Archive for October 12th, 2009
MakeUseOf.com has the list of good radio stations for your listening pleasure.
Skeptic Arguments and What the Science Says
Here is a summary of what the science says on each skeptic argument. Click here to view skeptic arguments by popularity.
1 "It’s the sun"
Solar activity has shown little to no long term trend since the 1950’s. Consequently, any correlation between sun and climate ended in the 1970’s when the modern global warming trend began.
2 "Climate’s changed before"
Past climate change actually demonstrates that the climate is sensitive to radiative forcing. Having determined climate sensitivity from empirical observations, scientists can calculate the climate response to CO2 forcing.
3 "There is no consensus"
That humans are causing global warming is the position of the Academies of Science from 19 countries plus many scientific organisations that study climate science. More specifically, 97% of climate scientists actively publishing climate papers endorse the consensus position.
4 "It’s cooling"
Empirical measurements of the Earth’s heat content show the planet is still accumulating heat and global warming is still happening. Surface temperatures can show short term cooling when heat is exchanged between the atmosphere and the ocean, which has a much greater heat capacity than the air.
The blog Skeptical Science: Examining the science of global warming skepticism should be on the radar of all global warming skeptics: only here are their arguments taken seriously, examined, and (alas) found wanting. Here’s a recent post:
We’ve just perused the empirical evidence that humans are raising atmospheric CO2 levels. In earlier posts, we noted that tallying up the planet’s heat content shows that our climate is accumulating heat, proof of global warming. But is there any evidence that links the two? Is there empirical data proving that increased CO2 contributes to the energy imbalance that causes global warming?
The greenhouse gas qualities of CO2 have been known for over a century. In 1861, John Tyndal published laboratory results identifying CO2 as a greenhouse gas that absorbed heat rays (longwave radiation). Since then, the absorptive qualities of CO2 have been more precisely measured and quantified by laboratory results and radiative physics theory (Herzberg 1953, Burch 1962, Burch 1970, etc).
Satellite measurements of the change in outgoing longwave radiation
So according to lab results and radiative physics, we expect that increasing atmospheric CO2 should absorb more longwave radiation as it escapes back out to space. Has this effect been observed? The paper Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997 (Harries 2001) attempts to find out. In 1970, NASA launched the IRIS satellite that measured infrared spectra between 400 cm-1 to 1600 cm-1. In 1996, the Japanese Space Agency launched the IMG satellite which recorded similar observations. Harries 2001 compared both sets of data to discern any changes in outgoing radiation over the 26 year period. The resultant change in outgoing radiation was as follows:
Figure 1: Change in spectrum from 1970 to 1996 due to trace gases. ‘Brightness temperature’ indicates equivalent blackbody temperature (Harries 2001).
What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as CO2 and methane (CH4) absorb energy. The change in outgoing radiation over CO2 bands was consistent with theoretical expectations. Thus the paper found “direct experimental evidence for a significant increase in the Earth’s greenhouse effect”.
This result has been confirmed by subsequent papers using the latest satellite data. Griggs 2004 compares the 1970 and 1997 spectra with additional satellite data from the NASA AIRS satellite launched in 2003. Chen 2007 extends this analysis to 2006 using data from the AURA satellite launched in 2004. Both papers found the observed differences in CO2 bands matched the expected changes based on rising CO2 levels. Thus we have empirical evidence that increased CO2 is preventing longwave radiation from escaping out to space.
Measurements of downward longwave radiation
What happens to longwave radiation that gets absorbed by greenhouse gases? The energy heats the atmosphere which in turn re-radiates longwave radiation. This re-radiated energy goes in all directions. Some of it makes its way back to the surface of the earth. Hence we expect to find increasing downward longwave radiation as CO2 levels increase.
Philipona 2004 finds that this is indeed the case – that downward longwave radiation is increasing due to an enhanced greenhouse effect. Evans 2006 takes this analysis further. By analysing high resolution spectral data, the increase in downward radiation can be quantitatively attributed to each of several anthropogenic gases. The results lead the authors 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.”
So we have multiple lines of empirical evidence for CO2 warming. Lab tests show CO2 absorbing longwave radiation. Satellite measurements confirm that less longwave radiation is escaping to space. Surface measurements detect increased longwave radiation returning back to Earth at wavelengths matching increased CO2 warming. And of course the result of this energy imbalance is the accumulation of heat over the last 40 years.
