Global Warming?

[Future Shock]

Originally posted by: LeatherNeck

Originally posted by: Future Shock
You are all forgetting one critical factor - the single largest heat source ON earth is radioactive decay, as proven by Ernest Rutherford. Rutherford's work with radioactive decay dating and heating estimates VASTLY increased the estimated age of the earth during the late 1800s. We now know the Earth to be nearly 4 billion years old - before Rutherford's heating theories, the best guesses by scientists like Lord Kelvin were less than 100 million years. So, apparently, that radioactive heating is quiet significant...

FS

Not quite. Seems like your mixing some findings here. Rutherford's work had to do primarily with radioactive half-life yes but not that the heat generated by radioactive decay was/is a significant heat source.

U-238 and U-235 with half-lives of about 4 billion years, are among the primary elements used to theorize the age of the earth. While their half-life is a useful indicator of elapsed time, and some heat is generated, nobody is "missing" anything regarding their contribution to the heating of the earth. Some heat is generated but it pales in significance to the heat received by the sun.

Please let me quote from page 146 (paperback edition) of Bill Bryson's excellent "A Short History of Nearly Everything":

At McGill University in Montreal the young New Zealand-born Ernest Rutherford became interested in the new radioactive materiels. With a colleague named Frederick Soddy he discovered that immense reserves of energy were bound up in these small amounts of matter, and that the radioactive decay of these reserves could account for most of the Earth's warmth. They also discovered that radioactive elements decayed into other elements - that one day you had an atom of uranium say, and the next you had an atom of lead. This was truely extraordinary. It was alchemy pure and simple; no-one had ever imagined that such a thing could happen naturally and spontaneously.
Ever the pragmatist, Rutherford was the first to see that there could be a valuable application in this. He noticed that in any sample of radioactive materiel, it always took the same exact amount of time for half the sample to decay - the celebrated half-life - and this steady, reliable rate of decay could be used as a clock....he tested a piece of pitchblend ore, the principle ore of uranium, and found it to be 700 million years old - very much older than the age most people were prepared to grant the earth...
In the spring of 1904, Rutherford travelled to London to give a lecture at the Royal Insititution...Rutherford was there to talk about his new disintegration theory of radioactivity. Tactfully - for the aging Lord Kelvin was present, Rutherford noted that Kelvin himself had suggested that the discovery of some other source of heat would throw his (Kelvin's) calculations of the age of the earth out. Rutherford had found that other source. Thanks to radioactivity the Earth could be - and self-evidentally was - much older than the 24 million years Kelvin's final calculations allowed.
Kelvin beamed at Rutherford's respectful presentation, but was in fact unmoved. He never accepted the revised figures and to his dying day believed his work on the age of the Earth his most astute and important contribution to science - far greater than his work on thermodynamics.

If you have sources that contradict Bryson, please post and we'll discuss. I think that you have been thrown off by the fact that few science textbooks give much light on the Age of the Earth debates that raged on for a century or more, and Kelvin's and Rutherford's roles in them. They present it as very much a fait accompli ("the earth is nearly 4 billion years old") and don't talk in detail as to the immense debates (with obvious religious and evolutioary overtones) that ran for those years.

Future Shock

 

[deepred98]

global warming doesn't have jack sh*& to do with humans

the earth warms and cools naturally (ex. Ice age)

global warming is a fairy tale made up by leftist tree-huggers

 

[f95toli]

Originally posted by: deepred98

global warming doesn't have jack sh*& to do with humans

the earth warms and cools naturally (ex. Ice age)

global warming is a fairy tale made up by leftist tree-huggers

This attitude is really starting to annoy me. Please leave that in P&N.

Anyone with some basic knowledge of thermodynamics will know that global warming is real.
Start by a simple model of the planet, e.g. round sphere covered by water.
We know the amount of energy coming from the sun. All you need know is the value a few constant (how much energy is reflected by the atmosphere, the ground, ans the tranmissivity at different wavelenghts) and then you can set up an equation which can be used the calculate the steady state temperature of the planet.
Now, decrease the amount of radiation which is radiated back into space (by adjusting the corresponding constant). which corresponds to adding CO2 to the atmosphere, and you will find that the steady state temperature has gone up = Global warming.


