Hot topic.
Yes, but this show was on the SUNDANCE CHANNEL!!!
Shouldn’t that read “Cool topic”, at least for the last decade or so? 
Say goodnight, Gracie…
That’s almost tautological. To get the most extreme predictions, of course you have to assume a lot of things that the science isn’t settled about. That’s what makes those predictions extreme. The more interesting discussion is around the non-extreme predictions.
You’re kidding, right? The noble reputation of environmentalists provides a perfect cover and would allow profiteers to get massively rich AND appear noble. Win-win. You know, a bit like Macy in “Miracle on 34th St.”
I’m not saying that’s really happening. I just think your rationale is deficient.
I can only assume Sundance Channel showed it with the same sense of seriousness they might show Reefer Madness.
This is a HuffPo link so as such will be panned by many but the claims are cited.
I think GIGObuster’s first link to the video pretty much demolishes the OP by itself but to add to the pile-on:
ClimateGate: The 7 Biggest Lies About The Supposed “Global Warming Hoax”
Chronos, I have no expertise in this area at all.
Sam Stone’s post contains a number of issues both evidence-based and argumentative (as is entirely proper in a legitimate debate). I have edited out much of what seemed to me to be argument to see if there is agreement about the assertions that are closer to evidence. I note your observation about tautology, but since you conclude with the observation about the non-extreme positions, I would be grateful for your observations about some of the material advanced by Sam.
Is 6-7 degrees over a hundred years an “extreme” position?
Is there still a legitimate debate about CO2 retention in the atmosphere?
Is it fair to describe the present understanding of the Earth’s feedback mechanisms as “weak”?
Is 3-4 degrees of warming the present “best estimate”? Is it generally accepted that warming below 2.5 degrees is a net benefit? Is it a legitimate position to take on the evidence that a benefit of the time in transitioning through this period may outweigh the detriment of 4 degrees?
"It appears that CO2 is warming the atmosphere, and that humans are contributing to this to some degree. What isn’t clear is how much damage this will cause to the planet as a whole, if any. It’s not clear whether the cost of curtailing CO2 emissions will outweigh the cost of the damage if there is damage. It’s not clear if we can gain the kind of consensus required to significantly curtail CO2 in the first place. "
So how do you proceed? You spend a whole lot more money on studying the science. You improve the quality of your ground-based measurements. You build models and validate them as time goes on. You invest in more study on the role of clouds, the sun, ocean currents, algae blooms, and anything else you can think of. You agree to maybe a 10-year period of study and analysis, to try to reduce the error bars. In the meantime, you make prudent investments in research for alternative energy, and start implementing it where it’s cost-effective to do so.
What you DON’T do is jump right in and try to pass sweeping, world-wide changes to our energy infrastructure.
If you want to approach this scientifically, then the thing to do is to work out the high and low estimates for warming, assign probabilities to each, and then work out the Pareto-optimal strategy for maximizing wealth for the next 100 years. Maybe it includes CO2 reductions, but maybe mitigation is a smarter strategy. Maybe it will be much easier to reduce CO2 ten years from now after a decade of research into alternatives, at which point we’ll also have a better grasp of just how much warming the planet is undergoing.
Or maybe the error bars are currently so big that you can’t base reasonable policy on the conclusions. The IPCC’s range for their estimate of temperature in 2100 is 1.8 degrees to 6.4 degrees. That’s a huge range. The natural warming of the earth in the inter-glacial period we’re in is about 1.1 degrees per century, as I recall. A lower estimate of 1.8 degrees means .7 degrees of warming over a century, which is almost inconsequential, and almost certainly beneficial to the planet as a whole. Do you want to put the world into a deep recession to avoid that?
On the other hand, warming of 6.4 degrees would probably cause trillions of dollars in damage and cause significant dislocation of future populations. It would be nice to avoid that if we can.
The IPCC’s overall ‘best estimate’ in the 4th assessment report is 3.7 degrees of warming by 2100. That is NOT a catastrophe. We could deal with that if we had to by simply transferring the wealth created in the temperate zones to the equatorial regions that will be hardest hit.
In short, the range of estimates is very wide, which will make policy based on them rather inefficient.
