The Definitive Global Climate Change (aka Global Warming) Thread — General Discussion and Questions
Thank you for posting Guy's video from the Age of Limits 2013. I felt really proud of myslef when I noticed that he had added the habitable zone study from the Astrophysics Journal that I tipped him to his presentation at 08:40-09:40.
Even more importantly, we can see Mark Cochrane responding to Guy at 31:18-36:29, 49:16-51:43, and 54:55-57:23. Unfortunately, the wasn't as much debate between the two as I hoped, but the dialogue is still interesting.
I think it's accurate to say the video makers assume extinction (of humans) is already underway, global collapse of the planet's eco-systems is now underway also, along with melting of all ice, etc.. As Mark Cochrane says in the video, when and how isn't clear. Could be "hundreds" of years; could be in his or his daughter's lifetimes. He doesn't "know" when. But, as the speaker and some of the audience say: political upheavals could preempt the "consequences" of global warming, or climate change, or climate disruption, or whatever you want to call it. And this is science! Predicting the future with weak theories which have a minimum of empirical, observational evidence!! See the last decade, and one half, to observe the effects of the theory. Climate change is progressing at, and within, normal variability despite accelerated human population growth, and industrialization rates (more emissions!). So, SOMEHOW, even though the evidence shows more co2, and methane, and other "pollutants" being emitted, the climate of earth has not changed beyond natural variability. Everything is the same. Give it ten more years and this theory is dust. The speaker said "2030" (I think) is about the time humans will be "extinct". Complete conjecture, and in my opinion GARBAGE.
http://www.youtube.com/watch?v=EYPapE-3FRw So how are the folks who believe so stridently in a future catastrophic climate always saying "it's science!". No one here knows the future. Not me. Not Mark. Not Stan. Nobody. None of us can use "science" as our "proof". What was hypothesized thirty years ago (global climate catastrophe), has not happened, yet. As Tony or Mark might say, it was hypothesized 100 years ago too. But regardless, it hasn't come close to happening yet. co2 concentration in the atmosphere HAS increased by all accounts. By almost half the pre-industrial level, supposedly. Yet what has the climate responded? How do we really measure that? The "vague" hypothesis in this video would be on the mark in my opinion to explain THAT.
The topic of Guy McPherson has been discussed here in the past. What he basically does is to take the most extreme (you can call it pessimistic if you like) read of the climate science and makes the assumption that this is what is going to happen. McPherson's analysis is within the appropriate parameters, but it's not a good descriptor for the most likely outcome. In other words, it's a possible outcome, but not a probable outcome. Personally, I find McPherson's lectures stimulating, since they drive the point home of why this issue shouldn't be entirely ignored. In my view, while the chance of his apocalypse playing out is not very high, it's a lot higher than humans going extinct due to a meteorite striking the earth.
One thing that should be taken into consideration when watching lectures of this type is to draw the line of when the science ends and the speculation starts. In this case the science ends when McPherson demonstrates the most extreme scenarios climate science has to offer, and the speculation starts when McPherson comes up with all kinds of hypotheticals if those extreme scenarios actualize.
Nonetheless, I do somewhat agree that while the climate hasn't really changed that much beyond natural variability, there is a good chance that it will. In my opinion the really big deal, or even the biggest deal, is the melting of arctic sea ice. If that happens, then all doubts about us being still somewhat within the realm of natural variability should be removed. Yes, in a decade or so we'll know. If things are then more or less as they are now, with no more warming (despite more atmospheric CO2), arctic sea ice still intact, we can conclude that something went badly wrong with the science. Maybe it is CFCs after all.
It’s worth repeating as some here seem to think that it’s still an open question: does CO2 (and other greenhouse gases) heat the atmosphere? The science has an overwhelming answer: YES! Perhaps those that doubt it would like to repeat the simple laboratory experiment that proves it but actually discover that heat is not retained. Good luck with that. No, really, good luck; that would be a tremendous achievement and all we’d be left with is figuring out how to avoid acidifying the oceans.
