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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Recommended supplemental reading:

Study: Why troposphere warming differs between models and satellite data by Zeke Hausfather, Carbon Brief, June 21, 2017

michael sweet at 02:50 AM on 29 June 2017

SkS Analogy 8 - I'll take the specialist

Art Vandelay,

Billions of dollars are wasted in the USA screening for prostrate cancer. Doctors make billions of dollars treating the poor souls who screen positive. Millions of American men have been rendered inpotent or incontinent by this treatment. Studies show that few deaths are prevented by all this treatment. In Europe, where the health system focuses on patient outcomes and not the profit of doctors, they have made much less use of the PSA screening test and have better overall health outcomes. The surgeons do not make as much money.

The fossil fuel industry has cried wolf many times during my lifetime over environmental regulations causing economic damage. You need to find a new analogy.

ubrew12 at 01:03 AM on 29 June 2017

Climate scientists just debunked deniers' favorite argument

Christy: "the models... would be inappropriate... in predicting future changes in the climate or for related policy decisions." Compared to what? Christy's intuition? Lamar Smith's faith that the future will be unlike the past? Inhofe's 'God is still up there'? The models are all policymakers have because the 'other side' of this debate steadfastly refuses to put together any models (or refuses to share the knowledge that they put them together, i.e. Exxon 1980). You would think an industry with a 22 trillion dollar stake in the outcome of this debate would be able to afford a better pointer to our climate future than James Inhofe's snowball.

peter7723 at 23:07 PM on 28 June 2017

Electric Cars are the Missing Link to a Zero Carbon Energy Grid

I installed a 3kW Solar PV system and needing a new car, purchased a plug-in hybrid. In my latitude, 38°S, comparing the year before with the year after, I reduced my annual petrol consumption from 1200L to 190L, saving $1,300. The PV system meant that my electrical energy did not increase. As for CO₂ emissions, the PV system displaced 4MWh per annum. The emissions intensity of petrol is about the same as that of the electrical energy generated from brown coal. The oil industry should be worried.

Swayseeker at 22:43 PM on 28 June 2017

New study confirms the oceans are warming rapidly

If we are going to be hotter and more humid then wet bulb temperatures could reach dangerous levels. One cannot cool oneself down below wet bulb temperatures by means of sweating, so one must reduce temperatures or humidity. One can reduce humidity by having a lot of convectional rain and "Understanding the sky" which can be found on the Internet tells us why the clouds are higher in the tropics than at the poles. Most of the tropical rain is conectional and this has "dried out" the atmosphere a bit, making dew points lower. Using Espy's equation tells us that with lower dewpoints (resulting from lower relative humidity) cloud bases are higher. 125 (T-Tdew) is a larger number if Tdew is smaller. Using solar air heaters on every rooftop can dry out air by continuous convection and rain. This will lower wet bulb temperatures.

Bob Loblaw at 22:41 PM on 28 June 2017

Models are unreliable

NorrisM:

With a legal background, and experience in trying to assess the credibilty of different sources, one thing for you to look for is inconsitencies in a position. Skeptical Science has a summary page listing contradictions in the so-called "skeptical" view of climate change.

Another issue to keep track of is how often someone expresses complete certainty on something. Generally, you will find that the science of climate change has a lot of "ifs" and "most likelys" - sources of error are discussed at length, and implications of uncertainty are noted. In the so-called "skeptical" view, you will often find very definitive statements (that often contradict other definitive statements). In science, admission of uncertainties is a strength, not a weakness.

Glenn Tamblyn at 19:49 PM on 28 June 2017

Models are unreliable

NorrisM

Firstly, for you as a lawyer, whose principle skill is the use of language...

"Can we not come up with a less pejorative term than "climate change denier" with all its connotations when literally none of the Curry, Christy et al group deny that the world is getting warmer."

This is standard rhetorical technique which I presume you would be adept at slicing through in a legal context. The term 'climate change denier' covers a range of differing 'denials' and by claiming it is being ascribing to one subset of of this 'population', aren't you are engaging in rhetoric.

Next, the purpose and function of climate models. They are, really, no different from weather models. Used to produce the weather forecast.

Climate models work at a coarser resolution than weather models but essentially attempt to produce differing results. A weather model takes what the weather is today and attempts to determine what the weather will be x days from now. In principle, exactly. Well, sort of...

A climate model, being coarser, has a snowflakes chances in hell of doing this. One run of a climate model will be significantly random. And another run of a climate model, with slightly differing starting conditions will also be significantly random.

What if we do many runs of the climate model, each with slightly differing starting conditions? Each run is different. But what does the average of many runs look like? Well this starts to have a pattern, an order to it.

Although each run differs, their average is much less chaotic. Because the underlying climate does vary in a modestly predictable way. The average has predictability.

But that does not mean that the actual day to day evolution of weather over climate timescales will accurately follow this average trend. Because day-to-day weather is chaos superimposed over an underlying order. And since we can't easily predict the chaotic component, the actual weather data will not ever match the climate exactly.

So we can't expect weather to progress with the regularity that the climate averages suggest.

scaddenp at 19:08 PM on 28 June 2017

SkS Analogy 8 - I'll take the specialist

"Conversely, cancer treatments also don't have advocates that overstate the effectiveness and avoid mentioning potential down-sides. So it cuts both ways."

I think you will many to dispute that, but rather offtopic.

I find your view of humanity depressing. Glad I dont live where you live.

Art Vandelay at 15:22 PM on 28 June 2017

SkS Analogy 8 - I'll take the specialist

Conversely, cancer treatments also don't have advocates that overstate the effectiveness and avoid mentioning potential down-sides. So it cuts both ways.

I agree though, with the exception of people in their 20's or younger, most of us will probably avoid the dire consequences of climate change. Speaking only for myself here, but I think the best thing that I can do for my children and future grandchildren is to leave enough money to help them live as comfortably as possible and in the best place possible, though I accept that that's a selfish motivation. But I guess that's my point anyway. Most people will act out of self interest before collective interest, and most people will plan for the short term before they plan for the medium or long term.

scaddenp at 14:42 PM on 28 June 2017

SkS Analogy 8 - I'll take the specialist

Fortunately most cancer treatments dont have do-nothing advocates exaggerating the cost of the treatment so they dont lose market share. In your brothers case another interesting analogy comes up. Suppose instead it was your 3 year old son. What route would take and whose advice would you trust about likelihood of surviving till a better treatment comes? Mostly we are making decisions about what a future generation would face.

