Evidence for CO2 causing global warming?

[Eriku]

Thank god man-made global warming was proven to be a hoax. Just imagine what the world might have looked like now if those conspiring scientists had been telling the truth. No doubt NASA would be telling us that this year is now, so far, the hottest since humans began keeping records. The weather satellites would show that even when heat from the sun significantly dipped earlier this year, the world still got hotter. Russia's vast forests would be burning to the ground in the fiercest drought they have ever seen, turning the air black in Moscow, killing 15,000 people, and forcing foreign embassies to evacuate. Because warm air holds more water vapor, the world's storms would be hugely increasing in intensity and violence -- drowning one fifth of Pakistan, and causing giant mudslides in China.

The world's ice sheets would be sloughing off massive melting chunks four times the size of Manhattan. The cost of bread would be soaring across the world as heat shriveled the wheat crops. The increased carbon dioxide in the atmosphere would be fizzing into the oceans, making them more acidic and so killing 40 percent of the phytoplankton that make up the irreplaceable base of the oceanic food chain. The denialists would be conceding at last that everything the climate scientists said would happen -- with their pesky graphs and studies and computers -- came to pass.

This is all happening today, except for that final stubborn step. It's hard to pin any one event on man-made global warming: There were occasional freak weather events before we started altering the atmosphere, and on their own, any of these events could be just another example. But they are, cumulatively, part of a plain pattern where extreme weather is occurring "with greater frequency and in many cases with greater intensity" as the temperature soars, as the US National Climatic Data Center puts it. This is exactly what climate scientists have been warning us man-made global warming will look like, to the letter. Ashen-faced, they add that all this is coming after less than one degree celsius of global warming since the Industrial Revolution. We are revving up for as much as five degrees more this century.

Yet as the evidence of global warming becomes ever clearer, the momentum to stop it has died. The Copenhagen climate summit evaporated, Barack Obama has given up on passing any climate change legislation, Hu Jintao is heaving even more coal, David Cameron has shot his huskies, and even sweet liberal Canada now has a government determined to pioneer a fuel -- tar sands -- that causes three times more warming than oil. True, the victims are starting to see the connections. The Russian President Dmitri Medvedev has been opposed to meaningful action on global warming, until he found the smoke-choked air in the Kremlin hard to breathe. But if we wait until every leader can taste the effects of warming in their mouths, the damage will be irreparable.

Given the stakes, the reasons why so many people still refuse to accept the evidence can seem oddly trivial. A common one is: "It snowed a lot in the US and Britain last year. Where was your warming then, eh?" But scientific theories are based on patterns, not individual events. You might know a 90-year-old woman who has smoked a pack of cigarettes every day of her life and is totally healthy. (I do.) It doesn't disprove the theory that smoking causes lung cancer. In the same way, one heavy snowfall doesn't prove anything if it is part of a wider overall pattern of dramatic warming. And that snow probably was. While it snowed a lot in a few places, there were at the very same time harsher, more bitter droughts in many more places -- making it globally the fifth hottest winter ever recorded, according to the US National Oceanic and Atmospheric Administration. (All the others were in the past decade). And that winter is your punchline proof that warming isn't happening?

But the broader public mood, smeared like sunscreen over us all, isn't active denial. No -- it's the desire to endlessly postpone this issue for another day. In 1848, a 25-year-old man called Phineas Gage was working on constructing the American railroads. It was his job to lay explosives to clear rocks out of the way -- but one day his explosive went off too soon, and a huge metal rod went through into his skull and out the other side. Amazingly, he survived -- but his personality changed. Suddenly, he was incapable of thinking about the future. The idea of restraining himself was impossible to grasp. If he had an urge, he would act on it at once. He could only ever live in an eternal present. As a civilization, we are beginning to look like Phineas Gage on a planetary scale.

Yet scattered among us there is a fascinating group of people who are offering a path to safety. Every summer since 2006, ordinary British citizens have built impromptu camps next to some of the most environmentally-destructive sites in Britain and taken direct action to shut their pollution down. So far, it has worked: They played a crucial role in the cancellation of the third runway at Heathrow and a big new coal power station at Kingsnorth.

