[billw55]

 Zelandakh, on 2012-November-17, 11:16, said:

Science is often unable to completely explain things. For example, the beginning of the universe is still a subject with many open questions. Would you suggest that it therefore never happened?

As I understand, that is in fact one theory, something about the space time geometry and terms like "finite but unbounded". Even philosophically, why is it in principle less absurd to believe that the universe can have infinite duration into the future, than into the past? Interesting stuff, although not applicable to GW theory.

 Zelandakh, on 2012-November-17, 11:16, said:

Put 10 AIs on TV in debate against sensible scientists and I think the results will be more positive for those proposing such measures as the carbon tax than 10 years of IPCC data and models.

This is one common problem: scientists aren't really good at live television debates. The debates they are used to play by certain rules, such as burden of proof , factual data, etc, that are largely ignored in this setting in favor of emotional persuasion in all its forms. Most scientists do not excel in such a debate.

[Al_U_Card]

An interesting and sensible discussion among climate scientists concerning the severity and attribution aspects of the Arctic sea-ice melt.

Not agenda, just science and opinion based on informed analysis


The Arctic sea ice extent has been decreasing steadily for the past three decades. Scientists discuss the potential causes of this decrease.

Below you find the introductory article that is written by the Climate Dialogue editorial staff. The guest posts of the invited scientists have been written in response to this introductory article.

We have chosen to place the different articles in so called custom fields. By doing this we can keep the articles all together on one url.

For practical reasons expert comments (comments by the invited scientists) are also separated from public comments. Anyone can comment. You need to subscribe once or use your own WordPress account. Public comments should be polite and on-topic and are moderated in advance.

We hope you will enjoy this new platform.

Climate Dialogue editorial staff
Rob van Dorland, KNMI
Bart Strengers, PBL
Marcel Crok, freelance science writer

[PassedOut]

Why a 4°C Warmer World Must be Avoided

Quote

The 4°C scenarios are devastating: the inundation of coastal cities; increasing risks for food production potentially leading to higher malnutrition rates; many dry regions becoming dryer, wet regions wetter; unprecedented heat waves in many regions, especially in the tropics; substantially exacerbated water scarcity in many regions; increased frequency of high-intensity tropical cyclones; and irreversible loss of biodiversity, including coral reef systems.

And most importantly, a 4°C world is so different from the current one that it comes with high uncertainty and new risks that threaten our ability to anticipate and plan for future adaptation needs.

The lack of action on climate change not only risks putting prosperity out of reach of millions of people in the developing world, it threatens to roll back decades of sustainable development.

It is clear that we already know a great deal about the threat before us. The science is unequivocal that humans are the cause of global warming, and major changes are already being observed: global mean warming is 0.8°C above pre industrial levels; oceans have warmed by 0.09°C since the 1950s and are acidifying; sea levels rose by about 20 cm since pre-industrial times and are now rising at 3.2 cm per decade; an exceptional number of extreme heat waves occurred in the last decade; major food crop growing areas are increasingly affected by drought.

Despite the global community’s best intentions to keep global warming below a 2°C increase above pre-industrial climate, higher levels of warming are increasingly likely. Scientists agree that countries’ current United Nations Framework Convention on Climate Change emission pledges and commitments would most likely result in 3.5 to 4°C warming. And the longer those pledges remain unmet, the more likely a 4°C world becomes.

This is not a reasonable risk to take, even if one expects the brunt to be taken by future generations.

[Daniel1960]

 Al_U_Card, on 2012-November-19, 10:18, said:

An interesting and sensible discussion among climate scientists concerning the severity and attribution aspects of the Arctic sea-ice melt.

Not agenda, just science and opinion based on informed analysis


The Arctic sea ice extent has been decreasing steadily for the past three decades. Scientists discuss the potential causes of this decrease.

Below you find the introductory article that is written by the Climate Dialogue editorial staff. The guest posts of the invited scientists have been written in response to this introductory article.

We have chosen to place the different articles in so called custom fields. By doing this we can keep the articles all together on one url.

For practical reasons expert comments (comments by the invited scientists) are also separated from public comments. Anyone can comment. You need to subscribe once or use your own WordPress account. Public comments should be polite and on-topic and are moderated in advance.

We hope you will enjoy this new platform.

Climate Dialogue editorial staff
Rob van Dorland, KNMI
Bart Strengers, PBL
Marcel Crok, freelance science writer

I have contributing to this site, and find it contains a wealth of information and commentary, not found on the websites that cater to either extreme of the global warming debate.

