CO2 impact on global temperature?

First off, nobody is talking about economic collapse. We're talking about spending a few percent of GDP, which grows at a rate of 3% each year. We're also talking about creating a lot of new green collar jobs.

Secondly, going from 280 to over 380 ppm of atmospheric CO2 is a 37% increase. You can make it sound small by saying it's only a fraction of a percent of the atmosphere, but 99% of the molecules in the atmosphere (nitrogen, oxygen, argon, etc.) aren't greenhouse gases. 100 ppm of arsenic is an even smaller concentration, but it will kill you.

Really what it boils down to is that this CO2 increase has caused a 1.6 W/m^2 radiative forcing (difference between incoming and outgoing energy). When you've got an energy imbalance like this, it's going to heat the planet.

Okay lets play with your numbers. So lets say that the number of CO2 molecules increased from 0.03% of the atmosphere to 0.04% percent of the atmosphere. That gives a change of 0.01% in C02 concentrations by simple subtraction.

A temperature change of 0.01% would be (for simplicity assume the temp of the earth is 300 kelvin) would be 0.03 kelvin. Let's just say that we will see a 0.03 kelvin increase every year, that is 0.3 increase in ten years and 3 kelvin increase in 100 years. Obviously, I am assuming a non-equilibrium condition between the earth and the sun which the increase in greenhouse gases would create, but the question becomes at what point is equilibrium reached.

Regardless, I think I answered your question how such a small amount of molecules can have a large impact. And since you seem to know something about physical chemistry, consider this. Think about the enthalpy that is needed to melt ice and the fact that polar ice caps are shrinking. That is an awful lot of enegy being absorbed into the system with no real change temperature.

Edit: To Adam, I did not mean for my explanation to have any scientific validity. Your explanation of a 33% change is no more valid.

Edit: I see the problem here and that is some confusion on the definition of temperature. Temperature is a tricky thing and gets very non-intunitive on the molecular level. What we call temperature is really an average of the energies of an ensemble of molecules. These energies can be split into rotational, vibrational, electronic, kinetic energies...and so on. To raise the temperature of a collection of 2500 molecules (to use your example), one need not raise the energy of every molecule. At any one particular time, the molecules in that collection will have all sorts of different energies and these energies will be distributed in a Bolztmann distribution (This distribution is actually what we call temperature) assuming equilibrium. To raise the temperature of the ensemble, one only needs to effect the energy of one of the molecules. Say for example increase the rotational energy of one other molecule by one quanta. This will shift the boltzmann distribution and increase the temperature of the ensemble. So your penny example does not work on the molecular level.

Stripped of the hyperbole, you say your "question is: what event is occurring that allows four molecules of CO2 to create a significant effect on the surrounding 9,996 molecules of air".

The straight answer is none. CO2 molecules (in terms of AGW) don't have any affect on the other 9,996 molecules of air. None of the theories, science, models, etc have ever postulated this so your question may as well have been "what is the connection between the letter 'E' and the existence of aliens?"

However, your implied question is one that has been asked many times which is how can such a small percentage of a substance have such a big effect? The increase - and doubling is not an insignificant increase - of a substance such as CO2 that traps more of the sun's energy on this planet leads to gradual yet steady warming - no "magic" involved and potentially disastrous.

Arsenic, botulism and other substances are poisonous in small amounts

Trace elements such as vitamins, iodine, zinc in maintain human health

The Printing riots of 1512 (where 3,000 people died) were caused by the use of a '/' in a publication, minor amendments made to the Ems telegram led to the Franco-Prussian war (and indirectly to WWI)

Our modern world revolves around tiny percentages - the amount of gasoline vapourised in each stroke of an engine is miniscule compared to the weight of the vehicle that it moves at high speeds.

Why do the sceptics want to deny the fact that small amounts of a thing can have a big effect? All human cultures have sayings that recognise how one small thing can cause calamity:

"The straw that break the camel's back","the "butterfly effect", "the drop that overflows the bucket"

P.S. And Dana is right - no one talks of "economic collpase" there are many countries with a high quality of life that are addressing the AGW issue right now and their economies are doing fine comparatively.

Edit:

OK, you didn't like my biological poison but then you say it's OK to use an analogy using an environmental pollutant: Instead of pee, use sarin in the ocean at the same concentration as CO2 in the air... we'd all be dead! The analogy is sound.

As for "beren has come closest" you obviously mean beren has come closest to agreeing with your world view rather than beren has come closest to the truth...