Art Vandelay at 10:11 AM on 28 June 2017

SkS Analogy 8 - I'll take the specialist

Climate change is more like a cancer than an injury though, taking a long time to present definite symptoms and requiring a variety of invasive treatments over a long period of time.

There are many cancer sufferers who decide not to undertake the treatments due to the high costs and known painful side-effects, particularly if a successful outcome has a low probability.

Similarly, with climate change mitigation, people will only be encouraged to pay for the treatments if there's a high probability that they will cure the disease, and they need to be confident that the treatments themselves don't create many years of misery. I have a brother with a rare form of Leukemia that could be treated today with highly invasive and high risk treatments, but he's chosen a path of non invasive and low risk measures that will hopefully buy him enough time to still be alive when better and safer treatments that offer a cure are available.

scaddenp at 09:43 AM on 28 June 2017

CO2 lags temperature

"Zero" on the graph is not really present day. At no time on that graph does CO2 ppm exceed 300pm. We are now over 400pm. The last time earth was at 400 was in the pliocene when it was too warm for ice age cycles.

And yes, there are long period cycles at work - the Milankovich cycles. A complex series of feedbacks accompany the ice age cycle. As ice extends down on NH, swamps freeze over, vegetation changes, sea level drops exposing more land for plant colonization, and as temperature of ocean drops, its ability to hold dissolved CO2 increases. All work to reduce CO2 in atmosphere. Works in reverse when orbital forcing changes the other way.

In summary you cannot change the temperature of the planet without also changing the CO2 concentration the atmosphere which then acts as a feedback to amplify that change (and to make NH driven changes into global changes). However, these are also very slow feedback systems, operating over 100s to 1000s of years (because it takes nearly a 1000 years for ocean to equilibrate). Eventually we will see these feedbacks cut in from our forced change to climate but not in this century to any great deal.

Art Vandelay at 09:21 AM on 28 June 2017

We are heading for the warmest climate in half a billion years

Humans can adapt in part, such as building climate controlled cities, such as the one proposed in Dubai, but I'm sure that geo-engineering will be implemented if the summer temperatures start to exceed 40C on a regular basis in large mid latitude cities. The risks of geo-engineering may be high but still much lower than doing nothing.

Tom Curtis at 08:58 AM on 28 June 2017

Human CO2 is a tiny % of CO2 emissions

Danilushka @309, the most recent plateau in temperature and CO2 level shown in the graph of the Vostock ice core data (which is called the Holocene), has lasted over 10 thousand years. Over that period, CO2 levels have increased from about 260 ppmv to about 280 ppmv just before the industrial revolution, ie, an average increase of 0.002 ppmv per annum. Since the industrial revolution, CO2 concentrations have increased by 120 ppmv over approx 270 years, or 0.444 ppmv per year, or 222 times as fast.

Needless to say, over 10 thousand years is "thousands of years".

Danilushka at 08:18 AM on 28 June 2017

Human CO2 is a tiny % of CO2 emissions

Please reconcile your statement in the first paragraph, "Before the industrial revolution, the CO2 content in the air remained quite steady for thousands of years." with the graph in the article entitled "CO2 lags temperature - what does it mean?" Figure 1: Vostok ice core records for carbon dioxide concentration and temperature change.

Figure 1's CO2 concentrations don't look quite steady for thousands of years at all. Not even close. Am I missing something?

https://skepticalscience.com/images/Milankovitch_Cycles_400000.gif

Danilushka at 08:09 AM on 28 June 2017

CO2 lags temperature

I am just trying to understand this so please bear with me. Looking at the series of temperature changes (3 in all in Figure 1 Vostok ice core records) in the graph of CO2 versus global temperature, there seems to be a long-period cycle at work. Or there was perhaps if man has changed things. It seems the current peak is actually lower than the first, despite man's injection of CO2. It is hard to separate the CO2 from the temperature for this recent peak due to the long period in the graph and large time scale.

Is there a graph with the same axes covering a shorter period such as the width of the previous cycle? It would also be interesting to see each of the 3 cycles split out with better resolution to see if this time, as early in the cycle as it is, is different and, if it is, by how much and how it is trending. I suspect this might be available somewhere, but I am new here and not sure how to find it or even ask so please forgive my lack of information on this.

scaddenp at 07:52 AM on 28 June 2017

New study confirms the oceans are warming rapidly

So those trying to blame oceans for global warming would appear to be in same boat as those claiming you could reduce deficit and increase government spending while cutting taxes?

Just like money, heat has to come from somewhere.

nigelj at 06:41 AM on 28 June 2017

We are heading for the warmest climate in half a billion years

A swamp like hot, wet climate will be an incubator for all sorts of tropical diseases, just at a point where we are having problems with antibiotics. And dont kid yourself technology will solve this, as new antibiotics will develop the same problems.

Some people argue a warmer climate is a good thing, but it has plenty of downsides. Heatwaves combined with higher humidity doesn't sound like a good combination, and this is costly to adapt to.

My country will get more rainfall, and has already seen an increase in rainfall. The trouble is this is mainly falling in the one geographical location where it's of no use to either electricity generation or agriculture.

This giant, unintended experiment with climate is high risk, and solutions like geoengineering would be high risk, ambulance at the bottom of the cliff approaches. But thats typical of humanity in so many ways, as our record in prevention isn't so great.

NorrisM at 04:01 AM on 28 June 2017

Models are unreliable

Tom Dayton, Eclectic & MA Rodger. I would like to thank all of your for your comments. I think I have to spend more time reading the full thread both for this topic as well as on questions of MWP etc. I think that I will withdraw from any further comments until I have at least read the full thread on this topic (this could be a long time!).

As a lawyer and not a scientist, I find the best way to come to a conclusion is listen to both sides similar to the process in determining any litigation (I am actually a business lawyer not a litigator). For this reason, my plan is to stay on this website and also the Nigel Lawson GWPF site. I actually have never even looked at the Skeptical Science website. I think I can "filter" things sufficiently to read postings on both sites.