You need to understand that the reason the global warming movement is steaming ahead so fast is that politics are getting way ahead of the science. There are a lot of vested interests out there that stand to gain from global warming treaties. A lot of countries that will benefit economically if other countries carry a preponderance of the burden. A lot of this is driven by ideologues seeking to use global warming as a springboard to achieve what they’ve always wanted - more global government, a decrease in nationalistic power, wealth transfer from the U.S. and Western Europe into the poorer countries in Africa and elsewhere, and lots of political control.
One key fact that continues to bother me is that there are many people saying that global warming is an imminent catastrophe, and yet it is very hard to get those same people to agree to nuclear power, which is the only feasible large-scale power source available today which doesn’t emit greenhouse gases. That tells me their motivation is more than just keeping CO2 out of the atmosphere. For some, it’s about reductions in energy output entirely, for others it’s about ‘green jobs’ or being able to exert control over the means of production.
The bottom line is that there are many agendas at play here, and a lot of smoke being thrown up by ideologues on all sides of the debate, and this is obscuring rational thinking on the issue.
From the IPCC 4th assessment synthesis report, page 38:
These numbers represent their best guesses as to the temperature change caused by a doubling of atmospheric CO2. The terminology in the IPCC reports regarding uncertainty are described as:
So, they’re saying that there’s a greater than 66% chance that climate sensitivity is between 2 to 4.5°C, with a 10% or less chance that it is below 1.5°C. But notice they don’t even try to assign a very unlikely assessment to values above 4.5°C, as they admit that there’s really no science to support it. They can’t exclude the possibility, because of course if you have no idea you can’t exclude something. But there’s not even enough evidence to allow an estimate of the probability of higher values.
From here, the question now becomes how much CO2 humans will release. A key piece of evidence is the Keeling Curve, a measure of CO2 concentrations on Mauna Kea from the late 1950’s to today. It shows that CO2 has increased from about 315 to 385 ppm over 50 years. You can extrapolate farther by looking at CO2 levels trapped in ice cores, which were about 284 ppm in 1832.
CO2 emissions have been increasing, and the rate of increase has been increasing. In other words, it looks like an exponential growth curve, and this scares people. But in fact, we really don’t know what the trend looks like. The rapid increase in the last 20 years undoubtedly has most to do with economic growth in Asia, caused by rapid industrialization and heavy energy use. But economic growth like that cannot be sustained, and as economies mature they start to stabilize in their CO2 output - gains in energy efficiency offset economic growth, which slows down anyway.
But let’s take some real numbers. From 1995 to 2005, atmospheric CO2 increased by 1.9ppm per year. At that rate, in 100 years, we’d add 190ppm of CO2 to the atmosphere. To double CO2 to get a warming of 2-4.5 degrees, we’d need to emit CO2 at an average rate about double of the last decade’s. And that’s entirely possible.
But note that each molecule of CO2 emitted has less effect than the last one - doubling CO2 gets you to 3 degrees, but to get to six degrees you need four times the CO2, and to get to 9 degrees, you need 8 times the CO2. It’s not a linear relationship.
So, we start with estimates that are pretty wide in the first place, and then we have to add estimates of how much CO2 we’ll generate, which is all about the nature of the future economy, which is very fuzzy indeed. For example, for 30 years from 1970 to 2000, the global economy was actually becoming less carbon intensive with each year. That changed in 2000, again, due to the rapid economic growth in Asia, which has very poor energy efficiency.
But assuming China and India follow the same growth path as the rest of the western world, they will reach a point where gains in energy efficiency will outstrip economic growth, and they will become less carbon intensive with each year as well. But no one knows at what point this will be reached, and how big the economy and energy output of China and India will be by then.
The way the IPCC handles the uncertainty about future growth is that they have developed various ‘scenarios’ or stories about the growth of the world, and then try to pull estimates from each scenario as to how much CO2 mankind would generate. This is very fuzzy stuff. Can you imagine how accurate similar scenarios generated in 1900 would be today? In any event, this is what they look like:
These are little more than educated guesses, and they have nothing to do with climate science. Rather, they are questions of economics, technological growth, political science, etc. Our track record in predicting such things is pretty weak.
In any event, the IPCC sets emissions rates of CO2 for each scenario, then gives estimates for how much warming there might be by the year 2100. They look like this:
So we have estimates that range from not much above the natural increase to about 6.4 degrees.
