Is global warming a reality?

[dixieflatline]

This has been brought up in another thread but I wanted to start a seperate thread to discuss this. Lot's of interesting viewpoints were brought up and the science that in the field is moving forward very rapidly so it can be hard to keep up with.

There are really two parts to the question. First, is the earth really heating up? And then if it is are human's to blame?

Let's start with the first question. There isn't any science behind this it's just a simple measurement. Here is a link to several graphs looking at the mean temperature of the planet:
hxxp://www.pbs.org/wgbh/warming/etc/graphs.html
This is from a NOVA-frontline production on PBS that aired april 2000. The first graph shows the mean temperature of the earth from records of measurements from thermometers. This record goes back to about 1850 and seems to show a recent increase. This is a very short period of time but scientists can also measure the earth's temperature indirectly by looking at trees and ice layers etc... Combining all of these indirect measurements the second graph shows the earth's temperature for the last 1000 years. On this graph it's pretty clear that the temperature is rising in the last 100 years. If you are interested in these indirect measures of the temperature more can be found on this at the PBS website.

So the earth is heating up. This doesn't mean that human's are the cause of the increase. The earth naturally goes though cycles of much wider temperature swings that we see on these graphs. One poster mentioned volcanos which play a huge role in the earth's climate. Natural causes like that or el nino's etc... certainly play an important role. How can we be sure that we are causing the increase?

In fact if you read the transcript or watch the show you will get lot's of guesses but no conclusion as to the scource of the temperature increase. The thoery that greenhouse gasses such as CO2 are to blame is presented and the next two graphs on the link show the ammount of CO2 in the air for the last 40 years(directly measured) and the last 400,000 years(indriectly measured again using the ice cores). Again it's pretty clear that the ammount of CO2 in the air has reached a significantly higher ammount in the most recent years. This doesn't prove that the CO2 was to blame though.

This program though was aired in early 2000 and today it's generally accepted in the science community that indeed global warming is caused by greenhouse gasses such as CO2. There now is a lot of evidence to support this claim but I'm am not an expert in the field so I am only going to show one compelling reason for why scientists now believe greenhouse gasses are to blame.

hxxp://www.esr.org/outreach/climate_change/mans_impact/man1.html
talks a lot about what I just said and at the bottom of the page they show several graphs that are computer simulations of the earth's climate and the real temperature over the last 150 years. The upper left plot shows these models only simulating effects from natural causes(volcanos etc...). This simulation does a reasonable but not great job up to about 1970 and then fails miserably. The upper right plot shows this simulations only using anthropogenic, or human, activity. This graph does a good job predicting the upswing in temperature around 1970 but was way off before that. The bottom plot shows the simulations using both the human and natural effects and now the simulations are spot on. They correctly predict an increase around 1920 that levels off and then another increase around 1970.

A huge technical report can be found at hxxp://www.grida.no/climate/ipcc_tar/vol4/english/index.htm
with more discussion about the computer models and other evidence. This was also talked about in a recent edition of Scientific American Frontiers. You can watch this part of the show here:
hxxp://www.pbs.org/saf/1404/video/watchonline.htm
It's the second second link titled "the heat is on". For some reason before they talk about trusting these computer simulations they show what these simulations predict for the polar ice caps so you can fastfoward through that part if you like.

Note that I haven't said anything about what the U.S. or other contries should do about this. This is a much messier question and I am not about to say that everyone should stop using fossil fuels but I think it's fair to say that the science does point to these CO2 emissions as the cause of global warming.

[Desnudo]

Pretty chilly up here today.

[NoMyths]

Pretty chilly down here today.

[Glengoyne]

Originally Posted by dixieflatline

...
This program though was aired in early 2000 and today it's generally accepted in the science community that indeed global warming is caused by greenhouse gasses such as CO2. There now is a lot of evidence to support this claim but I'm am not an expert in the field so I am only going to show one compelling reason for why scientists now believe greenhouse gasses are to blame.
...

There are a number of Scientists who don't accept that premise. As I understand it, when the Government(Congress) has held hearings on the topic, there are scientific presentations from both sides of the issue. I don't know how prevalent the computer models described in your post are in the debate, but the creation of computer models seems to be a pretty subjective process.

