I'm uncomfortable with this real-life test of geoengineering: http://www.grist.org/climate-change/2011-08-31-is-planet-cooling-balloon-full-of-hot-air
Maybe they could have started with some modeling?
Showing posts with label geoengineering. Show all posts
Showing posts with label geoengineering. Show all posts
2011-09-01
2010-11-30
UN not putting mirrors in space
An article in the Telegraph by Louise Gray carries the headline, "Cancun climate change summit: UN considers putting mirrors in space" [LINK]. That is a misleading headline, to put it mildly. What is really happening is that there's another "climate summit" happening now in Cancun, just like last year at Copenhagen. The difference with Cancun is that there aren't any expectations; for some reason people had high hopes for a deal at Copenhagen despite all the indications that it would not happen. This article, however, isn't really about the summit, it seems to be about the talk that Rajendra Pachauri (head of IPCC) gave at the summit. I haven't double checked, but it sounds like he gave an overview of the current IPCC endeavor, gearing up for the Fifth Assessment Report (AR5), which will be released in 2014-ish. What's with the mirrors, though? Well, the AR5 is going to change structure a little bit, just like all the other reports have done. New chapters are going to be added, for example dealing with clouds and aerosols (coverage of clouds and aerosols has been spread across several chapters in the past). The mirrors are a geoengineering idea, and for the first time geoengineering is going to be dealt with explicitly in the IPCC assessment. There won't be a separate report about it, nor even a separate chapter. Like other topics that have emerged in previous reports, geoengineering will be sprinkled throughout the AR5. Specifically, there are sections in the carbon/biogeochemistry chapter (Ch. 6), cloud/aerosol chapter (Ch. 7), the near-term climate change chapter (Ch. 11) in Working Group 1 (physical science basis), plus part of Ch. 5 in WG3's report. This was all laid out already by the IPCC and is available on their web site [LINK].
This was all just to criticize the coverage by the Telegraph. The "UN" isn't considering geoengineering implementation, as the story might lead you to believe. The fact is that research, serious research, is now being done to understand the consequences of geoengineering ideas. Since the AR5 is assessment of climate change science, it is natural to include these geoengineering results. The IPCC is not going to recommend putting mirrors in space.
Yet.
This was all just to criticize the coverage by the Telegraph. The "UN" isn't considering geoengineering implementation, as the story might lead you to believe. The fact is that research, serious research, is now being done to understand the consequences of geoengineering ideas. Since the AR5 is assessment of climate change science, it is natural to include these geoengineering results. The IPCC is not going to recommend putting mirrors in space.
Yet.
2010-06-16
Why make a point when you can just sound like you are?
Just read an article on Reuters with the headline: Whale poo helps offset carbon footprint. Sometimes articles get stupid headlines because the person writing the article isn't in charge of making the headline, but this article actually says this in the text. It's real short, go read it. I doubt you'll be as angered by it as I am, but maybe you'll see how incredibly stupid it is.
The story reports on science, which says that sperm whales in the Southern Ocean defecate in the upper ocean where phytoplankton use the iron from the feces to grow. This in turn, allows the phytoplankton to "absorb" more carbon. The idea is just like iron fertilization.
The point that they article makes is that the cycle actually reduces atmospheric CO2 because the amount of carbon used by the phytoplankton is twice as much as is breathed out by the whales. Thus, Michael Perry (the reporter) concludes, the whales offset their carbon and reduce their carbon footprint.
First off, whales don't have feet, so they have no footprint.
Second, though, whales also don't use fossil fuels, so whales have no carbon footprint.
The science sounds interesting enough, and it seems like they are showing that this aspect of the carbon cycle is a net sink of atmospheric carbon. One caveat that isn't dealt with is that the phytoplankton don't necessarily use the carbon immediately die and sink, there is also a lot of recycling in the upper ocean. So this "carbon sequestration" (which just means that the phytoplankton die and sink to the deep ocean) might not be as strong as this news article would lead us to believe.
A larger point is that in the absence of humans, this would just be one of many small carbon sinks that would balance a lot of carbon sources, closing the carbon cycle. Unperturbed ecosystems, much less individual species, are (over long time scales) in steady-state. Imagine that humans disappear, so all the anthropogenic CO2 stays around, but no more is added. These whales(+phytoplankton) might continue to act as a net carbon sink, but over the long run, they aren't going to suck all the carbon out of the atmosphere. Okay, I'll stop belaboring this point.
What makes this an even better example of lazy science reporting is that the really interesting point about the whales'(+phytoplankton's) role in the carbon cycle is buried in the last sentence:
UPDATE:
An AP story also has most of this, but better covers the whaling angle: [LINK]
The story reports on science, which says that sperm whales in the Southern Ocean defecate in the upper ocean where phytoplankton use the iron from the feces to grow. This in turn, allows the phytoplankton to "absorb" more carbon. The idea is just like iron fertilization.
