Here is the line of reasoning that appears convincing to me within the IPCC-2001 report. The report itself includes data supporting each of these assertions, and many reports in the intervening years provide further support. Which part or parts don't have you convinced?

1.The mean surface temperature of the earth is rapidly increasing.
2.Modern agriculture and landfill practices lead to higher atmospheric methane concentration.
3.The atmospheric concentration of methane has increased by about 150% since 1750.
4.The carbon dioxide content of the atmosphere is at a higher level than at any time in the past 750,000 years, at least.
5.Modern industrial energy production requires the combustio...

Here is the line of reasoning that appears convincing to me within the IPCC-2001 report. The report itself includes data supporting each of these assertions, and many reports in the intervening years provide further support. Which part or parts don't have you convinced?

1.The mean surface temperature of the earth is rapidly increasing.
2.Modern agriculture and landfill practices lead to higher atmospheric methane concentration.
3.The atmospheric concentration of methane has increased by about 150% since 1750.
4.The carbon dioxide content of the atmosphere is at a higher level than at any time in the past 750,000 years, at least.
5.Modern industrial energy production requires the combustion of fossil fuels such as bituminous coal and gasoline, which produces carbon dioxide that escapes to the atmosphere.
6.The recent increase in atmospheric carbon dioxide temporally correllates well with the amount of fossil fuel combustion since the industrial revolution, and it is therefore likely that human activity has caused the current increases in atmospheric carbon dioxide.
7.The greenhouse effect, in which the amount of so-called greenhouse gases (such as carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, and other fluorinated gasses), which are transparent to heat energy coming from the sun, but opaque to infrared radiation, regulates in part the temperature of the earth.
8.Therefore, we can conclude with high likelihood that the greenhouse effect is being caused by human activity and is causing in part, global warming.

Buches: I would like to know where you get your facts for numbers 4 and 6. I believe the Medieval warming period saw higher concentrations of CO2 than we have now.


The very ice core data Gore's movie points to so vehemently shows that the CO2 levels follow a rise in temperature, not the other way around. When temperature rises or falls, CO2 follows in kind but about 800 years later. Here is a paired down version of a competing movie to Al Gore's that I doubt you've seen: [url=http://www.youtube.com/watch?v=aJSupf6rkgE&session=tVBA7WZmJlo1bUdx1DHnLanFbjfOOsMRoq1Z5lhbJlhADqJ0H42G4SziHvleI3-pSTEa7y9_Hb9Fo0dOEXjMIfX-6UzelM7r_-12b74Dnrq_H9F_d3AupYqLq4MBVPVHzKFqQLi0tfSxmGiTEMEASsDy9n0XpEItVHf...

Buches: I would like to know where you get your facts for numbers 4 and 6. I believe the Medieval warming period saw higher concentrations of CO2 than we have now.


The very ice core data Gore's movie points to so vehemently shows that the CO2 levels follow a rise in temperature, not the other way around. When temperature rises or falls, CO2 follows in kind but about 800 years later. Here is a paired down version of a competing movie to Al Gore's that I doubt you've seen: The Great Global Warming Swindle

You said that the CO2 levels correlate with our fossil fuel combustion since the industrial revolution. I believe that is totally false and would like to know your source.

Simply making a bunch of statements regarding global warming and citing no source is not evidence that humans are to blame. Another common tactic I have seen is to simply say "the IPCC said so!". The IPCC certainly has said that humans are to blame, but even the IPCC must present evidence to that end and they have not.

If I say that human births and the stork population went up last year in Europe, that is not evidence that one caused the other.

Regarding point 6: My simple statement about the time correllation was much weaker than the climatologists' argument. For a peer-reviewed explanation, see National Academies:

That the burning of fossil fuels is a major cause of the CO2 increase is evidenced by the concomitant decreases in the relative abundance of both the stable and radioactive carbon isotopes3 and the decrease in atmospheric oxygen.

For a plain-english explanation by climate scientists, see RealClimate:

Over the last 150 years, carbon dioxide (CO2) concentrations have risen from...

read more»

Regarding point 6: My simple statement about the time correllation was much weaker than the climatologists' argument. For a peer-reviewed explanation, see National Academies:

That the burning of fossil fuels is a major cause of the CO2 increase is evidenced by the concomitant decreases in the relative abundance of both the stable and radioactive carbon isotopes3 and the decrease in atmospheric oxygen.

For a plain-english explanation by climate scientists, see RealClimate:

Over the last 150 years, carbon dioxide (CO2) concentrations have risen from 280 to nearly 380 parts per million (ppm). The fact that this is due virtually entirely to human activities is so well established that one rarely sees it questioned. Yet it is quite reasonable to ask how we know this. . . .

Regarding point 4: I think I misstated it. Peer-reviewed analysis of the data I provide below only states that CO2 is at its highest level in 650,000 years, not at least 750,000 years. Sorry about that.

