I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.
By: RickyRood, 13:48 GMT le 28 mai 2009
Stabilization of Carbon Dioxide (3)
See below new policy on comments on this blog.
In the previous two blogs I have been talking about the need for stabilization of carbon dioxide in the atmosphere. Take away messages are that we are committed to warming, that warming will be with us for a long time, and that if we were to reduce our greenhouse gas emissions by 70% or more over the next 100 years, then it would make a difference to the amount of warming that we would see. That is, it is within our wherewithal to make a difference. But, every year that we wait will lead to the accumulation of an additional 9 parts per million (ppm) . So far the discussion has focused on the physical climate system.
There is a growing literature on the impact of global warming on ecosystems. Warming directly impacts the ecosystem, but often the greater impacts to ecosystems are felt through the impact on water availability. If precipitation amounts and patterns remained the same, then increased warming would increase evaporation and, in general, reduce availability of water in the ground for plants and animals. Of course, precipitation amounts and patterns are expected to change, and the situation is far more complex that simply increased water stress. Since ecosystems evolve to be in balance with the availability of nutrients as well as climate, any changes in climate are expected to have related changes in ecosystems. Often these changes would be expected to appear as changes in the ranges of species, perhaps with the appearance of warm and temperate adapted plants and animals at higher latitudes. Another way changes are expected to occur is with spring coming earlier and fall lasting later into the year. (links to previous blogs at the end.)
Another way that ecosystems respond is species extinction. There have been numerous times of mass extinctions in the past, and we are, in fact, in a period of mass extinction today. The figure is from the Millennium Ecosystem Assessment, and it is a summary of extinction rates past, present and future. The past is based on the fossil record, and, for mammals, the historical rate of extinction was on the order of one mammal species for every 1000 mammal species in existence. The current rate of mammal extinctions is 50 to 1000 times that historical rate. This accelerated rate is largely related to humans, the expansion of humans over the globe, and the use of resources by humans and the impact of the waste of humans. Climate change is a part of that mix. Looking into the future, the rate of extinction is expected to increase even more.
Figure 1: Rate of Extinction from the Millennium Ecosystem Assessment.
This week the National Academy of Sciences released a small supplemental publication discussing the impact of climate change on ecosystems. ( Free Ecosystems and Climate Change Document ). This publication serves as a portal to a much more exhaustive study completed last year. The study talks about extinction. One conclusion is that if the planet were to warm at the rates projected in the business as usual scenarios of carbon dioxide increase, then 20-30% of the species that have been studied risk extinction. In some cases this due to stress related to climate change being the last straw for an already stressed species.
One of the major issues of warming and species adaptation or extinction is the speed at which the warming will occur. If carbon dioxide were to make it to 550 ppm or more in the next 100 years, a very likely scenario, then the Earth would see, in a century, changes in the amount of heat held near the surface of the Earth (i.e. the energy budget), that have previously occurred over tens of thousands if not millions of years. And these changes in the past have been associated with vast changes in ecosystems - for the most part, without the presence of humans. The speed at which this warming is expected to occur amplifies the rate of species extinction. It is an obvious conclusion that the same level of carbon dioxide reductions that would have significant impact on the physical climate system, would also help to maintain some of the biodiversity that we currently have. (And yes, the problem of ocean acidification from excess carbon dioxide remains to be addressed.)
Need for a policy on comments: Many of the recent comment streams have disappointed me. I have received notes from people about how the discussion has degraded, and I have seen this written in the comments on other blog sites. Therefore, I am going to start to manage the comments at some level. Neither I nor WU have the resources to moderate the blog comments. Therefore, the only real tool I have is to ban comments. So I plan to start banning comments from those who I feel are at some level abusing the forum and simply being disruptive. This means streams of comments from the same people that add nothing new and comments which pull an isolated fact or figure out of context and use these as darts just to toss at the climate change dart board. I welcome discussion and discourse, but annoying heckling and obsessive chatter is simply annoying. So I plan to use my power to ban, which I will do for a limited amount of time, with repeated abuse becoming permanent.
Ye Olde Stabilization Blog: A Strange Urgency
Previous Stabilization Blogs:
Warm for a 1000 Years
How Much Warming Can we Avoid
Previous Blogs on Phenology and Ranges of Trees
Series of Blogs in 2008 of Spring Coming Earlier
Trees Moving North
Updated: 16:22 GMT le 04 juin 2009
By: RickyRood, 22:48 GMT le 19 mai 2009
Stabilization of Carbon Dioxide (2)
In the previous blog I highlighted a couple of papers which addressed the issue of stabilizing the amount of carbon dioxide in the atmosphere. Two points were that 1) each year we delayed in reducing carbon dioxide would lead to an additional 9 parts per million (ppm) of carbon dioxide in the atmosphere, and 2) that the warming associated with excess carbon dioxide would be around for more than a 1000 years even if the carbon dioxide levels were stabilized.