[cherdano]

 Cascade, on 2012-November-17, 14:54, said:

As an illustration yesterday a friend posted a link in another forum showing only 24 out of 13950 peer-reviewed articles reject global warming. This is supposed to make the skeptical position look bad. However it is largely flawed:

1. Who cares how many as Einstein said if one, yes only one proves an obstacle then the theory is flawed.

This is not how climate science works.

Climate scientists make models trying to predict future climate. Any such model is a huge simplification. They have to use their judgment to determine which simplifications still yield valid results. This judgment isn't completely subjective - it can be tuned based on past data, the results can be compared with other models, etc. But there is still enough judgment involved that a smart well-trained scientist with idiotic judgment may get wrong results. His paper showing "If we make the following assumptions, an increase in CO2 emissions will result in global cooling." could still be worth publishing, because, well maybe its true that a model with these simplifications predicts global cooling. This isn't physics where you can make hundreds of experiments - there i s only one climate, and experiments on its reaction to large scale greenhouse emissions cannot be run very frequently.

Your argument is a bit like saying "10 weather forecasters predict rain tomorrow, one predicts sun, so we can't conclude anything". Or "10,000 doctors claim I should quit smoking, but 20 think it increases my health, so there is nothing I can do until about my health until I have understood why each of these 20 doctors is wrong".

[Al_U_Card]

Now, if they would take the models off of the "water-vapor multiplier" juice and just go with a climate sensitivity of around 1 deg. C / doubling (as empirical analysis is tending to demonstrate) then they might not get anywhere near 4 deg. C but then they wouldn't be able to scare anyone, would they?

[Cascade]

 cherdano, on 2012-November-19, 16:05, said:

This is not how climate science works.

Climate scientists make models trying to predict future climate. Any such model is a huge simplification. They have to use their judgment to determine which simplifications still yield valid results. This judgment isn't completely subjective - it can be tuned based on past data, the results can be compared with other models, etc. But there is still enough judgment involved that a smart well-trained scientist with idiotic judgment may get wrong results. His paper showing "If we make the following assumptions, an increase in CO2 emissions will result in global cooling." could still be worth publishing, because, well maybe its true that a model with these simplifications predicts global cooling. This isn't physics where you can make hundreds of experiments - there i s only one climate, and experiments on its reaction to large scale greenhouse emissions cannot be run very frequently.

Your argument is a bit like saying "10 weather forecasters predict rain tomorrow, one predicts sun, so we can't conclude anything". Or "10,000 doctors claim I should quit smoking, but 20 think it increases my health, so there is nothing I can do until about my health until I have understood why each of these 20 doctors is wrong".

1. I thought we were constantly reminded that the science is settled.

2. Powell didn't claim that 13926 were in favour of AGW and 24 were against he simply claimed based on a strict standard that 24 rejected AGW and made no claim about the other 13926. I suspect if he used a similarly strict criteria that there wouldn't be many of the others in the 'prove AGW' category or whatever is the opposite of 'reject AGW'.

So I would argue that my claim is nothing like what you suggest. Science is not a popularity vote its about establishing the facts. If there are 13949 who make certain claims and 1 that provides a legitimate counter example to those claims then it is necessarily the case that the 13949 are wrong and the one is right. That is one legitimate, substantiated, valid objection is enough to expose a flaw in any theory no matter how popular it is. If you say "all balls are blue" and I produce one red ball your theory is exposed. Similarly if the climate scientists say "the science is settled" and someone finds one thing that they have overlooked and that will have an impact then the science is not settled.

[Daniel1960]

 cherdano, on 2012-November-19, 16:05, said:

This is not how climate science works.

Climate scientists make models trying to predict future climate. Any such model is a huge simplification. They have to use their judgment to determine which simplifications still yield valid results. This judgment isn't completely subjective - it can be tuned based on past data, the results can be compared with other models, etc. But there is still enough judgment involved that a smart well-trained scientist with idiotic judgment may get wrong results. His paper showing "If we make the following assumptions, an increase in CO2 emissions will result in global cooling." could still be worth publishing, because, well maybe its true that a model with these simplifications predicts global cooling. This isn't physics where you can make hundreds of experiments - there i s only one climate, and experiments on its reaction to large scale greenhouse emissions cannot be run very frequently.

Your argument is a bit like saying "10 weather forecasters predict rain tomorrow, one predicts sun, so we can't conclude anything". Or "10,000 doctors claim I should quit smoking, but 20 think it increases my health, so there is nothing I can do until about my health until I have understood why each of these 20 doctors is wrong".

