Global warming - caused by humans or not?

[tdb]

Started in another thread:

I for one believe "Global Warming" is nothing but a cycle the earth goes through over thousands of years and has nearly nothing to do with humans. Yes we may help it along, but what is a car or factory in relation to a volcano? almost nothing. Then add how many volcanoes erupted since the ice age... we have nothing to do with it.

According to Wikipedia, Volcanic activity releases about 130 to 230 teragrams of carbon dioxide each year. Pulling some figures out of my hat, let's say that there are one billion cars in use, each being driven an average of 20 kilometers a day, and emitting 100 grams of CO₂ per kilometer. This works out to 2 teragrams per day, or 730 teragrams per year. While that's not enough to put us ahead in total emissions in the last 15000 years (given that we've driven cars in a large scale for less than 100 years), we're certainly making good progress towards that.

Sorry to turn this into a political thing but
A. it was a rhetorical question
B. Where did you get your numbers? that wiki entry has none relating to vehicles or factories.
C. you might want to check your math
D. you can't measure a gas in mass without density or volume
E. the two numbers that Wiki does have however is that of modern day activity where over 90% of volcanoes are dormant or destroyed

B. From my hat as I said The number of cars and amount of driving are guesses, emissions came from googling for "car emissions".
C. Sure. 1 teragram is 10¹² grams. 1 billion is 10⁹. 20 km/day times 100 g/km makes 2000 g/day (i.e. 2*10³) for a single car. Multiply that by one billion and we get 2*10¹² g/day. And that times 365 days/year makes 730*10¹² g/year, i.e. 730 teragrams per year. I know I am not infallible, so if you spotted an error I somehow missed, kindly point it out to me.
D. Sure you can. As strange as it might feel, gases do have mass. They consist of atoms, and every single atom has a mass.
E. I couldn't find any graphs or other information going back more than about 200 years, but from those it seems that volcanic activity has actually been increasing recently.

While looking for graphs of volcanic activity, I found one interesting piece of information: "According to the US Geological Survey, however, estimates are that human activities generate more than 130 times the amount of carbon dioxide emitted by volcanoes."

Now, please take a look at these graphs. Note how the global temperature was declining very slowly for nearly 1000 years, then took a sharp turn and started to rise relatively fast in the early 20th century. Also note how CO₂ levels are now significantly higher than at any point during the past 400000 years. Can you claim that these have nothing to do with humans and industrialization?

 

[Civ Fuehrer]

I don't think your hat should be a viable source, but I'm not going to lie, I'm a terrible debater. I would like to see the sites from the google search that gave you the car emission numbers. Being 3:00AM here, i can't think too clearly although i do know gas is made of atoms and have known that for 8 years now back in 4th grade(yes, i'm a senior in HS). But all that's beside the point, it is inevitable, it's merely a cycle that we've barely sped up, and it can't be stopped. You've started a fight against someone who wasn't looking for one just because your a liberal who wanted to protect a fanciful idea that humans are the cause of a warm apocalypse when it is just a cycle. And for god's sake, look up what a rhetorical question is before you answer. This is suppose to be a fun game that simulates earth in what-if map layout and game play, not a fight of off-topic political ideas. I may have learned a few things, but my belief still stands; it is an inevitable cycle. Now goodnight.

 

[tdb]

I don't think your hat should be a viable source, but I'm not going to lie, I'm a terrible debater. I would like to see the sites from the google search that gave you the car emission numbers.

This one. The number I used is close to the cleanest cars, while the dirtiest are almost 5 times as bad.

But all that's beside the point, it is inevitable, it's merely a cycle that we've barely sped up, and it can't be stopped.

Yes, history clearly shows that cycles of warm and cool periods are a natural occurrence. But if we speed the process up too much, can we adapt to the changes fast enough?

You've started a fight against someone who wasn't looking for one just because your a liberal who wanted to protect a fanciful idea that humans are the cause of a warm apocalypse when it is just a cycle. And for god's sake, look up what a rhetorical question is before you answer.

I wasn't so much answering the rhetorical question as countering your point about humans having no effect on global warming. See above about hastening the inevitable. While global warming is not all our fault, we definitely have some effect on it.

This is suppose to be a fun game that simulates earth in what-if map layout and game play, not a fight of off-topic political ideas.