That's how earlier this week I found myself on a high wooden siege tower in a camp in the Scottish hills, staring down across a moat towards the glistening, empty offices of the Royal Bank of Scotland (RBS). You own this bank: 84 percent of it belongs to the taxpayer after the bailouts. Yet it is using your money to endanger you by funding the most environmentally-destructive behavior on earth, like burning the tar sands. The protesters chose to come here democratically -- everything at the climate camps is done by discussion and consensus -- because they have a better idea. Why not turn it into a Green Investment Bank, transforming Britain into a global hub for wind, solar and wave power? Why not go from promoting misery across the world to being a beacon of sanity?

So the protesters risked arrest in marching on RBS' offices because they know the stakes. As Professor Tim Flannery, one of the world's leading climate scientists, explains:

My great fear is that within the next few decades -- it could be next year, or it could be in fifty years, we don't know exactly when -- we will trap enough heat close to the surface to our planet to precipitate a collapse, or partial collapse, of a major ice shelf... I have friends who work on the West Antarctic Ice Sheet, and they say [when a collapse happens] you'll hear it in Sydney... Sea levels would rise pretty much instantaneously, certainly over a few months. We don't know how much it would rise. It could be ten centimeters, or a meter. We will have begun a retreat from our coasts... Once you have started that process, we wouldn't know when the next part of the ice sheet would collapse, we don't know whether sea level will stabilize. There's no point of retreat where you can safely go back to... I doubt whether our global civilization could survive such a blow, particularly the uncertainty it would bring.
Nature doesn't follow political fashion. Global warming may not be hot today, but the planet is -- hotter than ever. When you stare out over the wave of Weather of Mass Destruction we are unleashing, who looks crazy -- the protesters, or the people who have yet to join them?

An excellent source of clear, accessible videos debunking denialist claims can be found here.

Johann Hari is a writer for the Independent.

http://www.huffingtonpost.com/johann-ha ... 96704.html

[mistermack]

Aaand, I think I'll probably leave this discussion there. (As you might have been able to tell from my earlier posts), I wasn't very well read on these particular issues!, and your questioning here has prompted me to read up and try to learn about them so I can pass it on, because I found the discussion interesting at least!

Likewise, and thanks for your input. I will reply to this, but I'm sure you wouldn't agree with my replies, so nobody is claiming that having the last word "wins" in any way.

You're right - the cause does have to come before the effect, and we know what the cause and effect are, and how they interact. However, the term covariance doesn't imply any causality!

Agreed, but this is what I referred to :

This covariation provides compelling evidence that CO2 is an important forcing factor for climate

I agree it's not worth persueing, but it's not semantics, the meaning of the words is crystal clear, and the opposite of the truth.

Even across those past records, we're talking about only a couple of degrees warming on average over a periods of tens of thousands of years - that alone should indicate how much different the current trend is.

Not really. We are comparing a miniscule blip, ( 35 years ) to tens of thousands of years, you can't do that. Those averages hide many thousands of blips and spikes, some up, some down. Look at the temperature graph again, it starts off smooth, 450,000 years ago, and gradually gets more and more spikey, and the last thousand years is incredibly spikey. This must mean that the "spikeyness" is gradually lost as the samples get older. Not surprising considering their age.

The last 25,000 years probably gives the best indication of real variation, but I doubt if even that gives a real idea of just how variable temperatures were over timescales of less than fifty years.
What we've had in the last fifty would probably not even register, to people taking cores in 100,000 years time.

The insolation graph at the bottom here shows how much of the suns energy falls over the northern hemispehre. ((Link) - and as the orbit changes slightly, those variations even below the 100,000 year timescale do match up to the ice cores quite remarkably.

They do, fairly well, but something doesn't look right. The insolation spikes seem to start AFTER the temp and CO2 spikes, by several thousand years. Maybe it's just badly drawn.
In any case, this seems to point at the sun being more responsible for climate variation, than the greenhouse effect.
You can cling to the idea of it being just a trigger, but I believe you should look at the obvious first.