I don't know the truth myself. I do hear statements like "the Earth hasn't been this warm in over two thousand years", that make me wonder what the hell people were doing two or three thousand years ago to heat up the planet.

[DeToxRox]

Let's just make our own theory.

More people = My body heat = Warmer temps.

There. I am king.

[Easy Mac]

hxxp://www.technewsworld.com/story/news/37932.html

God save the polar bear.

And NoMyths, it feels great here.

[dixieflatline]

Originally Posted by Glengoyne

There are a number of Scientists who don't accept that premise. As I understand it, when the Government(Congress) has held hearings on the topic, there are scientific presentations from both sides of the issue. I don't know how prevalent the computer models described in your post are in the debate, but the creation of computer models seems to be a pretty subjective process.

I think that you would find fewer and fewer scientists that disagree. I am not sure when the hearing you are talking about took place but much of the confusion about this issue is that only very recently has there been enough evidence to link CO2 and global warming. If you would have asked the question 5 years ago you would have gotten a much different answer.

The computer models are actually much less subjective than you might think. I should have pointed out that if someone came along with a model that would predict the recent(1970+) increase in temperature then that would change everything. The scientists believe in these models because, ignoring human effects, they match the data well up until recently. This means these models are doing a good job of modeling natural effects on the earth's climate. The fact that these models fail miserable with the recent data tells us that there is something that these models aren't taking into account that now is affecting the system. When you add CO2 effects into these models then they correctly predict the recent increase in temperature.

[Warhammer]

Just my .02.

If you go farther back that 400,000 years I believe the CO2 in the atmosphere increases. However, there are so many other factors besides CO2 that affect globabl temperature it is not even funny.

During the time of the dinosaurs, I believe that the average global temp was 10C hotter than it is today. Scientists believe that the Permian extinction was caused in part by the oceans turning into HCO3 (the oceans leached carbon out of limestone and the temperature was hot enough to cause carbonic acid to form), and killing off most fish species.

Until proven conclusively, and not just looking at a couple of factors that point to their POV, I will not be persuaded that man is causing global warming.

[Raiders Army]

Freaking tree huggers.

Edit: Added a smiley so I wouldn't be a troll.

[sabotai]

Originally Posted by DeToxRoxDVHStyle

Let's just make our own theory.

More people = My body heat = Warmer temps.

There. I am king.

Well then, the solution is pretty clear. We have to kill a few billion people. I'll start rounding up a hunting gang.

[rkmsuf]

I don't see how it's much of discussion. Nobody knows nothing.

Check back in 1,000 years and then we'll talk.

[dawgfan]

A few comments:

- The Earth has gone through many warming and cooling phases. Obviously then there are natural factors that are always involved. Based on previous climes, we are currently considered to be at the tail end of an ice age. It's important to note that average global temperatures don't deviate greatly between "warm" periods and "ice ages" - I believe the average difference is less than 10 degrees farenheit.

- Up until the last century or so, activity by man has been essentially negligable when assessing factors that determine global temperature. Things have now changed - our influence is growing exponentially. The fact that up until now temperature changes on the Earth have all been due to natural causes does not mean that human activity is not now a major factor to be considered.

- Regardless of how much human activity is causing the recent warming trend, human civilization will be affected, perhaps in severe ways. One of the major issues facing humanity is the distribution of resources and how national boundaries are affected by these changes. Access to fresh water will increasingly become the prime strategic resource around the world. There's little credible resistence in the scientific community that the Earth is warming. There is a lot of debate about the cause, but we're all going to feel the effects of the change regardless. However, if there's a possibility that human activity is a major part of the current climate change, then we owe it to ourselves to place great importance on studying the cause - if there are activities we are engaging in that are contributing to this climate change, we need to know this and make informed choices about what is more damaging - ceasing or greatly reducing these climate changing activities, or the results on our ecosystems of allowing these effects to continue to modify our climate.

[sterlingice]

Originally Posted by Warhammer

Just my .02.