Of course you can not use this model to actually predict anything, but the basic physics stays the same in more complicated models. Now, we can argue about whether the change in temperature per decade due to the extra CO2 will be 0.0001K, 0.1K or 5K; in order to answer that question we need to use complex computer models.

Saying that "global warming doesn't have jack sh*& to do with humans" is however flat out wrong.

Another thing we need to keep in mind is that the issue is about timescales, no one is denying that the climate changes over time but this is ususally a very slow process compared to e.g. the lifetime of a human.
The problem with the adding CO2 to the atmosphere at our current rate is that it is causing major changes over a period of only a few decades, much faster than any naturally occuring process that we know of.

 

[chcarnage]

FutureShock

For earth's surface, radioactive warming isn't very important. According to the GermanWikipedia (translated by me):

The power output resulting from radioactive decay roughly equates 16*10^12 Watt. Calculating with an average earth radius of 6371 km, the geothermal power output at earth's surface is circa 0.0032 Watt per square meter.

But the Earth constantly absorbs a part of the energy which is emitted by the sun: 17*10^16 Watt or, depending on daytime, up to 1367 Watts/m^2 (Source)

 

[sao123]

Originally posted by: Future Shock
If you have sources that contradict Bryson, please post and we'll discuss. I think that you have been thrown off by the fact that few science textbooks give much light on the Age of the Earth debates that raged on for a century or more, and Kelvin's and Rutherford's roles in them. They present it as very much a fait accompli ("the earth is nearly 4 billion years old") and don't talk in detail as to the immense debates (with obvious religious and evolutioary overtones) that ran for those years.

Future Shock

I dont have a contextual source, as i didnt have time to read up yet... but perhapes he was referring to this radioactive decay as helping to power the geothermal earth's core... from sources such as that of radioactive material deep within the earth. the underlined sentence is not very clear with respect to context of what the earth's warmth really meant.

 

[Future Shock]

Originally posted by: chcarnage
FutureShock

For earth's surface, radioactive warming isn't very important. According to the GermanWikipedia (translated by me):

The power output resulting from radioactive decay roughly equates 16*10^12 Watt. Calculating with an average earth radius of 6371 km, the geothermal power output at earth's surface is circa 0.0032 Watt per square meter.

But the Earth constantly absorbs a part of the energy which is emitted by the sun: 17*10^16 Watt or, depending on daytime, up to 1367 Watts/m^2 (Source)

WTF - you know better I hope than to quote the global constant...that is merely the amount of solar radiation that the earth is EXPOSED to - not how much is actually absorbed and not reflected, which is only a percentage of what we are exposed to. It takes ozone and other reactions to capture that heat and not reflect it - and most of it IS reflected. So even though the exposed power is 4 orders of magnitude greater, you can't quote me a figure of it's actual absorptive power...

FS

 

[chcarnage]

Why is it cold at night and warm during the day? It would be a tough job keeping Earth's average temperature with only, say, one geothermal Watt per square meter.

 

[LeatherNeck]

Originally posted by: Future Shock
Please let me quote from page 146 (paperback edition) of Bill Bryson's excellent "A Short History of Nearly Everything":

At McGill University in Montreal the young New Zealand-born Ernest Rutherford became interested in the new radioactive materiels. With a colleague named Frederick Soddy he discovered that immense reserves of energy were bound up in these small amounts of matter, and that the radioactive decay of these reserves could account for most of the Earth's warmth. They also discovered that radioactive elements decayed into other elements - that one day you had an atom of uranium say, and the next you had an atom of lead. This was truely extraordinary. It was alchemy pure and simple; no-one had ever imagined that such a thing could happen naturally and spontaneously.
Ever the pragmatist, Rutherford was the first to see that there could be a valuable application in this. He noticed that in any sample of radioactive materiel, it always took the same exact amount of time for half the sample to decay - the celebrated half-life - and this steady, reliable rate of decay could be used as a clock....he tested a piece of pitchblend ore, the principle ore of uranium, and found it to be 700 million years old - very much older than the age most people were prepared to grant the earth...
In the spring of 1904, Rutherford travelled to London to give a lecture at the Royal Insititution...Rutherford was there to talk about his new disintegration theory of radioactivity. Tactfully - for the aging Lord Kelvin was present, Rutherford noted that Kelvin himself had suggested that the discovery of some other source of heat would throw his (Kelvin's) calculations of the age of the earth out. Rutherford had found that other source. Thanks to radioactivity the Earth could be - and self-evidentally was - much older than the 24 million years Kelvin's final calculations allowed.
Kelvin beamed at Rutherford's respectful presentation, but was in fact unmoved. He never accepted the revised figures and to his dying day believed his work on the age of the Earth his most astute and important contribution to science - far greater than his work on thermodynamics.