The gun is already loaded. The ice ace does that for you, it has a massive albedo from reflecting ice, lots of greenhouse gasses trapped in the ice sheets which are quite happy to be released. The moment you add that small warming trigger to that mix you'll set things off. Start melting the ice a bit, warm the ocean a bit, release more C02.. and etc etc. Considering it takes in the thousands of years to leave an ice age, the ~800 year lags turn out to be pretty insignificant, there is more than enough time for them to get to work.

But you seem to be saying that the feedback loops are constantly primed to go both ways. I would have thought that highly unlikely. Feedback means the effect amplifies the cause. Why would the global temperatures take a dive in 1945, after rising for fifty years. Just as CO2 output rose dramatically? This is directly contrary to a fifty year feedback loop. And you can't claim it ran out of "feedback fuel", because it resumed rising around 1970 ish.

I don't see the falls as being incredibly gradual on any of the ice core graphs. They're a bit less pronounced than the temperature increases, but not massively.

This is what I see as trends in the Temp graph. Obviously time flows the opposite way to the arrows.
I think it shows we are due for a significant cooling period.

Positive feedback loops are one of the most powerful things in science, if only because they can keep going through until one of the stages of the loop becomes saturated. For example, in the loop I use in my main example, if the amount of C02 that can be output by the ocean warming begins to slow down, then the absorption can one again overtake the output and will start reversing the activity of the previous loop. The climate sensitivity from such feedback loops has been discussed (link, link) - and found to be significant.

I think there is a huge danger in proposing feedback loops for the future. It's multiplying one piece of speculation with another.
You could maybe use it to interpret the past, but even that is dicey, in a field where so much is not yet understood.
By all means use past records to try to forcast the future, but remember it's pure guesswork, especially when trying to forcast climate for just the next 100 years. The spikeyness of the graphs shows just how unpredictable that is.

Anyway, thanks again for the input. You have made me look a bit closer at the subject.

To be brutally honest, at my age, it's no great concern. I quite like the milder winters, although that's tailed off a bit. But if they are a bit shorter, I'm happy with that. And I'm similarly unconvinced about a couple of degrees warming being all that bad for the world. It would be great for Russia, and Canada.
.

[mistermack]

There are few unbiased reports available on global warming, but even those who are "on message" have to admit to gaping holes appearing :

Climategate U-turn as scientist at centre of row admits: There has been no global warming since 1995

He also admits there has been no "statistically significant" warming in the last 15 years. Click below for the article :
http://www.dailymail.co.uk/news/article ... nised.html

What happened to global warming?
This headline may come as a bit of a surprise, so too might that fact that the warmest year recorded globally was not in 2008 or 2007, but in 1998.

http://news.bbc.co.uk/1/hi/8299079.stm

What has happened to the missing heat?
Current observational tools cannot account for roughly half of the heat that is believed to have built up on Earth in recent years, according to a "Perspectives" article in this week's issue of Science.

http://www.physorg.com/news190558013.html

How come they can give all these highly speculative possibilities, but can't bring themselves to even mention the possibility that the models are wrong? That the heat is escaping past the CO2 as it usually does?
.

[Warren Dew]

Note that the lower graph has been moved about 800 years to the right, making an excellent match.
http://en.wikipedia.org/wiki/File:Vostok_Petit_data.svg

It looks to me like the peaks are offset by about the same amount as the axes are offset. That makes the peaks coincident, with no 800 year delay.

Can you be specific about where you are seeing an 800 year delay?

[mistermack]

Note that the lower graph has been moved about 800 years to the right, making an excellent match.
http://en.wikipedia.org/wiki/File:Vostok_Petit_data.svg

It looks to me like the peaks are offset by about the same amount as the axes are offset. That makes the peaks coincident, with no 800 year delay.

Can you be specific about where you are seeing an 800 year delay?

Well, it's not just me saying it Warren, several scientific studies have been done on the ice core records, and the conclusions vary, but they all identify a delay, and the latest and most extensive ones conclude an 800 yr delay as the best average.
As the offset should be less than one fiftieth of one graduation, it's not going to be that obvious anyway.
I must confess, I can't make out the offset that you mention though.
.