The point that they article makes is that the cycle actually reduces atmospheric CO2 because the amount of carbon used by the phytoplankton is twice as much as is breathed out by the whales. Thus, Michael Perry (the reporter) concludes, the whales offset their carbon and reduce their carbon footprint.
First off, whales don't have feet, so they have no footprint.
Second, though, whales also don't use fossil fuels, so whales have no carbon footprint.
The science sounds interesting enough, and it seems like they are showing that this aspect of the carbon cycle is a net sink of atmospheric carbon. One caveat that isn't dealt with is that the phytoplankton don't necessarily use the carbon immediately die and sink, there is also a lot of recycling in the upper ocean. So this "carbon sequestration" (which just means that the phytoplankton die and sink to the deep ocean) might not be as strong as this news article would lead us to believe.
A larger point is that in the absence of humans, this would just be one of many small carbon sinks that would balance a lot of carbon sources, closing the carbon cycle. Unperturbed ecosystems, much less individual species, are (over long time scales) in steady-state. Imagine that humans disappear, so all the anthropogenic CO2 stays around, but no more is added. These whales(+phytoplankton) might continue to act as a net carbon sink, but over the long run, they aren't going to suck all the carbon out of the atmosphere. Okay, I'll stop belaboring this point.
What makes this an even better example of lazy science reporting is that the really interesting point about the whales'(+phytoplankton's) role in the carbon cycle is buried in the last sentence:
Lavery said that without whaling there may have been 120,000 sperm whales in the Southern Ocean and, according to her calculations, some 2 million tonnes of carbon may have been removed from the atmosphere each year through this process.So what this says is that if the whale population was what it should be, the carbon source would be ten times larger (there are currently ~12,000 sperm whales in the Southern Ocean). So the interesting twist, in my opinion, isn't that the whales are "carbon negative," but really that whaling represents an increase in atmospheric CO2 by reducing a natural sink. This is just like (though much smaller than) land-use change, which removes carbon-absorbing ecosystems with cropland, removing a terrestrial sink. Does this raise the question of whether over-fishing represents such a decrease in a natural sink? So instead of going off half-cocked to do geoengineering through iron fertilization [e.g.], we should make a legitimate attempt to allow the natural ocean ecosystems to recover from the past couple of centuries of abuse.
UPDATE:
An AP story also has most of this, but better covers the whaling angle: [LINK]
2009-04-09
The super chimney that will save us all!
Yesterday I threw up a teaser for a future post about the Super Chimney, and here it is. I can not resist the pull of this posting, it has been rattling in my head since I found the Super Chimney (via SGTU podcast #192). The site that is home to the Super Chimney is simply superchimney.org, and is run by a man named Michael Pesochinsky. I know nothing about Mr. Pesochinsky, his motives, his background, or his mental state. I can only take the site at face value, as there is no indication that it is farce, and it appears that some effort has been put into the site, excepting quite a few grammar and spelling errors.
Here is the skinny on the Super Chimney: Mr. Pesochinsky suggests that building a few (around 10) Super Chimneys of diameter 1 km and height 5 km, anthropogenic global warming will be mitigated, the world's energy problems will be solved, and carbon will be sequestered in the newly arable land that is created by rain around the chimneys. So, what is the idea, well by clicking a link to the "principle," it is quite simply explained: "Hot air rises above cold air because hot air is less dense and therefore, it is lighter than cold air." Quite right, and really the underlying principle for a surprisingly large amount of the atmospheric sciences. The Super Chimney idea simply says that you can throw up a structure with openings at the bottom and top, and hot near-surface air will rush in at the base and rise with striking speed up the chimney because the surface air is so much hotter than the air at 5 km up. Along the way, harness all the kinetic energy of the updraft by installing turbines.
The idea is simple, and at first makes sense to a lot of people, which makes it a bit dangerous. In this post, I want to address two points: (1) be skeptical of things that seem too good to be true, and (2) the Super Chimney is a ridiculous and naive idea that has no hope of working in any way.
So, the first point about being skeptical. Whenever a new idea is presented, whether a product like a "dietary supplement," a medical treatment, intelligent design, or a mitigation strategy for global warming, there are several levels of skepticism that have to be addressed. If the idea/product/etc claims to solve even one "grand challenge" problem, that is a red flag, and if the claim is that multiple important problems are solved, many, many red flags should be waving in your head. These difficult problems, the problems of all humanity, are hard to solve, and lots of people are working to solve them. Rarely does one obscure idea emerge from the din to successfully tackle an important problem. This goes back to the old saying about something being too good to be true... Also, it is good to ask whether this miraculous idea/device/medicine/etc has been vetted by the scientific community, or have the interested parties gone straight to the media or public? And consider the source itself. Is this a single person, from outside the field, or a respected professional? Does the person have any experience relevant to the topic at all, and is there any information even available about the background?