EPICA (the European Project for Ice Coring in Antarctica)

Here we report the recovery of a deepice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok.

Vostok is another ice core previously available from Antarctica, which showed data for the past 430,000 year...

Regarding point 4: I think I misstated it. Peer-reviewed analysis of the data I provide below only states that CO2 is at its highest level in 650,000 years, not at least 750,000 years. Sorry about that.

EPICA (the European Project for Ice Coring in Antarctica)

Here we report the recovery of a deepice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok.

Vostok is another ice core previously available from Antarctica, which showed data for the past 430,000 years.
Environment; Jan/Feb2006, Vol. 48 Issue 1, p6-7

This article reports that ice core samples drilled in the eastern section of Antarctica show record levels of carbon dioxide and other greenhouse gasses in the air. Carbon dioxide is 27 percent higher than any other time in the last 650,000 years. The ice core samples show that levels of methane in the atmosphere are also elevated.

Regarding the lag you mentioned, this is also explained in the climate science literature. I'll briefly summarize the sources I have read, and provide some links.

In the past, climate changes have begun (obviously) due to nonhuman causes, such as the wobble of the earth's orbit, for example. The reason the increase in CO2 "lags" the increase in temperature is because of "positive feedback": increases in temperature cause increases in CO2, and increases in CO2 cause increases in temperature. Once the temperature starts to go up for whatever reason, the earth will soon begin to source CO2, which will cause the earth to warm up even more, which will bring about more CO2 . . . and so on, u...

Regarding the lag you mentioned, this is also explained in the climate science literature. I'll briefly summarize the sources I have read, and provide some links.

In the past, climate changes have begun (obviously) due to nonhuman causes, such as the wobble of the earth's orbit, for example. The reason the increase in CO2 "lags" the increase in temperature is because of "positive feedback": increases in temperature cause increases in CO2, and increases in CO2 cause increases in temperature. Once the temperature starts to go up for whatever reason, the earth will soon begin to source CO2, which will cause the earth to warm up even more, which will bring about more CO2 . . . and so on, until it reaches a threshold, ending the runaway feedback.

Now, due to the combustion of fossil fuels, we're pumping CO2 up there, which will cause the earth to warm, which will cause the earth to source CO2, which will cause the earth to warm . . . and so on. This is the reason for alarm.

Both from the National Academies:
Climate Change Science: An Analysis of Some Key Questions
(2001)

Abrupt Climate Change: Inevitable Surprises (2002)
(lots of data about historic abrupt changes in the climate; I highly recommend reading about the Younger Dryas event)

buches, haven't you read the numbers that this very clip is about? The CO2 present in our atmosphere is tiny compared to all of the other greenhouse gasses. Of all the CO2 present in our atmosphere, only a tiny portion was created by man. The vast majority of CO2 comes from the ocean. Every breathing thing on the earth emits CO2. Even leaves emit CO2 when they fall off of their trees. Termites alone produce more CO2 than man.

By your very admission, CO2 increases after temperature rises, and temperature rises (although only by a tiny amount) as CO2 increases. Given that, how can you possibly prove that the rise in global temperature is attributable to humans? It seems to me that you'...

buches, haven't you read the numbers that this very clip is about? The CO2 present in our atmosphere is tiny compared to all of the other greenhouse gasses. Of all the CO2 present in our atmosphere, only a tiny portion was created by man. The vast majority of CO2 comes from the ocean. Every breathing thing on the earth emits CO2. Even leaves emit CO2 when they fall off of their trees. Termites alone produce more CO2 than man.

By your very admission, CO2 increases after temperature rises, and temperature rises (although only by a tiny amount) as CO2 increases. Given that, how can you possibly prove that the rise in global temperature is attributable to humans? It seems to me that you're saying CO2 increases as temperature rises regardless of the reason for the temperature increase.

Given that, isn't it possible that something else (perhaps the Sun for example) is to blame for our tiny (around 1 degree globally) temperature increase and that CO2 levels are rising for that reason?

I think that CO2 levels are at a very high level if you ignore millions of years of data and focus only on the last 50 years or so. Here's a good article that summarizes the last 300 million years of CO2 levels and compares them to todays levels.

1. Mostly correct - If human generated CO2 were to double, triple, quadruple, it would only make a tiny difference in global temperature.

2. Certainly humans generate CO2, but there is no proof that humans are the cause of the noticed increase in CO2 levels since the 70's. In fact, CO2 levels actually decreased during our industrial age and began increasing during a recession after the ...

I think that CO2 levels are at a very high level if you ignore millions of years of data and focus only on the last 50 years or so. Here's a good article that summarizes the last 300 million years of CO2 levels and compares them to todays levels.

1. Mostly correct - If human generated CO2 were to double, triple, quadruple, it would only make a tiny difference in global temperature.