[mistermack]

Even scientists who are advocates of global warming agree with the 800 year lag, it's pretty well undeniable from the careful studies that have been done.
http://www.realclimate.org/index.php/ar ... ice-cores/

http://www.newscientist.com/article/dn1 ... rming.html

http://joannenova.com.au/global-warming/ice-core-graph/

If you google 800 year lag CO2 you will get pages of proponents performing logical somersaults, trying to explain it, or negate it, but they all accept the basic fact.

And here is what I think is a fairly good summary of the arguments being used to try to explain it away, and a better treatment of the feedback loop argument than I gave :

http://www.coyoteblog.com/coyote_blog/2 ... r_lag.html

And this page gives plenty of references to the studies, and their conclusions.

http://www.co2science.org/articles/V6/N26/EDIT.php
.

[mistermack]

I'm disappointed. I started this thread to see if there was good evidence out there, that I had somehow missed. I didn't get any.
The only evidence referred to was from Tero, pointing to raised CO2 levels, which isn't in dispute.
It's evidence for a causal link that the OP asked for, and I never got a scrap. Beige argued well for "feedback loops" that could cause warming AND cooling. But that's just an argument, not evidence. And the evidence FOR any feedback loop operating at the moment is non-existant.
The lack of any further significant warming, over the last 15 years, is surely evidence against that.
As are the ice-cores, which clearly show that a CO2 based feedback loop would take about 800 years to start. (raised CO2 causing a rise in CO2).

I can only conclude that the Ratzers are like christians when it comes to global warming. You obediently accept what "big brother" is telling you.
That is, you're not treating it as something that might be true or false, you are accepting it without any evidence, just because you've been told it.
( or maybe you all have evidence, but are too mean to share it ).

I'm disappointed. Surely self appointed sceptics should declare themselves unconvinced, till they see the evidence? And be critical of any opinion either way, till you see it supported?

I have to ask myself, why am I not convinced, when lots of people are? I don't know the answer to that, but I seem to have proved that it's not because i've missed some vital piece of evidence.
Perhaps it's because I'm older. I was born in 1950, and for the first 25 years of my life, the question was 'are we heading for the next ice-age?'. And the greenhouse effect was only mentioned as something that could possibly delay that.

In fact, they had a point. At least that was based on the facts. We ARE actually in a warm interglacial period, and ARE due to go back to ice-age conditions, ( over the next 100,000 yrs ), going on the history of the planet.

Here's the ice-core graphs yet again :

(ICE CORE GRAPHS)

Time runs from right to left, and it covers about 450,000 years.
You can clearly see that we are at a point where the earth HAS warmed dramatically over about 20,000 years, and is probably at it's highest point in the cycle. ( long term that is ). So the warnings about an imminent plunge in temperatures were at least supported by the evidence.
Looking at that graph, I can't help but feel that if manmade CO2 has any effect, it will be a plus, in stopping an overdue fall into ice-age conditions. But I remain to be convinced that it will.
( not that any of us will live long enough to know ).
.

[PsychoSerenity]

Oh just stop it, will you mistermack? Everyone got bored of trying to explain it to you when you kept on completely ignoring what was being said. You're still going on about the "lack of any further significant warming, over the last 15 years", despite that being one of the issues addressed in the videos Ani posted on the first page. The Daily Mail article, that you linked to a few posts back, was the same fucking article as the one discussed in the video, so you clearly didn't watch them!

[mistermack]

Too right, that guy is a windbag, and full of it. I've seen the one ani linked before, and watched the next one, but they are poor, and basically just propaganda masqerading as an even handed critique.
He basically puts all his eggs in the feedback loop theory, even though he grudgingly accepts the 800 year lag. But nowhere does he explain how the feedback loop can happen in FIFTY years, not 800.
And then the next video he just says over and over again, "all these people think it's so, so you should too", the tired old concensus argument. It's just the same old crap you hear over and over again.
You obviously can't discern between science and propaganda. I couldn't watch ten episodes of that old tripe, I get irritated when people insult my intelligence.
So no, I didn't get as far as the bit you referred to, basically because my bullshit detector was making too much noise by halfway through the third one.
.

[Gawdzilla Sama]

Is anybody on this site at all sceptical of the claims for greenhouse gases causing global warming?

There are several threads on this over at JREF, and many more at abovetopsecret.com.

