What historical evidence is there that carbon emissions drive temperature change on earth?

Question

How accurately can we see that carbon emissions have caused temperature change in the past? How do we know that carbon emissions and temperature change are not both caused by some third variable? Wikipedia says water vapour is the main factor of global warming. Has there been any change in it's effect or concentration on global temperatures over the last 200 years?

Answer 1

I'm no expert but I learned in my Archaeology class that deep sea core samples have been able to map the temperatures of the seas for thousands of years in the past and ice cores show the levels of CO2 from the past.  The amounts fluctuate based on the climate patterns of the ice age and so on and they have found that the regular ups and downs have begun to show a large increase in CO2 in our atmosphere.  I believe that pumping any designated "greenhouse gas" into our atmosphere will have negative consequences.

Answer 2

First, you need to learn to do better research than wikipedia, which is written by anyone who has an opinion on the subject.  Second, water vapor is the most prevalent greenhouse gas in the atmosphere, but it doesn't absorb and emit heat to the same extent that carbon dioxide does, which means that carbon dioxide is the most important greenhouse gas in global warming.  You can also line up temperature and carbon dioxide changes, and you will see that the changes correlate with each other.

Answer 3

None what so ever.

Answer 4

we are in uncharted waters. we have to rely on models and predictions.

Answer 5

The scientific data says global warming is happening and it's mostly caused by us.

Very short version:

http://en.wikipedia.org/wiki/Image:Clima...

The best summary of the data available:

http://www.ipcc.ch/SPM2feb07.pdf

Scientists have seen much stranger things than global warming (like Einstein's relativity or quantum mechanics) proved to be true by data.  So the data, not "logical" arguments, is what they go by.  The data is why why the vast majority of scientists agree that it's real and mostly caused by us.  Data about that here:

http://www.sciencemag.org/cgi/content/fu...

If you want to know more, here's the best website (warning - it's very big) with lots of data:

http://www.realclimate.org

"climate science from climate scientists"

Answer 6

Actually theres very little scientific evidence that CO2 is responsible for global warming other than conjecture and speculation.

This is most interesting as right now we are experiencing the coldest April in 113 years. I saw it is snowing in Texas, Oklahoma and Kansas, with another snow storm working up from Georgia and the Atlantic sea coast.

http://www.agweb.com/get_article.aspx?pa...

Actually, this recent cold spell may be proof that Global Warming isn't caused by carbod dioxide at all.

According to skeptics of the carbon dioxide/global warming theories, the main source of fluctuations in global temperatures is directly due to changes in the sun.

Interestingly we are currently having minimum sunspot activity in the solar cycle, which has particularly just bottomed out over the last week or two, with practically no sunspot activity at all. According to some theories, lack of sunspot activity can cause colder temperatures on Earth, and lots of sunspot activity can cause higher temperatures on Earth.

This is not something Al Gore and the "global warming alarmists" want you to know.

While sunspots cycles usually last about 11 years, they have been increasing overall. However right now, we are in the lowest point of the current cycle, and there have been almost no new sunspots for about 1.5 weeks (as of 4/12/07)

To see the major difference between the warmest April on record and the coldest April (this year) compare these two pages showing what was going on in April 2006, the very warmest April ever on record verses this year.

April 2006 (the warmest April ever on record):

http://www.dxlc.com/solar/old_reports/20...

April 2007 (so far the coldest in over 100 years)

http://www.dxlc.com/solar/indices.html

Notice a pattern???????

Pretty amazing isn't it.

Answer 7

Fat Al said so,not Sharpton,the other one,he found that out in the internet that he invented

Answer 8

Hi Will,

Just read some of your previous questions and answers so I know you're an intelligent person who knows geology and the like.  You'll already know some of the following points but I've included them for everyone's benefit...

We have a record of atmospheric composition stretching back 750,000 years; this is obtained from Antarctic ice core samples.  When snow falls it traps air, in time the snow is compressed into ice and the ice builds up.  By drilling into the ice we can recover air samples for analysis.  On this basis we have an accurate record of CO2 and other gas levels from the past.  Beyond 750,000 years we rely more on oxygen isotope analysis and can extend the record right back for 542 million years, not as accurate as ice cores but still within a margin of about 1%.  Any further back and the only life forms on Earth were single celled organisms and this makes it difficult to obtain data.

Obtaining past temperature records involves biological and ecological analysis, sediment analysis and a lot more work in general.  Still, by analysing enough samples and sometimes by extrapolating data we can compile an accurate temperature record.  As with atmospheric composition, the further back in time we go the less reliable the results. All the same, we can go back millions of years within an accuracy of 1 degree.