It really is not one or the other. There is an entire range of possible scenarios that could exist. These range from the no warming attributed to CO2 (i.e the 24) up to large warming (perhaps there are only 24 is this range also). The difficulty is distinguishing the CO2-forced warming from other contributors. There are several different models that have been fine tuned to past results, but show vastly different projections. Which is correct? Unfortunately, we do not know yet. Although, I think we can discard any model that shows an increase in CO2 results in global cooling.

[Al_U_Card]

 PassedOut, on 2012-November-19, 12:09, said:

Why a 4°C Warmer World Must be Avoided


This is not a reasonable risk to take, even if one expects the brunt to be taken by future generations.

We are talking about the World Bank....and we do know who benefits from the international exchange of carbon credits and the like.

[Zelandakh]

 cherdano, on 2012-November-19, 16:05, said:

This is not how climate science works.

Too right. One of the main things against climate science is the lack of proof of the level required for physical sciences. If we take the Mann modelling technique for example, it uses a well-established mathemtaical process but throws out the key statistical test used to decide of the resulting data is meaningful, replacing it with a different test. Why? Because using the standard statistic says that the data is not meaningful. In the same vein, if you take only Northern hemisphere temperature records included in the modelling proxies you would probably expect a large LIA and MWP since both of these are reported in several regions. And yet, the dominance of the Urals data flattens out the resulting data to nothing within this period. I understand the argument that the Southern hemisphere data removes these "local" effects, but taking only Northern hemisphere data too? Come on, even ardent supporters of AGW must be able to see something is wrong there.

 cherdano, on 2012-November-19, 16:05, said:

Climate scientists make models trying to predict future climate. Any such model is a huge simplification. They have to use their judgment to determine which simplifications still yield valid results. This judgment isn't completely subjective - it can be tuned based on past data, the results can be compared with other models, etc. But there is still enough judgment involved that a smart well-trained scientist with idiotic judgment may get wrong results. His paper showing "If we make the following assumptions, an increase in CO2 emissions will result in global cooling." could still be worth publishing, because, well maybe its true that a model with these simplifications predicts global cooling. This isn't physics where you can make hundreds of experiments - there i s only one climate, and experiments on its reaction to large scale greenhouse emissions cannot be run very frequently.

The way the models are produced, with forcings and feedbacks, provides a very wide array of possibilities that match the past data record. One of the positive thing about the models is that the outputs are reasonably consistent even for quite different input criteria. However, you are right to point out that all of the models use a great deal of subjective input. This is a real problem in a branch of science that is reliant on a particular hypothesis being correct and goes some way to explaining why almost every model uses a positive feedback for cloud formation even whe there is very little science to back this up. As a mathematician I believe strongly in modelling as a valid and useful approach to problems such as this. However, it is clear that you need to keep a skeptical head when producing such models, making sure to check a range of possibilities in unknown inputs. Otherwise you run the considerable risk of ending up with a GIGO model.

 cherdano, on 2012-November-19, 16:05, said:

Your argument is a bit like saying "10 weather forecasters predict rain tomorrow, one predicts sun, so we can't conclude anything". Or "10,000 doctors claim I should quit smoking, but 20 think it increases my health, so there is nothing I can do until about my health until I have understood why each of these 20 doctors is wrong".

A better analogy is that 10 weath forecasters predict a 100% chance of rain for the next week, one predicts a 90% chance of rain every day. It only takes one dry day for the models used by the 10 to be faulty, even if it is only a small discrepancy. Or that 10000 doctors claim that I have a 100% chance of getting cancer because I smoke and my only chance of surviving is to give up smoking and pay $20000 per month for treatment (of which the doctors themselves get a 10% kickback), whereas 20 notice that if I pay $20000 per month I will be bankrupt and homeless in 6 months and suggest that I try an alternative treatment that only costs $20 per month but will reduce the chance of getting a fatal cancer to 10%.

I know these are stupid examples. So are yours. That is characteristic of the arguments on both sides sometimes. The truth is that we have the technology already to deal with excess greenhouse gases in the atmosphere. If it turns out that the problem is extreme then they could be implemented quickly. Naturally the cost of doing this would be greater than taking the same action over a longer time frame starting now. In this respect it makes sense to make changes now which have little impact on the existing economies and standards of living, or are already beneficial. It does not make sense to take the drastic action that has at times been suggested by some ecology groups (turn off all coal-powered power stations, etc).

