I wonder if Mr. Ebell has similarly hostile belief about the output of economic models? Surely the huge undertaking required to shift the government’s economic policies in the face of what these economic models tell us is pure folly and should not be done; at least that is true if I understand the implications of Mr. Ebell’s opinion.
Great idea for a Blog! Just to give you an idea of the kind of inconsistent sloppy thinking you’re up
against; The other day a winger explained to me that climate change hasn’t been ‘proven’ so spending
millions of dollars on it is not warranted. The same guy admonished me a few days later when I
Brought up Iraq and the cost that ‘the effectiveness won’t be known for awhile and we have to wait
If this is an “economic” or “political” comment, I apologize, but this site has the potential to revolutionize media reporting on climate change. If we just end up talking to each other, it will not have lived up to its full potential.
This site could be an excellent antidote to our popular, “balanced” media. Maybe this isn’t what you want to get involved with, but this site could be used as a tool whereby readers bring up questionable reporting in the media, bring the info to this site, and then the expert could provide the antidote. In turn, the readers or contributors could go back to the media and correct whatever misinformation was lurking in the news reports.
Hopefully, media people will become aware of this site and use it as a reality based resource when reporting on global warming. They seem to always make sure they go to organizations such as the Competitive Enterprise Institute. The provide “balance” by quoting so called environmentalists, a mushy term which is really sort of a kiss of death.
I couldn’t get at the article by Stott, but isn’t it a weird coincidence that the professional anti-environmentalist Philip Stott shares a last name and U.K. residence with the professional climatologist Peter Stott?
This blog is a wonderful idea, long overdue. The vast majority of people equate global warming with pollution. A Disney movie about the “Ice Age” did nothing to clarify the confusion. Question: is climate change part of the school science curriculum in the US?
I don’t wish to unfairly tar respected scientists, but isn’t it likely that they are also incentivated to come up and highlight specific results which may further thier careers? It strikes me that there isn’t much money in “status-quo is ok”, so we cannot claim that scientists are magically without biases.
Though I agree with you entirely that an obiously biased economist should have thier opinion taken with a giant grain of salt, I think it is unreasonable to ask that people hand over their critical judgetment of issues to the community of “respected scientists”. I know this may make a scientists skin crawl to think thier judgements could be critiqued by those outside the scientific community, but it is perhapse a necessary evil.
To add on to the comments about economic models, I have yet to see an economic model or projection about the costs of Kyoto that did not have some phrase in the methodology similar to “the benefits of the implementation will not be considered in this study”. In other words, they only show costs.
Anyway, that is probably getting away from the science being presented. Great site and Illegitimi Non Carborundum!
My sixth and seventh grade students will be logging onto your Blog to
learn more about your latest findings. We are currently studying climate
and using the American Red Cross module “Masters of Disaster” in learning
how to prepare for blizzards, hurricanes, etc.
Ms. York, Science Teacher Queen Anne School
I don’t wish to unfairly tar respected scientists, but isn’t it likely that they are also incentivated motivated to come up and highlight specific results which may further thier careers? Yes. That’s why repeatability is critical in science and it also cuts both ways. But if you don’t know enough to distinguish the BS from the legit, use the tobacco comparison. Given mountains of clinical data which indicate that smoking is unhealthy, and the massive informed opinion of researchers that that is indeed the case, and a tiny minority of scientists who are funded by the tobacco lobby dissenting, the conclusion should be that the latter are more suspect of the type of bias you suggest.
I agree completely DS about which conclusion is more trustworthy. Its just I worry about the stifling of criticism, and was pointing out that respected scientists cannot credibly claim to be without biases. Repeatability doesn’t prove that the right things are being looked at. Maybe I am being too postmodern or something, I don’t know.
When talking about which research to believe however, surely ad homeniem attacks are not the correct way to deal with dissenting claims. Which is basically all “funded by x” and “educated in X not Y” is.
1. when did human induced CO2 emissions actually begin to have a measurable effect on the earth’s climate.
Response: If you mean measurable in terms of clearly coming out of the “noise” in the observations, it appears to be relatively recently (i.e. the last couple of decades). If you mean at what point did anthropogenic CO2 start to have a warming effect, that would be in the late 19th Century – however at that point it was not particularly large compared to the other things going on (volcanoes, solar, land use etc.). -gavin
2. what time lag is there with respect to CO2 emissions and a warming response, i.e. is
current warming due to the CO2 that is in the atmosphere now – or some years ago.
