How do we know Global warming is man's fault and not cyclical, since it happened before man existed as well?

Question

Ice Ages and Global Warming have happened many times on the earth. Why is it man's fault this time?

To those of you who say I am espousing something - I am not. I am asking. Isn't what this sight is for? I am asking for proof it is man. If I get proof, I will believe which ever side gives me proof.

I am not going to believe anyone whose proof is that I am on the wrong side of the discussion. I am on neither side.

Good grief, can't anyone answer a question without foaming at the mouth?

Answer 1

Interesting first reply. One fact and that takes care of it?

How about this one? The planets in our solar system are all registering higher temperatures right now. Quite a few of them have no humans on them. The Mars polar caps are melting. What is the common denominator in all of these planets, if not man? Hmmm. Let's see. Could it be the sun?

Ah yes, the sun. That big thing in the middle of the solar system is making all of the planets hotter. I am sure the Mars caps melting is not the fault of humans. Unless, hmmm, the missing Mars ships aren't really missing! That's it! They landed at the poles and are heating the Mars caps so we will think it is the sun, not us! Brilliant! Nothing like a nice conspiracy theory, is there?

Answer 2

Whoever stated you're espousing an issue said that b/c that is a tactic anti-GW's use.
Yes, warming and cooling effects within the climate have happened before but now we have the science and knowledge to counteract it. Humankind has added to a problem that already exists. Yes, the climate may have started warming up as a natural change but emitting so much CO2 into the air is making it worse. I believe it is cyclical but also that humankind's activities could alter the severity of those changes.

Answer 3

I work with many meteorologists, and I will try to give an unbiased and concise explanation.

1. No one has or will ever be able to offer proof that man is the primary cause of today's global warming trend. There are too many unknowns and not enough centuries of climatic data to rule out other factors that affect climate change (i.e. precipitation distribution, polar cap sizes, sun cycles, volcanic eruptions, etc.)

2. There is scientific data (mainly the rise in CO2 emissions) that shows a correlation between the rise in CO2 and global temperatures. Many people (not necessarily scientists -- sorry Parrot!) believe that correlation indicates that man is contributing to some extent to global warming. Whether man is contributing 0.00001% or 100%, no one can prove, although it's surely some number in between.

(As a side note, I know that some people here have cited computer models that "prove" man has caused global warming. This is a common fallacy; these computer models have only shown that a correlation between man-made CO2 and global warming exists, and these computer models then predict future trends or explain past trends based on that correlation. I stress to you that these climate models are not perfect and are built from limited and incomplete data sets. Furthermore, correlation is not the same as proof. After all, there is a correlation between global warming and the Cubs not winning the World Series. That doesn't mean that global warming will continue until the Cubs win it all. Again, correlation is not the same as proof.)

3. The real question that needs to be answered is this: Can man STOP global warming? Even if every human on this planet moved to Mars, it's possible that global warming would continue regardless. There's not enough research yet to know one way or another.

Given man's lack of technology to date of being able to control weather (much less accurately predict it consistently for any period outside of four days), I share healthy skepticism when anyone offers man-made solutions "guaranteed" to stop global warming.

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Parrot: "Climate models are not stastical models, they are physical in nature. They're built from the laws of physics, not data."

Sorry, Parrot, you are so wrong on this one. ANY advanced computer-based climate model used by meteorologists has to be initially seeded with real or simulated data. Without that data, you'd never get the pretty climate outlooks like those found at http://www.cpc.ncep.noaa.gov. And even with the initial data, these climate outlooks are rather vague when it comes to conclusions.

Perhaps you're talking about long-term (years/decades) climate models that simulate atmospheric changes. Given the time frames involved, the predictions those models make are even less reliable than the ones NOAA's Climate Prediction Center pumps out. To support wide-sweeping climate theories with those models is nothing more than educated guesswork -- not evidence and/or proof.

Answer 4

This is what two scientists in New Zealand are saying. That climate goes through natural cycles.

http://www.scoop.co.nz/stories/SC0704/S00023.htm

Climate has gone through many drastic changes in the past. It has even gone through extremely fast changes. It is hard to "globalize" climate because different parts of the earth are tilted different ways towards the sun. There are also jet streams that change directions. El Ninos and La Ninas. Ice Ages, etc... On earth, you cannot have a global formula for the greenhouse effect. You can only measure it locally. The reason is that most of the earth is made up of ocean which dissipates the effect of greenhouse gases. The climate system is very complicated.

Climate science is like Astrology. Astrology is a well worked out system. It is very mathematical. It has correlations of cause and effect with direct measurements of the movements of every heavenly object available. But the results are always wrong. The reason? It's a cargo cult science.

Read Richard Feynman's description of cargo cult sciences

http://en.wikipedia.org/wiki/Cargo_cult_science

http://www.lhup.edu/~DSIMANEK/cargocul.htm

Sounds a lot like Climatology!

Answer 5

Much is known or inferred about past warming periods that were, of course, caused by natural forcings.

