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midtskogen
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05 Feb 2017 11:03

Continued from the old forum...

The news of a whistleblower in NOAA is all over sceptical blogs this weekend.  It's already been compared to the ClimateGate scandal, but doesn't really add so much new insight to the state of climate science in my opinion.  So, a pause buster paper was rushed to publication for political reasons.  Even if the paper is corrected, the corrections will be in hundreds of a degree, not tenths of a degree.  It shouldn't matter much.  But it's a matter of world politics.  The world is crazy.
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General global warming / climate chage discussion

05 Feb 2017 12:36

Sadly if there is even one scandal the problem is people immediately ignore all climate change evidence.
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05 Feb 2017 18:12

There is a very real problem of bias in science, especially when it has political implications as is the case in climate science, and if data were indeed wrongly manipulated to exaggerate an effect then that should be the end of that scientist's career.  This has happened before.  Of course the popular thing to do these days is hack emails to try catch evidence of a scientist doing wrong by their communications.  But one of the more powerful cases, which sometimes happens, is when someone takes the time to check how errors propagate in the calculations, and find that in order for their error bars to be as small as they are, some of that scientist's measurements must have had negative uncertainty.  Oops!  
 
That being said, I think also important not to let the scope of that problem cloud judgement on the scope of our understanding of the science and the extent of the uncertainties.  The nature of the pause is pretty well understood as an effect of heat transfer between different parts of the Earth system (particularly between atmosphere and deep ocean water), and not so much a problem of our understanding of global warming as a change in the radiation balance between Earth and space.  Corrections to the projections of future warming based on these internal variations aren't negligible, but it still doesn't change them much.
 
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midtskogen
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General global warming / climate chage discussion

06 Feb 2017 01:22

A pause during a strong warming event, even strong warming, isn't necessarily a falsification of the warming, so it's difficult to understand this desire, other than for political reasons, to publish a pause buster paper, and how this has been so embraced by the people at realclimate and others.  Reinterpreting data is so bias prone.
What climate science has failed badly at, is to communicate uncertainty to the public.  The confidence is not the same for everything.  For instance:
1. Human emissions cause global warming (high confidence)
2. The climate sensitivity is high (low confidence)
3. Strong warming has catastrophic effects (low confidence)
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06 Feb 2017 04:55

I don't really know how uncertainties in climate science could be communicated more effectively than how they already are in the IPCC summaries for policy makers.  I mean, they're free for everyone to view, they aren't that long or that technical and have pretty pictures for laymen, and I don't know how anyone interested in climate science would not be aware that they exist.

What do you think could work better?
 
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midtskogen
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06 Feb 2017 12:46

Your premise seems to be that climate scientists only come out of their cave every few years to publish summaries for policy makers.  That is, of course, not the case, so I wasn't primarily thinking of how to improve those summaries.  Anyway, the summaries could be improved as well.  Our main concern should be the catastrophic part and its confidence. Reading table 1 in the latest WG1 SPM, for instance - should we be scared?  I think it depends on what colour your glasses are.  A place to start for improvements is to remove all references to binary outcomes (warmer vs colder, increase vs. decrease) when the change hasn't been precisely quantified and what that change means in real life.
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06 Feb 2017 16:50

There are a very large number of climate scientists doing studies and publishing papers constantly, and most of these papers are highly technical and specific to a narrow topic of climate science.  It is probably not reasonable to expect that most people would try to keep up with them, if what they want is a quick way to get a general sense of what's going on and our confidence for it.

What is reasonable is that they could refer to IPCC summaries, because that's what they are for.  The IPCC is essentially a literature review of everything going on in climate change research, and the summaries are specifically intended for those who want to get "the bottom line" very quickly, without requiring a lot of technical expertise in the field.  They are also intended to give a representation of our level in confidence on the basis of the bulk of available research.  Individual scientists can have different views and models, and different papers may obtain results that agree or disagree with each other by varying amounts.  So a good sense of the overall confidence comes from seeing how these compare across the board and how well the different components of climate science research fit together -- i.e. by performing a literature review just like this.

midtskogen wrote:
Source of the post Reading table 1 in the latest WG1 SPM, for instance - should we be scared?