The figure below, from IPCC, shows a set of stabilization curves. This was in the 2001 IPCC report . The thick red line is the emissions for a business as usual scenario. The other curves show a future in which we start to reduce emissions below business as usual. We are already well beyond the 350 ppm curve, and we are approaching the time where we have to start reducing emissions to stay less than 550 ppm. And business as usual? Until the recession came upon us, we were increasing our emissions.
Figure 1: Stabilization of Atmospheric Carbon Dioxide as a Function of Emissions (from IPCC). (Note 20130117: This figure is flawed, and in fact, suggests stabilization more quickly and at smaller values as revealed by future research.)
We are, therefore, committed to significant warming. It makes sense to ask the question - what would be the impact of reducing our emissions? Can we do something that matters?
It has often been posed that in order to avoid “dangerous” climate change that we need to keep the average warming at the surface to less than 2 degrees centigrade above the pre-industrial values. We have already used half, or more, of those 2 degrees in the 20th century. So, with this criterion, we need to keep the warming in this century to 1 degree or less. As we start to think about the reality of this challenge, then we have to consider not only carbon dioxide, but other greenhouse gases such as nitrous oxide and methane. And, of course, we have to consider the greenhouse effect of water vapor which will increase as the atmosphere warms.
In a recent paper, Warren Washington and colleagues posed the question - How much climate change can be avoided by mitigation? They performed a series of experiments that compared business as usual to a reduction of carbon dioxide emissions by 70% in 2100. The numerical simulations were done with the Community Climate System Model . This paper is summarized with a good color figure in a press release from University Corporation for Atmospheric Research.
The most basic result from this paper is that with this reduction about one half of the expected warming would be avoided. The biggest absolute impact would be at high latitudes, consistent with the global warming being strongest at the poles. Following through, the impacts in Canada and Siberia are amongst the largest; hence, the reduction of greenhouse gases by 70% in 2100 would save a substantial amount of permafrost. Similarly, it would be possible to stabilize and maintain some Arctic sea ice. Very important, the sea level rise due to thermal expansion of water is reduced by more than one third.
This study suggests that if we were reduce the greenhouse gas emissions by 70% it would be enough to make a difference. It would stop what seem to be runaway impacts in the Arctic with melting permafrost and sea ice. The impact on the melting of ice sheets around the perimeter of Greenland was not explicitly calculated, but it is possible to determine that it would take many centuries for the ice sheets to stabilize. There would still be enormous ecological changes.
Going back to the previous blog … The amount of carbon dioxide in atmosphere in these stabilization experiments is about 450 ppm. We saw in the previous blog that with an aggressive reduction in carbon dioxide emissions starting today we would see 475 ppm. Therefore, our ability to keep warming at the level indicated by the Washington paper is already in doubt. And the reduction used in the Washington study is the minimum that gives us a chance of avoiding the 2 degree global average temperature rise. Given our commitment to economic growth, the relation of the economy to energy, and the low cost of fossil fuels, I conclude that we have to develop other ways of managing carbon dioxide than simply through the reduction of emissions. Note, I chose managing carbon dioxide, rather than managing the heat budget of the planet.
Ye Olde Stabilization Blog: A Strange Urgency
Previous Blog: Warm for a 1000 Years
Updated: 22:01 GMT le 17 janvier 2013
By: RickyRood, 23:46 GMT le 10 mai 2009
Stabilization of Carbon Dioxide (1)
In January of 2009 Susan Solomon and colleagues published a paper called Irreversible climate change due to carbon dioxide emissions. The article appeared in the Proceedings of the National Academy of Sciences. This paper focused specifically on carbon dioxide in the atmosphere and made the argument that the effects of man-made carbon dioxide on the climate would last more than 1000 years – their definition of irreversibility.
The lifetime of carbon dioxide in the climate system, specifically in the atmosphere is more difficult to calculate than for many greenhouse gases. This is because of the role of the oceans and the terrestrial ecosystems. A balance develops between the terrestrial carbon dioxide, the carbon dioxide in the ocean and in the atmosphere. While one can find citations that the lifetime of carbon dioxide in the atmosphere is on the order of 100 years, Solomon and her co-authors point out that when one considers how long today’s “excess” carbon dioxide from industry influences the climate, it is in excess of 1000 years. It for this reason that if we stopped burning fossil fuels immediately, that the Earth’s surface would continue to warm and remain warm.
