I’ve really been enjoying the Advanced versions of Skeptical Science’s rebuttals to common misconceptions about climate change. So far, they have all been written by someone going by the name of dana1981, who I would like to give a huge shout-out to. I am a new B.Sc. student who is interested in pursuing a career in climate change research, and these articles have been very helpful in giving me a taste of basic atmospheric science.
In “How do we know more CO2 is causing warming?”, I was introduced to the relatively simple equation required to calculate the radiative forcing of increased atmospheric carbon dioxide, as well as the expected equilibrium temperature change from CO2, using the range of values for climate sensitivity provided by the IPCC (as calculating climate sensitivity is not quite so simple!)
In “The human fingerprint in global warming”, dana1981 discussed different attribution studies, and explained how anthropogenic warming has certain “fingerprints” – more warming at night than during the day, a cooling of the stratosphere, and a rise in tropopause height – all of which have been observed. I had a basic understanding of these fingerprints and why they occurred, but it was great to read about the current research in attribution studies, with impeccable citations.
“How sensitive is our climate?” was similar to the first article, but also addressed the common misconception that climate sensitivity is specific to different forcings. If the climate has low sensitivity to CO2, it also has low sensitivity to solar radiation, cosmic ray feedback, etc. The equilibrium temperature change doesn’t care if the extra few W/m2 is from the greenhouse effect or planetary albedo – it changes with the same speed either way, which disproves many skeptical arguments. Additionally, since the prehistoric record shows large swings in climate resulting from relatively small forcings, scientists are confident that climate sensitivity is not very low.
“Solar activity & climate: is the sun causing global warming?” was absolutely fascinating. The equations required to calculate solar forcing using total solar irradiance were new to me, and dana1981 went so far as to analyze early 20th-century warming, calculating how much was due to an upswing in solar irradiance and how much was due to anthropogenic greenhouse gases. During the latter half of the 20th century, solar irradiance has dropped back down, but warming has only accelerated.
Skeptical Science’s recent efforts to expand their rebuttals to include beginner, intermediate, and advanced levels of explanation were inspired by a RealClimate post written by Dr. Gavin Schimdt. He thoughtfully wrote,
I think we should be explicitly thinking about information levels and explicitly catering to different audiences with different needs and capabilities. One metaphor that might work well is that of an alpine ski hill. There we have (in the US for instance) green runs for beginners wanting a gentle introduction and where hopefully nothing too bad can happen. Blue runs where the technical level is a little more ambitious and a little more care needs to be taken. Black expert runs for those who know what they are doing and are doing it well, and finally, double black diamond runs for the true masters. No-one accuses ski resorts of being patronising when they have green runs interspersed with the more difficult ones, and neither do they get accused of elitism when one peak has only black runs going down (as I recall all too painfully on my first ski outing). People self-segregate and generally find their way to the level at which the feel comfortable – whether they want a easy or challenging ride – and there is nothing stopping them varying the levels as their mood or inclination takes them.
Skeptical Science took up this challenge, and although their efforts have largely been focused on creating “plain-English” beginner articles, as a huge target audience for climate change communication is the general public, I’m extremely grateful that they’re also catering to new science enthusiasts such as myself with the advanced articles. Please, keep them coming!
While we’re on the topic, I should also mention a great new post by Skeptical Science, which is not part of their argument database – “The contradictory nature of global warming skepticism”. You can’t hold the objection that the world isn’t warming and then turn around and say that global warming is natural, but these and other self-disproving arguments reach us on a daily basis. Deniers can’t seem to agree on a single unified objection to anthropogenic global climate change, and some individuals, as the post shows, contradict themselves up to five times in six months.
And hey, I just realized right now – that post was also written by dana1981. Whoever this writer is, he or she is doing a great job.
ClimateSight 
Wow, I didn’t expect any shout-outs. Thanks! Always nice to know that one’s efforts are appreciated.
I always enjoy your blog posts too, so the feeling is mutual.
Was that you?! I knew I had a regular reader named Dana but I didn’t make the connection. Congrats, and keep up the great work! -Kate
I am very impressed with this blog you have here. As a young person myself (21) I rarely see individuals who are willing to put in the time and energy to do the research in this field and who really work hard to get the message across. You are certainly welcome over at skepticalscience at any point and I’m sure John would love to have you contribute and join into the fray (we need all the help we can get) over there. We have a large group of very enthusiastic authors (43 so far) and are always looking for more people to help comment and work on articles prior to publishing.