In the case of the Super Chimney, let's see if the idea really merits much consideration just based on these questions. Well, the claim is that building 10 Super Chimneys will produce arable land, sequester carbon, generate the world's energy needs, and mitigate global warming. No small feat!! So, it sounds too good to be true, and claims to solve huge problems. The source seems only to be this website, and there's no scientific publication to back up the claims. On the plus side, there are no testimonials on the site yet. Finally, Mr. Pesochinsky is not a climate scientist, and we don't really know anything about him. None of this suggests that the proposal should be considered seriously. How does it stand up to scrutiny?
To start, let's suppose that it is feasible to build towers of the size suggested (1km wide, 5km tall); there are some issues with this, but I'm totally willing to concede the engineering is possible.
Next, let's not get caught up with the end results for now, and only address the physical principle underlying the proposal.
HOT AIR RISES
Yes, hot air rises, and it is because hot air is less dense than cold air. The Super Chimney relies on hot air at the surface entering the tower and then rising because, as is stated, "As we climb up, the temperature drops 10° C (roughly 20° F) every 1000 meters." So because of this unstable situation, i.e., cold air over warm air, the warm air rises.
Hold on a second.... there's warm air at the surface -- check -- the temperature decreases with height -- check -- warm air rises -- check... BUT ALL THE AIR HIGH UP IS COLDER THAN THE AIR AT THE SURFACE!!! Everyone please don't panic, proceed to the nearest shelter, we expect the Earth's atmosphere to blow upward from the surface at supersonic speeds at any moment. Just as soon as the atmosphere realizes that the surface is warmer than the air aloft.
There is a logical fallacy going on here. The air at the surface is warmer than the air aloft, but it is not necessarily buoyant, and where it is, it does indeed rise. An important aspect of atmospheric dynamics exactly involves instability and convection, with the take-home message that convection acts to eliminate instability. This really means that the atmosphere will convect, i.e., air will rise, as long as it can and then it will stop.
Imagine you take a blob of warm air from the surface up to some height, and you do it such that all the energy in the blob is retained. Physically, this transformation has to change the temperature of the air in the blob. When you are done moving the blob and you measure the temperature inside the blob and outside the blob (at the same height), if the temperature of the blob is greater than the environment, it is buoyant and could continue to rise, but if it has cooled to a temperature less than the environment it would sink. We'd say that in the former case the blob is unstable to this "adiabatic" transformation while the latter situation is stable. The way that meteorologists make this kind of problem simple is by defining alternative temperatures; in this case the quantity that would be of particular value would be the potential temperature, which is simply the temperature air would have if it were brought to a reference height in this kind of transformation. It turns out to be very easy to derive an equation that says that the temperature decreases by 10 degrees C per about 1000 m of height with no vertical motion. That explains why the air above the surface is colder than the air at the surface without being unstable; in a dry atmosphere this would be the situation everywhere, but it turns out that the condensation of water changes this temperature change, and for the tropics and sub-tropics the change is more like 6.5 degrees of cooling for every 1000m of height.
The fact that the surface air is NOT unstable to vertical displacements makes the Super Chimney idea fall flat. Of course, if you warm the air at the surface enough, it will become unstable and rise, but doing so requires pumping energy into the air, and removes any benefits that could be achieved by the chimney. It simply can not work.
Additional Considerations?
There are a host of other potential problems with the physics of the Super Chimney idea. In fact, every claim that is made on that site is suspect, and most of them are demonstrably wrong.
Unfortunately, given the fundamental flaw in the premise of the Super Chimney, it is impossible to address many of the outrageous claims made. For instance, take the idea that the venting air at the top of the chimney would cool down, condense water vapor, and rain in the vicinity of the tower. My first thought is that, no, this won't happen, you will really get the cloud forming inside the tower, and rising up out of it. However, that requires the air within the tower to have a reasonable temperature profile, which immediately invalidates the crazy claims of a constant updraft of more than 100 m/s. If you did have an updraft in the tower, though, the cloud base would form about where liquid water can exist, which in most environments would be around 1-2km above the surface. The result would be, among other things, a downpour within the tower itself which would cool the lower part of the tower as liquid water fell into the warm air and evaporated, and this would stabilize the column by cooling the low levels. You could actually then imagine outflow from the the base of the tower! (And, by similar reasoning to the original Super Chimney idea, maybe you could then pump cold air down to the surface and solve global warming via refrigeration!)