( Roger Pielke, Sr. wrote a piece, Narrow Thinking In A New PNAS Paper “”Irreversible Climate Change Due To Carbon Dioxide Emissions” By Solomon Et Al 2009 challenging not the science-basis analysis of Solomon’s paper, but stating that it exaggerated the role of carbon dioxide relative to other causes of climate change. Solomon’s paper is quite clear that it is focusing on carbon dioxide.)
The Solomon paper highlights the fact that the decisions we make today with regard to carbon dioxide emissions will be consequential for the future. That is, what we do in the short term matters a lot to the stabilization of atmospheric carbon dioxide. Stabilization is the word that is used to mean limiting the amount of carbon dioxide to some specified value. The Solomon paper affirms that we must be anticipating and preparing for adaptation to global warming and sea level rise. They also note the likely intensification of the dry season in dry parts of the world.
Another paper that I find useful is by Bryan Mignone and his co-authors. The paper is Atmospheric stabilization and the timing of carbon mitigation . The paper appeared in 2008 in Climatic Change . This paper evaluates the difference between starting a 1% per year reduction of carbon dioxide emissions versus continuing our greater than 2% per year increase. If we started this reduction then we could stabilize the concentration of carbon dioxide at about 475 parts per million (ppm) , which can be compared with current values, about 390 ppm, and the pre-industrial value of about 280 ppm. Every year we delay, we commit to an extra 9 ppm.
One of the goals of limiting carbon dioxide in the atmosphere is to avoid “dangerous climate change.” Often numbers such as 450 and 550 ppm have been posed as the maximum amount that is allowed. Jim Hansen has been arguing that we are already in the realm of dangerous climate change and that we need to target a stabilization amount of 350 ppm. His arguments are made on an examination of past climates, and calculations of the amount of warming that can tolerated to stabilize ice sheets, sea ice, alpine glaciers, and ocean acidification. ( see here as well)
Barring sustained economic retraction, which we fight with all of our might, carbon dioxide will continue to increase for many years. Even though several countries and states have announced plans to have measurable reductions by 2020, and politicians talk about 50 – 80% reductions by 2050, the path to that reduction is not obvious. Technological development and deployment of new technology is needed. Not only is it required to develop alternative energy sources enhance efficiency, but it is necessary to develop sinks of carbon dioxide. Every time I walk through this problem, no matter by which path, I come to the conclusion that we will be required to not only sequester carbon dioxide, but also to develop the technology to remove carbon dioxide from the atmosphere. We cannot rely upon the ecosystems and the oceans; it’s too much carbon dioxide.
Next blog will focus on modeling studies that show the impact that different stabilization strategies might have on the climate.
Ye Olde Stabilization Blog: A Strange Urgency
Figure 1: Stabilization of Atmospheric Carbon Dioxide as a Function of Emissions (from IPCC).
Updated: 02:18 GMT le 11 mai 2009
By: RickyRood, 14:08 GMT le 04 mai 2009
There are Windmills
Saturday afternoon I saw a truck hauling cars. A Hummer H2 was on the top deck, along with a couple of large Jeeps. These looked new, but not fresh. On the bottom deck was a collection of used cars, including a crushed Mazda. This was the only truck hauling cars that I saw on a drive from Kalamazoo, Michigan to Sutton, Nebraska. On the radio, I heard that car dealers were holding on to trade-ins with less than 135,000 miles, whereas a year ago the dealers were pushing off cars with more than 80,000 miles to used car lots. The definition of high mileage has changed.
In trucks going east in Iowa were the blades of wind turbines. They look like whales, with little trailers holding up their tails. These were followed by gear boxes and poles and large chunks of glossy, clean hardware. There may have been 50 blades. On some of the ridges between the swales are farms of slow turning three-bladed wind mills. It was like a dream, where in slow motion, you avoid the beaters of the mixer.
A year ago, on much the same trip, were billboards for clean coal, and hand made signs along the interstate – Corn Ethanol for America.
The Mississippi and the rivers of Iowa are full.
I spent the night in Sutton, Nebraska in the midst of vast fields and many cows. There is an ethanol plant on U.S. 6 to the west of town. It smells better than the feedlots. This strip of southern Nebraska seems to be doing all right. The Fox Hollow Motel on the edge of town is nice, but it could use some more customers. They told me the place to eat was the American Legion Hall. So I dressed for the Legion and sat at the bar in Argonne 61 and talked with Eddie. He is 92; he told me a little of the dust bowl, and how they had a big dust storm just a few weeks back. The dust was black. He said that the farming had been good in the area for a long time. In the back of the hall they were auctioning baked goods. The broasted chicken is as good as advertised. Soup, salad, chicken, potato, and a gin and tonic – $10.50. Sutton, Nebraska is robust and proud and making food and energy and people who care about America.
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