Just figured I would extend the offer. Good luck in the future and I will be bookmarking this page.
Robert Way
Msc Student, Memorial University of Newfoundland
Thanks, Robert – it’s nice to meet another young Canadian interested in climate science! Are you doing your Master’s in a related area?
Thanks also for the invitation to help out at Skeptical Science. Send me an email, or have John send one, if you would like to discuss it further. I’m always willing to help out with such an admirable project! -Kate
We do have some more advanced rebuttals in the works, by the way. I’ve got one on mid-century cooling coming up, and started another on Hansen’s 1988 projections. And another author is writing a good one on runaway global warming (and the lack thereof).
New Skeptical Science authors are always welcome, too. I only started writing rebuttals for the site a few weeks ago.
http://www.skepticalscience.com/contact.php
I completely agree. The advanced versions are a treat, and skepticalscience is becoming an ever better resource for this topic. I usually don’t really follow climate blogs because a lot of them are not very trustworthy, but skepticalscience is one of the notable exceptions (so much so that I decided to help translate it – though I haven’t contributed a lot yet).
‘dana1981 is doing a great job’ – and so are you, Kate. Keep it up :)
Yep that’s me – small world with not too many Danas in it!
Well, I was about to link to Dana’s Yahoo Answer’s profile where he reveals himself to be “a 29-year-old Environmental Scientist with a BA in astrophysics from UC Berkeley and an MS in physics from UC Davis”, but then I discovered that he’s already reading this blog!
You might also notice that he’s a level 7 contributor to Yahoo Answers, which is no mean feat, since it has involved writing answers to over 12,000 questions, about 1/3rd of which have been selected as the “best answer” to that question, either by the person who asked the question or by the votes of readers. Somehow, he also has time to write all these Skeptical Science posts as well.
I’m a lowly level 4 YA contributor, with only 340 answers… I stand in awe.
Hah well thanks Byron. I’ve been using Yahoo Answers for over 4 years on pretty much a daily basis, so that’s how I’ve managed to put up so many answers (almost entirely in the site’s Global Warming section).
PS Dana, in case I haven’t made the link clear before (I can’t remember), I am BGS, very occasional commenter in the Global Warming section for the last six months or so.
Oh yeah, I was wondering. Hi BGS!
My mid-century cooling advanced rebuttal went up today.
http://skepticalscience.com/How-much-did-aerosols-contribute-to-mid-20th-century-cooling.html
And Neal’s advanced ‘runaway warming’ a couple days ago.
http://www.skepticalscience.com/positive-feedback-runaway-warming-advanced.htm
Next up for me – Hansen’s 1988 global warming projections. And I see Kate joined the Skeptical Science Authors – welcome aboard!
Let me also say thank you for the good work, Dana.
[inflammatory]
The runaway greenhouse scenario is one of the common ‘turn-offs’ I encounter when discussing AGW with colleagues, students and members of the public; people reasonably see it as alarmist and I think some environmental groups lose some people when they advance this argument, and as noted, it is misused by the professional denialists… er, skeptics.
I appreciate the effort put into Neal King’s rebuttal of a ‘runaway greenhouse’ referenced in Dana’s post, but I think the complexity of the provided mathematical argument for your average-joe skeptic (as opposed to some skeptical geologists or other mathematically literate people) will have then stop reading at 1st encounter of the math. Nonetheless, for some, as evidenced by posts on SkepticalScience in response to Neal’s model, his presentation is useful.
My perspective is rooted in the geological past, as some ClimateSight readers will know from previous posts of mine here. I would argue that a simpler rebuttal that CO2 greater than say 560ppm, even 2000ppm will lead to a ‘runaway greenhouse’, is in the geological record. As shown on Richard Alley’s great online video (http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml), and also in various papers by my research team and many others (see here for a great summary: Zachos et al. 2008: An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics. Nature 451, 279-283), for most of Earth history prior to the last 2 million years CO2 in the atmosphere has been higher than 400ppm, and the world was populated by abundant life including great polar forests. In the Early Eocene (50-55 million years ago), the last great greenhouse climate, CO2 was at least 400ppm and for peak warm times CO2 was around 800-1200ppm, depending on which proxy you use. No runaway greenhouse then, no runaway greenhouse in our future.