Response: There is a lag of around 20 years, since it takes a while to heat up the ocean once the CO2 levels have increased. Thus even if we keep CO2 at the same level it is now, we are likely to see another ~0.5 degree C warming as the ocean catch up. -gavin
Reference to tobacco in the climate debate is quite interesting. Many scientists were paid handsomely to justify the proposition that smoking was benign. As I understand it, some of them concealed data and conclusions that did not support their employersâ?? objectives. Those of the contrary view outside the industry were in comparison poorly funded. What finally ended the argument was disclosure of facts and data. We may all be pre-eminent in our respective fields but no one is actually infallible, and some may be unethical. Peer reviewed papers have in the past proved to be fraudulent as well plain wrong. It may be a pain in the neck to have every crackpot with a computer checking your data, programmes and models but so long as it can said that the science of global warming is not freely open and fully available doubters will persist. Of course, as in the case of tobacco, the doubt may be dispelled but those opening up may get unpleasant surprises!
Thanks for your reply. Just a quick follow up question.
Can we conclude (from your responses) that
the bulk of the warming in the early 20th century (around 1910-45) was NOT due to human-induced CO2 emissions – whereas most of the warming since about 1980 is due to human-induced CO2
Response: As you can see from this figure CO2 forcing has been significant for a long time, and for the period 1910-1945 it is actually the dominant postive forcing. There is a decrease in the amount of volcanic forcing, and a small presumed increase in solar at the same time – both of which add to the warming. I don’t have the perecentage attribution of each immediately on hand, sorry. – gavin
Senator Lautenburg seems to be genuinely interested in trying to get to facts based on science. Two weeks ago his office sent an email to several Rutgers University science departments in search of graduate students who are studying coastal management and coastal resources. The email appeared to be an effort to find young scientists who would be interested in helping his office gather facts for some sort of presentation. I don’t know how common these sort of requests are comming from politician’s offices, but this helped rekindle some hope regarding our country’s governance. I will send an email to Senator Lautenburg informing him of this site. Perhaps other readers and contributor’s could do the same if they have not already.
Whatever can be done to direct reporters to your weblog will help. Seemingly, even the best reporters have little time for fact checking scientific nuances or for distilling “snap shot” summaries of the state of scientific understanding. Several conservative groups have taken strategic advantage of this circumstance, providing a convenient and consistent interpretation for reporters. This alternative service is crucial for that reason.
SLAP suit threats could potentially happen if an alternative service is percieved to have caused certain others to have lost credibility or audience. Good Science is the best preventive.
I am confused, I thought CO2 was good for trees and plants because they use CO2 as food and convert it to O2? The more CO2 sould make Plant life grow stronger and faster?
Response: The comment represents a common misunderstanding of the hypothesized so-called “Co2 fertilization” effect. This effect is unlikely to offset a significant fraction of the projected anthropogenic increases in co2 over the next century. See our discussion of CO2 fertilization in the glossary. -mike
The response to (22) above and the link to ‘CO2 fertilization’ in the glossary concentrates on atmospheric science-namely that it is highly unlikely that vegetation will be a major carbon sink mitigating the build-up of C02 in the atmosphere. However, the question posed by Scott was whether climate change will positively impact vegetation (‘more CO2 should make plant life grow stronger and faster?’), not whether carbon uptake by vegetation will significantly slow climate change. Perhaps a more detailed answer is in order?
I think the briefest answer to the question would be yes, some positive impacts of increased CO2 on plant productivity are expected, but some negative impacts on vegetation are also expected, and many uncertainties remain concerning vegetation responses to increased CO2 and climate change. A more detailed analysis can be found in chapter 5 of the second working group of the IPCC’s TAR (http://www.grida.no/climate/ipcc_tar/wg2/196.htm), and in some of the more recent scientific literature.
I will try to summarize some of the main points here (mostly based on the IPCC reference above).