So, that's how we get the info and how reliable it is.

If you were to look at the two sets of data plotted in graph form you'd see immediately that there's a very good correlation between the two.  If you were to superimpose the two graphs you'd notice a slight offsetting between the peaks and troughs - rising temperatures preceding rising CO2 levels.  This is one of the factors some people use when disputing anthropogenic global warming, primarily because what's happening now is the other way around.  However, this is to be expected due to the Feedback Process.

To illustrate how the feedback process works I'll use one example but there are many others.  In Siberia in the last few years a million square kilometres of permafrost has melted.  The permafrost overlies the world's largest peat bog and trapped within the peat is an estimated 70 billion tons of methane (the methane having been created by methanogenesis).  Methane (CH4) is 296 times as effective as CO2 when it comes to the greenhouse effect - it's said to have a Global Warming Potential (GWP) of 296 (the 100 year GWP).  If all the Siberian CH4 were released it would be the equivalent to emitting 2 trillion tons of CO2.

As the world warms the permafrost melts, as it melts it releases CH4, the CH4 compounds the greenhouse effect leading to further warming, this melts more ice and so ad infinitum - the cycle is self propagating.

You mentioned 'third variables'.  Global warming and cooling has happened since the earth was formed a little over 4.5 billion years ago but it's not as simple as either warming or cooling.  There are several layers of cycles nested within each other, for example, whilst the world has generally been in a warming phase these last 18,000 years this is a very small phase within a 50 million year cooling trend.

For warming phases to switch to cooling phases and visa versa and similarly for trends to reverse, there needs to be some sort of catalyst - something to trigger these changes. This could for example be a volcanic eruption, the SO2 and other emissions from volcanoes reflecting sunlight back into space.  Most recently this occurred in 1991 with the eruption of Mount Pinatubo, for a few years after the world cooled.  A much larger explosion in 1815 (Tambora) had an even more pronounced effect.  Cataclysmic eruptions could trigger a reversal of trends.

Solar Variation can also play a role, over short periods of time the effect is barely noticeable but slight changes compounded over thousands of years could trigger a warming or cooling cycle. Similarly, Milankovitch Cycles (the way the Earth moves) can be a factor.

As for water vapour - by volume this is by far the greatest of the greenhouse gases.  The atmosphere can be as much as 4% water vapour (the average is about 1%), by comparison all other greenhouse gases account for about 0.03% of the atmosphere.  It would be reasonable to assume that the effect of water vapour completely overshadowed that of the other GHG's.  However, water vapour is far less effective at contributing to the greenhouse effect; some synthetic greenhouse gases (CFC's and HCFC's) are a million times more effective.

Two other important things about water vapour are the atmospheric lifespan and variations in concentrations.  Water vapour exists in the atmosphere for about 4 days.  The other primary GHG's are CO2 which has a lifespan of about 100 years, methane about 10 years, nitrous oxide (NO) about 115 years and difluorodichloromethane (CCl2F2) forever.

Water vapour forms part of the natural water cycle - it evaporates from the seas and oceans and when there's too much in the atmosphere (saturation point) it forms water droplets which fall to earth as precipitation.  It's not possible to increase levels of water vapour beyond that which the atmosphere can physically tolerate, if we tried all that would happen is it would rain. The contribution humans make to levels of water vapour in the atmosphere is miniscule.

What we do see is that as global temperatures increase so too does the amount of water vapour in the atmosphere - the warmer an air mass is the more water vapour it can contain; another example of the Feedback Effect, although in this case a small one.

Answer 9

I have been searching for that for a long time .... Still haven't found any evidence.

Answer 10

The concentration of CO2 in the atmosphere is 0.038%

There is no way that anyone is ever going to convince me that as this miniscule percentage rate  of CO2 content increases, that the earth's climate is going to be affected.

I believe that the earth has been in a continuous warming cycle ever since the end of the last ice age. How can the ice have melted if the earth wasn't warming, and it has been warming for 10,000years. Maybe it was all those cro-magnon  campfires that ended the ice age.....you bet.

I believe the the sun is in a cycle that is causing the earth to warm, and that when the warming cycle ends, that a cooling cycle will begin and we will head into anothe ice age, and when that cycle is done that the earth will warm again.

Answer 11

none, it is sunspots.  As the earth warms the oceans and lakes can hold less CO2 because the CO2 dissolves best in cold water.   Historical evidence is that changes in global temperature are also caused by volcanic activity (blots out the sun.)   these happened even before man discovered fire.

Don't believe Al Gore's propaganda.