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Is global warming a fact?

  1. Nov 23, 2009 #1

    Wax

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    I'm just wondering if Global Warming is considered a fact within the science community? I'm not talking about man made global warming, just global warming in general whether it be caused by nature or man.
     
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  3. Nov 23, 2009 #2

    Xnn

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    Yes; it's a fact.

    Global surface temperatures are rising as is the
    temperature of the Oceans to several hundred meters while
    there is an overall melting of ice and permafrost.

    Sea levels are rising (actually accelerating) as expected primarily
    from the thermal expansion with a contribution from melting ice.



    http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-ts.pdf

    Notice that most of the heat of global warming is going into
    the oceans. Only about 2% of the heat is going into surface temperatures.
    See Figure TS.15 of the above link for a breakdown.

    Also, the following reports month by month surface measurements.

    http://www.ncdc.noaa.gov/oa/climate/research/anomalies/index.html [Broken]
     
    Last edited by a moderator: May 4, 2017
  4. Nov 24, 2009 #3
    That is very interesting that most of the heat goes into the oceans. Is that due to the ice melting and perhaps warming the ocean, or is an indication that the warming is coming from other sources, such as the surface or the sea floor? I have always read that water absorbs more CO2 when it is colder, and as it warms it releases the CO2. (I have no practical experience doing so) Perhaps the sea water is absorbing the CO2 instead and thus heating the oceans?

    That is incredibly interesting about the Mt.Pinatubo Volcanic Eruptions actually cooling the planet. I have always read that it had the opposite effect and that it was entirely negligible. Perhaps it is? What effect do hydro thermal vents, and underwater eruptions have on the effect of the oceans "salinity".

    In particular, what is required to starve an ocean of oxygen? Will more Carbon Dioxide in water reduce it's ability to retain oxygen?
     
    Last edited: Nov 24, 2009
  5. Nov 24, 2009 #4
    Yes...but that doesn't mean much! During the 1970's the consensus was that an new ice age was "imminent" and was featured,for example, on the cover of Time magazine. (around 1974 or 1975).

    It is far more accurate to say that the earth undegoes warming and cooling cycles due to a wide variety of factors; ice ages, mini ice ages and warming periods are all part of the natural cycle and not fully understood.
     
    Last edited by a moderator: Nov 24, 2009
  6. Nov 24, 2009 #5

    BCO

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    Last edited by a moderator: Nov 24, 2009
  7. Nov 24, 2009 #6
    Certainly there was no IPCC in 1970 that "declared" a consensus as the current IPCC "declared" one.

    There certainly was a lot of talk in the 70s about cooling. Were you alive back then?
     
  8. Nov 24, 2009 #7

    Xnn

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    Because the oceans are thousands of feet deep, they have a much larger heat capacity than the atmosphere. So, the oceans have been absorbing the bulk of the heat over the years. It's only because they are so large that they have been absorbing most of the heat.

    The fact that sea levels are rising from thermal expansion and that overall ice is melting are independent confirmations that the globe is warming. There are also plenty of studies showing that the range of plants and animals are responding to climate change and climate zones shift poleward, so I don't see how anybody can reasonably dispute that there is warming going on.

    Anyhow concerning the 1970's, my impression is that there were some people who noticed that a few years were cooler than some previous years and started wondering if perhaps there might be global cooling. The idea was discussed, but never got very far.

    However, there are some similarities to today. Some people exclaim that 2005 or 1998 were very warm years and wonder if maybe the warming role of CO2 might be over stated since last year wasn't a record warm year. However, that is short sighted and counter to the consensus science of greenhouse gases.

    Never the less, it's obvious that some people are extremely opposed to the whole idea of global warming, but it's not a legitimate scientific objection. Rather it seems more political. That they broke into computers shows me that honesty and integrity mean very little to them. They seem to be trying to make mountains out of mole hills in a fundamentally dishonest type of way.
     
  9. Nov 24, 2009 #8
    OKay, UNderstood. There are three camps? Pro Human Global Warming and Pro Climate Change, and Pro No change.

    I am fairly certain we are living on a dynamic planet. I have no doubts about this.

    What concerns me are articles like this.

    http://www.unep.org/geo/yearbook/yb2009/ [Broken]
    What would cause the oceans to deplete of oxygen? Would more carbon dioxide added into water prevent it's ability to retain oxygen?

    To my understanding, there are prehistoric records of oxygen deprived oceans existing throughout the geological record and some even claim that it is cyclical. (I am not sold on the concept 100% at the moment)

    I am also not sold on the concept that the "dead zones" are caused only by fertilizers. What could have possibly caused it throughout the geological record? Maybe volcanic sulfur? Are volcanoes primarily spitting out Nitrogen in any regards?

