.. climatologists are right when they say we should be worried about what we're doing to the global heat balance.
A commenter on my previous post asked
What aspects of the science do you feel are most convincing in demonstrating the link between fossil fuel emissions and rising global average temperatures?
To which I offered one glib and one sincere but pass-the-buck response. I want very much to get past the whole "what's the evidence for climate change" thing. But on reflection, it's important to remind those who are new to the debate, especially younger participants, just why we have as much confidence in the anthropogenic global warming theory. So if you're in one of those categories....
There are three pieces of science that do the trick for me.
- The "extra" carbon that's in the atmosphere comes from burning coal, oil and gas. Radioisotope analysis identifies fossil-fuel combustion as the source. We know this because fossil fuels contain a different ratio of C-13 to C-12 than we find in the carbon emitted by living organisms. See this post at Real Climate for more details.
- The physical reality that carbon dioxide, methane and other greenhouse gases reradiate infrared heat, something that's been known for about 150 years. See this 1861 paper by John Tyndall.
- Temperature records for the past 250 years show an almost inexorable trend upward that correlates strongly with the cumulative amount of carbon we've been adding by burning coal oil and gas. See this 2009 paper.
In other words, the laws of thermodynamics and molecular chemistry tell us we should be seeing a rise in temperatures, we do see such a rise, and analysis of the composition of the atmosphere tells us what's responsible. It's that simple.
- Log in to post comments
I agree completely with points 1 and 2 but have questions about #3: Why did you choose to look at 250 years of past temperature data? Would you see the same warming if you looked at 500 or 1000 years of temperature data? A thousand years ago the earth was in the midst of the medieval warm period.
I agree completely with points 1 and 2 but have questions about #3: Why did you choose to look at 250 years of past temperature data? Would you see the same warming if you looked at 500 or 1000 years of temperature data? A thousand years ago the earth was in the midst of the medieval warm period.
Hi there James,
Do you mind if I link to you on my blog? I think this site is a great source with credible information that is easy to understand.
Thanks
Kate
Kim,
A 250 year look-back is reasonable in that it captures a resonable lead-in period to the industrial revolution, and the beginning of our consumption of fossil fuels for energy.
The historical correlation between rising fossil fuel originated carbon dioxide (#1) and rising global temperature is striking. Note this is correlation; no presumption of causation can be made.
This is where #2 comes in. A priori knowledge of how carbon dioxide might work as a 'greenhouse gas' motivates construction of models to test the hypotheses as to what part of global warming is C02 dependent.
Decades of such work leave us where we are today; the global consensus of informed investigators is that global warming is largely an antropogenic phenomenom, with catastrophic potential for us and the world at large.
As I'm sure Kim knows, we have reconstructions of temps going back a couple of thousands of years that shows a "hockey stick" with recent warming, that the National Academy of Sciences says that the much-publicized Mann '98 reconstruction was most likely right for the last thousand years, and that further work has strengthened the case.
Kim may or may not be familiar with denialsphere claims that the "hockey stick has been debunked" (sans scientific publication of any significance), that they lie about what the NAS said in their report, etc.
In fact, his reference to the MWP as though it were a global, rather than regional, phenomena makes it almost certain that this Kim is a blind follower of the denialsphere.
Why not consider clean coal technology?
Despite what you may have heard or read, the FutureGen project has not been cancelled -- citizens and legislators from its proposed site of Mattoon, Ill. are continuing to work towards the original plan of building a commercial-scale coal-generated power plant using clean coal technology.
We know this because the Americaâs Power team has been traveling around the country talking to the people who are behind the production of cleaner electricity from coal on the Factuality Tour.
Mattoon residents understand what a great boost the plant will be to the local economy â and how much the technology will mean to the rest of the world. Hear what they have to say at http://sn.im/factuality5.
When did using science to question science become, DENIAL. Good science demands that it be continually questioned and challenged. When you stop questioning the accepted wisdom and just blindly accept it, it becomes dogma not science anymore, and dogma is exactly what good science is continually fighting against. Which means science has to always be open to asking questions, challenging your assumptions, re-evaluating your observations, etc. Not blind acceptance.
Exactly. Which is why I have so much confidence in the science outlined in the post. It has been challenged, repeatedly, and it stands up.
But there's big difference between informed skepticism and stubborn denial. If the price of not accepting something is the increased likelihood of disaster, then you're not longer being skeptical, you're being foolish. -- JH
James, I am curious about the use of that particular manuscript for point #3. The author doesn't necessarily examine the link between carbon and temperature increase (I like the "natural" vs. "natural + anthropogenic" charts in AR4 better - WG1 FAQ 9.2 Fig 1) and points out the other rapid temperature rises in the local CET record. Maybe I read it too fast.
As dhogaza points out, the 1000+ year proxy records are also useful in this regard; they cover a longer period and wider geographical range.
The commenter's question is an example of something that has always annmoyed me; it's usually, in my experience, asking what's the single most important piece of evidence for evolution.
I always answer that it's the thousands of pieces of evidence from many disciplines and using many different techniques that all point to the same conclusion.
When did using science to question science become, DENIAL. Good science demands that it be continually questioned and challenged.
You should check out the denialism blog for the difference between debate and denialism. When people are making up their own "facts" to challenge science, that's not science, that's denial. When people are disingenuously citing temperature records since the last big El Niño year, that's not science, that's denial.
JH:
As I am the commenter in question, I appreciate you taking time to post a response to my inquiry. Your post was helpful in understanding the basis for your view of the link between fossil fuel emissions and rising global average temperatures. I also appreciated the cautious and careful language in the final paragraph of the Mills paper, which appears consistent with Plukyâs response to Kim that âthis is correlation; no presumption of causation can be made.â
Pluky also stated that â. . . the global consensus of informed investigators is that global warming is largely an antropogenic[sic] phenomenom[sic], with catastrophic potential for us and the world at large.â It seems that to go from global warming to âcatastrophic potentialâ is a next order inquiry, and I am curious as to whether you also share this view.
Finally, QrazyQat, it seems that it would be entirely reasonable to ask someone what the most compelling piece of evidence is for global warming, evolution, or any other viewpoint, and that no apology would be necessary for asking such a question. In this case, however, I am not guilty of even that minor indiscretion. You will note that JH had made a concrete statement about the link between fossil fuel emissions and rising global average temperatures. My question was posed in that context and was very specific, and JH provided a cordial and meaningful response.
This was my take in a similar vein:
http://scienceblogs.com/illconsidered/2008/10/what_is_the_evidence_that…