If you want to know if you should be concerned, then it would be better to look at WG2 (actually, all three together).  WG1 is the physical science basis for the changes that are happening.  WG2 focuses on how vulnerable we are to the effects of those changes, and how well we can adapt to them.  WG3 focuses on what we could do do mitigate changes.

I don't think we need to be "scared", because we have a lot of options available to us for decreasing the severity of climate change as well as reducing our vulnerability to those changes.  But doing nothing isn't a good solution.  What would scare me personally is if we continue to operate under business as usual and climate sensitivity does not turn out to be at the bottom of the probability distribution.
 
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06 Feb 2017 17:36

I posted this video on the old forum, but I feel it may be worth reposting it here, especially if someone hasn't seen it yet:



Thoughts?
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06 Feb 2017 18:57

Yeah, the thrust of the video is that we've delayed taking serious action on climate change long enough that all realistic scenarios for staying below 2C of warming now require something like geoengineering or carbon sequestration.  Which is true, and basically it boils down to "the longer you wait to try to prevent total accumulated emissions from crossing some threshold, the more dramatic the change you'll need to make."  This is the tyranny of procrastination.  

Is it alarming that all pathways for staying below 2C now implicitly assume such action?  Kinda -- those actions are largely untested on the scale that they would need to be performed to make a significant difference.  The bigger takeaway is that the tyranny of procrastination doesn't stop there.  Wait longer with business as usual, and it will be the 3C, and maybe even 4C thresholds that become increasingly implausible to avoid.

I don't think the bulk of evidence suggests that RCP 8.5 is "unsurvivable", but the impacts are a lot more severe and with more uncertainty as to how bad they could get, and I think the risk is really better avoided.  We know how to avoid it an we know it can be done in an economically viable manner.
 
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06 Feb 2017 19:35

By itself, RCP 8.5 probably isnt unsurvivable, but combined with oceanic acidification and other problems, it might be.
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midtskogen
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06 Feb 2017 22:56

PlutonianEmpire wrote:
Source of the post  posted this video on the old forum, but I feel it may be worth reposting it here

Once concern here is that the projections presented in the video are also science fiction, i.e. based on science in the sense that it can't rule it out.  IPCC says on the equilibrium climate sensitivity: "there is high confidence that ECS is extremely unlikely less than 1°C and medium confidence that the ECS is likely between 1.5°C and 4.5°C and very unlikely greater than 6°C".  "Medium confidence" that it is within a very large range.  How can one create a graph like the one in that video based on that?
Anyway, I think "tropical Earth" is survivable.  If we had found an exoplanet with that climate, its climate would be perceived as so perfect for human settlement that a lot of people would already begin to plan for it.  It's not a matter of whether a human civilisation can exist or not, rather whether we want such changes.
Watsisname wrote:
Source of the post This is the tyranny of procrastination.

Even worse than procrastination is futile, symbolic action, taking resources away from the long term solution.  Which is cheap and abundant energy.  We do not have that technology yet, but if it exists, it pretty certain that it depends on Einstein's equations and we've only taken the first step, fission energy, which we would never have managed to make had it not been for fossil fuel.  Other sources of energy, fossil, hydro, wind, solar, tidal, whatever, will have their niches, but shouldn't hinder more revolutionary progress.  Even without climate scares we need that abundant energy.

More on the Karl paper controversy.
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General global warming / climate chage discussion

07 Feb 2017 03:37

midtskogen wrote:
Source of the post  Once concern here is that the projections presented in the video are also science fiction, i.e. based on science in the sense that it can't rule it out.  IPCC says on the equilibrium climate sensitivity: "there is high confidence that ECS is extremely unlikely less than 1°C and medium confidence that the ECS is likely between 1.5°C and 4.5°C and very unlikely greater than 6°C".  "Medium confidence" that it is within a very large range.  How can one create a graph like the one in that video based on that?