Another ludicrous claim is that just 10 of these towers would dramatically alter the Earth's climate. Just from a scaling perspective, this can be dismissed. A single tropical thunderstorm is an updraft that reaches from near the surface up to 15km or so, and is several km in diameter. There are thousands of such storms at any given time across the tropics. Yes the energy contained within them is enormous, but the idea that just putting 10 small, but intense storms in fixed locations and expecting them to completely change the temperature structure of the atmosphere is beyond the pale.
In retrospect, I probably should have ignored this topic, as the more I look at that site and think about it, the more and more crazy it is. The whole thing is based on completely misunderstanding the basic physics of the atmosphere, and that is even before we start considering the implications for global warming or energy production. The lesson to be learned is that if an idea doesn't pass snuff on the basic skeptical questions, it probably isn't worth digging into it in any depth, at risk of your own mental well-being. However, just as a reminder that craziness can have consequences, I suggest checking out the website WhatsTheHarm.net.
Here is the skinny on the Super Chimney: Mr. Pesochinsky suggests that building a few (around 10) Super Chimneys of diameter 1 km and height 5 km, anthropogenic global warming will be mitigated, the world's energy problems will be solved, and carbon will be sequestered in the newly arable land that is created by rain around the chimneys. So, what is the idea, well by clicking a link to the "principle," it is quite simply explained: "Hot air rises above cold air because hot air is less dense and therefore, it is lighter than cold air." Quite right, and really the underlying principle for a surprisingly large amount of the atmospheric sciences. The Super Chimney idea simply says that you can throw up a structure with openings at the bottom and top, and hot near-surface air will rush in at the base and rise with striking speed up the chimney because the surface air is so much hotter than the air at 5 km up. Along the way, harness all the kinetic energy of the updraft by installing turbines.
The idea is simple, and at first makes sense to a lot of people, which makes it a bit dangerous. In this post, I want to address two points: (1) be skeptical of things that seem too good to be true, and (2) the Super Chimney is a ridiculous and naive idea that has no hope of working in any way.
So, the first point about being skeptical. Whenever a new idea is presented, whether a product like a "dietary supplement," a medical treatment, intelligent design, or a mitigation strategy for global warming, there are several levels of skepticism that have to be addressed. If the idea/product/etc claims to solve even one "grand challenge" problem, that is a red flag, and if the claim is that multiple important problems are solved, many, many red flags should be waving in your head. These difficult problems, the problems of all humanity, are hard to solve, and lots of people are working to solve them. Rarely does one obscure idea emerge from the din to successfully tackle an important problem. This goes back to the old saying about something being too good to be true... Also, it is good to ask whether this miraculous idea/device/medicine/etc has been vetted by the scientific community, or have the interested parties gone straight to the media or public? And consider the source itself. Is this a single person, from outside the field, or a respected professional? Does the person have any experience relevant to the topic at all, and is there any information even available about the background?
In the case of the Super Chimney, let's see if the idea really merits much consideration just based on these questions. Well, the claim is that building 10 Super Chimneys will produce arable land, sequester carbon, generate the world's energy needs, and mitigate global warming. No small feat!! So, it sounds too good to be true, and claims to solve huge problems. The source seems only to be this website, and there's no scientific publication to back up the claims. On the plus side, there are no testimonials on the site yet. Finally, Mr. Pesochinsky is not a climate scientist, and we don't really know anything about him. None of this suggests that the proposal should be considered seriously. How does it stand up to scrutiny?
To start, let's suppose that it is feasible to build towers of the size suggested (1km wide, 5km tall); there are some issues with this, but I'm totally willing to concede the engineering is possible.
Next, let's not get caught up with the end results for now, and only address the physical principle underlying the proposal.
HOT AIR RISES
Yes, hot air rises, and it is because hot air is less dense than cold air. The Super Chimney relies on hot air at the surface entering the tower and then rising because, as is stated, "As we climb up, the temperature drops 10° C (roughly 20° F) every 1000 meters." So because of this unstable situation, i.e., cold air over warm air, the warm air rises.
Hold on a second.... there's warm air at the surface -- check -- the temperature decreases with height -- check -- warm air rises -- check... BUT ALL THE AIR HIGH UP IS COLDER THAN THE AIR AT THE SURFACE!!! Everyone please don't panic, proceed to the nearest shelter, we expect the Earth's atmosphere to blow upward from the surface at supersonic speeds at any moment. Just as soon as the atmosphere realizes that the surface is warmer than the air aloft.
There is a logical fallacy going on here. The air at the surface is warmer than the air aloft, but it is not necessarily buoyant, and where it is, it does indeed rise. An important aspect of atmospheric dynamics exactly involves instability and convection, with the take-home message that convection acts to eliminate instability. This really means that the atmosphere will convect, i.e., air will rise, as long as it can and then it will stop.