Which is why I moved the discussion off the game forum.

 

[AngryZealot]

a fight of off-topic political ideas.

We've got a problem if we're confusing science with politics; or, more accurately, if we're letting science be politicized.

In any case, does this look like "merely a cycle" to you?

 

[sedna17]

In any case, does this look like "merely a cycle" to you?

Careful here -- although the climate cycles are not apparent on the timescale of a few thousand years, they are real and possibly start on very short timescales. This chart is from the Vostok ice cores, and you can clearly see that there are very large temperature cycles (obviously the temporal resolution is insufficient to say if these events ever started as quickly as the temperature rise we are currently seeing). This shows that non-human causes can have a profound impact on global temperature, which of course does not prove anything one way or another about the impact of human activity on the present and near-term global temperature, for that you would have to look at the rest of the scientific evidence.

 

[uppi]

You might want to compare the CO2-concentrations on your chart and the current CO2 concentrations in the atmosphere.

Looks man-made to me.

 

[sedna17]

Oh, certainly the CO2 concentrations are much higher than at any other time in the recorded history of the planet, and by far the best explanation for that (really the only logical one given the timing of its rise and the fact that we do in fact pump lots of CO2 into the atmosphere) is human activity.

This is not a priori connected to temperature rise -- although CO2 is certainly a greenhouse gas the earth is a complex system. It is connected to temperature rise (mostly) through the predictions of models which show that the details of temperature increase we are seeing (as a function of latitude and altitude for example) are well modeled by increasing in CO2 in patterns consistent with human activity.

 

[peter grimes]

Here's a challenge:

If you doubt that humans are a major factor in climate change, why not donate some of your processor time to help refine the computer models that will resolve the issue?

http://climateprediction.net/

 

[Ghpstage]

Here's a challenge:

If you doubt that humans are a major factor in climate change, why not donate some of your processor time to help refine the computer models that will resolve the issue?

http://climateprediction.net/

Thank you for using the term climate change . Its a much better term as we don't entirely understand the result of the huge number of diffferent things we are doing that affect the environment.
Plus with 'global warming' you get the "2 degrees warmer is a good thing" crowd.... also I wonder why our direct output of CO2 seems to be the only thing people ever mention in these discussions .
The deforestation we have caused in the past, erm 2,000+ years (Just when did we become good at this anyway!?) must have had a considerable effect right? Then we have dessertification that humans have contribututed to, and the drying out of lakes and a whole host of other things that are barely ever mentioned in the popular media.

Does anyone know of any credible (Kinda discounts anything attached to the Bush Administration US government ) sources that have evidence to argue against human caused climate change btw?

 

[AngryZealot]

Careful here -- although the climate cycles are not apparent on the timescale of a few thousand years, they are real and possibly start on very short timescales. This chart is from the Vostok ice cores, and you can clearly see that there are very large temperature cycles (obviously the temporal resolution is insufficient to say if these events ever started as quickly as the temperature rise we are currently seeing). This shows that non-human causes can have a profound impact on global temperature, which of course does not prove anything one way or another about the impact of human activity on the present and near-term global temperature, for that you would have to look at the rest of the scientific evidence.

I don't mean to offend, but it sounds a lot like hand waving. The big challenge climate change skeptics have to overcome is this:

The computer models generally predict the trend in climate change, but only if they include anthropogenic CO2 in their calculations.

It's not perfect, but all else aside, that's as close to a smoking gun as you are going to get. (Again, all else aside; there's a lot more supporting anthropogenic climate change.) What is the refutation to these computer models?

 

[peter grimes]

I'm not sure why people latch onto the CO2 more than other things. After all, we've been hearing an awful lot about ruminant methane lately. But again, this is due to human activity, not wild herds.

My own view is that whenever humans start doing anything it's going to have an effect - just by due to the sheer efficiencies at our disposal. even stone-age man was able to achieve continent-wide ecosystemic alteration, and yet at much lower population densities. To be sure, there's still some dispute about that. But we are very good at whatever we put our minds to. So if we decide that Mammoth steaks are the tastiest thing around, we'll make sure to eat every last one...

 

[Ghpstage]

After all, we've been hearing an awful lot about ruminant methane lately. But again, this is due to human activity, not wild herds.

