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YouTube video on the empirical evidence for man-made global warming

Posted on 28 February 2010 by John Cook

A common skeptic argument is that there is no empirical evidence for man-made global warming. People who make this claim can't have looked very hard. As most don't have the time to scour through the peer-reviewed scientific literature, the multiple lines of independent evidence for global warming are given here. To make the science even more accessible in this time of multimedia and short attention spans, there is now a YouTube video outlining the empirical evidence for man-made global warming.

The video is by greenman3610, producer of the Climate Crock of the Week series. Also be sure to check out the (more info) link in the right margin where links to all the peer-reviewed papers are provided. This is a powerfully visual way of communicating the science of climate change - I strongly recommend you all view the video, pass it onto your friends (and if you're feeling really energetic, follow the paper links to learn more about the science).

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Comments 151 to 156 out of 156:

  1. #147 doug_bostrom at 10:48 AM on 4 March, 2010 "Cherry Snow" I didn't do that, used all available data. Quadratic fit was a joke, as I've indicated (it is also a joke when applied to tide gauge data). However, the fact remains. The less sunshine the less trend you get. Even snowiest month is switching from February to January. It strongly suggests some underlying cause other than "trapping" OLR. Emissivity of snow in thermal IR is excellent. In other words it is snow white in visible, pitch black in IR. It is very effective in cooling itself provided IR can escape freely to space (i.e no cloud cover). Short wave absorptivity of fresh snow is low. But as it is getting dirty, it goes up rapidly. I does not make a difference in deep winter as sun is mainly hiding behind the globe (or clouds). But it is highly relevant in springtime with skyrocketing insolation. My bet is soot (black carbon) and plain dirt, not carbon dioxide. Due to land use change more dust is carried by winds. In fall all agricultural regions of NH called ploughland are turned into artificial wet deserts at the end of growing season. With the occasional drying up of thin upper layer of bare soil, it gets windborne and deposited elsewhere, possibly on snow. Filtering smoke for fluffy carbon particles is entirely possible, not prohibitively expensive and is already done in Europe. Wind erosion of soil can also be mitigated by dividing fields up, planting tree stripes. Both techniques have immediate local benefit, do not need international treaties and heavy government intervention to enforce. Just some public attention. Which is in short supply, should not be diverted by scaremongering. As I have said, the question can be decided by looking at regional NH winter snow cover trends (moisture vs. temperature limited areas close to perimeter). A pointer to literature? Also, it is not entirely true that spring insolation is constant. There is a Gregorian calendar effect, Veneral equinox retreating along calendar year since 1900, a 648 sec/year rate on average until year 2100 when it will be reset. There are full day jumps in leap years. In 2008 spring came more than a day earlier than in 1967. Of course the effect for autumn is the opposite.
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  2. CBDunkerson Referring to the graph you posted here as relates to the question that was never answered... In the graph, there is an orange and a blue region. ( Orange on my screen.) The orange region represents extra heating of atmosphere and land combined. The blue, oceans. Whereas the heat capacity of the atmosphere and land is much lower than that of water, and whereas CO2 imparts heat directly into the atmosphere, it is hard to fathom how 20 times the amount of heat is ending up in the oceans?? In light of the graph, I should re-phrase the analogy I provided above... from "Sort of like a household budget where for years every month you basically spent every penny with zero saving, and then find out you have million dollars in the bank." to "Sort of like a household budget where for years every month you did save a penny or so, and then find out you have million dollars in the bank." "a penny or so" in any case being the orange area. The million dollar is the blue.