First of all, increased CO2 does-under certain conditions-lead to increased primary productivity of many plants. This has been confirmed experimentally for several crops, although information for many tropical crops is lacking. However, the relationship between atmospheric CO2 and the primary production of vegetation is not linear, as some people might assume. One reason for this is due to complications arising from other factors limiting primary production, such as nutrient availability (nitrogen, phosphorus, water, micronutrients, etc.). Also, the positive impacts of CO2 fertilization should not be considered in isolation from some of the other impacts of climate change on vegetation, caused by changes to temperature, precipitation, cloud cover, timing of seasons, etc. Depending on the nature and extent of regional climate change, net impacts on vegetation can be either negative or positive.
A recent interesting article related to this topic analyzed satellite and climate data, and showed an apparent greening of the global biosphere from 1982-1999 (Nemani et al 2003) (you can access this article free of charge at: http://cliveg.bu.edu/globalgarden/nemanietal-science.htm). Global net primary productivity (NPP) increased by roughly 6% over this period, with large increases of NPP in some tropical ecosystems. Although the nature of the problem makes it difficult to tease apart the exact influence of recent global climate change, the overall result is likely due to a combination of CO2 fertilization, as well as nitrogen deposition, regional climatic changes, and possibly agricultural development and conservation initiatives as well (see paper). Regional climatic changes played a role as well, which was particularly relevant in Amazon rainforests, which accounted for 42% of the global NPP increase, owing mainly to decreased cloud cover and the resulting increase in solar radiation (note that it is basically impossible to determine how much of this increase in NPP is a result of recent global climate change vs. natural climate variability, although both are likely to have played a role). So, it appears based on this paper that overall, recent impacts of climate change on vegetation have been positive.
However, with each passing decade of the 21st century, as CO2 continues to build up in the atmosphere, the risk that major negative impacts of increased CO2 will outweigh the positive impacts on vegetation and agriculture will increase concomitantly. For example, the IPCC states with high confidence, based on experimental evidence, that grain and forage quality declines considerably when CO2 enrichment is combined with significant temperature increases. Also, a recent article on climate-vegetation dynamics concludes that, due to poor scientific understanding of ecological thresholds and their relationship to climate change, we cannot accurately predict how or when vegetation will change due to global warming, or even whether these changes will be reversible (Maslin, 2004).
So what should people make of this complex topic? I think a key message for the public is that, as stated by the American Meteorological Society, an uncontrolled and unplanned experiment with the Earth’s climate system is already underway. Also, because we only have one biosphere to experiment with, it would be wise for society to begin to slow down the ongoing buildup of greenhouse gases in the atmosphere. Although people may believe that policies to reduce GHG emissions are not warranted based on this, they should not disguise the fact that such a position basically indicates a willingness to gamble with the only biosphere that we have.
Response: Thanks for your helpful and insightful comment. In my reply to comment #22, I assumed that the commenter was responding to previous comments #14 and #16 which deal with the issue of CO2 as a radiative forcing of climate. I assumed, in this context, that the commenter was referring to the specific often-made claim that the direct response of vegetation to increased CO2 might act as a negative feedback on the radiative forcing itself (through increased uptake of CO2 by the terrestrial biosphere. i.e., the “CO2 fertilization” effect). Indeed however, as your post nicely illuminates for our readers, there are a more general set of questions dealing with the complex issue of how vegetation will respond not just to CO2 changes, but to the climate changes themselves that may result from the associated radiative forcing. To the helpful set of references you’ve provided dealing with this broader set of questions, I would in a shamelessly self-promoting manner also offer this publication that deals with the issue of how atmospheric circulation changes associated with anthropogenic climate change might alter growing season length in the Northern Hemisphere:
Thanks for your reply–your papers look interesting but also quite heavy and difficult to absorb in one reading. Incidentally, I also came across another interesting reference on this topic:
Clark,D.A., Piper,S.C., Keeling,C.D. and Clark,D.B. 2003.
Tropical rain forest tree growth and atmospheric carbon dynamics linked to interannual temperature variation during 1984-2000. PNAS 100:5852-5857.
The authors analyze data on Costa Rican tree growth and climate (particularly El Nino events), to show reduced productivity during the strong 1997-98 El Nino event, as well as forests becoming a large source of CO2 at the time. Authors conclude from this and other evidence from process models that warmer climates may enhance tropical forest release of CO2, thus accelerating atmospheric CO2 accumulation through a positive feedback. (this last sentence I lifted from this site:http://www.msc.ec.gc.ca/education/scienceofclimatechange/publications/developments/atmospheric_comp-03_e.html)
Response:Thanks for the additional helpful comments and references -mike