Because greenhouse gases retain heat (and are thus “pollutants” only in this sense and thus destabilise our climate), it’s inevitable that the atmosphere will warm until the outgoing energy equals the incoming energy from the sun.
I don’t know whether Eric is right that climate is still within natural variability but the human signal has been evident since the turn of the century. The last 30 years or so have each been warmer than the average global temperature of the last century. The last 12 years have been among the 13 warmest on record. Perhaps this is still within natural variability but it will get hotter. That is a consequence of the CO2 already in the atmosphere, never mind future emissions. Even if the warming remains sluggish for the next 10 years, it will get hotter, until the energy balance is restored.
Some people think it’s no big deal. There have been many links posted here about extreme weather and about studies of particular events that may technically be within natural variability but have occurred against a low probability that they would. There have also been links to studies about other impacts of a warming world.
So, just to reiterate. Greenhouse gases trap heat. As a consequence of increased such gases in the atmosphere, the surface of the planet will get hotter. If the doubters can post some science that blows apart our understanding of greenhouse gases, please put up or shut up.
Ever so reasonably we re-introduce Doubt.
Roy Spencer has compared 73 CMIP-5 climate model runs with actual satellite and balloon borne atmosphere observations here. The result shown below don't need much explaining. The model mean is off by about as much as the global warming of the entire last century. As Eric recalled Feynman's take on results such as this, if it disagrees with careful observations, it's wrong.
Note that the graph above is for a limited zone of the earth. I don’t know if the guy Spencer’s data is right but he’s certainly cherry picked. His notions of minimal human impact on climate change and that modelers think climate change doesn’t happen without human intervention are nonsense and his views have been debunked many times.
I refer to my earlier response about CO2 impacts.
I read through your source, but couldn't find the answer to two questions. Could you please be so kind and elaborate:
1) Is it an apples to apples comparison, i.e. comparing real troposphere temperatures to what is being modeled?
2) Does that include all the climate models that track this or only those that have been overestimating warming.
If that data is as good as it seems, this would mean that the most disastrous scenarios (4-6 C warming by mid century) should at least be reduced by 1 C, maybe even by 3/4ths of the expected warming, resulting in the disaster scenarios being 3-5 C and 1-1.5 C.
One thing that truly frustrates me now – and this is by no mean your fault Stan – is that I've spent roughly 1h virtually every day for the last 8 months (a total of 230 hours or so) trying to understand climate change by reading this thread and everything you guys link to (I've tried to be as impartial in my reading as possible). The end result: I have learned more science than I ever cared to learn, but have been utterly unable to evaluate the true risk of climate change or what actions (political or financial) to take against it on top of the basic peak-oil, supply chain etc. issues that I'm nonetheless trying to resolve. Maybe rational ignorance is the route to go…
Having replayed Mark's adlib summary during the question & answer portion[see the previous pg. post 1360…thanks John] a no. of times; it seems a couple of primary differences in their beliefs/interpretations are:
-belief that the clathrates are going to release gradually …Mark. [Guy-the clathrate gun/bomb is fast release I presume]. This issue appears to me to relate directly to the slow process of melting ice per Mark, but he did not specifically address the clathrates; but states the significant btu's involved in melting that is currently not a heat increase for water/land.
-Mark's reference that the higher temps will cause a mitigating feedback as energy is released at a "to the 4th power, square of a square" higher rate [the normal rate is a square?]. This is the only non-self-reinforcing feedback I have heard of. [i have wondered if the gulf stream shutting down will help slow the artic from melting?] i hope to get more info on such.
Here is a link Guy posted on his site when asked about this['age of limits' post in the comments section]. He noted ,"It’s the real deal, although the feedback apparently is relatively minor compared to the positive feedbacks."
These above issues seem to frame their primary differences; if there are others I'd welcome the info.
Mark please treat me as a saboteur, if for whatever reason this is not something you want to followup on.