If you go farther back that 400,000 years I believe the CO2 in the atmosphere increases. However, there are so many other factors besides CO2 that affect globabl temperature it is not even funny.

During the time of the dinosaurs, I believe that the average global temp was 10C hotter than it is today. Scientists believe that the Permian extinction was caused in part by the oceans turning into HCO3 (the oceans leached carbon out of limestone and the temperature was hot enough to cause carbonic acid to form), and killing off most fish species.

Until proven conclusively, and not just looking at a couple of factors that point to their POV, I will not be persuaded that man is causing global warming.

Yeah, well, that's all well and good but if we are somehow heating up, we need to find ways to counteract it. If limiting CO2's will do it, great, start doing that. The argument that just baffles me is when people say "well, it was really hot X years ago so it's just part of the natural cycle". While this is true, there weren't people in {insert coastal city here} X years ago so I would think we have a vested interest in controlling this cycle and decreasing the amplitude of said cycle.

SI

[Blackadar]

I don't think there's really almost any dispute as to wether the Earth is warming up. There are *very* few scientists who claim there isn't a warming trend.

The disputes are the cause of the warming (is it normal or have humans and the burning of fossil fuels had a substantial impact), the term (is this a long term thing or a short-term abberation) and the impact (disasterous or nothing to "sweat" over).

[Glengoyne]

Originally Posted by sterlingice

...I would think we have a vested interest in controlling this cycle and decreasing the amplitude of said cycle.

SI

Rage against the ....Planet?

[sterlingice]

Originally Posted by Delebar

Here's Bush's response to global warning - I'm sure Glengoyne would approve were he aware of it, which I'm equally certain he's not.

Um... I'm pretty sure that was uncalled for since he really hasn't said much in this thread, particularly not belligerent...

SI

[Glengoyne]

Originally Posted by sterlingice

Um... I'm pretty sure that was uncalled for since he really hasn't said much in this thread, particularly not belligerent...

SI

Thanks for the support SI. I too was wondering what I said in this thread to earn that.

My position on global warming is that I don't know that man is responsible for it. That may be the case, but I don't think it can be called a certainty. I do agree with you that it would be prudent to do what we can to curtail it. I am not sure we should make a large investment in an attempt to slow/stop/reverse global warming, when that attempt(Kyoto accord) is simply someone's best guess as to what will actually slow/stop/reverse the current warming trend. I mean I think we need/want to do something, but I'd like to be more confident that there will be results. I'm not saying we should write off any attempt to control greenhouse gas emissions, or whatever other measures people have put forward. I'm just saying it seems risky to adopt a practice that might result in no net results in the next 50 or 100 years.

Now that I've laid out my position, I'm sure Delebar feels I deserved his initial post, because I'm certain my position differs from his own, and was therefore arrived at in ignorance.

[JAG]

That would be definitely uncalled for.

[JeffNights]

In short? No.

but i do believe its part of the Earths natural cycle.

[Dutch]

Has anybody asked the people freezing their nuts off in Tierra Del Fuego if they want us to fight global warming?

[sterlingice]

Originally Posted by Dutch

Has anybody asked the people freezing their nuts off in Tierra Del Fuego if they want us to fight global warming?

Because I'm sure one example in a global system is representative of the entire system and trends.

SI

[Dutch]

It was a joke SI, go to bed and get some sleep, brother!

[sterlingice]

Originally Posted by Dutch

It was a joke SI, go to bed and get some sleep, brother!

*whines* But I can't! I have to finish homework for Networks and Databases. Why else do you think I'm on here?

SI

[Desnudo]

If North Korea ever completes that sun shield we're all doomed anyway.

[sterlingice]

Originally Posted by Desnudo

If North Korea ever completes that sun shield we're all doomed anyway.

You got it all wrong. Mr Burns made the sun shield. The North Koreans made a giant sun-based space laser.

SI

[Chief Rum]

Originally Posted by sterlingice

Um... I'm pretty sure that was uncalled for since he really hasn't said much in this thread, particularly not belligerent...

SI

A huge overreaction from Delebar? No, that's never happened before.

CR