[Tero]

Policeman voice: Move along folks, nothing here to see.

[nellikin]

Hmmm - I don't know if I should embark on this one. Firstly, I have to admit that I haven't read the whole thread. Please ignore/excuse my repeating something that has already been said - I do apologise if I'm being repetetive/not helping the discussion.

From my skimming of the thread I gather that the main concern is the lag between Temp rise and CO2 rise as derived from ice cores. There is a scientific explanation for this which is beautifully logical. Firstly, I assume that in ice cores, as in speleothems (cave formations), temperature is reconstructed using oxygen isotopes, which are subject to fractionation processes during cloud formation/precipitation. As the fractionation is temperature dependent, this is linked with climate and the isotopic composition (016:018 generally) can be used to reconstruct past climate scenarios. When water freezes into ice, the oxygen is frozen with it at that time. Later precipitation events cause more ice formation above the older layers and each layer preserves the oxygen isotopic signal from its time of formation. As the ice has pores, gases are trapped within these pores. However, the gases are - unlike the solid ice - can diffuse in and out of the ice through the pores, enabling a (limited) exchange with the atmosphere above and the gases trapped below. When the ice layer becomes thick enough, it effectively seals the gases into the layers below - stopping this diffusion. Hence, the CO2 signal is not fixed at exactly the same time as the ice is formed - it continues to exchange with the atmosphere (which may have different CO2 levels) and with layers below until diffusion is effectively ceased in a given layer. This results in a time difference between ice formation and the entrapment of the corresponding atmospheric gases in the ice - the gas signal will be mixed for a period of time until the layer is sealed. This time difference is called a lag time and is around 500 years (A hydrologist told me that - 800 years is the same order of magnitude).

Does this clear things up?

[mistermack]

Does this clear things up?

Well, it would if all that wasn't adjusted for in the calculations for the studies. But it was. I've seen references to it in the extracts from the papers.
Anyway, it's highly unlikely they would risk ridicule and publish without taking that into account.
These ice core studies, and their conclusions, are widely accepted by GHGGW proponents and sceptics alike, and the lag is now consistently estimated at 800 years + -.

In fact, what the mobility of gas in the ice cores DOES do, is average out the record, and remove the extreme spikes and dips. This can be clearly seen in the graphs, the temp line gets less and less spikey and thinner as it gets older.
It's likely that a fifty year spike like the one we are having now, would probably not register at all in the core record, due to gas exchange with previous and following layers. You're only looking at longer term averages in those cores.
.

[nellikin]

I can access most databases so if you let me know the papers titles and authors/journals, I'll check on the "references in extracts". As to ridicule - publishing original scientific data - so others can check it - is not unusual and does not open oneself up to ridicule! The scientific community lives on the review process, not merely the publication of opinions.

The averaging out would not apply to temperature - this is modelled on oxygen isotopes in the solid ice, which are not subject to the same diffusivity of enclosed gas bubbles, so your comment seems illogical to me. And yes, an averaging of CO2 conc. out would occur but it would also lead to a lag as it would take time for higher atmospheric concentrations of co2 to be fully reflected in ice cores due to dilution.

Then there is the formation of clathrate - lattice compounds formed from the gases. This can preferentially remove gases from the bubbles at the depth in which clathrates are formed, altering the diffusivity and hence the ratio of CO2 to other gases in the bubbles. This makes individual point measurements less reliable for past climate reconstruction and it has been proposed that measurements be averaged over larger depths (cm scale) to account for this...

Is science beautiful? When questions arise - people think about them, come up with possible solutions, devise methods to test these solutions and then reject or support the ideas based on evidence. Not mere rejection of ideas because it conflict with our belief systems...

[PsychoSerenity]

You obviously can't discern between science and propaganda. I couldn't watch ten episodes of that old tripe, I get irritated when people insult my intelligence.
So no, I didn't get as far as the bit you referred to, basically because my bullshit detector was making too much noise by halfway through the third one.
.

What, and your bullshit detector didn't go off when you read the Daily Mail?! You need to get a new bullshit detector.

All the guy in the video had to do, was point out the numerous contradictions between the Mail's spin and what the original source actually said.