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  3. Hi gallopingcamel Thanks. I spent many years in the trenches of the academy in a research lab. I didn't study environmental science, but I do have first hand experience with how "science" works, from the bottom (i.e., coming up with a testable hypothesis, designing and experiment and/or model (preferably both), analysis, interpretation) to the top, (i.e., finally taking all that data and telling (one hopes) a compelling story about some aspect of how the universe works (grounded in the data), and then putting the work through the hoops, i.e., presenting the work at invited talks, conferences, etc., and then, THEN, submitting the work for publication and dealing with reviewers and editors). It's a BIG DEAL. Anyone who's consistently producing work is a GOOD scientist. The job isn't to be "right." Perhaps only God knows the "truth." It is instead to successfully, creatively, intelligently apply known methods and techniques to the data, draw conclusions grounded in the data, than then present that to the world in the hopes that, in some way, it'll, advance and inspire the thinking of others. The smearing of hard working published scientists (not that anyone in this blog is doing that) announces loud and clear "I have not a clue about how scientific knowledge is produced, and worse, I don't care, I have an agenda to pursue, an axe to grind." - Cheers, Christopher Skyi,
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  4. Well, I have looked into the spring insolation issue. NASA has a small fortran program to calculate Insolation at Specified Location, it is called SRLOCAT.FOR and can be downloaded freely. The calendar effect turned out to be pretty large. It is even more interesting that average insolation for a specific month also depends on longitude. At the International Date Line spring can come a full day later east of it than on the other side. However, actual time zone boundaries are rather haphazard, making proper adjustment tricky. It is part of the reason monthly or seasonal averages should be handled with care. Anyway, here is average March insolation for several locations and years: 1967 (80;180) 57.75 W/m^2 (80;-180) 61.76 W/m^2 2008 (80;180) 62.02 W/m^2 (80;-180) 66.16 W/m^2 1967 (70;180) 129.17 W/m^2 (70;-180) 133.28 W/m^2 2008 (70;180) 133.57 W/m^2 (70;-180) 137.74 W/m^2 1967 (60;180) 199.09 W/m^2 (60;-180) 202.95 W/m^2 2008 (60;180) 203.25 W/m^2 (60;-180) 207.13 W/m^2 1967 (50;180) 263.59 W/m^2 (50;-180) 267.01 W/m^2 2008 (50;180) 267.31 W/m^2 (50;-180) 270.74 W/m^2 1967 (40;180) 320.35 W/m^2 (40;-180) 323.21 W/m^2 2008 (40;180) 323.50 W/m^2 (40;-180) 326.36 W/m^2 1967 (30;180) 367.53 W/m^2 (30;-180) 369.74 W/m^2 2008 (30;180) 370.00 W/m^2 (30;-180) 372.20 W/m^2 The closer the Pole, the larger the effect gets (up to than 4+ W/m^2). With retreat of Veneral Equinox, spring insolation increases, by as much as 6 W/m^2 in two hundred years (because 2000 was a leap year unlike a regular turn of century). The 8 hours retreat of equinox in 44 years is responsible for about 1 W/m^2 spurious increase in spring insolation. Also, if sum of snow covered area remains the same, just shifts from Asia to Europe, to Northern America can introduce a spurious trend. GHCN also has this time zone issue. Average longitude of GHCN stations shifted eastward by 52 degrees between 1900 and 2009. If one takes averages by latitudal bands and does not correct for longitudial shift, gets a spurious increase of some 0.5 W/m^2, in this case for autumn.
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  5. Berényi Péter at 19:01 PM on 4 March, 2010 Soot is indeed a player in this drama. For my part, I can't see putting all stakes on one hand. Here's a pretty rigorous model treatment with well described methods of soot's role in the climate, building on a pretty huge pile of previous inquiry: Climate response of fossil fuel and biofuel soot, accounting for soot’s feedback to snow and sea ice albedo and emissivity The paper is worth reading not only for its particular line of investigation but also because it reviews and builds on so much prior research. The conclusion is that soot plays a role but it's not dominant.
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  6. Two more Annals of Glaciology 5 1984 Impurities in Snow: Effects on Albedo and Snowmelt (review) Stephen G Warren PNAS Soot climate forcing via snow and ice albedos James Hansen and Larissa Nazarenko, November 4, 2003
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