The real graphs of course have error bars, and they have also shifted down slightly with the latest updates to our understanding of climate sensitivity.

► Show Spoiler


How we make those graphs and determine the uncertainty involves the fascinating subject of error analysis.

What you are quoting with climate sensitivity are qualitative descriptions of a quantitative measure called a probability distribution.  Anyone who does statistics will be familiar with these -- they define how likely it is that the true value lies within some range.  The most well known of these is the Gaussian, though this one is not a Gaussian (it's not symmetric about the mean).  Here's an example of it, though it's already pretty dated:

Image

This probability distribution for climate sensitivity will correspond to uncertainty in future projections of warming.  There are two other important sources of uncertainty as well:

-Uncertainty in what happens due to internal variability.
-Uncertainty in what happens due to what humanity decides to do (what our emissions over time looks like).

As it turns out, the uncertainty due to what we decide to do is the most significant one, by far.  A particularly useful graphic for this can be found in chapter 11 of WGI:

Image

This is also the motivation for using the RCP -- "Representative Concentration Pathway" -- scenarios. They deal with the uncertainty in what we choose to do by showing us what happens under different plausible paths that we might take.  RCP 8.5 is a high emissions scenario which assumes we continue to intensively rely on proven fossil fuel reserves.
 
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General global warming / climate chage discussion

07 Feb 2017 04:56

What could we do to create a turnaround?
I mean, even banning carbon we couldn't avoid an increase of 0.5/1.5 degrees before 2040, can't we just plant more threes or find a way to "re-terraform" (yeah, the term is just wrong) the earth? After all, the only way we have to keep our civilization alive until we'll start to colonize other planets (if we ever will) is maintaining our planet habitable, but since capitalism is what moves every kind of action, procrastinating all interventions is the only future I clearly see, even because who lives now and the future generation won't be affected by climate change, no more than we do right now.
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General global warming / climate chage discussion

08 Feb 2017 01:54

I think it's a neat fact that much of the mass of a tree is actually from carbon sequestered out of the air.  So planting new trees does help mitigate some of global warming.  This also happens without our help -- for example more trees are growing in the Arctic as it warms up and ecological zones shift poleward.

The problem is that there is only so much viable area for which new trees can realistically grow, and it's not enough to deal with the magnitude of our emissions for decades to come.  Another problem is that as the world warms, a lot of systems which act to remove carbon from the atmosphere become less effective at doing so, or even become net carbon sources.  The classic example is that warmer oceans store less CO2.

The most viable solutions to the problem are multifaceted -- we can improve the efficiency with which we use our energy, transition to renewable energy (and different energy sources are more useful in different areas), and perhaps use carbon capture techniques on a larger scale.  There is also a balance in terms of how much do we want to focus on limiting the warming versus how much do we want to focus on increasing our resilience to the effects of warming, and over what timescales.  It's not very viable to stop all of the warming right away, nor is it very viable to continue following high emissions and deal with all the impacts, so there is some more optimal path somewhere in between.  

These different pathways, and the details for what we would have to do in order to follow them, are the essence of the RCP scenarios.
 
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General global warming / climate chage discussion

08 Feb 2017 02:27

I never hear people talk about the anthropogenic causes of global warming. We debate whether there is or is not a warming trend or if there was or wasn't a pause etc but never what portion of all this is caused by mankind or what portions are natural causes. The 97% of scientist agree figure is thrown around as irrefutable proof we are to blame. But it was just a polling of 250 or so scientist that never quantified the degree to which we affect it, that portion was not included in the Cook study. Some say that only 1.6% of the scientist say we are 100% to blame. We need to get to the root of the problem and see if indeed mankind has had that much of an effect. Certain we have had some input to the change, but if it is such a determining factor and our influence is so great then it should be just as easy to fix climate change as it was to fix the hole in the ozone. Just my 2¢.
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