If you have sources that contradict Bryson, please post and we'll discuss. I think that you have been thrown off by the fact that few science textbooks give much light on the Age of the Earth debates that raged on for a century or more, and Kelvin's and Rutherford's roles in them. They present it as very much a fait accompli ("the earth is nearly 4 billion years old") and don't talk in detail as to the immense debates (with obvious religious and evolutioary overtones) that ran for those years.

Future Shock

Once again you don't seem to understand the text you cite and the science behind it.

Somebody has already pointed out that the issue at hand had to do with the heat of the Earth's core. Kelvin had argued for a young Earth because the Earth's core was still really hot and, given cooling over millions of years, would have cooled down.

Rutherford was arguing that an explanation might be radioactive decay (by the way, did you notice the "could" in that statement?) which is keeping the earth's core from cooling down. The issue at hand was that the core of the Earth itself was hot and staying so from radioactive decay and not that the earth was so hot from radioactive materials that it was heating up the atmosphere.

Even without technical knowledge of radioactive decay it doesn't take a rocket scientist to figure out that the Earth is not really hot to the touch and heating up the air which is what would be necessary according to your thesis. Uranium miners don't have to wear asbestos suits to mine uranium. Radioactive materials are just, quite frankly, not very hot to the touch when they are decaying naturally. They are in a fission or fusion reactor but that is an entirely different process altogether.

By the way, I have an undergraduate degree in Nuclear Engineering. So I'm not making this stuff up. If you want me to find some textbook titles I'll try to find some. I'm also not ignorant of some of the young earth/old earth debates and that Lord Kelvin was a staunch Creationist. Radioactive decay is by no means settled as a theory as to why the Earth's core is so hot after 4 billion years but that has nothing to do with global warming which is the subject of this thread.

 

[Kyteland]

Originally posted by: rgwalt
Humans are not causing a significant increase in global temperatures.

Originally posted by: deepred98
global warming is a fairy tale made up by leftist tree-huggers

Originally posted by: f95toli
Anyone with some basic knowledge of thermodynamics will know that global warming is real.

Actually nobody knows if humans have had any impact on global temperatures and climate. We simply haven't kept track of data for long enough to really know. We do know that we've increased the amount of CO2 in the atmosphere, but we don't know exactly what that's done to the climate.

There was an interesting thread in OT the other day about global climate change (linky) if you can get past some of the chaff posts. I'll relink the articles I posted there.

OCEAN SCIENCE: THE FATE OF INDUSTRIAL CARBON DIOXIDE
Interesting article about what is happening with all of that extra CO2 we've put in the atmosphere in the last 100 years.

GEOPHYSICS: ON THE SNOWBALL EARTH HYPOTHESIS
Another article that describes the chemical process by which the Earth maintains its temperature.

 

[deepred98]

hey f95toli

i didn't say global warming isn't real i said it has nothing to do with human activity
the amount of pollutants humans add to the atmosphere is not nearly enough to cause global warming
the globe warms and cools naturally as has happened many times before
yes there is research proving global warming and i agree the world is getting warmer by it is not because of us

 

[f95toli]

Originally posted by: deepred98
hey f95toli

i didn't say global warming isn't real i said it has nothing to do with human activity
the amount of pollutants humans add to the atmosphere is not nearly enough to cause global warming
the globe warms and cools naturally as has happened many times before
yes there is research proving global warming and i agree the world is getting warmer by it is not because of us

And as I pointed out that is simply not correct. Adding CO2 to the atmosphere WILL make the globe warmer, it is simple physics.
But again, how large the effect is of course still an open question. However, in order to answer that question we need computer models, there are no simple arguments that can be used to say that the increase is e.g. 0.00001K or 2K. We need to calculate it, no one can say "it is not because of us" unless they have computer simulations to back up that statement. AFAIK all computer simulations give the same answer: The CO2 we are adding to the atmosphere is having a significant impact on the climate.