One further example of this is the 4 degree link posted by PassedOut. Question: at the current rate of warming, how long will it take for the world to warm by 4 degrees? Given that solutions are available, is this a realistic scenario? You may as well post a link on why a 20 degree cooler world must be avoided. One example from the introduction: "Scientists agree that countries’ current United Nations Framework Convention on Climate Change emission pledges and commitments would most likely result in 3.5 to 4°C warming." So everyone agrees and the science is settled. Except that 3 paragraphs later comes: "We are well aware of the uncertainty that surrounds these scenarios and we know that different scholars and studies sometimes disagree on the degree of risk." Errrr, so is the science settled or not? This is Wayne's point. Also, the very next sentence is: "But the fact that such scenarios cannot be discarded is sufficient to justify strengthening current climate change policies." Scientists also cannot rule out the scenario of aliens landing on Earth and starting an intergallactic war - does that mean we should strengthen our policies against an alien invasion? Nor of a large interstellar body crashing into Manhattan - perhaps we should proactively evacuate all the inhabitants to underground bunkers just to be on the safe side.

This is precisely the problem. For every piece of rubbish AI posts here there is at least one equally as misleading posted on the AGW side. It is a little like the advertising for the American presidential race. Separating out the pieces of science based on good maths and statistics is not an easy task and it is no surprise that some sections of society have started to wonder what to think. It is tough enough even when you have some knowledge of the methods involved. Let us make an agreement - any link posted in this thread is regarded as bogus until someone else posts a meaningful argument as to why the underlying science in the linked article is indisputable. My guess is that very few links will meet this criteria (ignoring fanboi arguments).

[Al_U_Card]

 Zelandakh, on 2012-November-20, 03:42, said:

throws out the key statistical test used to decide of the resulting data is meaningful, replacing it with a different test. Why? Because using the standard statistic says that the data is not meaningful.

For every piece of rubbish AI posts here

Welcome to the club, then.

[Winstonm]

 Cascade, on 2012-November-19, 20:01, said:

1. I thought we were constantly reminded that the science is settled.

Science is not a popularity vote its about establishing the facts.

You seem trapped in the same mindset I see almost always with deniers - a comparison of science to religion/philosophy.

Science is not in the "proof" business - that is religion/philosophy/law. Everyone but the jurors "knew" the facts about O.J.

In unknowns, we can only take our best guess and live with the results. If you are waiting for total proof, see O.J.

[Al_U_Card]

 Winstonm, on 2012-November-20, 07:11, said:

You seem trapped in the same mindset I see almost always with deniers - a comparison of science to religion/philosophy.

Science is not in the "proof" business - that is religion/philosophy/law. Everyone but the jurors "knew" the facts about O.J.

In unknowns, we can only take our best guess and live with the results. If you are waiting for total proof, see O.J.

So, the accused presents exculpatory evidence of their innocence and they are still to be convicted?

What you posted is the type of logical fallacy that most "believers" use along with various strawman, consensus or arguments from ignorance (we don't know what else it might be so it must be that...) .

[Zelandakh]

 Winstonm, on 2012-November-20, 07:11, said:

Science is not in the "proof" business - that is religion/philosophy/law.

I would say it is maths personally. This is one of the reasons why it is so galling to here phrases such as "the science is settled". Admittedly you tend to hear this from politicians and campaign groups rather than scientists. Indeed, and this should really end the debate on the subject, here is a link to one of the most popular (pro) AGW sites dismissing the idea that "the science is settled". As always there is some blurring on where the lines between "unequivocal", "with high confidence" and "uncertain" might fall. While I agree with RC that the answer to "Is AGW real" would be yes with high confidence, finding a consensus of nearly all scientists on precisely how much warming and what the feedback factors are would be a different question entirely.

This is where the robustness of models to different input criteria is reassuring but equally is the recent trend away from the precitions from those models confusing. I have little doubt that the next piece of the puzzle will be found in due course and added. I also have little doubt that the models are broadly on the right track, although the subjective nature of certain feedbacks worries me. But even then, when my prediction would be that catastrophic warming is not unlikely if we were to continue without change, I am not overly worried. In exactly the same way as technological improvements have broadly kept pace with the catastrophe scenario of my youth (overpopulation and food levels) so I expect something similar to come into play with respect to GHGs. The technology is there already and just needs someone to pay for it. I trust world leaders to get their act together on this before we reach one of the tipping points. I do not expect it to happen in my lifetime but I would be genuinely astounded if we were to reach such a point when removing or countering GHGs is so simple.

