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Reilly
Mountain climber
The Other Monrovia- CA
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Jul 24, 2010 - 12:53pm PT
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DrDeeg,
Nicely and, above all else, succinctly put!
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Chiloe
Trad climber
Lee, NH
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Jul 24, 2010 - 07:21pm PT
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Thought I'd drop by to share this nifty cycle plot, which became "graph of the week" on a couple of Arctic sites.
Downward trends through every month of the year, over 30 years of satellite observation.
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Chiloe
Trad climber
Lee, NH
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Jul 24, 2010 - 10:22pm PT
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Yes. exactly.
The October squiggle, for example, tracks the mean Arctic Sea Ice extent for each October from 1979 to 2009. And so on, one squiggle for each month.
September is always the minimum month, but recent Augusts have been lower than Septembers a few years back.
The cycle plot idea was suggested to me by Nicholas Cox, who wrote an article called "Graphs for All Seasons."
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DrDeeg
Mountain climber
Mammoth Lakes, CA
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Jul 25, 2010 - 12:17am PT
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Nice graph Chiloe. A creative way to convey a lot of information. And your response to weschrist's question would be a good caption.
Declining sea ice, especially in summer, is an example of a positive feedback. The less sea ice, the more open water. Sea ice (white) is much more reflective than open water (dark). Therefore, whatever causes the sea ice to melt more (warmer ocean temperatures? different circulation?) causes additional warming because more solar radiation is absorbed.
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Chiloe
Trad climber
Lee, NH
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Jul 25, 2010 - 02:28pm PT
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For Wes & Dr D, I added a subtitle to make that cycle plot a little clearer:
One other thing that stands out when I look at those squiggles is the increasing rates of change.
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DrDeeg
Mountain climber
Mammoth Lakes, CA
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Jul 25, 2010 - 03:37pm PT
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2007 was the minimum year. Looks like 2010 is tracking it pretty well. Started off in April with more, but as of yesterday (24 July 2010) 2007 and 2010 are close.
No one ever said the trend in climate is monotonic, and people on both sides of the debate make the mistake of short-term interpretations (like the Accuweather link). The 2010 cold winter on the east coast of the U.S. doesn't disprove a general warming trend. Nor does the 2010 hot summer prove it. Same with upward or downward trends in measurements at a single location.
On the other hand, Chiloe's graph shows a huge amount of information about sea ice for the entire period of record. The satellite measure of sea ice coverage is one of the longest records we have of the spatial extent of an important variable. The record of temperature and precipitation measurements from weather stations is much longer, of course, but they don't tell you what is happening in between.
And I do think everyone agrees that sea ice reflects more solar radiation than open water.
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Douglas Rhiner
Mountain climber
Tahoe City/Talmont , CA
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Jul 25, 2010 - 03:50pm PT
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And I do think everyone agrees that sea ice reflects more solar radiation than open water.
DrDeeg,
What is the term for this? Albedo?
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DrDeeg
Mountain climber
Mammoth Lakes, CA
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Jul 25, 2010 - 03:58pm PT
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Yes. Albedo is the ratio of the reflected solar radiation divided by the incoming, so it varies from 0.0 for a perfect absorber to 1.0 for a perfect reflector. Without an adjective, we usually mean over the solar spectrum (from 0.3 to 3 micrometers), and sometimes we say "broadband albedo" to make this clear. We also use the term "spectral albedo" for the same ratio at a specific wavelength.
Black asphalt has an albedo of about 0.05. Clouds can be about 0.9 and very fine, clean snow is 0.8 or higher. In the visible part of the spectrum, both are 0.98 or so, but they are darker in the wavelengths beyond the visible so the broadband value is lower.
In April, I did a short interview on NPR about snow albedo. Here's the link
What's an Albedo, and Why You Should Care
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DrDeeg
Mountain climber
Mammoth Lakes, CA
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Jul 25, 2010 - 04:34pm PT
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Chief - As of yesterday, Arctic sea ice is below the last three years and about the same as 2007.
Indeed, snow is one of the negative feedback mechanisms to warming. More snow means less solar radiation absorbed. This is the reason that the Ice Ages were driven by the effect of orbital variability in the northern hemisphere. The glacial periods correspond to periods when the northern hemisphere climate is more even (less difference between winter and summer). In warmer winters, you get more snow (at high enough latitude or altitude that you still get snow instead of rain). In cooler summers, you melt less. The northern hemisphere has a lot more land area at high latitude than the southern. You spread snow over the northern hemisphere and you cool the planet. So even though the radiative forcing caused by orbital variability is asynchronous between the hemispheres, the Ice Ages were synchronous.
The climate variability caused by orbital changes is at long time scales, so it will be a few thousand years before conditions are optimal for an Ice Age.
At shorter time scales, interannual variability in the Asian monsoon is sensitive to snow cover in Tibet. The Tibetan Plateau is the only place on Earth where there is a big area at high altitude, hence a source of heat for the atmosphere at 17,000 ft or so. When snow cover there persists longer than normal, the surface is colder, the atmosphere is heated less and so weakens the monsoon.