The information on Steve Koonin is quite interesting given his statements in the transcript of the APS panel hearing where he professes surprise a number of times on what he was hearing. I thought I was reading the questions of independent physicists who were trying to get at the facts (I just about said "truth"). But I do commend that transcript to all of you, if only to hear how these significant IPCC climatologists respond to the questions.

But one suggestion to the editor of this website. I think that "ad hominen" comments on the persons contributing to this website should be fully deleted and never appear at all on the website. Just "stroking them out" but allowing everyone to read them just encourages those kind of comments to be made. I do find that the proponents of anthropogenic global warming seem to be much more in "attack mode" than the other side. Can we not come up with a less pejorative term than "climate change denier" with all its connotations when literally none of the Curry, Christy et al group deny that the world is getting warmer.

This term "fake skeptic" is awfully close to "fake news". Is it recently invented since the advent of Trump?

Having said all of this, the recent post today indicating that Stephen Hawking is onside and part of a new organization gives me a significant degree of comfort. Reading his History of Time was a challenge but I got through it. Unless I have missed another YouTube, I was very disappointed with the Neil DeGrasse Tyson video explaining global warming because it is so simplistic and does not explain any of the challenges in trying to "predict" future changes in the climate. I appreciate why he has done this, reaching for the lowest common denominator amongst the public, but I think scientists do have a responsibility to qualify absolute statements. Otherwise, they move into the political arena which then undermines the confidence the public has in their scientific statements.

In any event, thanks very much for all of your comments. Lots of reading ahead of me.

Moderator Response:

[DB] "This term "fake skeptic" is awfully close to "fake news". Is it recently invented since the advent of Trump?"

The term "fake-skeptic" has been used in this venue since at least 2010. The denial of the science by the venues you note is well-established over the years.

[PS] Your "truth search" understandably seems to be about determining the reliability of witnesses. How many bits of GWPF propoganda, misinformation and denial would we have to demonstrate to you before you decided they were unreliable witnesses?

Art Vandelay at 01:16 AM on 28 June 2017

Explainer: Dealing with the ‘loss and damage’ caused by climate change

OPF@25, you say, " I disagree as passionately as is possible in text to the following claim: "Ultimately, it's emisisons per square foot or meter of land that a country will be paying for."

People, not land area, are causing the problem. The accumulation of the per-person impacts of everyone in a nation, through the entire history of that nation, make up that nation's total impact. Land area is irrelevant."

I belive we are actually in agreement. My point was that people (population) is what matters, because it's people that create emissions. A country such as Australia has a relatively small population of big emitters, but if every country in the world had the same population density and emissions per capita as Australia, there would be no global warming problem at all. Conversely, if every country had the same population density and emissions per person as India (2017) there would be a very substantial global warming problem. Ultimately, the world can tolerate some amount of (equivalent) CO2 emissions per square mile or km of land, so in my view it should be the responsibility of each sovereign government to manage their population and emissions per capita within a taget limit based on total land area. This would force countries such as Australia, who want a big population, to become sufficiently CO2 efficient to support it. Likewise , countries with big populations would be encouraged to reduce or stabilise population levels.

MA Rodger at 20:00 PM on 27 June 2017

Models are unreliable

NorrisM @1047,

A big long comment from you setting out a lot of stuff. Can I home in on the things you describe as "what also troubles me in everything that I have read so far on climate change." (As you say it is off topic for the thread but...)

(1) The Mediaeval Warm Period. This you describe as being "at least 200 years in at least Greenland and Northern Europe close to or equal to our present temperature." The temperature at the top of Greenland can be reconstructed from ice cores with some accuracy. GISP2, for instance shows results like this graph and some will take the last few thousand years of this graph as proof that recent warming is trivial when compared with previous centuries, as this SkS post describes. Yet the most recent GISP2 data dates from 1855 and when you graft on modern temperature data things look a whole lot different. The idea that Greenland experienced temperatures "close to or equal to our present temperature" is not borne out by the evidence.

2. "During the 1600's and 1700's there was ... skating on the Thames." We do have the CET Central England Temperature record stretching back into the 1600s, temperatures recorded a few dozen miles up the road from the Thames at London. This shows seriously cold winter month have been occuring occasionally throughout the record with the last occuring in 2010. History tells us that Ice Fairs were rare events and they do coincide (almost always) with these exceptional cold CET months. Ice Fairs stopped not because of a Little Ice Age ending or because of global warming but because the old London Bridge was demolished and the banks of the river were embanked. It's all a bit nerdy, but ancient accounts of the Thames freezing continue back in time and continue through the Mediaeval Warm Period (prior to the bridge being built) and are even found for the centuries called by some the Roman Warm Period.

3. You are on much safer ground suggesting that reconciling the temperature record and climate forcing in the first half of the 20th century is not straightforward but very much less safe with the so-called hiatus. There is a lot of comment on these elsewhere within the SkS site. You do raise the idea that if the hiatus was the product of La Nina sucking the warming from the atmosphere and down into the ocean depths. (It is not controversial to state that the years 2007-13 saw lower global temperatures due to La Nina and withut these years the so-called hiatus is truly a non-event.) From this you speculate whether it was potentially the oceans warming the atmosphere 1975-98. You are not the first with such speculation. Bt if there was such a warming from the oceans, there would be evidence of it in the Ocean Heat Content data as it takes a lot of heat to both warm and keep warm the atmosphere. The level of heat required would certainly have to be evident in the OHC data. It is not evident.

Moderator Response:

[PS] Thanks for contribution but it would be more appreciated if you had followed the request to put it on the correct place since MWP is offtopic here.

Eclectic at 18:15 PM on 27 June 2017

Models are unreliable

NorrisM @1047 , if I may add some background to Tom Dayton's posts :-

When considering climate models, it is well to remember that the models are based on the physical realities of this world.

And the most basic of relevant points, is that the natural greenhouse effect from CO2 etc. has been "artificially" (anthropogenically) pushed higher by the addition of fossil-origin CO2 to the atmosphere. The result is that the world is warming up — it is gaining heat at the rate of approx. 2 watts per square meter. (Which may not sound very much : yet if you think it through planetwide and decades-long, then it represents a major problem for this planet.) Also, if you think it through (regarding where that heat is going and how it moves about within the system of the planet) then you will realize that a pause or hiatus is simply not possible until such time as the system eventually reaches equilibrium (in 2 or 3 centuries' time).

Therefore if Koonin says there is a real "Hiatus", then he talks nonsense.

