Human fingerprints on climate change

[n2doc]

BY JOSEPH ROMM


7 OCT 2011 1:46 PM
The Yale Project on Climate Change Communications asked Americans, "If you had the opportunity to talk to an expert on global warming, which of the following questions would you like to ask?"

The top question, said their report, "Global Warming's Six Americas in May 2011," is "How do you know that global warming is caused mostly by human activities, not natural changes in the environment?"

So this is a question that all climate hawks should be able to answer, and the figures/charts in this post are ones that you can refer to. I just used this post myself yesterday during a radio interview.

Given the popularity of my recent "Illustrated Guide to the Science of Global Warming Impacts," which collected and summarized dozens of posts covering some 50 scientific articles, I thought I would occasionally repost updated versions of other important pieces and reviews.


more (with figures)

http://www.grist.org/climate-change/2011-10-07-guilty-as-charged-proof-of-human-fingerprints-on-climate-change

[saras]

1. And the other half, from the same site - who gains from denial?

http://www.grist.org/list/2011-10-04-how-climate-change-denial-lets-the-fuel-indust-in-one-handy-char

[eppur_se_muova]

2. I saw a good program on this recently ...

wish I had written down the name, etc. I'm pretty sure it was on PBS, and was a rerun. Possibly this: http://www.pbs.org/wgbh/pages/frontline/heat/

The short answer to "how do we know" is this: carbon isotopes. C-14, a natural radioactive isotope of carbon, decays with a relatively short half-life. Fossil carbon (coal, oil, gas) contains very little C-14, since it has had time to decay. CO2 from volcanoes is likewise depleted in C-14 (IIRC). Burning of more recently formed biomass (from tropical deforestation, etc.) returns C-14 to the atmosphere, but there is not much observed increase in C-14 in the atmosphere. So the increase in CO2 must come largely from "old" carbon, either volcanoes or fossil fuels. Fossil fuels are derived mostly from plant matter, and plants preferentially incorporate C-12 vs C-13 (both stable, i.e. nonradioactive, isotopes). Thus burning either fossil fuels or recent biomass would increase the C-12/C-13 ratio. This is what is observed, without the accompanying C-14 that recent biomass would release. Only burning fossil fuels could lead to the observed changes in isotope ratios.

This is far from the only evidence -- in fact, even without isotope results, the evidence is convincing -- but it's a particularly tight argument. The fact that independent lines of evidence all lead to the same conclusion is pretty overwhelming. Further evidence is only going to lead to refinements in the predictions of decreasingly relevant magnitude.


Note that there's an "advanced" option at the site: http://www.skepticalscience.com/its-not-us-advanced.htm


Oh, and there's an 11th fingerprint now:
http://www.skepticalscience.com/Paper_Archives_Reveal_Pollutions_History.html

[Dover]

3. I'm thinking maybe the energy companies are doing it to melt the ice caps

so they can drill there. No? :P
All that research on terraforming Mars being used right here at home....
Of course it could be debated that 'big energy' folks are not exactly human. :evilgrin:


But seriously...

I'd like to see more info on that poll they took.
Does a majority really question our role in the current
climate crisis? That's hard to believe.

[truebrit71]

4. I don't question that poll...consider that well over half of the US population...

..claim to believe in invisible cloud beings....