Imagine you take a blob of warm air from the surface up to some height, and you do it such that all the energy in the blob is retained. Physically, this transformation has to change the temperature of the air in the blob. When you are done moving the blob and you measure the temperature inside the blob and outside the blob (at the same height), if the temperature of the blob is greater than the environment, it is buoyant and could continue to rise, but if it has cooled to a temperature less than the environment it would sink. We'd say that in the former case the blob is unstable to this "adiabatic" transformation while the latter situation is stable. The way that meteorologists make this kind of problem simple is by defining alternative temperatures; in this case the quantity that would be of particular value would be the potential temperature, which is simply the temperature air would have if it were brought to a reference height in this kind of transformation. It turns out to be very easy to derive an equation that says that the temperature decreases by 10 degrees C per about 1000 m of height with no vertical motion. That explains why the air above the surface is colder than the air at the surface without being unstable; in a dry atmosphere this would be the situation everywhere, but it turns out that the condensation of water changes this temperature change, and for the tropics and sub-tropics the change is more like 6.5 degrees of cooling for every 1000m of height.
The fact that the surface air is NOT unstable to vertical displacements makes the Super Chimney idea fall flat. Of course, if you warm the air at the surface enough, it will become unstable and rise, but doing so requires pumping energy into the air, and removes any benefits that could be achieved by the chimney. It simply can not work.
Additional Considerations?
There are a host of other potential problems with the physics of the Super Chimney idea. In fact, every claim that is made on that site is suspect, and most of them are demonstrably wrong.
Unfortunately, given the fundamental flaw in the premise of the Super Chimney, it is impossible to address many of the outrageous claims made. For instance, take the idea that the venting air at the top of the chimney would cool down, condense water vapor, and rain in the vicinity of the tower. My first thought is that, no, this won't happen, you will really get the cloud forming inside the tower, and rising up out of it. However, that requires the air within the tower to have a reasonable temperature profile, which immediately invalidates the crazy claims of a constant updraft of more than 100 m/s. If you did have an updraft in the tower, though, the cloud base would form about where liquid water can exist, which in most environments would be around 1-2km above the surface. The result would be, among other things, a downpour within the tower itself which would cool the lower part of the tower as liquid water fell into the warm air and evaporated, and this would stabilize the column by cooling the low levels. You could actually then imagine outflow from the the base of the tower! (And, by similar reasoning to the original Super Chimney idea, maybe you could then pump cold air down to the surface and solve global warming via refrigeration!)
Another ludicrous claim is that just 10 of these towers would dramatically alter the Earth's climate. Just from a scaling perspective, this can be dismissed. A single tropical thunderstorm is an updraft that reaches from near the surface up to 15km or so, and is several km in diameter. There are thousands of such storms at any given time across the tropics. Yes the energy contained within them is enormous, but the idea that just putting 10 small, but intense storms in fixed locations and expecting them to completely change the temperature structure of the atmosphere is beyond the pale.
In retrospect, I probably should have ignored this topic, as the more I look at that site and think about it, the more and more crazy it is. The whole thing is based on completely misunderstanding the basic physics of the atmosphere, and that is even before we start considering the implications for global warming or energy production. The lesson to be learned is that if an idea doesn't pass snuff on the basic skeptical questions, it probably isn't worth digging into it in any depth, at risk of your own mental well-being. However, just as a reminder that craziness can have consequences, I suggest checking out the website WhatsTheHarm.net.
2009-04-08
oh, a good post is coming...
Thanks to the Skeptical Guide to the Universe, I have come across superchimney.org. The premise is that by constructing a very large chimney, we can defeat global warming (by producing electricity) and create arable land in the desert. I have only had a couple minutes to look at the site, but I already have several ideas for how to prove that this idea does not work. It's bunk from the premise, so consider this a teaser for a more complete post later.
2008-10-12
A geoengineering teaser
So, just read the "News and Views" piece in Nature Geoscience (Vol.1, (644), 2008; doi:10.1038/ngeo326) called "Climate change: Cool spray" by Heike Langenberg. I can't spend the time to really get into it, but I certainly will in the short term. The article simply reports some ideas presented by John Latham in two papers in the Philosophical Transactions of the Royal Society (Phil. Trans. R. Soc. A doi:10.1098/rsta.2008.0137; 2008, and Phil. Trans. R. Soc. A doi:10.1098/rsta.2008.0136; 2008). According to Langenberg, Latham proposes as a low-cost geoengineering fix to anthropogenic global warming the injection of sea salt into the marine boundary layer. This takes advantage of the Twomey effect, whereby additional condensation sites lead to smaller cloud droplets which reflect a higher fraction of incident light (a cooling effect).