My other point was that it is a question of timescales, of course the climate has changed but the global average temperature has changed very slowly. If global warming was happening on a timescale of hundreds of years there would be plenty of time to adapt (like we have done in the past), but large changes occuring over only a few decades is something new. THAT is the problem.

 

[deepred98]

uh the changes in the last few decades has not really been accurately measured and there is really no definitive proof that CO2 is the problem here.

" If global warming was happening on a timescale of hundreds of years there would be plenty of time to adapt (like we have done in the past)"

uh what past?
we humans have been existant for a documented 7000 years (give or take) in geological time (or whatever it is called) that's not very long

 

[piasabird]

The Cycle of Sun and radiation from the Sun may have something to do with it. The orbit of the earth may also have a cycle that moves us farther and closer to the sun from time to time. Then there is Volcanic activity. More than anything is probably the temperature of the Ocean. It affects weather more than anything I have observed.

Man has observed temperature reading for a very short period of time to truly understand what is going on. I think in the grand scheme of things that cars are a minor factor. Cars have been getting to be cleaner and cleaner running over time. I think it is a waste of time to have vehicle emission tests just in high pollution areas. Pollution moves eastward accross the United States so every car in the US should have the same standard. The West Coast even gets pollution from China.

 

[Calin]

The "short" cycle of Sun has a duration of somewhere aroung 11 years. And the Earth's orbit is not circular, but it repeats itself each year.
While in regards to heat, volcanic activity can be easily ignored, the problem would be lots and lots of ash (or smoke) sent to high altitudes, floating in the air, or deposited on things. This has a much bigger thermal effect than all the hot lava

 

[Vee]

Originally posted by: piasabird
The Cycle of Sun and radiation from the Sun may have something to do with it. The orbit of the earth may also have a cycle that moves us farther and closer to the sun from time to time. Then there is Volcanic activity. More than anything is probably the temperature of the Ocean. It affects weather more than anything I have observed.

Man has observed temperature reading for a very short period of time to truly understand what is going on. I think in the grand scheme of things that cars are a minor factor. Cars have been getting to be cleaner and cleaner running over time. I think it is a waste of time to have vehicle emission tests just in high pollution areas. Pollution moves eastward accross the United States so every car in the US should have the same standard. The West Coast even gets pollution from China.

"Pollution", in your context, and greenhouse gases need to be understood separately. Cars becoming "cleaner" helps local environment and public health. Even with clean emissions, they continue to realease the same or larger amount of greenhouse gases.

Global heating due to greenhouse gases was predicted before that effect could be seen in temperature readings. Our observations merely fit a pattern already predicted. That includes oceans absorbing a lot of heat and gas and for a while work like buffer. It includes more frequent and more violent hurricanes. It includes more floodings in northern Europe. It includes shrinking glaciers. It includes more ice movements in Antarctica, etc.

Of course, the fact that global warming due to greenhouse gases would be consistent with what we know about natural sciences sofar, - and the fact that it can be observed in reality to correlate reasonably well with computer predictions, doesn't mean that it is a proven fact, or that we know all or even enough about this. But frankly that should not be used to take comfort from.

Taking that as some excuse or license to continue to burn fossil fuels, resembles all too much the behavior of continuing smoking as long as the tobacco industry insisted "it has not been conclusively proven that smoking causes cancer".

It is quite likely that the effects on climate due to variations in spin axle tilt, variations in Earth's core nuclear reactions, variations in solar activity or variations in earths solar orbit are completely dwarfed compared to the magnitude of effect that the composition of the Earth's atmosphere has.

It is particularly worrying that the former can hardly lead to really disastrous changes, within likely perimeters, - but greenhouse gases can concievably lead to total disaster. At some point the system will break down. The reason Mars and Venus are sterile and unhabitable, is not really for certain due to the difference in distance to the sun compared to Earth. It is due to the makeup of their atmospheres.

Large volcanos will rather tend to temporarily cool down the earth, due to dust, but are too insignificant to consider. Heat released by any human activity is likewise ridiculously insignificant.

 

[Calin]

Originally posted by: Vee
The reason Mars and Venus are sterile and unhabitable, is not really for certain due to the difference in distance to the sun compared to Earth. It is due to the makeup of their atmospheres.

I don't really agree about that. A Earth-like planet at the distance where Mars is will have survivable temperatures, but I really don't think it will have any spot warmer than freezing point, making sustainability difficult at best.
And at Venus' distance, I really think it would be too hot (but I don't know for sure).