[hrothgar]

 Zelandakh, on 2012-November-20, 08:36, said:

In exactly the same way as technological improvements have broadly kept pace with the catastrophe scenario of my youth (overpopulation and food levels) so I expect something similar to come into play with respect to GHGs. The technology is there already and just needs someone to pay for it. I trust world leaders to get their act together on this before we reach one of the tipping points. I do not expect it to happen in my lifetime but I would be genuinely astounded if we were to reach such a point when removing or countering GHGs is so simple.

Guess that I am a fair bit more cynical than you.

I saw how well issues arising from "over population and food level" played out in Rwanda...
I know just how far people will go to make buck
Genocide isn't nearly as rare as we like to think

Consider what's going on with tobacco.

Here in the US, consumption has plummeted as folks have finally wised up about the health risks associated with smoking. With this said and done, we're still perfectly happy to promote and sell tobacco throughout the world, so long as we can make some easy cash.

Global warming is no different. It is going to be extremely difficult to convinced people to spend money to benefit folks on the other side of the planet.

[Daniel1960]

 Zelandakh, on 2012-November-20, 08:36, said:

I would say it is maths personally. This is one of the reasons why it is so galling to here phrases such as "the science is settled". Admittedly you tend to hear this from politicians and campaign groups rather than scientists. Indeed, and this should really end the debate on the subject, here is a link to one of the most popular (pro) AGW sites dismissing the idea that "the science is settled". As always there is some blurring on where the lines between "unequivocal", "with high confidence" and "uncertain" might fall. While I agree with RC that the answer to "Is AGW real" would be yes with high confidence, finding a consensus of nearly all scientists on precisely how much warming and what the feedback factors are would be a different question entirely.

This is where the robustness of models to different input criteria is reassuring but equally is the recent trend away from the precitions from those models confusing. I have little doubt that the next piece of the puzzle will be found in due course and added. I also have little doubt that the models are broadly on the right track, although the subjective nature of certain feedbacks worries me. But even then, when my prediction would be that catastrophic warming is not unlikely if we were to continue without change, I am not overly worried. In exactly the same way as technological improvements have broadly kept pace with the catastrophe scenario of my youth (overpopulation and food levels) so I expect something similar to come into play with respect to GHGs. The technology is there already and just needs someone to pay for it. I trust world leaders to get their act together on this before we reach one of the tipping points. I do not expect it to happen in my lifetime but I would be genuinely astounded if we were to reach such a point when removing or countering GHGs is so simple.

I generally agree with your comments. While temperatures are likely to increase with increasing CO2 concentrations, quantitating that increase is highly uncertain. Catastrophic warming, while possible, seems unlikely based on the scientific observations. Thus far, the catastrophes only exist in the models. That is where I tend to differ with sites like RC, who promote the worst-case model-based scenarios, and ridicule those who disagree with them.

[blackshoe]

About the only thing you can be sure of coming out of this whole AGW thing is that the politicians are going to screw us all.

[hrothgar]

 Al_U_Card, on 2012-November-19, 21:52, said:

We are talking about the World Bank....and we do know who benefits from the international exchange of carbon credits and the like.

It always so hard to remember whether today is "Attack bankers day" as opposed to "Complain about ad hominem attacks day"

[Al_U_Card]

 blackshoe, on 2012-November-20, 09:41, said:

About the only thing you can be sure of coming out of this whole AGW thing is that the politicians are going to screw us all.

And that the bankers will get paid and the corporations will profit.

[Daniel1960]

 hrothgar, on 2012-November-20, 08:55, said:

Guess that I am a fair bit more cynical than you.

I saw how well issues arising from "over population and food level" played out in Rwanda...
I know just how far people will go to make buck
Genocide isn't nearly as rare as we like to think

Consider what's going on with tobacco.

Here in the US, consumption has plummeted as folks have finally wised up about the health risks associated with smoking. With this said and done, we're still perfectly happy to promote and sell tobacco throughout the world, so long as we can make some easy cash.

Global warming is no different. It is going to be extremely difficult to convinced people to spend money to benefit folks on the other side of the planet.

I am a bit more optimistic. Currently, people spend significant funds to help the poorest, both here and abroad. While not everyone supports this idea, there is a large number that do. Regarding food, just check out how much food production and production efficiency has increased over the past 40-odd years, since the Population Bomb was written. Neither mass stravation nor social upheavals have resulted due to overpopulation. Even in Rwanda.