Okay, well, I haven't read the papers yet, but I will. And since this is one of those areas where I know something, I should be able to address some of the issues that this plan raises. As has been pointed out regarding other geoengineering ideas, this one is fundamentally a shortwave effect, while the global warming is a longwave one. That means that the crux of the plan relies on reducing the total energy in the climate system, probably by using thin ribbons of clouds over subtropical oceans. Meanwhile, outside of those regions, the same sunshine comes in, and the same CO2 is sitting in the atmosphere, and presumably there's still enhanced water vapor. The effect of those clouds is to change the surface temperature beneath them, creating temperature gradients in the surface air temperature and sea surface temperature. This perturbs the low-level circulation. The low level circulation moves some energy around, but the majority of the north-south energy transport in the climate system is accomplished through storms grabbing energy from the low latitudes and moving it northward. So depending on the placement and extent of this cloud shield, the effects on both the low-level wind field and the indirect effect on the storm tracks will significantly alter the naive expectation that reflecting more light back to space will offset human-induced warming.
But more on the details in a future post.
Okay, well, I haven't read the papers yet, but I will. And since this is one of those areas where I know something, I should be able to address some of the issues that this plan raises. As has been pointed out regarding other geoengineering ideas, this one is fundamentally a shortwave effect, while the global warming is a longwave one. That means that the crux of the plan relies on reducing the total energy in the climate system, probably by using thin ribbons of clouds over subtropical oceans. Meanwhile, outside of those regions, the same sunshine comes in, and the same CO2 is sitting in the atmosphere, and presumably there's still enhanced water vapor. The effect of those clouds is to change the surface temperature beneath them, creating temperature gradients in the surface air temperature and sea surface temperature. This perturbs the low-level circulation. The low level circulation moves some energy around, but the majority of the north-south energy transport in the climate system is accomplished through storms grabbing energy from the low latitudes and moving it northward. So depending on the placement and extent of this cloud shield, the effects on both the low-level wind field and the indirect effect on the storm tracks will significantly alter the naive expectation that reflecting more light back to space will offset human-induced warming.
But more on the details in a future post.
2007-04-30
ye olde iron fertilizing effect
So apparently people now think they can make money by throwing iron into the ocean... YES, throwing iron into the ocean.
Here's the, actually very good, story on NYTimes.com: [The Energy Challenge: Recruiting Plankton to Fight Global Warming]
The basic idea is that plankton reproduce like mad when the conditions are right, and in large swaths of the ocean the conditions are right. Except there isn't enough iron. So, when you dump some iron on those areas, plankton bloom, creating regions of increased biological activity. The upside to this, according to some, is that the plankton use carbon from the ocean to make their little calcium carbonate exoskeletons, which when the critters die, can sink to the bottom of the ocean. This means that carbon is removed from the atmosphere-ocean system... it is sequestered, like an OJ juror. So now at least two companies, so cleverly named Planktos and Climos, think they can get governments (or companies working under cap and trade systems) to pay them to go throw some iron into the ocean.
I do not reject this idea outright. There are clearly some good ideas here, but we have to be careful. Here are a couple of my primary concerns.
First, I'm worried that these plankton species will produce a lot of methane waste, possibly negating any decrease in atmospheric CO2 that they might be responsible for. There is similar concern with nitrous oxide, apparently.
Second, the amount of carbon actually deposited might be less than has been thought recently. This is actually in this week's Science [LINK].
Third, as these operations scale up, will they account for their own carbon emissions. Boats are notoriously bad for emissions, and there's going to have to be a lot of boating involved. Also, where is this iron coming from, and how much energy (i.e., carbon) is going into collecting and transporting it?
Finally, there are possible feedbacks that could negate any good this will do. Including the old DMS-cloud condensation nuclei, in which more biology produces more aerosol (in the form of dimethylsulfide, DMS) which acts as nucleation sites for cloud droplets, making more cloud. The effect could be to shade the surface, reduce SST, and thus reduce biological productivity, leaving a rusty sea surface instead of a nice, healthy green one. I don't know if this is feasible, but things like this always seem to come up.
Also consider the amount of carbon dioxide that needs to be removed from the atmosphere. I've just come from a talk that reminded me of this. Carbon dioxide, when frozen, has about the same density as water. That means that a ton of CO2 is about one cubic meter (size of a coffee table). You're now talking about removing billions of tons of carbon dioxide annually, which is an enormous mass, many cubic kilometers of frozen CO2. The ocean is a big place, but we've got to be careful about how and where such deposits are made, or they'd just be mixed back up to the atmosphere. There's just so many potential pitfalls that it is hard to imagine a successful implementation. But as I said at the beginning, I'm willing to keep an open mind on the subject, and would be happy to see a successful strategy.
