Good meetup, both presenters were entertaining and informative. I was a little dissappointed that Dr. Diem decided to take a "teach the controversy" approach, as it put him in a position of giving junk science equal screen time with high quality research.

Talking about climate change is hard. The deniers are quite aware that the illusion of debate is just as politically useful as genuine debate. How to avoid falling into this trap without being dogmatic?

I just want to note that I am in no way a denier of global warming. The globe has been warming over the past several decades. Anthropogenic activities have caused an increase in greenhouse-gas concentrations, and, with the absence of any natural forcings, an increase in those gases would certainly cause an increase in tropospheric temperatures. I showed one slide (the Medieval Warm Period reconstruction) with a graph created from data not from the IPCC or a U.S. agency.

Jeremy, There will always be natural forcings that can moderate (or amplify) the effects of anthropogenic contributions to climate change. I would guess that many thought your presentation leaned towards the deniers' perspective because of what appeared to be a wait and see attitude. So much of the hard science seems to supporting the concept that the continuation of
a business as usual approach would push CO2 levels beyond the limits that might be considered tolerable.

Hi again. If anyone is interested in trying out a prototype of a climate-change learning module I created, please download the following file:

http://gossamer.gsu.edu/data/NASA_G1112/Lab10.zip

Username and password are student369

Detailed descriptions of the exercise are in Lab10.pdf. Blue words in that document have links to the appropriate files.

In addition to Adobe Acrobat, you will need Microsoft Excel, Google Earth, and Quicktime.

Hi. It?s tough to provide a thorough overview of climate change -- a complex and highly debatable topic -- in 30 minutes. Here are my major points from the presentation: (1) the globe may have been just as warm 1,000 years ago as it is today; (2) global warming exists; (3) anthropogenic emissions of greenhouse gases are targeted as the major cause of the warming since 1750; (4) we may not experience substantial warming over the next 20 years due to the cold phase of Pacific Decadal Oscillation.

Jeremy, You claim to be in no way a denier of global warming, but your positions reflect the typical skeptic talking points. (1) The 20th century was the warmest in the last 1000 years and that warming was most dramatic after 1920." (4) PDO- "When all forcings are included, net forcing shows good correlation with global temperatures. As our climate continues to absorb more energy than it emits, we can expect the long term warming trend to continue with short term fluctuations."

Steve. From what peer-reviewed, scientific article did you obtain those quotations, especially the information about the PDO? I could only find information that matched the text in your post on a Web site called "Skeptical Science: Getting skeptical about global warming skepticism." Thanks for leading me to that site. I am now aware of the 107 arguments of global-warming skeptics. This really is useful for me.

Hi Jeremy, Back to the PDO; In your opinion, are we now in a global cooling period that will offset the effects of rising CO2 levels? That is a common position of climate change skeptics. Allow me to lead you to a NASA/Cal Tech site that addresses the PDO issue. I sincerely hope that you find it even more useful. http://climate.nasa.gov/news/index.cfm?NewsID=271

Hi Jeremy,
Sorry, I didn't mean to imply that you're a denier. (And it's kind of a sad state of affairs when we have to clarify what side we're on before having a discussion...) I think most of us have a healthy desire to see (and teach) both sides of an issue, and believe that actual deniers intentionaly exploit that tendency. Sorry if my "junk science" statement was harsh...there was one slide that correlated sunspots with temperature, which kind of got my skeptical side on alert.

Hi. (1) My best guess is that over the next 20 years we will not experience the rate of warming we had from 1977 to the late 90s or so. El Nino events should be less intense -- and these events cause spikes in the global temperature. (2) An increase in sunspots increases the earth's solar constant which in turn increases temperatures. The Modern Maximum in sunspot activity contributed to the 20th century being a hot century. There is no doubt CO2 also contributed. Then there are feedback effects

Don, Don't think that was meant to be taken as a personal attack. Just indignation aimed at the idea of hacking into internal emails. Why not look for an unbiased analysis of the email controversy. You may not like this source, but here is an example:
http://www.pewclimate.org/docUploads/east-anglia-cru-hack... Anyway, it's not like East Anglia's CRU was the only source of data used to support anthropogenic climate change. Check out and critique Storms of my Grandchildren.

Hi. I'm enjoying the discussion about climate-change science. It's nice to find out what people in the real world (i.e. not at a university) are thinking. In Discover magazine, there is an interesting interview with Judith Curry, one of Greg Huey's colleagues at Tech, and Michael Mann, the inventor of the "hockey stick." Go to http://discovermagazine.com/2010/apr/10-it.s-gettin-hot-i....

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