For example, beren says that 0.03% to 0.04% is a change of 0.01%, which it is... but it also represents a 33% increase - this is playing with statistics.

He then goes on to say that we can use this 1% increase (which is actually a 33% increase) in a 1:1 proportionality with temperature - there is no science that suggests this!

What this assumption is saying is that:

CO2 is the only factor in planetary temperatures;

that the planet would be at absolute zero without CO2 and;

that CO2 warms the planet directly.

This is absolute hogwash and not supported by any science whatsoever.

It also doesn't take into account any catalytic affects or positive reinforcers or anything... his reasoning is at about the same level as when CO2's role in GW was first postulated in the 19th C; we have moved on from there.

beren's logic is akin to:

Assume a human weighs 50kg & sweaters weigh 1kg.

A person wearing 1 sweater has a temperature of 310 degrees K.

1 sweater = 2% of the persons weight.

2 sweaters = 4% of the persons weight hence adding 1 more sweater means an increase of just 2% (when, in reality it doubles the number of sweaters).

A 2% increase in temperature is 6.2 degrees.

So a person who wears five sweaters would have a temperature of 335 degrees K or 62 degrees C and would be very dead.

Look, if you want to believe or not believe in something, fine. But if you want to understand, you have to open your mind.

You use examples wherein small amounts of a thing don't make a big difference to the whole but refuse to accept examples where small amounts of a thing make a huge difference.

This is called prejudging and is a sign of a closed mind - you simply do not want to understand how a small amount of CO2 in the atmosphere can have a profound effect despite 150 years of scientific evidence across multiple disciplines involving hundreds of thousands of researchers...

You have my pity for living in such a dark and tiny place.

The point should be made that good science has already proved that Co2 increase is an after the fact side effect of previous warming. Several people have already pointed out that NASA has already begun the shift to the skeptic view not that they have repaired some of the corrupt data files that led to the whole AGW thing. On the Co2 greenhouse effect I will repeat the link another posted this morning showing the reality about it.

http://www.junkscience.com/Greenhouse/

Tiny amounts spread across the surface of an entire planet added up to a large amount. If the Earths atmosphere had no greenhouse gases it would be around -30 and it would be frozen solid, as it was in its very early history. Know one is denying co2 is a trace gas and its contribution to GW is small and the temp rise has been quite small 2% and it's not just co2 but methane as well, we have spent the last 200 years breeding ever better cattle that produce far more methane than wild cattle and are breed by the 100's of millions to feed us or keep us in milk and while we produce far less methane than co2, methane is a far stronger greenhouse gas than co2.

Compared to natural climate change of the past the current 1deg is a quite minor temp rise, but in the distant past there were no cities in coastal regions to be flooded. The Q/A's that appear here talking about this being the end of the world are nonsense but there are going to be some serious consequences even if the sea rise is only the 24in predicted by the IPCC.

Pirates of the Caribbean: Co2 is not related to or affecting the ozone layer they are two different issues, ozone depletion was caused by CFC's which are now banned world wide and the hole is slowly repairing itself.

Of course CO2 can warm the planet a few degrees. It's just a physics calculation for a scientist.

The basic idea is that you don't have to hold in very much extra of the Sun's heat to cause warming, and that each "layer" of CO2 (for example, from 1 feet to 2 feet, 2 feet to 3 feet, etc.) has a cumulative effect.

Of course it's not in distinct layers, the actual calculation involves integration over distance (calculus). The layer idea is just to make it clearer.

Do you honestly think the vast majority of the scientists in the world are messing up on this basic point?

In working with hazardous ,most of the time U watch the oxygen. 20.9% of our atmosphere . Convert 380 ppm to percent it is .000,380% it is very obvious that the amount of CO2 is nothing. Another is that CO2 is very heavy, in fact so heavy it will put out a fire by smothereing it. Most of the CO2 here on earth is very near the ground.

For all the claims of scientific proof, you can't measure a significant increase in atmospheric absorption from CO2 by deploying instruments in the atmosphere or doing a test in a laboratory.

The enhanced greenhouse theory is all theory - no experimental evidence.

ask the survivors of the pleistocene era about what percentage increase in (real) greenhouse gasses is needed to effect the sort of dramatic and drastic climate change that gore and his ilk are hawking as justification for destroying Americas (only) economy.

it'll take a chain reaction including a super caldera blowing, all the frozen methane buried at the bottom of the entire ocean thawing and surfacing and ashes coating the troposphere.

Co2 is being put into the air daily cutting into the Ozone Layer which causes an advanced greenhouse effect which warms up our earth little by little which is Global Warming.