting of the fall. Beer served at 7:30pm, and the formal program begins at 8pm. At the Cosmos Club in Dupont Circle.

Saturday, September 20: I'll be leading my "History Before History: the Geologic Saga of Washington, DC" walking tour as part of Walkingtown, DC. The tour runs from 1pm until about 4pm, and involves about 2.5 miles of walking from Adams-Morgan to Georgetown. Limit of 30 people; interested walkers should reserve a spot with Cultural Tourism, DC, the nonprofit group that sponsors Walkingtown, DC each spring and fall.

Sunday, September 21: For those who can't make it Saturday, I'll again be leading my "History Before History: the Geologic Saga of Washington, DC" walking tour as part of Walkingtown, DC. The tour runs from 1pm until about 4pm, and involves about 2.5 miles of walking from Adams-Morgan to Georgetown. Limit of 30 people; interested walkers should reserve a spot with Cultural Tourism, DC, the nonprofit group that sponsors Walkingtown, DC each spring and fall.

Wednesday, September 24: Another Geological Society of Washington meeting, but I'll be delivering a talk at this one. My talk's title is "Rise of the geoblogosphere."

Sunday, October 5: I'll be delivering a talk called "A Geologist's Perspective on Climate Change" at the Chinn Park Regional Library in Woodbridge, Virginia. 2pm-3pm.

Friday & Saturday, October 10-11: The Virginia Geological Field Conference, in Marion, VA. "Geology of the Saltville and Pulaski Fault Blocks" is this year's topic. *This is the one item on the list that is not in the immediate DC metro area, and also the one item on the list that costs money -- registration is $45 for professionals, $20 for students. Transportation, lunch, and guidebook will be provided. See more details on the website. If you're interested in comparing and contrasting two Valley and Ridge fault blocks shoved westward during Alleghenian mountain-building, this might be of interest to you.

Thursday, October 23: the Earth's birthday, according to James Ussher. 4004 BC to 2008 AD; does that make it 6012 years old? Or is it 6011 years old, since there was no year "0"? Tricky... Regardless, I'll be serving lithosphere/asthenosphere cake/pudding to NOVA students in celebration of the day. (I posted on visiting Archbishop Ussher's church here.)

Wednesday, October 22: Another GSW meeting. Same time, same place, but this time I'll be back where I belong: in the audience.

Friday, October 24: "Geology Along the Billy Goat Trail," I'll lead this hike along the infamous Billy Goat Trail, examining its exquisite display of metamorphic geology and geomorphology. 12:30pm-4:30pm. Reserve a spot through the good folks at the Great Falls Tavern Visitor Center.

If you're into geology and you'll be around, I hope you'll join us on one or more of these events.

Labels: blogs, climate change, CO2, dc, geology, global warming, gsw, nova, piedmont

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, energy, 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/Pg (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