If you are a Black-Letter lawyer, you will wish to examine "fake-skeptic" comments without considering their provenance or any ad-hominem aspects. Yet as a pragmatic man-of-the-world lawyer, you will wish to take into account the background information regarding the four protagonists you mentioned [Koonin, Christy, Curry, Lindzen], when you come to assess their evidence.

And you will be aware of human frailties — particularly that frailty called "Motivated Reasoning" : where even very intelligent people (such as Koonin) do bend their rationality and end up deceiving themselves. And doing so, very staunchly! And with apparently honest demeanor!

Climate science is a large area, where you can educate yourself considerably — and if you do so, you will find yourself in agreement with the extensive and almost unanimous consensus of experts (e.g. the U.S. National Academy of Sciences; the U.K. Royal Society; the Vatican's Pontifical Academy of Sciences; and dozens more of peak scientific bodies). All in consensus about Global Warming. Indeed, there is only a score or so of Koonins, Christys, Currys, and Lindzens who hold an outlier position in disagreement with the overwhelming preponderance of scientific experts. And as you yourself gain education in climate science, you will understand that these 4 protagonists, despite their intelligence, have all managed to make a very poor judgment of the actual position. And that, as you look beyond their rhetoric, you will find that their apparently scientific arguments are empty and false.

How is it possible for 4 intelligent people to be so very wrong? It is because their emotions have pushed them into motivated reasoning. Motivated reasoning by Koonin / fundamentalist religious bias from Christy and Lindzen / and something less clear, from Curry [about whom you need ask: Cui Bono ].

In the strictest sense, these four are not being scientists — because they have allowed their emotions to override their dispassionate intellects.

They have muddied the waters and confused your understanding of the significance of models (and of the physical realities).

Tom Dayton at 12:48 PM on 27 June 2017

Models are unreliable

NorrisM, you asked

Is it “solid physics” that:
1. Water vapour will in fact increase as modelled?
2. Water vapour will cause the predicted additional increase in temperature by a factor of 2 to 3 times?

Answers: Yes. I assume you are familiar with the concepts of relative and absolute humidity, at least from weather reports you've read and seen your entire life. Perhaps you've noticed that cold air (e.g., winter) is drier than warm air (e.g., summer). For more details, read the Basic and then the Intermediate tabbed panes here.

Moderator Response:

[PS]"In addition, water vapor concentrations have increased throughout the troposphere at about 1.2% decade−1 since the ERBE period (Trenberth et al. 2005, 2007b). " from here. Also see Clausius–Clapeyron relation for seriously settled science. Water vapour is not the only feedback.

Tom Dayton at 12:41 PM on 27 June 2017

Models are unreliable

NorrisM, your claim

The models predicted that our temperature would increase on a linear basis. There were no “waves” in the models.

is incorrect.

All the models projected (not "predicted") inconsistent ("wavy") temperature increase. None projected monotonic ("linear") increase. The mean of models usually is shown in graphs, but all the individual model runs that contribute to that mean are "wavy." For ease of viewing, sometimes graphs of climate models show only the models' mean, or show the individual runs' spread as a shaded area. But the actual runs look like spaghetti.

We do not expect the actual temperature to fall exactly on the "ensemble mean" hindcast and forecast, because that mean has far too little variability. In fact, we expect the temperature to have wild ups and downs as you see exemplified by the orange and blue skinny lines in Figure 2 here, because we expect there to be El Ninos and La Ninas, variation in solar radiation, volcanic eruptions, changes in human-produced aerosols due to varying economic activity, and a slew of random and semi-random factors. It would be downright shocking if actual temperature followed the ensemble mean, because that would mean all those variations in forcings and feedbacks were far less variable than we have observed so far. So we judge the match of the real temperature to the projected temperature by whether the real temperature falls within the range of the entire set of individual model runs. Even so, we expect the real temperature to fall within that range only most of the time, not all of the time. The range you see drawn as a shaded area around the ensemble mean usually is the 90% or 95% range, meaning the set of individual model runs falls within that shaded range 90% or 95% of the time. That means, by definition, we fully expect the real temperature to fall outside that range 10% or 5% of the time. So occasional excursions of the real temperature outside that range in no way invalidate the models, when "occasional" means 10% or 5% of the time.

Moderator Response:

[PS] An example graphic of real output of models and discussions is here. Realclimate also has a FAQ on models - written by the modellers themselves so not heresay.

One Planet Only Forever at 12:06 PM on 27 June 2017

2017 SkS Weekly Climate Change & Global Warming News Roundup #25

New news report in the NYTimes.

Carbon in Atmosphere Is Rising, Even as Emissions Stabilize

Tom Dayton at 11:40 AM on 27 June 2017

Models are unreliable

NorrisM, initially I'm going to assume you are who you claim to be, though the content of your post makes me suspicious--very suspicious--that you are one of SkepticalScience's fake-skeptic, trolling, chronic sock-puppeteers, and one in particular.

Your statement

The APS panel consisted of six (6) arm’s length physicists (with no axe to grind) chaired by Steve Koonin who were asking hard questions of both sides. What actually struck me as very astounding was how honest Koonin was about his previous lack of understanding as to how uncertain climate science is owing to the uncertainties underlying the climate models.

is incorrect. Steve Koonin is a notorious fake skeptic, who has both the background and the subsequent, repeatedly delivered, information to know that most of what he says and writes is factually and drastically incorrect. Christy has and continues to make claims that are factually incorrect, and is motivated primarily by political and religious beliefs. Christy's partner in crime is Roy Spencer, who is a member of the Cornwall Alliance that claims human-caused global warming is impossible because God promised Noah there would not be any more floods. Really. LIndzen's pet theory about the "iris" mechanism that self-regulates the Earth's temperature conclusively and repeatedly has been proven wrong (obviously, since Earth's temperature has varied drastically--Snowball Earth, ice ages,...) but that has had no effect on his opinion, and he very much resents and takes personally the criticisms. Curry once was an adequately productive climate scientist, but for reasons I won't speculate on here, has become quite the opposite.

Moderator Response:

[PS] That is uncalled for tone. I know all too well how tiring the denier trolls are but polite and reasonable enquiries are to be encouraged, as are substantive responses.