2. Certainly humans generate CO2, but there is no proof that humans are the cause of the noticed increase in CO2 levels since the 70's. In fact, CO2 levels actually decreased during our industrial age and began increasing during a recession after the industrial age.

3. The vast majority of greenhouse gas on this planet is not CO2. If global temperatures were to rise to amazing highs as described in Al Gore's film, CO2 will likely not be the cause.

Buches said:

Here is the line of reasoning that appears convincing to me within the
IPCC-2001 report. The report itself includes data supporting each of
these assertions, and many reports in the intervening years provide
further support. Which part or parts don't have you convinced?

This reasoningf from the IPCC is pretty good too.

The fact that the global mean temperature has increased since the late 19the century and other trends have been observed does not meant that an anthropogenic effect on the climate system has been identified. Climate has always varied on all time-scales, so the observed changes may be natural.
(IPCC, 2001a, pg 97)

The difference in your citat...

Buches said:

Here is the line of reasoning that appears convincing to me within the
IPCC-2001 report. The report itself includes data supporting each of
these assertions, and many reports in the intervening years provide
further support. Which part or parts don't have you convinced?

This reasoningf from the IPCC is pretty good too.

The fact that the global mean temperature has increased since the late 19the century and other trends have been observed does not meant that an anthropogenic effect on the climate system has been identified. Climate has always varied on all time-scales, so the observed changes may be natural.
(IPCC, 2001a, pg 97)

The difference in your citation and mine is that yours comes from the IPCC Summary for Policy-makers and Journalists and mine comes from the actual report.

The Summary for Policy-makers was written by politicians, not scientists.

Martin Manning the vice-chair of the IPCC says; "The pocess used to produce the IPCC is not ideal and distorts the real messages from the available science. Some government delegates influencing the SPM do not understand the methodologies being used and misinterpret or contradict the lead authors.

Buches, I can understand having concern for climate and having a sense of interest, but your motivated by blind faith, ignorance, and/or ideology.

bferman, why are you ignoring the data I linked, and the study I quoted, that show that CO2 is much higher than any level in the last 650,000 years? The article you linked does not dispute this. In fact, the article in Nature magazine that it cites for the 300 million year data agrees, and notes that CO2 is a greenhouse gas that affects the climate.

You have asserted many times in this thread that CO2 only makes a tiny change in the temperature, without any support. I have been providing support for my arguments, I ask you to do the same. For example, above, I linked several authorities that discuss such changes in detail. [url=http://books.nap.edu/openbook.php?record_id=10139&page=7]I...

bferman, why are you ignoring the data I linked, and the study I quoted, that show that CO2 is much higher than any level in the last 650,000 years? The article you linked does not dispute this. In fact, the article in Nature magazine that it cites for the 300 million year data agrees, and notes that CO2 is a greenhouse gas that affects the climate.

You have asserted many times in this thread that CO2 only makes a tiny change in the temperature, without any support. I have been providing support for my arguments, I ask you to do the same. For example, above, I linked several authorities that discuss such changes in detail. In the National Academies book, when taking feedback effects into account,

a doubling of the concentration of carbon dioxide (from the
pre-Industrial value of 280 parts per million) in the global atmosphere
causes a forcing of 4W/ m2. The central value of the climate
sensitivity to this change is a global average temperature increase of
3°C (5.4°F), but with a range from 1.5°C to 4.5°C (2.7 to 8.1°F)

To understand the magnitude of what a 3°C change really means, note that

global warming rates as large as 2°C (3.6°F) per millennium may have
occurred during the retreat of the glaciers following the most recent
ice age.

Is the end of an ice age a tiny change?

bferman,

there is no proof that humans are the cause of the noticed increase in
CO2 levels since the 70's. In fact, CO2 levels actually decreased
during our industrial age and began increasing during a recession after
the industrial age.

I don't know your standard of "proof," but I cited above extensive evidence that humans are the cause of the currently increased cause of CO2. See my post above "Regarding point 6." It has to do with precise measurements of the ratio of different carbon isotopes in the CO2 in the atmosphere. Read the National Academies source! It's short, and it answers every question you have asked, with detailed analysis.

Also, the data directly contradi...

bferman,

there is no proof that humans are the cause of the noticed increase in
CO2 levels since the 70's. In fact, CO2 levels actually decreased
during our industrial age and began increasing during a recession after
the industrial age.

I don't know your standard of "proof," but I cited above extensive evidence that humans are the cause of the currently increased cause of CO2. See my post above "Regarding point 6." It has to do with precise measurements of the ratio of different carbon isotopes in the CO2 in the atmosphere. Read the National Academies source! It's short, and it answers every question you have asked, with detailed analysis.

Also, the data directly contradicts your assertion that CO2 "actually decreased" at any time since the industrial revolution. See Mauna Loa, Hawaii (direct measurements since 1957) and 400,000 years of ice core data (also note the data's sources at the bottom of the page).