I thought about summer/winter temperature differences at 45 latitude but this would be wrong. I would like to have some data of temperatures around equator in summer/winter, showing differences for the 3.4% difference in distance to Sun

 

[f95toli]

Originally posted by: deepred98

uh what past?
we humans have been existant for a documented 7000 years (give or take) in geological time (or whatever it is called) that's not very long

Homo Sapiens has been around for at least 160 000 years, probably somewhat longer (200 000-400 000 years) and moderns humans for around 100 000 years.

During that time the climate has changed quite a lot.

 

[f95toli]

Originally posted by: piasabird

Man has observed temperature reading for a very short period of time to truly understand what is going on.

We have ice-core data going back 740 000 years. I would not call that a short time.

 

[Calin]

Hmmm... temperatures in Quito look like 58 and 59 degrees (monthly averages). I have to find something else to base my temperature/distance relations

 

[deepred98]

Homo Sapiens has been around for at least 160 000 years, probably somewhat longer (200 000-400 000 years)

uh i said documented as in people actually writing down stuff
not half monkeys that i really don't consider human

and uh our climate hasn't really changed that much right now
it has gotten warmer by at most a couple degrees celcius which i really don't think is that much and anyways during the ice age temperatures dropped a lot more then that even if it were over a longer period of time so don't you think maybe this is just earth's way of balancing out the ice age
and anyway new research shows taht earth's magnetic field has switched poles quite a few times already and these switches happended over about a century you may think this has nothing to do with global warming but doesn't that just show that earth really isn't that predictable.

out of curiosity are you like a left-wing enviromentalist? Just wondering

 

[f95toli]

Originally posted by: deepred98
out of curiosity are you like a left-wing enviromentalist? Just wondering

No, I am a physicist, I base my conclusions on available facts by e.g. reading scientifitc journals,
My views about global warming has absolutely nothing to do with politicts.

(and I guess you could call me social-liberal, I don't vote for the Green Party if that is what you are asking)

 

[deepred98]

uh oh cool

uh don't a lot of scientific journals contradict each other and most of those are written by left-wing enviromentalists anyway
i'm not saying your wrong about your info
you do seem smart
but i really don't believe that humans have screwed up the world that bad

 

[Noworkia]

How does carbon dioxide trap heat? Does anyone have a link to a model or experiment showing the process on a small scale?

 

[f95toli]

Walk into a greenhouse (no, really).

In a greenhouse short wavelength IR (IR=heat radiation) from the sun passes through the glass, but the waves are reflected back from the ground back as long wavelength IR. Since long wavelength IR is reflected by glass these waves are then reflected around the greenhouse until they are absorbed.
This is why it is warm in a greenhouse.

Greenhouse gases (mainly water, methane and CO2) work the same way: They let sunlight through but the IR which is radiated by the ground is reflected back.

On a more physical level this has to do with the rotational and vibrational spectra of these molecules.

Of course this won't go on forever (it doesn't get infinitly hot in a greenhouse); hot object radiate more energy than cold ones (also at other wavelenghts) so eventually a steady state condidtion is reached (assuming no more greenhouse gases are released into the atmosphere) but the average temperature is higher then before.

 

[Noworkia]

Originally posted by: f95toli
Walk into a greenhouse (no, really).

In a greenhouse short wavelength IR (IR=heat radiation) from the sun passes through the glass, but the waves are reflected back from the ground back as long wavelength IR. Since long wavelength IR is reflected by glass these waves are then reflected around the greenhouse until they are absorbed.
This is why it is warm in a greenhouse.

Greenhouse gases (mainly water, methane and CO2) work the same way: They let sunlight through but the IR which is radiated by the ground is reflected back.

On a more physical level this has to do with the rotational and vibrational spectra of these molecules.

Of course this won't go on forever (it doesn't get infinitly hot in a greenhouse); hot object radiate more energy than cold ones (also at other wavelenghts) so eventually a steady state condidtion is reached (assuming no more greenhouse gases are released into the atmosphere) but the average temperature is higher then before.

I know how a green house works, but it is its ability to maintain energy and controll the lost of the energy by conduction, convection and radiated heat, not the reflected IR light.
http://en.wikipedia.org/wiki/Solar_greenhouse_%28technical%29

Anyone have a link explaining carbon dioxide in a science model detailing the effects.