    However, from a chemical perspective. What causes water to lose it's ability to retain Oxygen. And is there anything in physics which would cause ocean water to absorb more heat than usual, perhaps additional CO2 would cause it to heat up? Or perhaps the release of CO2 would cause it to heat up?

    This is something I have trouble understanding. Shouldn't there be a latentcy between the time the surrounding air heats up the oceans due to greenhouse gases?

    If I put a glass of cold water in a room filled with hot air, the water takes it's time absorbing that heat, and it never rises beyond room temperature. Not to my knowledge anyways. Would more CO2 or nitrogen in the Oceans cause it soak up the heat in the atmosphere morseo that the surrounding "air"? Or is the sunlight penetrating more deeply with more force and more heat into the oceans?

    What really freaks me out, is that whenever I search for things about underwater volcanoes off the gulf of mexico, that instantly, anti-human-global warming websites pop up. I am obviously not the only one who is questioning it.
     
    Last edited by a moderator: May 4, 2017
  10. Nov 24, 2009 #9

    Xnn

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    Going OT here, but the Black Sea is a huge natural dead zone.
    It is caused by the bottom water being isolated from mixing with the surface.
    Whenever the bottom waters are isolated from the surface there
    will be a dead zone since oxygen comes from the surface.
    Of course, there are other causes too.


    It does take time for the oceans to warm. However, the oceans have something like a hundred times the mass of the atmosphere. So, if they both warm up by the same delta temperature, then the oceans will have absorbed a hundred times the amount of heat.

    An equal rise in temperature does not mean an equal amount of heat energy.
    What is more massive (assuming similar specific heat capacity) will absorb more heat.
     
  11. Nov 24, 2009 #10
    Sorry I didn't mean to go off topic. I am just trying to understand the science through the politics.

    So a dead zone can be accomplished through poor circulation and nitrogen (according to msn.com)


    Still not understanding this. But I do understand the temperatures taken in the above refer mostly to the first 700 meters in depth. What about the rest?

    I will be honest... I am not 100% certain that human influence is the prime suspect in climate change.

    I am more inclined to believe that it's simply a natural phenomenon. Probably to do with the volcanoes, hydro thermal vents, and rift systems which pour lava into the ocean continually. To my knowledge, however, this is also one of the least researched areas of the earth. So I guess perhaps it's easy to "guess" it might be responsible for it.

    Shouldn't the sea temperature be cooling if massive ice sheets are melting into the oceans?
     
  12. Nov 24, 2009 #11

    Evo

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    No, actually SST (sea surface temperature) is only the first 1-2 meters of surface water.

    http://www.csc.noaa.gov/products/gulfmex/html/datadesc.htm [Broken]
     
    Last edited by a moderator: May 4, 2017
  13. Nov 24, 2009 #12

    sylas

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    Here's my proposal for a short summary statement on a huge question.

    • It is a fact that Earth as a whole warms, or cools for a variety of reasons, and that it has done so throughout its long history.
    • It is a fact that the Earth has recently (over the last century) warmed significantly.

    There are different estimates for the amount of warming over the last century. They are invariably more than 0.5C and less then 1.0C, and tend to be around 0.7C in total, for the change in average global surface temperatures. The changes tend to be greater over the land than over the ocean and there are substantial regional differences.

    Anything "fact" in science is still always open to question in principle. The two facts above are about as solid as science gets for measurements like this. There is of course on going work to get more refined measurements, and more accurate estimates of how warming distributes over time, and over Earth's surface. There is on-going research finding out about changes in the past, and quantifying how current changes compare in the rates of change and extent of change with other episodes of change in the past.

    There are also other indicators of temperature than surface temperature which can be used. Surface temperature may be the easiest to measure in the present and also probably the most directly relevant for immediate impact.

    Cheers -- sylas
     
  14. Nov 24, 2009 #13
    Let me establish where I am coming from so you know how much salt to take with my posting. I grew up in Pennsylvania, where you often saw news about coal mines in the newspapers. The words were almost always followed by disaster, and preceded by another. Coal mining is dangerous. Also, go visit Scranton sometime and look at the miles and miles of piles of coal overburden covering what once was fertile farmland.

    Whatever the effect of carbon dioxide on the weather, I worry about the effects on humans. We were not evolved as a species the last time carbon dioxide levels were this high. I'd gladly vote money to see if CO2 levels have anything to do with obesity, autism, or what have you. I'm pretty sure that there are some conditions of the elderly that are made worse by higher CO2 levels.