NorrisM at 08:59 AM on 27 June 2017

Models are unreliable

I would first like to state that I have finally found a website that is balanced on this very emotional issue. I also want to thank SemiChemE and Tom Curtis (along with a few others) who have engaged in a very fascinating discussion on climate models.

My intention is to pose a question on climate models in keeping with this blog, however because this is my first post, I would like to explain my background. I am a lawyer by training and have a very limited base in physics (took Latin in Grade 12 rather than physics) although I always did well in science. I will also disclose that I do have an involvement in the Canadian oil and gas industry notwithstanding that I live in Vancouver, BC.

Ever since the issue of global warming came to the fore in the late 1990’s and since, I have to admit that I have tended to accept the “scientific consensus” if only because I had no reason to question it. Climategate shook my confidence in 2009 but if Neil DeGrasse Tyson still believes that the principal causes are anthropogenic then far be it for me to question it. However, it always seemed logical to me that a first step in reducing the effects of CO2 should be to move from oil and coal to natural gas (especially for electrical generation) which puts about one half of the pollutants into the air compared to coal and oil. After spending enough holidays in France, I have also thought that a switch to nuclear energy made more sense than disfiguring our planet with massive wind turbines and great areas of solar panels. Driving from LA to Palm Springs is not a pretty sight. But I do appreciate that there are real concerns relating to disposing of nuclear waste and issues of terrorists getting their hands on nuclear fuel. However, someone as significant as James Hansen believes that we will not achieve our goals without a turn to nuclear energy.

In any event, my recent interest in the causes of global warming really came about because I have two sisters who are just about no longer on speaking terms owing to their disagreements on global warming. When one sister called me asking where I stood on climate change and if I truly believed that this was all a “global conspiracy of the left” to increase taxes and government control over our lives, I promised her that I would buy some books on both sides of the argument and get back to her. Needless to say, I do not believe in conspiracy theories of any sort.

So the two books I located were The Science & Politics of Global Climate Change by Dessler and Parson and Climate Change the Facts edited by Alan Moran.

By the time I was finished with Dessler’s book I was convinced of the science. Then I read the essays in the Moran book and found myself at least questioning some things.

I actually then went back and re-read Dessler’s book to see where the gaps were. I have to say that when I found that Mark Steyn had an essay in the Moran book I almost did not read the book because of his extreme views. Just to make my political views clear, I think Donald Trump poses a major threat to liberal democracy in the US and to the world in many ways. But it does look like the US institutions may be able to withstand him and his cohorts. I also follow Sam Harris’s podcasts “religiously”.

Since reading these two books I have largely pursued my research on the web even reading the submissions of the four climatologists on March 25, 2017 to the House Committee on Science Space and Technology.

Based upon Judith Curry’s reference in her submission, this led me to the most fascinating discussion of the topic of climate models by a panel of physicists formed by the American Physical Society (APS) which posed questions to six (6) well-known climatologists having “different perspectives”. Three (3) of them (Collins, Santer and Held) are IPCC climatologists and the other three (3), Curry, Christy and Lindzen are on the other side of the debate. This was the 2014 Workshop sponsored by the APS as part of its 5 year review of its Climate Change Policy Statement.

As a lawyer, I have to admit that if I treated (i) the IPCC 2013 Assessment as an appellate lawyer’s factum, (ii) the Workshop Framework posed as questions from the bench, and (iii) the 600 page transcript of the panel hearing as the “give and take” between the judges and lawyers during the oral argument of the appeal, I would have predicted a “win” for Curry, Lindzen and Christy and a “loss” for Collins, Santer and Held. Both the Workshop Framework questions and the transcript are on the APS.org website. Just search “Climate Change Statement Review”. If anyone has read any legal transcript of a hearing you know it is a simple read so don’t be put off by the “600 pages”.

The APS panel consisted of six (6) arm’s length physicists (with no axe to grind) chaired by Steve Koonin who were asking hard questions of both sides. What actually struck me as very astounding was how honest Koonin was about his previous lack of understanding as to how uncertain climate science is owing to the uncertainties underlying the climate models.

This panel hearing took place in February 2014. By November 2015, the judgment of the Board of Directors of the APS was in. The connection between increases in CO2 and global warming was “compelling”. However, the APS did acknowledge that there were significant uncertainties in the science and urged sustained research in climate science.

Where my comparison with an appellate hearing breaks down is that no appellate court would render a significant judgment without providing its reasons. We do not get any reasons from the panel as to why it recommended to the Board of Directors (as I assume it did) that the APS “stay the course” with its policy statement notwithstanding the serious reservations you could see in Koonin’s and other panel members questions to Collins, Santer and Held and the weak answers provided by them. The IPCC climatologists in effect admitted that Christy’s now famous chart showing how far apart the average predictions of the climate models were from actual observations was “old information” and did in fact represent the existing state of models predictions versus observations. See Santer page 504. The IPCC climatologists effectively said that they could not trust the observations! Koonin’s rhetorical question to Held to this "observational" response earlier was: “So the ability then to reproduce historical data is neither necessary or sufficient to predict the future. Is that what I understand?” See page 453 of the transcript. Held effectively avoids answering the question. See page 454. Read it yourself and see if you disagree with my view of his response.

So here is my question.

From everything that I have read so far, other things being equal, a doubling of CO2 in the atmosphere from pre-industrial levels of CO2 of around 280 ppm to 560 ppm will increase the global surface temperature by about 1 to 1.2C and the balance of the predicted range of 1.5C to 4.5C of the IPCC 2013 Assessment is based upon “positive feedbacks” resulting from increased water vapour that is assumed will form arising out of the 1C increase by CO2. I accept (or understand) that the 1C increase is “solid physics” or “hard science”.

Is it “solid physics” that:

1. Water vapour will in fact increase as modelled?
2. Water vapour will cause the predicted additional increase in temperature by a factor of 2 to 3 times?

Although this next observation is not specifically focused on the climate models, what also troubles me in everything that I have read so far on climate change is the following:

1. The Mediaeval Warming Period had temperatures for at least 200 years in at least Greenland and Northern Europe close to or equal to our present temperature.

2. During the 1600's and 1700's there was a "Mini-Ice Age" when they were skating on the Thames. We were just coming out of this cold period at the beginning of the American Revolution (good timing).