Sadly, most of the time I hear about this it takes the form of a bizzare counterargument against climate change that I think, is created due to the "CO2 is the only cause of global warming" straw man.
The most common form is that as methane is a more potent greenhouse gas than CO2 and most of the methane produced on Earth is from cows then cows are responsible for climate change not us....

To me this issue seems scarily similar to the Creationist-Evolution issue in the US, where Creation 'Scientists' (Oxymoron!) funded by laregly pro-religious institutions (in this case its almost exclusively US based industry like Exxon Mobil) create lots of confusion in the public through the use of straw men, misrepresenting data, and claiming conspiracies and discrimination everywhere .
(i.e. in the case of climate change, holding on to the term 'global warming' term and then declaring that if it gets colder we can't be having any effect at all ).

Unfortunately these groups realise that while science isn't a democracy, what is done with the science IS driven by 'democracy' (even in the private sector)

it's merely a cycle that we've barely sped up, and it can't be stopped. You've started a fight against someone who wasn't looking for one just because your a liberal who wanted to protect a fanciful idea that humans are the cause of a warm apocalypse when it is just a cycle

Underlined - Science realises there are cycles involved in this, but just because there are cycles doesn't mean we don't have much effect. The worldwide general consensus of relevant scientists says we are having a significant impact, the debate is mostly about: How significant? What will it cause? What to do about it?

Bold - Yay ad hominem, and whats wrong with being 'liberal'?

 

[AngryZealot]

It was an ignorant statement, but it wasn't an ad hominem. Reality has a well known liberal bias .

 

[sedna17]

I don't mean to offend, but it sounds a lot like hand waving. The big challenge climate change skeptics have to overcome is this:

The computer models generally predict the trend in climate change, but only if they include anthropogenic CO2 in their calculations.

It's not perfect, but all else aside, that's as close to a smoking gun as you are going to get. (Again, all else aside; there's a lot more supporting anthropogenic climate change.) What is the refutation to these computer models?

I think you misunderstand my point. I agree with you that computer models are the key to proving that human are driving climate change, and I agree that they show this. I just think it's generally important that people understand that this is the connection required to prove the point.

 

[peter grimes]

...computer models are the key to proving that human are driving climate change...

Maybe, maybe not. The only thing the models are good for is predicting the future climate trends based on the past trends. Models themselves won't say that humans are the cause or not. The models rely implicitly on data we feed in - data about concentrations of different gasses, oceanic circulation patterns, vegetative coverage - many of the things that SimEarth was doing when I was in college 15 years ago

We only have solid input data after around 1950 - present. The closer you get to the present, the more data there is, and of a finer resolution. Input all that into a model, and press rewind. If the model accurately 'predicts' what happened in the past (as near as we can tell), then we can assign a higher confidence in the predictions of the model.

But here's one thing I don't know anything at all about: Are there climate change skeptics who run the same models, and derive different results? It's one thing to say 'Climate change isn't going on - it's just a bunch of liberal baloney'. But it's quite another to use the same methodology and still claim bias...

 

[peter grimes]

just saw this on ScienceDaily...

 

[raigainousa]

I'm not sure why people latch onto the CO2 more than other things. After all, we've been hearing an awful lot about ruminant methane lately. But again, this is due to human activity, not wild herds.

Yes I agree with you. Methane is 23x more powerful than CO2.

it's merely a cycle that we've barely sped up, and it can't be stopped. You've started a fight against someone who wasn't looking for one just because your a liberal who wanted to protect a fanciful idea that humans are the cause of a warm apocalypse when it is just a cycle

Cycle? We need to remember that earth's atmosphere is sensitive to ANY change...

 

[Narz]

just saw this on ScienceDaily...

Way To Cut Cattle Methane, Threat To Environment, By 25 Percent

If people ate 50% less beef you could cut it by 50% even!

If people stopped wasting food you could probably cut methane by another 10-25%. My first job was a dishwasher at a restaurant & on a very busy night I probably thru away half a cow's worth of beef. And that's just one guy @ one suburban restaurant on a Friday night.

 

[peter grimes]

And that's just one guy @ one suburban restaurant on a Friday night.

I'd add a qualifier to that: one guy at one [American] suburban restaurant... it's well known that the USA consumes more beef per capita than any other society.

 

[Narz]

Yeah, we also waste a lot of food in general.