    So for me, coal is very bad, and rising CO2 levels are worse. As for global warming? I'm not sure I am against it, even if it is caused by CO2 levels.

    Back to the 1970s. You may not remember but there was a major global concern by pilots. The horizon was disappearing. This was considered by pilots to be a severe problem because they relied on the horizon to orient themselves while flying. The disappearing horizon was due to what we would call today nanoparticles of carbon and hydrocarbons suspended in the air, mostly from 707s and other commercial jets. The solution? It had already started. Turbofan (as opposed to turbojet) engines were much more efficient for passenger planes. In a turbofan some of the air taken in by the first fan stage bypasses the compressor and burners. It also results in complete combustion when the bypass air mixes with the air that passed through the compressor and turbine. Airlines all switched to turbofan engines for the fuel savings, and within a few years the horizon returned. I had to wonder if turbofans got extra thrust by burning up unburned particles left by turbojets. I would have expected them to take decades to fall out of the stratosphere.

    Anyone who lived in the LA area I am sure remembers a similar phenomena, smog. Diesel engines tuned for maximum efficiency emitted similar particles, as did poorly tuned automobiles. I'm sure we could have had clean air in LA without catalytic converters on automobiles, as long as they got the diesel trucks--and required frequent emissions checks on automobiles. Oh, well. The catalytic converter for everyone approach worked, it just took a lot of research to design automobile engines that worked efficiently with them.

    Where am I going with this? I think that given time, the CO2 problem will be corrected like the horizon problem. I can already see that cars five years from now will be at least twice as efficient as today's cars. In part because of worries about high fuel costs, in part due to the improvements in efficiency that come sort of for free when you use electricity instead of a drive shaft. Braking energy is recovered instead of wasted. Even if you have a gasoline engine, it can be tuned to be much more efficient if it runs at just one speed. What about fuel cells? They are coming, but not that fast. And the big thing to sort out is whether they will use hydrogen, methane, methanol, ethanol, or some other fuel. In reality eventually the real fuel is protons (hydrogen ions). The rest is about how you store them, and get them into the fuel cell.

    My guess? Methanol, or a methanol/ethanol mix will win out. It is compatible with current delivery systems and also with driver's expectations. The fact that methanol is a much less dangerous fuel in a crash is just a nice side benefit. But all that will take place whether or not a treaty to replace Kyoto is ever signed. It is progress, it is more efficient, and thus saves money. Saving the planet is nice, but doing it at a profit is nicer.

    As for base load electrical power, the sooner politicians bite the bulllet and start approving nuclear power plants again, that problem will go away. I could write a whole article on the improvements in nuclear power plant designs and safety, but I won't do that here. The base load problem won't go away. The possibilities are wait until fossil fuel prices go through the roof, build nuclear plants now, or hope for a miracle.

    Huh? Green renewable power is nice. It can also potentially provide a lot of swing power, and if done without subsidy, at a sensible price, it won't bust the federal budget. What it can't do is provide reliable power when a blizzard hits the northeast in January. Even if there are lots of wind turbines. ;-) A certain fraction of the electric power generating capacity needs to be reliable in all kinds of weather, and wind and solar are not.

    There may be some technology out there that can eventually replace nuclear power without burning coal. But it won't have much of an effect on US or European or Chinese power generation before 2020. And we need to start building new generating plants now, not next decade, or the decade after. We also need to get the Chinese to stop building one new coal plant a week, and do it by example, not by raising the price of coal. (Although that might work. ;-)
     
  15. Nov 24, 2009 #14

    russ_watters

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    To quantify that, the mass of a column of air the height of the atmosphere is equal to the mass of a column of water about 10m deep. Since the oceans are about 65% (?) of the surface area of the earth, once you've gone down 15m, you're already dealing with more mass of water than there is air in the atmosphere.
     
  16. Nov 25, 2009 #15

    atyy

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    An ad-hoc committee of the American Physical Society recently reviewed the that Society's 2007 Statement on Climate Change. The committee's report reads in part:

    "There are a number of problems with this statement. The first sentence presents as a fact what is only a surmise. Although the evidence is strong that climate warming has anthropogenic sources, as described above, anthropogenic warming is not a proven fact. Consequently, the wording in the first sentence “are changing the atmosphere” should have been “are probably changing the atmosphere”. In the second paragraph, the first sentence states that the fact of climate warming is incontrovertible, which is true. However, by its context this is easily misread to mean that anthropogenic warming is incontrovertible. The only clue that there are uncertainties in the predictions for the global climate is the phrase “likely to occur” in the second paragraph. This hardly conveys the great uncertainties in analysis displayed in PSB. The paragraph as a whole has an alarmist tone that belies the underlying uncertainties. ..........