Here's the, actually very good, story on NYTimes.com: [The Energy Challenge: Recruiting Plankton to Fight Global Warming]
The basic idea is that plankton reproduce like mad when the conditions are right, and in large swaths of the ocean the conditions are right. Except there isn't enough iron. So, when you dump some iron on those areas, plankton bloom, creating regions of increased biological activity. The upside to this, according to some, is that the plankton use carbon from the ocean to make their little calcium carbonate exoskeletons, which when the critters die, can sink to the bottom of the ocean. This means that carbon is removed from the atmosphere-ocean system... it is sequestered, like an OJ juror. So now at least two companies, so cleverly named Planktos and Climos, think they can get governments (or companies working under cap and trade systems) to pay them to go throw some iron into the ocean.
I do not reject this idea outright. There are clearly some good ideas here, but we have to be careful. Here are a couple of my primary concerns.
First, I'm worried that these plankton species will produce a lot of methane waste, possibly negating any decrease in atmospheric CO2 that they might be responsible for. There is similar concern with nitrous oxide, apparently.
Second, the amount of carbon actually deposited might be less than has been thought recently. This is actually in this week's Science [LINK].
Third, as these operations scale up, will they account for their own carbon emissions. Boats are notoriously bad for emissions, and there's going to have to be a lot of boating involved. Also, where is this iron coming from, and how much energy (i.e., carbon) is going into collecting and transporting it?
Finally, there are possible feedbacks that could negate any good this will do. Including the old DMS-cloud condensation nuclei, in which more biology produces more aerosol (in the form of dimethylsulfide, DMS) which acts as nucleation sites for cloud droplets, making more cloud. The effect could be to shade the surface, reduce SST, and thus reduce biological productivity, leaving a rusty sea surface instead of a nice, healthy green one. I don't know if this is feasible, but things like this always seem to come up.
Also consider the amount of carbon dioxide that needs to be removed from the atmosphere. I've just come from a talk that reminded me of this. Carbon dioxide, when frozen, has about the same density as water. That means that a ton of CO2 is about one cubic meter (size of a coffee table). You're now talking about removing billions of tons of carbon dioxide annually, which is an enormous mass, many cubic kilometers of frozen CO2. The ocean is a big place, but we've got to be careful about how and where such deposits are made, or they'd just be mixed back up to the atmosphere. There's just so many potential pitfalls that it is hard to imagine a successful implementation. But as I said at the beginning, I'm willing to keep an open mind on the subject, and would be happy to see a successful strategy.
2006-08-21
Crutzen's sulfur ideas
"Wait, don't do it!"
That was my first reaction after reading about Paul Crutzen's semi-crazy idea to ameliorate anthropogenic global warming by filling the stratosphere with sulfur. In case you've missed the story, there's a wired article that covers the main points [LINK]. It all stems from an editorial Crutzen published in Climatic Change, [LINK] . The idea is that putting sulfur into the stratosphere (about 20 km above you, say) would reflect sunlight, reducing the amount of energy reaching Earth's surface. That would cool the globe, no doubt, but there are problems.
We know it will work. Volcanoes do this same thing, more or less. We also know it would be temporary, because the sulfur would only float around the stratosphere for a few years before being used up in chemical reactions and slowly deposited back into the troposphere and back to the surface. Crutzen covers all this in the paper, which is mostly a quick back-of-the-envelop calculation mixed with some previous results. Crutzen, it should be pointed out, is not actually in favor of the idea; the media doesn't really seem to be mentioning that so much. In the paper he is extremely hesitant, saying essentially that if we keep pumping CO2 into the atmosphere we may start to experience catostrophic warming (~5 degrees C), which would necessitate rapid action to reduce the global temperature. To that end, he proposes a community wide, multidisciplinary effort to test this geo-engineering scenario. He thinks we need to model the effects, but also consider possible ecological consequences.
So what are the problems with reducing the sunlight getting to the surface? Well, one that is pointed out by the Wired article is that it will directly impact plants and photosynthesis. This might be especially pronounced in the tropics, where plants have evolved to expect a lot of sunlight. Changing the amount of light reaching the surface might give some plants a benefit and others a disadvantage, which could potentially throw the natural balance out of whack. Land-use issues aside, we don't have any idea really what the distribution of plant species in the tropics means for the global carbon cycle, not to mention the hydrological cycle. A second potential problem is that the additional sulfur in the stratosphere might change the stratospheric heating rates, which would change the temperature distribution, which would alter the large-scale temperature gradients, and might impact the Brewer-Dobson circulation. This would have unknown effects on the general circulation of the midlatitudes, possibly altering large-scale weather patterns (think El Nino or North Atlantic Oscillation). A third issue, also mentioned by Crutzen, is that cooling the surface won't save the ocean. As CO2 increases, it will continue to be taken up by the ocean. Unfortunately, that increases the acidity of the upper ocean, where lots of little creatures grow. Many of those little creatures grow calcium carbonate shells, but they can't do it in acidic conditions. That means they die. Not only do those organisms play an important role in the carbon cycle (and other biogeochemical cycles), but they are also the foundation of the entire marine food chain. If they die, then large species suffer, and larger ones suffer even more, and even humans who like to eat seafood will suffer.