3. From 1990 to 1940 we experienced about .3C warming; then from 1940 to 1975 there was a levelling off or cooling period; then from 1975 to 1998 we experienced .5C warming; and then there was a levelling off (termed the “hiatus” by the IPCC) of now about 17 plus years that may or may not have ended in 2015 (El Nino event 2015-2016). I appreciate that 1998 was an El Nino year but the IPCC 2013 Assessment recognized the “hiatus” up to that time.

If climatologists cannot explain why these other warming and cooling periods occurred which, other than the 1975-1998 period, were primarily or completely caused by natural climate change, then why can they so confidently claim that this one warming period was primarily caused by the CO2 rise? Just because there was a concomitant rise in CO2? What about the rise of CO2 from 1950 to 1975?

The models predicted that our temperature would increase on a linear basis. There were no “waves” in the models. I guess based upon Michael Mann’s most recent testimony the most recent peer reviewed papers are now suggesting that we will be going up in steps or waves. Can we now expect that the new models with show the steps or waves?

So where did the “warming” go during this “hiatus”? If the answer is into the oceans, then why did the “warming” not come from the oceans during the period 1975-1998? Could we have had a cooling period during the “hiatus” that offset the warming from CO2 during this period? What are the impacts of a decrease or increase in low clouds caused by natural factors which impacts the amount of sunlight hitting the earth? Because of computer capacity issues, we can only make “parameterizations” of clouds in the models. These are the kinds of questions that make me question the validity of the models.

When we talk of the difference between weather and climate we say we cannot predict weather but we can predict climate because we know that next July it will be warm. But why do we know that? Not from models, from observation. If observations and models do not correspond, when do we admit that the models do not have sufficient predictive value to be relied upon? It is OK for science to say “we just do not presently understand the science sufficiently to make reasonably accurate predictions”.

On the other hand, here are the major science societies of the world like the APS, the US National Academy of Sciences and the UK Royal Society coming out strongly in support of the proposition that man-made global warming is a serious problem and is going to get worse. My worry is that they got on a band wagon in the early 2000’s before the “hiatus” was apparent and they now find it very difficult to get off even when they see that these models are not predictive.

I apologize for such a long-winded initial blog. If you think I have to reduce it, please advise.

Moderator Response:

[PS] Welcome to Sks. We really like to keep things on topic, (see the comments policy) so we would prefer you put your questions about MWP on the appropriate thread after first reading the article. (your questions are pretty well answered in the IPCC WG1 as well). Ditto, other questions not about modelling. Could responders please stick to modelling questions only on this topic? Thank you for your cooperation.

scaddenp at 08:25 AM on 27 June 2017

Satellites show no warming in the troposphere

Arent the low frequency channels used for water vapour not temperature?

One Planet Only Forever at 08:07 AM on 27 June 2017

Explainer: Dealing with the ‘loss and damage’ caused by climate change

Art Vandelay@23,

I disagree as passionately as is possible in text to the following claim: "Ultimately, it's emisisons per square foot or meter of land that a country will be paying for."

However, nations/regions/societies need to get their acts together and correct/penalize those in their populations who are producing the biggest impact. The people who are causing the biggest impact through their personal consumption need to be limited, even if imposing the limits goes against their personal interest in being free to believe and do whatever they please. Popularity and profitability clearly do not justify anything, neither does a claim to the Right to Freedom to Believe and Do whatever you want.

scaddenp at 07:11 AM on 27 June 2017

Explainer: Dealing with the ‘loss and damage’ caused by climate change

Art, what do you mean by soon? If I look at historical contributions (using data from here), and then current emissions, it looks to me like its going to take a while for the difference in emissions between Asia and just USA+EU to catch up that historical gap. Especially when China seems to be actually taking emission reduction seriously.

Daniel Bailey at 04:49 AM on 27 June 2017

Satellites show no warming in the troposphere

A primer on both surface and satellite temperature records:

Satellite-measurements-warming-troposphere-advanced

Primer-Tropospheric-temperature-measurement-Satellite

A-history-of-satellite-measurements-of-global-warming

Why-we-can-trust-the-surface-temperature-record

Assessing-global-surface-temperature-reconstructions

Microsite-influences-on-global-temperature-intermediate

Dropped-stations-introduce-warming-bias-intermediate

OfAveragesAndAnomalies_pt_1A

OfAveragesAndAnomalies_pt_1B

OfAveragesAndAnomalies_pt_2A

OfAveragesAndAnomalies_pt_2B

Eschenbach_satellite_part

James-Taylor-Forbes-UAH-rebuttal

New_Research_Special_Satellites

Surface_Temperature_Or_Satellite_Brightness

http://www.realclimate.org/index.php/data-sources/

Eclectic at 00:34 AM on 27 June 2017

Satellites show no warming in the troposphere

Indeed, I speculate/conjecture that the satellite record achieves its "lowermost" layer of tropospheric temperature, by lateral scanning compounded with vertical scanning — such that the horizontal resolution is so poor it has difficulty differentiating very elevated land from near-sea-level land. In other words, T1 channel has low validity.

It would be interesting to hear an expert opinion on the realities of the "lowermost" section of the measurements.

Either way, the satellite recordings (even apart from their manifold problems) have some value in studying the upper atmosphere — but little value in studying surface temperatures. But in providing some distraction from actual surface temperatures [including ocean-warming and ice-melting] they provide a modicum of illusory comfort to climate change deniers.

Tom Curtis at 23:35 PM on 26 June 2017

Satellites show no warming in the troposphere

Eclectic @67, the AMSU comes with a variety of channels. T2 in the diagram below is used for the middle troposphere (TMT) and by some mathematical manipulations relating to the difference in weighting between nadir and limit scanners, also for the lower troposphere (TLT). Channel T1 is not used for any of the standard temperature products, but does indeed peak near the Earth's surface.

I am unaware of why it is not used for a temperature record, but it may not have appeared on all satellites over the satellite era, or the AMSU era, making a continuous record impossible. It may also not be able to handle changes in surface altitude without significant distortion. Somebody more expert on the subject may well be aware of other potential reasons, or indeed, may know the actual reason rather than merely conjecturing.

Eclectic at 22:47 PM on 26 June 2017

Surface Temperature or Satellite Brightness?

Qwertie @38, the peaking "near ground level" is a relative term. Relative to the even higher altitude measurements of the other channels.