Acknowledgements: A big thanks must go to AGW Observer. Their lists of papers on changes in outgoing longwave radiation, changes in downward longwave radiation and laboratory measurements of CO2 absorption properties made this post possible.
- 57% of British consumers purchased one or more books last year,
compared to only 50% of Americans;
- Mystery and Romance books accounted for a whopping 57% of all fiction
books purchased by Americans last year, versus just 31% of fiction
purchases in Great Britain;
- Men were less important to the adult fiction market in the U.S. (29%
of purchases) than in Britain (40%) in 2008;
- The #1 channel for books in the U.S. is the Internet (23% of books
purchased), while the dominant channel in Great Britain continues to be
retail bookstore chains (34%).
I do like the Borowitz Report. Check out what he has now on his site.
The planet is heating up, thanks to human-generated emissions of greenhouse gases. But as a new NOAA-led study, “An observationally based energy balance for the Earth since 1950” (subs. req’d, release here) concluded:
[S]ince 1950, the planet released about 20 percent of the warming influence of heat-trapping greenhouse gases to outer space as infrared energy. Volcanic emissions lingering in the stratosphere offset about 20 percent of the heating by bouncing solar radiation back to space before it reached the surface. Cooling from the lower-atmosphere aerosols produced by humans balanced 50 percent of the heating. Only the remaining 10 percent of greenhouse-gas warming actually went into heating the Earth, and almost all of it went into the ocean.
Note that this Journal of Geophysical Research-Atmospheres study was done “without using global climate models.”
Figure 1: “Total Earth Heat Content [anomaly] from 1950 (Murphy et al. 2009). Ocean data taken from Domingues et al 2008.”
That figure comes from the first of two posts by the terrific website Skeptical Science, which I repost below. Skeptical Science is an excellent, well-organized site to send convincible people for a shredding of the standard, long-debunked denier talking points.
Now I’m sure the deniers and delayers out there are shrieking, “There are peer reviewed analyses that document that upper ocean warming has halted since 2003!” — a claim I dealt with in my July post, “Like father, like son: Roger Pielke Sr. also doesn’t understand the science of global warming — or just chooses to willfully misrepresent it.”
Subsequently, however, another JGR article, “Global hydrographic variability patterns during 2003–2008” (subs. req’d, draft here) details an analysis of “monthly gridded global temperature and salinity fields from the near-surface layer down to 2000 m depth based on Argo measurements.” Background on Argo here. Their findings are summed up in this figure:
Figure : Time series of global mean heat storage (0–2000 m), measured in 108 Jm-2.
Still warming, after all these years! And just where you’d expect it. The study makes clear that upper ocean heat content, perhaps not surprisingly, is simply far more variable than deeper ocean heat content, and thus an imperfect indicator of the long-term warming trend.
UPDATE: Yes, I am aware of the recent upper-ocean heat content data on the web. Please note that plots of very recent, highly variable upper-ocean content heat data down to 700 meters from unpeer-reviewed sources do not trump peer-reviewed analysis of much longer-term data down to 2000 m. Is it too much to ask people to actually read this entire post before posting comments?
What follows is a repost of two articles from Skeptical Science discussing these figures and the recent studies in more detail: …
This post is well worth reading in its entirety. The update is put first—the post itself begins:
NBC just did a piece about today’s gay rights march in Washington. For the political context of the gay community’s ire, NBC went to Chief Washington Correspondent John Harwood. Harwood was asked if the White House was worried about "the left as a whole," and concerns they have that the White House isn’t doing things that "the left" expected them to do. Harwood said the following:
Barack Obama is doing well with 90% or more of Democrats so the White House views this opposition as really part of the Internet left fringe.
Harwood then went on to say:
For a sign of how seriously the White House does or doesn’t take this opposition, one adviser told me those bloggers need to take off the pajamas, get dressed, and realize that governing a closely divided country is complicated and difficult.
So the gay community, and its concerns about President Obama’s inaction, and backtracking, on DADT and DOMA, are now, according to President Obama’s White House, part of a larger "fringe" that acts like small children who play in their pajamas and need to grow up. (And a note to our readers: The White House just included all of you in that loony "left fringe.")
I wonder how the Human Rights Campaign is going to explain how the White House just knifed our community less than 24 hours after he went to their dinner and claimed he was our friend.
Someone in that White House needs to be fired. Here’s the video: …