(There is a lot of interesting stuff about climate that is unrelated to climate change. My own focus on water resources is partly driven by the fact that humans don't deal well with the interannual variability in water, and any strategies that help us deal with variability will also serve us well if there are trends. So, in a sense, I think what I do is important, regardless of who's right about climate trends.)
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DrDeeg
Mountain climber
Mammoth Lakes, CA
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Jul 25, 2010 - 04:52pm PT
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Interesting to also see that the Sea Ice Content this past winter was very near the norm for over 4 months.
Yep, Chiloe's graph shows that although there is a decline in winter ice over the last 3 decades, it is less than the decline in summer ice. So the trend is that the increase in summer melt is the big change.
(I gotta sign off for now. I have a stack of proposals to review.)
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WandaFuca
Social climber
From the gettin place
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Jul 25, 2010 - 06:29pm PT
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Oh yeah, anthro CO2 was not even around then....
Yeah and people who don't smoke have died from lung cancer . . . so smokers shouldn't quit?
The earth changes, people change. Sh#t happens.
But humans are taking much of the carbon that was sequestered during very long ancient warm periods and rapidly injecting it into the present oceans and atmosphere. Global average temperatures are warming. This is the big gamble, this is the big experiment with our earth.
Trying to cut back is not the experiment or tinkering with the earth that you portray.
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Mimi
climber
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Jul 25, 2010 - 06:51pm PT
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Chief, you can't make such sweeping generalizations about who's sacrificing what. The more people participate in trying to improve their ecological impact on any level, the better. And that's coming from someone who frequently paints with broad strokes.
This problem is so overwhelming in its scope that most of us feel that no matter what we do, it won't help. I personally, have a limited positive influence because I elect to fly jets for travel for example.
No matter what you believe, it is a giant experiment we're witnessing. We must be mindful that our lifestyle (humans) has consequences.
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WandaFuca
Social climber
From the gettin place
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Jul 25, 2010 - 06:53pm PT
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E-7 you obviously cannot be reasoned with. You have admitted that nothing could change your mind.
You do not deserve the patience, politeness and thoughtful replies that DrDeeg and others have provided you.
You have serious issues. Anti-elitism is something prominent in your posts; did the big, bad officers run all over the poor E-7?
I obviously don't have a problem with you being anonymous, but do you really require everyone to call you "The Chief"; that's kind of pathetic. We never called my father "The Colonel", and I can't help but laugh imagining your wife and kids calling you "The Chief," and you correcting a waitress that makes the mistake of calling you sir.
You are the hypocrite E-7. Doesn't the Navy make long-term contingency plans and act on them? Why are you arguing so vociferously on this thread? Don't you have a retirement and plan for the future?
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Mimi
climber
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Jul 25, 2010 - 07:08pm PT
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Chief, I'm not disputing the temp increase. I agree with you on that one, but the current CO2 increase is not BS. What will result is the mystery that has potentially scary consequences. The next dispute is what do we sensibly do to mitigate it?
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Mimi
climber
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Jul 25, 2010 - 08:16pm PT
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Chief, CO2 emissions have increased due to mankind. Every combustion source generates CO2, H2O vapor, and other compounds. Burning any type of fuel or activities such as volcanic activity, underground coal mine fires, industry, transportation (about 40% of total in US), home heating by natural gas, campfires, forest fires, etc. Think of all the combustion sources.
Water vapor is also a greenhouse gas, but it isn't considered a 'dangerous pollutant' like CO2. Imagine regulating water vapor under the Clean Air Act? That would make for an even livelier debate.
Methane Edit: I left out cows and other ruminants. CH4 or methane is also a regulated greenhouse gas (GHG). Swamps and marshes also contribute and other natural seeps.
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Mimi
climber
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Jul 25, 2010 - 08:40pm PT
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Okay, so we come in second place. We are cranking this compound into the atmosphere. What if this could trigger the next ice age? I would be really bummed to see all of Canada, New England and especially Manhattan under a mile of ice. Knott in my lifetime of course.
If you sat at the Council of Elders and could change things, what would you do? Start trying to regulate or knott?
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Mimi
climber
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Jul 25, 2010 - 08:53pm PT
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Dude, if that is your beef, get over it. You're getting caught up in the smokescreen. Don't be a hater; haters always lose. While you're expending all your energy hating on a caricature, these folks get to eat your lunch. Been there done that. Stop yelling at the cardboard cutout.
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Mimi
climber
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Jul 25, 2010 - 09:02pm PT
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You're splitting hairs. Science and industry are a mystery to the majority of voters. Due to a lack of education in the sciences, our society is unable to hold a conversation. Period. Or hold politicians to any standard of dialogue.
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Mimi
climber
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Jul 25, 2010 - 09:53pm PT
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Methane is a combustion byproduct. It has increased just like any other combustion byproduct. A fuel is burned, pollutants are released in the smoke. Depending on the temperature of the combustion device and residence time, the range of byproducts and their concentrations vary.
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