2011-03-05 18:52:20Feedback needed: Article for ABC Arizona
John Cook

john@skepticalscience...
124.186.229.6

ABC15 asked if I could write a 500 word article on "does CO2 cause global warming and how?" for their website - so I took my existing, unpublished "walks like a duck" article and pared it down to 500 words. Also did a simplified version of the human fingerprints graph. Feedback welcome before I send it off.

How we know carbon dioxide is causing global warming

In 1859, physicist John Tyndall ran an experiment demonstrating how the greenhouse effect works. Visible sunlight easily passes through our atmosphere to warm the Earth. However, invisible heat rays rising from the Earth’s surface, otherwise known as infrared radiation, don’t easily escape back to space. What Tyndall showed by shining heat rays through tubes filled with different gases is that certain gases like water vapour and carbon dioxide block the heat rays. These became known as greenhouse gases.

Tyndall also predicted distinct characteristics of greenhouse warming. Nights should warm faster than days. This is because at night, the Earth's surface cools by radiating heat out to space. Greenhouse gases trap some of this heat, slowing the night-time cooling. It took over 130 years before Tyndall's prediction was confirmed. Over the last few decades, surface measurements have observed nights warming faster than days; a greenhouse signature has been found in global warming.

Another prediction was that greenhouse warming should cause winters to warm faster than summers. Again, temperature trends over the last few decades match expectations. Both thermometers and satellites find winters warming faster than summers.

In fact, if our greenhouse gas emissions are causing global warming, we expect to see a range of greenhouse signatures. With all this heat being trapped in the lower atmosphere, the higher layers of the atmosphere cool should cool while the lower layers warm. Satellites and weather balloons both observe this curious contrast between upper cooling and lower warming.

We should see less heat escaping to space. Indeed, satellites measuring infrared radiation coming from Earth find less heat escaping to space over the last few decades, at those exact wavelengths that carbon dioxide absorbs energy. The researchers who analysed this data described this as "direct experimental evidence for a significant increase in the Earth's greenhouse effect".

If less heat is escaping to space, there's only one place it can go - back to Earth. Measurements of infrared heat coming down from the atmosphere confirm the satellite data - more heat is returning to the Earth's surface. This extra piece of evidence on top of all the existing evidence led the scientists to conclude that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming." Sadly, the scientists underestimated the human capacity to ignore evidence staring us in the face.

We see all the distinctive signatures of an increased greenhouse effect. To be skeptical of human-caused global warming, you must believe two things: Something unknown is causing warming that happens to mirror the greenhouse effect; and something unknown is somehow suppressing the clearly evidenced greenhouse warming.

The saying goes if it walks like a duck and quacks like a duck, then it must be a duck. But climate skeptics are trying to convince us it's some other, undefined animal impersonating a duck that's also mysteriously hiding the real duck.

2011-03-05 19:06:55
nealjking

nealjking@gmail...
91.33.103.53

"Over the last few decades, surface measurements have observed nights warming faster than days. A greenhouse signature had been found in global warming."

=>

"Over the last few decades, surface measurements have observed nights warming faster than days. A greenhouse signature has been found in global warming."

or:

"Over the last few decades, surface measurements have observed nights warming faster than days."

===================================================================================

"To be skeptical of human-caused global warming, you must believe two things. Something unknown is causing warming that happens to mirror the greenhouse effect. And something unknown is somehow suppressing the clearly observed greenhouse warming."

=>

"To be skeptical of human-caused global warming, you must believe two things: Something unknown is causing warming that happens to mirror the greenhouse effect; and something unknown is somehow suppressing the clearly evidenced greenhouse warming."

2011-03-07 06:11:20comments
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.107.233

Looks good.  I'd combine these two sentences into one:

"Over the last few decades, surface measurements have observed nights warming faster than days. A greenhouse signature had been found in global warming."

Something like "Over the last few decades, surface measurements have observed nights warming faster than days; a greenhouse signature has been found in global warming."

"With all this heat being trapped, the lower atmosphere should warm while the upper atmosphere actually cools." => "With all this heat being trapped in the lower atmosphere, the higher layers of the atmosphere cool should cool while the lower layers warm."

I agree with neal's edits too.

2011-03-07 09:21:51
Alex C

coultera@umich...
67.149.101.148

I think that since the prompt asks for "how," a more accurate description of the greenhouse effect besides that it "blocks" or "traps" CO2.  Doesn't have to be lengthy, but something along the lines of "absorbs and reradiates" or transfers kinetically between molecules.

[Edit: now that I think about it though, that line (in the sand) of detail may be arbitrary as the full explanation itself would go well beyond 500 words, and "reradiated" doesn't do any more justice to the layman than "traps."  The way you have it worded now is good.]

Another recommendation I have is that since you include the final link to the fingerprints page, using references to concise peer reviewed literature that demonstrate the points might be better than linking to the rebuttals here.  From the POV of an outsider to the debate or SkS, it might be taken as "Well they're just citing their blog."  This may not be a large concern.

2011-03-07 14:51:31Thanks for the feedback, all
John Cook

john@skepticalscience...
124.186.229.6

Have emailed this off to ABC15. Will post here if they publish it.