Several things are different about the current warming:
1) The rate of warming is much faster than past natural warmings.

http://gristmill.grist.org/story/2006/10/26/20495/240


2) The amount of warming can be accounted for by an increase in the greenhouse gas, carbon dioxide. The increase in carbon dioxide is well-observed, and in models of the Earth's atmosphere, adding that much carbon dioxide essentially explains the observed warming.

http://gristmill.grist.org/story/2006/12/22/224450/84

3) The excess carbon dioxide has an isotopic signature that is consistent with its origin being the burning of fossil fuels. Furthermore, the amount of greenhouse gasses released by human activity is known, and the "excess" carbon dioxide is less than the amount released by human activity.

http://gristmill.grist.org/story/2006/12/17/235212/60


4) Humans continue to burn ever larger quantities of fossil fuels, leading to ever higher values of atmospheric carbon dioxide.

The big question for the future is the rate of natural greenhouse gas release and sequestration. These natural process have the potential to either amplify, or diminish, the effects of anthropogenic greenhouse gasses. There is much uncertainty about what will happen, and some of the plausible scenarios are very bad indeed.

Answer 6

We know, or are at least very confident, that humans are mostly responsible global warming for several reasons.

Scientists have produced very refined and very accurate physical models of the climate. Scientists can input the various factors affecting the climate into these models. And they have found that when only natural factors are included, the model projections do not match the observed data. But when they add both natural and anthropogenic factors into the models the projections match the observations almost perfectly. This tells us that no known natural forcing can be responsible for the observed warming.

Another line of evidence is that atmospheric concentrations of many gases--primarily carbon dioxide, methane, and nitrous oxide-- have been increasing because of human activities. We know these physical properties of these gases, and we know they trap thermal energy in the atmosphere through the well know "greenhouse effect" and warm the planet, making life on Earth possible. Adding more of these gases to the air will cause the planet's temperature to go up.
We know these gases are increasing because of human activities. Some of them, such as the halocarbons once used as refrigerants, have no natural source. For the others, such as carbon dioxide, two important observations demonstrate where they came from. First, the geographic differences in the levels of these gases show that their source is primarily over land in the heavily populated northern hemisphere region. Second, analysis of isotope ratios reveals whether or not the gases resulted from natural processes of the combustion of fossil fuels.

3DM, you may feel free to tear into my post at your leisure.

Edit: Fotpunk, There are no scientists who believe that the correlation between temperatures and CO2 levels is proof of anthropogenic warming. The correlation is simply evidence supporting the theory. It is a common mistake to assume it is the basis of it.

Climate models are not stastical models, they are physical in nature. They're built from the laws of physics, not data. The only inputs required are the boundary conditions and the changes in external forces (such as orbital variations, the solar constant, and greenhouse gases). They do not attempt to extrapolate future trends based on historical trends.

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Fotpunk, I edited the post just before you replied. See my new and improved (it makes julienne fries!) wording.

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Fotpunk, this (in highly condensed form) is how scientists construct a physical climate model:

"Here are the laws of physics. Here is what the climate is doing now. Here is a scenario of some possible future forcing (say, emissions doubling what they are now). Play."

They =don't= say:

"Here is what the climate =was= doing. Here is what we think it =will= do based on that."

This is what I meant by "Climate models are not stastical models, they are physical in nature. They're built from the laws of physics, not data."

Check out this RealClimate article for more detail:

http://www.realclimate.org/index.php/archives/2007/04/learning-from-a-simple-model/

Answer 7

Simple; we don't. Research on climate change is relatively new and there is still a lot to be discovered.

I still do not understand the politics that spew from both sides of this "debate." There is really nothing to argue over, we have what the scientists know and we wait for and speculate over what they don't know. In the meantime we can do our best to be good stewards of the earth as far as practicality allows, keep ourselves up to date on any new developments with climate change and be prepared for any ill weather that may come our way.

PS: I'm also sick and tired of seeing wikipedia as a source, especially from people who should know better. One of the first things you learn when writing research papers in college is DO NOT USE WIKIPEDIA.

Answer 8

The fact that the planet has gone through natural climate changes (attributed to Milankovich Cycles as described by nj above) does not mean that humans can't cause a climate change. This is a logical fallacy.

We know humans are the primary cause of the current global warming because natural causes simply can't account for it:

http://news.bbc.co.uk/2/hi/uk_news/6290228.stm

The very first effects scientists put into their climate models were natural ones like solar and volcanic contributions, but they didn't even come close to accounting for the recent acceleration in warming. Only when they factored in human greenhouse gas emissions (which they determined have caused 80-90% of the warming over the past 40 years) could they account for the increased global warming:

http://en.wikipedia.org/wiki/Image:Climate_Change_Attribution.png

Answer 9

The Earth was coming out of an ice age anyhow, so we haven't really caused global warming, but we have probably accelerated it.

However, the world has been much warmer than this before now and with no ice caps, and life survived quite happily, so for me we should not be trying to stop global warming but figuring out the best way to adapt to it.

Answer 10

It's a matter of degree. There have been warmings and coolings before, but nothing on this scale since life has been on land.