    Despite the uncertainties in detailed predictions, it is the conviction of this committee that the APS would be well advised not to retract its support for policies and actions that are aimed at reduction in the production of greenhouse gasses. The weight of the evidence we have examined points to this as a prudent policy position."
     
  17. Dec 7, 2009 #16
    Well, in terms of the scientific literature, it is the prime suspect for climate change since the middle of last century.

    On other time scales there are other prime suspects. The glaciation and interglacial cycles of the last million years and perhaps two are suspected to be primarily from Milankovitch cycles, by a physical mechanism that is not understood. Certainly CO2 provides an important feedback, but does not explain most of the temperature change from the top of an interglacial to the bottom of an ice age.

    Specifically the 170 to 270 ppm variation of CO2 should make about 2°C of the about 10°C temperature change.

    The bulk of it, AFAIK is ice-albedo feedback.

    Volcanic forcing (being aerosol forcing) is well considered. Geothermal heat is understood to be a negligible source of heat to the atmosphere and ocean. It's pretty much all the sun.

    The last time I did the figures, the radiative imbalance due to the enhanced greenhouse effect is more than the latent heat of fusion of the melting sea ice.
     
  18. Dec 17, 2009 #17
    its weird, when i was younger i always thought that the planet was getting warmer and warmer because its covered in billions of buildings all using electricity and cars people etc. so much going on on the surface it just seems if you isolate it as a system there is a large amount of energy wrapped around the planet, then in the 9th grade global warming by CO2 gasses was introduced to me. Ive been skeptical the whole time, i accept the physics of greenhouse gases but it doesnt seem apparent to me that the greatest source of global warming is CO2 and that it is an immediate problem.
     
  19. Dec 17, 2009 #18
    I don't guess that the global warming is a fact!
    Tha planet is very strange, but this the result of the millions years of evollution
    For me, this is normal, the planet needs change!!!
     
  20. Dec 17, 2009 #19

    sylas

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    The original source of warming for the Earth is the Sun. Nothing else even comes close to making the slightest difference as an energy source. All climate impacts come from changing in some way the flow of energy that comes from the Sun.

    The Sun itself is remarkably constant; but the way that energy flows through the Earth is not. Earth radiates all the energy it receives from the Sun. This is called "energy balance". There can be a short term imbalance with energy actually being stored or released from the Earth, but this cannot last. The amount of energy is too large.

    What makes a difference for temperature is basically two things.

    • Albedo. How much solar energy gets reflected. Reflected energy does not contribute to heating.
    • Emissivity. This is a measure of how efficient the Earth is at radiating heat. This is where carbon dioxide makes a difference. It makes it a bit harder for the thermal energy radiated from the Earth to get out into space; and that means you end up with higher temperatures just to keep radiating the same amount of energy.

    To accept the physics of greenhouse gases MEANS to recognize a strong effect on temperature from just this effect. The physics involved implies higher temperatures when you have more greenhouse gases.

    Cheers -- sylas
     
  21. Dec 17, 2009 #20
    Yep, the physics is easy--if you have growing levels of greenhouse gases (GHG) in the atmosphere. However, the primary GHG is water vapor. If the amount of water vapor was constant, then it would be easy to make working models of the atmosphere that include radiative forcing from CO2. But it is not that simple by any means. Clouds increase albedo, and thus reflect more sunlight, but they also trap heat, preventing radiative cooling from the ground or ocean under the clouds. So do clouds cause warming or cooling? Both, and sometimes at the same time. :-(

    Remember that I am in favor of reducing CO2 levels. I just don't think that radiative forcing from CO2 is real.

    There is not much research money these days for studying the Gaia hypothesis, that natural feedback paths make Earth's climate self regulating. But given that the solar constant has not been constant when looked at over billion year timescales, something has kept Earth from being an iceball or a Venus-like hothouse.

    To be perfectly fair, current research seems to indicate that the Earth did go through an iceball (or slushball) phase several times over half a billion years ago. But it didn't stay locked in that mode. There are scientists trying to fit models that make CO2 responsible for leaving the icehouse mode. I happen to favor mountain building as the solution. And the long north-south mountain chain along the Pacific edge of the Americas as why the recent (in geological terms) Ice Ages didn't become Iceball Ages.
     
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