So those are my first three potential problems with this plan. However, I'll take Crutzen's side. He basically says that our policy makers have their heads in their behinds, partly because they don't have good solutions and partly because they are not forward thinking, and so there is not going to be a reduction in greenhouse gas concentrations any time soon. Since we know we will face global warming, we need to figure out what to do if the warming starts to get out of control. This sulfur parasol effect is one possibility, and it should be investigated. Along the way, we will continue to learn important things about the climate system, even if the sulfur parasol turns out to be an untenable solution.
Additional reading
1. BioEd Online: Should we flood the air with sulphur? [LINK]
2. Crutzen, Paul J., 2006: Albedo Enhancement by Stratospheric Sulfur Injections: A contribution to resolve a policy dilemma? Climatic Change doi: 10.1007/s10584-006-9101-y [possible LINK]
3. Geo-engineering in vogue, on RealClimate [LINK]
That was my first reaction after reading about Paul Crutzen's semi-crazy idea to ameliorate anthropogenic global warming by filling the stratosphere with sulfur. In case you've missed the story, there's a wired article that covers the main points [LINK]. It all stems from an editorial Crutzen published in Climatic Change, [LINK] . The idea is that putting sulfur into the stratosphere (about 20 km above you, say) would reflect sunlight, reducing the amount of energy reaching Earth's surface. That would cool the globe, no doubt, but there are problems.
We know it will work. Volcanoes do this same thing, more or less. We also know it would be temporary, because the sulfur would only float around the stratosphere for a few years before being used up in chemical reactions and slowly deposited back into the troposphere and back to the surface. Crutzen covers all this in the paper, which is mostly a quick back-of-the-envelop calculation mixed with some previous results. Crutzen, it should be pointed out, is not actually in favor of the idea; the media doesn't really seem to be mentioning that so much. In the paper he is extremely hesitant, saying essentially that if we keep pumping CO2 into the atmosphere we may start to experience catostrophic warming (~5 degrees C), which would necessitate rapid action to reduce the global temperature. To that end, he proposes a community wide, multidisciplinary effort to test this geo-engineering scenario. He thinks we need to model the effects, but also consider possible ecological consequences.
So what are the problems with reducing the sunlight getting to the surface? Well, one that is pointed out by the Wired article is that it will directly impact plants and photosynthesis. This might be especially pronounced in the tropics, where plants have evolved to expect a lot of sunlight. Changing the amount of light reaching the surface might give some plants a benefit and others a disadvantage, which could potentially throw the natural balance out of whack. Land-use issues aside, we don't have any idea really what the distribution of plant species in the tropics means for the global carbon cycle, not to mention the hydrological cycle. A second potential problem is that the additional sulfur in the stratosphere might change the stratospheric heating rates, which would change the temperature distribution, which would alter the large-scale temperature gradients, and might impact the Brewer-Dobson circulation. This would have unknown effects on the general circulation of the midlatitudes, possibly altering large-scale weather patterns (think El Nino or North Atlantic Oscillation). A third issue, also mentioned by Crutzen, is that cooling the surface won't save the ocean. As CO2 increases, it will continue to be taken up by the ocean. Unfortunately, that increases the acidity of the upper ocean, where lots of little creatures grow. Many of those little creatures grow calcium carbonate shells, but they can't do it in acidic conditions. That means they die. Not only do those organisms play an important role in the carbon cycle (and other biogeochemical cycles), but they are also the foundation of the entire marine food chain. If they die, then large species suffer, and larger ones suffer even more, and even humans who like to eat seafood will suffer.
So those are my first three potential problems with this plan. However, I'll take Crutzen's side. He basically says that our policy makers have their heads in their behinds, partly because they don't have good solutions and partly because they are not forward thinking, and so there is not going to be a reduction in greenhouse gas concentrations any time soon. Since we know we will face global warming, we need to figure out what to do if the warming starts to get out of control. This sulfur parasol effect is one possibility, and it should be investigated. Along the way, we will continue to learn important things about the climate system, even if the sulfur parasol turns out to be an untenable solution.
Additional reading
1. BioEd Online: Should we flood the air with sulphur? [LINK]
2. Crutzen, Paul J., 2006: Albedo Enhancement by Stratospheric Sulfur Injections: A contribution to resolve a policy dilemma? Climatic Change doi: 10.1007/s10584-006-9101-y [possible LINK]
3. Geo-engineering in vogue, on RealClimate [LINK]
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