It is misleading to make any real equivalence of T1 channel to actual surface temperatures. Humans plants & animals live down at ground-level/sea-level. Not thousands of feet up in the air (where T1 applies). Sadly, the satellite-measured temperatures have little or no relevance to real surface temperatures.

Eclectic at 22:35 PM on 26 June 2017

Satellites show no warming in the troposphere

Qwertie @66 , his "peaking near ground level" description is simply false.

The satellite data (usually quoted by Spencer as the so-called The Lower Troposphere) averages out over much of the height of the troposphere — and with a small amount of stratosphere added to the mixture as well !! [a bias which they attempt to remove]

It could be taken as equivalent to the temperature on top of a very tall mountain. But is he seriously suggesting that way-up-high mountain-peak temperatures are in any way a reasonable representation of the world's ground-level & sea-level temperature? He is pulling your leg (or his own).

Perhaps his next comment will be that we should only look at the warming trend measured at Mt Everest Base Camp ;-)

DPiepgrass at 22:17 PM on 26 June 2017

Surface Temperature or Satellite Brightness?

"Microwaves do not measure the temperature of the surface, where we live. They measure the warm glow from different layers of the atmosphere."

Another article on SkS says that "T1, MSU Channel 1" peaks "near ground level." Is there some reason it could not be used to measure surface temperatures?

Eclectic at 22:06 PM on 26 June 2017

Temp record is unreliable

Serial Sockpuppet (of #416) seems to take very personally the criticism of Mr Heller.

The graphs he alludes to, both demonstrate a skyrocketing of global temperature during the past 2 decades.

— So what on Earth is the point he is trying to make, other than a pointless persistent peevishness?

The world is heating up rapidly: regardless of deniers.

(Moderator, please abridge or delete my post, at need.)

DPiepgrass at 21:51 PM on 26 June 2017

Satellites show no warming in the troposphere

Why is "T1, MSU Channel 1" which is "peaking near ground level" seldom used?

I'm talking to a guy who seems to be claiming the satellites show half or less as much warming as the "land" temperature record. So I would be interested to see a land temperature reconstruction from the satellites to find out if there's any truth to that. Do clouds prevent an accurate reconstruction of ground temperatures by satellites?

Tom Curtis at 21:36 PM on 26 June 2017

Temp record is unreliable

RobJones @416, if you are going to accuse me of lying, it behoves you to use my actual words. I did not talk about a change in scale, but a change in the range of the y-axis. Specifically, I said:

"Heller's giff does not demonstrate any significant change in values. Rather, it exhibits a change in the range of the y-axis from -0.6 to 0.8 for "NASA 2001" to approximately -0.85 to 1 for "NASA 2015". That represents a 32% increase and accounts for nearly all of the apparent change in trend - particlularly post 1980."

Nearly all of the apparent change in trend post 1980 is a result of the warming trend continuing for another 14 years, a fact obscured by Heller's method of presentation. This is evident when you simply overlay the data as in the graph I showed. By changing the range of the y-axis between graphs, Heller creates an optical illusion, without which his case falls to pieces.

As it happens, Heller's scales are also not identical, as is shown by your graph, and as I have independently confirmed. This can be seen by noting that the decimal points of the two graphs are aligned at 0.2 on the y-axis, but not aligned at 0.8. Thus, you have conveniently demonstrated that Heller also changed the scale. The effect, however, is minor and works against his preferred indoctrination, and so can be ignored.

Continuing on, you write:

"I compared these plots with those used by Tony Heller in his .gif animation, and except for scale, they were identical. BTW, these are the datasets I am referring to when I talk about the doubling of warming trends with the "corrections" of 2015. The statement bu Tom Curtis
"It is very clear that use of the new data sets make almost no difference to the trend."
obviously does not apply here as substantial data re-writing was done for the entire 20th century, most of which should not have been touched."

First, thank you for confirming that your current account is a sock puppet by referring to your prior talk about doubling. I note that you talked about a doubling of the trend in the last decades of the 20th century, and clearly there is no doubling of between the lowest and the highest trends among different GISS versions as shown in the graph I show.

Second, the specific changes in methodology detailed @413 are applied across the entire century. More importantly, when additional stations are added, they can have data across any period of the record. Consequently, on both accounts we would expect revisions going as far back as 1880. Once again, if you have a problem with the methods, criticize them.

Finally, I note your hypocrissy in being shocked that I should accuse Heller of lying (even though I didn't); while hapilly defending Heller whose whole career in climate science has been based on claims that climate scientists are lying; a claim you appear to make in your following post ("field of study isn't already riddled with corruption").

nigelj at 19:55 PM on 26 June 2017

Exxon, Stephen Hawking, greens, and Reagan’s advisors agree on a carbon tax

Bvangerven @14, thank's for clarifying that. I totally agree, particularly your comments on some countries relying on encouraging renewable energy as the only real strategy, and hoping this would drive emissions down, and your coffee / tea analogy. This wont really work well enough. I really just meant it's absurd that they are going down that road, as nobody with any sense should be promoting that.

The obvious example is America. I think it has had only very modest results looking at the numbers, and has mainly lead to emissions reductions for electricity generation, but not much uptake of electric cars or things like that.

But go one stage further to Germany. They have mostly relied on cap and trade combined with subsidising wind power etc. This has again reduced emissions from coal fired power (sadly somewhat reversed due to the nuclear issue), but this combination has not been enough to cause much uptake of electric cars. It becomes clear they need specific subsidies for electrtic cars, or maybe it requires a state funded recharging network.

In other words it is fairly clear that subsidies alone are helpful but insufficient, but also that carbon taxes (or cap and trade) alone are useful but insufficient as well. Further even both together only go so far and development of electric transportation needs some form of initial support as well (and it may not require much, this is the important thing). So you need a combinational approach that deals with discouraging fossil fuel use and all elements of renewable energy.

Yes an emissions trading scheme is complex, but a carbon tax will have some complexity, although not quite as much. The biggest problems with emissions trading are that they are opaque schemes where its very hard to get to the bottom of whats going on (and I have tried), perhaps so called commercial sensitivity is part of this. They also rely on globally traded agreements and forestry units, that come form all sorts of countries, and many of these countries dont have terribly reliable or trustworthy commercial practices. By the time we figure outs whats going on the damage is done, and my country has had a specific problem of this kind with imported credits that turned out to be worthless, admitted by our government.