Do you think that even Neal’s basic version of that argument is too complex, David?
Joe Romm reprinted my advance ‘climate sensitivity is low’ rebuttal over at Climate Progress, by the way (and added a bit of his own), which is pretty cool.
http://climateprogress.org/2010/09/19/climate-sensitivity-lukewarmers/
David, it seems that there are multiple meanings for “runaway” climate change. At one end are writers like James Hansen, who speak of activating positive feedbacks of a scale which will (over the long term) boil away the oceans and leave Earth as Venus Mk II. But in my reading, it seems that others use the term to simply refer to any positive feedback mechanism that ends up dwarfing human emissions and taking our final climate destination out of our hands. This needn’t end in Venus, as there may be negative feedbacks that kick in at some point in the future limiting warming to xºC. The point in this latter use of “runaway” is that the activation of positive feedbacks of a scale comparable or larger than human emissions, rather than such processes being unstoppable until we reach Venus-like conditions.
Byron, yes of course there are feedbacks and these are critical in understanding where we will end up. So I agree with your statement that “positive feedback mechanism that ends up dwarfing human emissions and taking our final climate destination out of our hands. This needn’t end in Venus …” I know what is meant; we start something that grows and ‘takes on a life of its own’, but there are natural limits to how far these feedbacks will take the world climate. My chief objection is that the term ‘runaway greenhouse’ has a particular meaning in the media (as in ‘we’re headed to be like Venus’) – a point you make in your post – and like the argument over whether AGW is called ‘global warming’ or ‘climate change’ opens the door for all kinds semantic disputes by deniers and those that think they’re sceptics (but aren’t) that divert from the main message; AGW is bad for our civilization as it will affect our ability to feed 6+ billion people and flood low-lying areas where many of them live, not to mention lead to extinctions of species. The planetary biosphere will survive; it has survived far worse (the Permian mass extinction, 251 million years ago, ended 70-90% of all species).
‘Venus like conditions’ as a forecast or prediction for a future climate state as a consequence of humanity’s GHG emissions, in my professional opinion as a paleoclimate scientist, are a complete fantasy; they are unhelpful at best, and at worst are downright dangerous in their political consequences. It is in the interest of quashing such blatant alarmist statements that I made my point, and I will continue to hammer this point because in my opinion it is the worst kind of populist science in the character of some of the alarmism of the early environmental movement.
As I have noted in my earlier posts, I started my professional career as an AGW sceptic. The facts of current climate change and my own growing understanding of the earth’s history of climate, and of how climate models work (I was tutored on climate models by people like Lisa Sloan at UC Santa Cruz, and Matt Huber at Purdue – both very active modellers of climate in the geological past), caused me to shift my opinion to accepting that our society is pushing the world’s climate to a state not seen since the Eocene. As I noted in my post, atmospheric CO2 has been at least 800ppm in the geological past (at the Paleocene-Eocene Thermal Maximum or ‘PETM’), and by some proxies may have been 2x that (2000ppm); recent revisions of the CO2 record, however suggest CO2 levels similar to those projected for 2100 prevailed during the main warm geological periods, around 1000ppm.
The PETM event has been tagged as analogous to our current ‘grand experiment’ because a spike in GHGs then was of a geologically similar magnitude and time-frame (10,000-30,000 yrs; temps at high latitudes jumping 6-8°C, perhaps more), and was accompanied by many feedbacks; there are several competing hypotheses behind the spike at the PETM, including the role played by a methane pulse from the ocean floor (methane hydrates), initially triggered by warming (the phase change is triggered by temperature) commencing from other GHG sources. pCO2 jumped about 2-fold in about 10K years as all that methane degraded into CO2 and water (as many know, water vapour is itself a potent GHG), enhancing warming. Profound shifts in the world’s terrestrial vegetation ensued as tropical-style forests appear to have moved well north in response to this transient warming, and extinctions were caused in the oceans and on land, but other groups flourished. The world recovered over the subsequent millennia as the extra GHGs were drawn down. The whole PETM lasted about 200K years.
See Breecker et al. (2010: PNAS 107 no. 2, pp. 576-580; should be free to read here http://www.pnas.org/content/107/2/576.full.pdf+html ) for a good recent study on levels of CO2 in the geological past, adjusting these lower than older published estimates and positing that levels in the Mesozoic and Cenozoic ancient greenhouse climates that CO2 levels were about 1000ppm, so comparable to projected levels for 2100.