As an aside, I’d like to point out the IPCC’s estimate for sea level rise for the various scenarios:
Make note of the fact that the IPCC’s highest prediction, for the highest temperate increase scenario, is .59m of sea level rise. Also note that the ‘natural’ level, if man were not producing CO2 at all, would still be somewhere between .1 and .3 m.
You can find numbers all over the map on this. Most sources say “50-200 years”. Some AGW advocates say “hundreds of years”. There are outliers - some people claim that the effect of a molecule of carbon added to the atmosphere today will be felt for a thousand years. Some seem to think the carbon is removed on the order of a decade.
It’s actually not a simple problem, because CO2 recycles through the atmosphere multiple times before it is sequestered. It’s absorbed in a plant, the plant burns, and it’s back in the atmosphere. Or it’s absorbed in algae, which is eaten by whales, which die and decompose and release their carbon back into the cycle. Eventually, the stuff gets locked away (sinks to the bottom of the ocean, mineralizes, gets locked up in plant life which winds up being petroleum in the next 100 millions years, etc). I couldn’t find a definitive number for CO2 lifespan, and I’m not sure there is one.
The IPCC talks a lot about the various questions around feedback. They admit that much is unknown, and in fact the estimates in the 4th assessment report were changed before publication because of new information about some feedback mechanisms.
See the quotes from the IPCC above for the best estimate values. As for economic costs, moderate warming would have a net benefit on agricultural output and would open up a lot of new land in the northern regions. But to be fair, there are a lot of non-economic costs associated with global warming. Species extinction, habitat changes, changes to animal migration patterns, etc. It’s hard to put a value on this, and it’s ultimately going to be an ideological decision.
Source documents:
IPCC 4th Assessment Synthesis Report
IPCC 4th Assessment Chapter 2 - Changes in Atmospheric Constituents and in Radiative Forcing
Note that I’ve been using the numbers straight from the IPCC, not from any of the ‘skeptics’. This is the stuff that everyone is supposed to agree on.
Thanks for the effort, Sam. I appreciate it. But you will of course appreciate that there is actually a debate about this, and I am trying to figure out what the parameters of the debate are. Each side has been accused of being selective with the evidence (not that I am accusing you of that - I am simply in no position to judge).
That is why I though it would be useful to me at least if I could determine where there is agreement, and that is why I asked Chronos for his views of your post. He seems to take a different position from you, although I am wary of assuming that any one individual is some sort of spokesperson for one of two rigidly polarized positions.
While there are expressions of disagreement at all levels, it may be that the primary points of contention are at the level of primary facts (is warming real? is it man-made?) or at the level of inferences from those facts (what will the world’s climate be like in 100 years?) or at the level of response (what is the cost/benefit analysis of an aggressive but expensive response as opposed to a less expensive response or even doing nothing?)
Both sides of the debate in the large (and I am not suggesing you personally) have been guilty of seeking attention by catastrophising their opponents position, and the media has magnified this effect by selectively emphasising worst case scenarios advanced by both sides. For all I know, The Truth may well be one of the worst case scenarios, but if that is not really where the debate is at, I am keen to know.
To know the size of the debate, it is helpful to know where its edges are. Hence my question to Chronos.
Sure. Always good to seek a second opinion.
But note that I didn’t give you my opinion - I gave you the straight facts from the UN’s panel on climate change. This is the report that is considered the definitive statement on global warming. I linked to the source documents so you can see if I took anything out of context or fudged the numbers.
The effects of drastic global temperature change either way would be catastrophic in a great portion of the world. I think most agree on this. What will be ironic is the return of a “little ice age” as occurred from the 13th - 19th centuries. I can see it now; documentaries, commercials, magazine ads and web sites like this encouraging everyone to paint their roof black, turn off the windmills, take down the solar panels and burn all available fossil fuel possible in order to enhance CO2 based global warming.:smack: Not trying to make a big joke about it, but it would be ironic indeed. I certainly don’t claim to be an expert in this matter but from what I’ve learned from both sides of the issue is that the ice age scenario is just as feasible.
chappy
Nope.
Of course, you seem to try to talk about the near future, on that the consensus on the earth cooling to the levels of the previous decades is unlikely.
Have you read any of the other posts in this thread?
No, it’s really not. The vast preponderance of evidence is that the earth is warming. No one in the scientific community seriously disputes this. Very few people dispute that man is contributing in some degree to the warming.
If you chose not to believe this, then I have to join with the others and say you’re adopting an unscientific attitude.