See Higgins & Schrag (2006: Earth and Planetary Science Letters 245, pp. 523–537; should be free to read http://environment.harvard.edu/docs/faculty_pubs/schrag_beyond.pdf ) for a reasonable summary of the PETM and its relevancy for understanding AGW, including a discussion of feedback loops; see also this summary on Wikipedia http://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum which seems to reasonably accurate from my reading of the primary sources.
This article by Harrington & Jaramillo (2007: Journal of the Geological Society, London, Vol. 164, 2007, pp. 323–332 http://striweb.si.edu/publications/PDFs/CJL_Harrington_G2007_P_paleogene_f.pdf ) provides a nice individual study of the impacts of the PETM warming in North America.
This one by Collinson et al. (2009: Grana, 48, Issue 1, pp. 38 – 66 – NB: subscription required http://www.informaworld.com/smpp/content~db=all~content=a909651574 ) describes a study of vegetation changes due to the PETM in the UK (one of the coauthors is a former student of mine).
So … no ‘Earth as Venus Mk II’ in the geological past with CO2 at projected levels for 2100, no ‘Earth as Venus Mk II’ in our future. Period.
So rather than your phrase ending ‘This needn’t end in Venus …’, I would argue it should have read ‘This won’t end in Venus.’
We need to focus on those predictions that are well grounded in science and not science fiction.
Dana, yes. If my 1st year undergrads can’t understand it, I doubt Joe-average will. We live in a world (well, North America) where most of the population don’t understand that trends (in temperature, for example) need not be monotonic to be ‘real’, who don’t understand even basic probabilty or uncertainty, and who view all statistics as ‘damn lies’ promulgated by we scientists to ‘pull the wool over our eyes’. The whole ‘trick’ farce of the stolen emails saga.
I live in a rural city (44,000) surrounded by farms and villages of 40-500 people. Some of these people rely on dial-up internet that just can’t cope with most modern web sites (no cable, so no high speed internet). These people are good folk, but rely on sound bytes of news on radio or easier accessible internet sites, or articles in the local press which is decidely conservative in opinion. The denier wagon-train rolls through regularly, with the likes of Tim Ball and his ilk promulgating simple hokey messages aimed to appeal to the audience, who is typically under-educated and suspicious of ‘elites’. Neal’s mathematical explanation, as erudite and elegant it is to us, might as well be written in hieroglyphics for these people. And they’re not stupid, far from it. Just not posessed of the skill set that would allow them to decode Neal’s explanation.
What do we do? I don’t have an answer (well, see final remarks below). And I do not imply in any way that Neal’s post on SkepticalScience is not valuable and helpful. It is. But I still maintain it will lose many people we need to reach. We’re preaching to the choir.
On the climate-CO2 sensitivity debate, again I would argue that the geological record informs loudly on this point. Some of the articles I cite above in my response to Byron address this point as well.
Maybe this is the central point, and clearly I am biased by my own perspective, but I have found that people respond well to analogies; if I tell them ‘in the geological past when GHGs were high, there were crocodiles in Saskatchewan and palm trees in Alaska’, they get it and will ask intelligent questions like ‘Was Alaska in the same place then? Or was it further south?’ When I show them a plot of temperature with appropriate error bars showing that it was 12°C on Ellesmere Island at latitude 75°N in the Early Eocene and 25°C in Wyoming at 40°N, their eyes glaze over and they start muttering amongst themselves, and some bright spark will say ‘those error bars look wide … ‘ and proceed to tear apart my statistics.
I gave a talk on climate change a few years back to a group from Kiwanis (a service club) here in Brandon. I had the response I describe above, but after I spoke about the Eocene crocodiles and the palm trees, and how we were returning to that condition, I seemed to strike a chord. After the talk a fellow (an accountant I think) spoke to me and said I had sowed a seed of doubt in his mind, that he may be willing to accept AGW. I asked him why. He said ‘Well, how else could those crocodiles have been living in Greenland? If it happened before, and we sure burn a lot of fossil fuels, then it can happen again.’
Cheers, David
Dana,
You have an exc. blog and after 30 years as a forecaster, you are choosing one of the most fascinating fields there is.
If I had it to do over, I would do a PhD in some climate related field. Paleoclimate is a great detective story! (I may do that yet!)
Keep it up and keep your options open- there is a lot of fascinating science to be done.
Dan