Emissions trading schemes have a form of accounting that also looks to me to be very open to all sorts of abuses. In addition Europe has allowed all sorts of exemptions under their scheme to keep industry competitive against imorted products, but the end result has been a weak scheme. But you probably know all this anyway and, I have only scratched the surface.

In comparison carbon taxes are a pretty visible sort of cost and any exemptions would appear tobe more visible or harder to hide, a benefit of such a scheme. You have less commercial sensitivity problems, or difficult to access contracts with dubious conditions attached.

Emissions tarding schemes do have the virtue of encouraging innovation, but I think more in theory than in practice. And any form of tax or regulation can encourage innovation to at least some extent.

Encouraging energy efficiency is just so obviously desirable. A "no brainer".

The problem is some people want a singular magic answer. People who promote cap and trade see this as the only thing needed. This just isn't convincing.

We need a strategy that combines a number of tools. As I stated above, the most viable and politically plausible is a revenue neutral carbon tax combined with lightly subsidising some aspects of renewable energy and electric cars ( and transport in general), and rules around energy efficiency. This brings all elements close together, and closes the gap. The whole package could be revenue neutral or close to it, if required.

Ultimately a carbon tax may reach its own limits of effectiveness, but that is far off and can be dealt with if it happens.

bvangerven at 17:47 PM on 26 June 2017

Exxon, Stephen Hawking, greens, and Reagan’s advisors agree on a carbon tax

@nigelj,

I don’t think we disagree. I just want to make the point that we should be skeptical about climate policies. In my opinion a climate policy should be engineered, it should be modelled like a climate model to identify all expected and unexpected consequences.

We don’t have much time left, and we only have one opportunity to get it right. If after a couple of decades it turns out we implemented the wrong policy (also the EU ETS comes to mind) we won’t have a second chance.

Regarding my statement that renewable energy may well cause an increase in demand for fossil fuels, you say: "That would only happen if renewable energy was developed and spread widely and was very affordable, and there was no carbon tax or other control on fossil fuels. Nobody is suggesting that scenario."

But … that scenario is the reality is many countries. There are many countries – that signed the Paris agreement ! - that don’t have any policy to discourage the use of fossil fuels, they are just focussing on improving energy efficiency and the deployment of renewable energy.

I just don’t believe you can drive the consumption of fossil fuels to zero that way. It’s the same as trying to stop people drinking coffee by putting tea on the market. People won’t stop drinking coffee. In the best case they’ll drink a little less coffee.

Or to put it another way: there are policies that shift the system’s stable equilibrium point to a low-carbon state. A carbon tax that is high enough does this. An emission trading scheme may perhaps achieve the same results – if it is well designed, and the cap is really a cap, and measures are taken to avoid carbon leakage. But an emission trading scheme is much more complex and hence it’s effect is much more difficult to assess.

And there are other policies that don’t shift the system’s equilibrium point, but these measures will help us to reach the equilibrium point faster and with less disruptions (f.i. improving energy efficiency and rolling out renewable energy).

These two kinds of policies should not be confused. And the second kind cannot replace the first kind.

RobJones at 17:44 PM on 26 June 2017

Temp record is unreliable

(-snip-)

Moderator Response:

[DB] Serial sock puppet of serial spammer cosmoswarrior snipped. Please ignore this user.

bozzza at 15:43 PM on 26 June 2017

Factcheck: Grenfell Tower fire and the Daily Mail’s ‘green targets’ claim

Hear, Hear: I can't believe there was no sprinkler system but will expect this to be made publicly/(globally) known as the most glaring mistake in highrise buildings aka dog-boxes.... how did that journalist miss so many elephants?

The people in these apartments are being treated with contempt but such has our society become. It is all of our responsibility to make sure this is never forgotten for the calculated murder it is!!

Art Vandelay at 14:23 PM on 26 June 2017

Explainer: Dealing with the ‘loss and damage’ caused by climate change

Nijelj@1, just to offer the comment in reply, that the west's total contribution to GHG's will soon be overtaken by developing countries in Asia. Yes, per-capita emisisons are higher in the west but a large population naturally incurrs higher emissions. Ultimately, it's emisisons per square foot or meter of land that a country will be paying for.

Art Vandelay at 14:06 PM on 26 June 2017

Explainer: Dealing with the ‘loss and damage’ caused by climate change

bvangerven@3, you ask, "who is going to pay".

Well, let's hope that each country is made responbsible to pay for its emissions over a 200 year time-frame, and let's also hope that emissions also include those associated with land use changes, including deforestation. But there still remains the question of where that money goes and how that money is used to mitigate or adapt to climate change. Also, depending on the rate and severity of the change, geo engineering might actually be the cheapest and best solution over the short to medium term. Sure, there may well be very undesirable side effects, but those would be weighed against the even more severe consequences of 3 or 4 degrees of planetary warming.

nigelj at 07:35 AM on 26 June 2017

Exxon, Stephen Hawking, greens, and Reagan’s advisors agree on a carbon tax

bvangerven @12, I agree the economy is complex, and there can be unintended consequences in various emissions reduction strategies, or negative side effects.

Of course as you would appear to agree this is not a reason to do nothing or try nothing, and we have to simply try to think the issues through as much as we can, and minimise problems through classic harm minimisation strategies, and also accept some "experiments" may not work. That is the price we may for making any form of progress. Given the way renewable energy is plumetting in price, many of these "experiments" have been a spectacular success.

However I agree biofuels have had unintended consequences. I thought they were a dubious idea this from day one, instinctively. I also understand the use of corn or maize for biofuels was driven more from political and farm lobby motives than to reduce climate change, so if the motives are dubious then it's likely the results will be of dubious value as well. However it was possibly still an experiment worth trying, and something viable may come from other forms of biofuels.

However I'm going to disagree in part about your comments on carbon taxes and renewable energy. Even carbon taxes could have unintended consequences or some problems. For example a revenue neutral tax will give money back to people one way or the other, and there's nothing to stop some being spent on fossil fuel products, negating some of the effect of the tax. However both the theoretical modelling and real world evidence suggests much is not spent on petrol, as use of petrol has declined in countries trying these taxes. So the bottom line is a carbon tax is not going to be perfect, but is a very good idea that still ticks all the boxes.

Regarding renewable energy you say "When renewable energy is deployed on a massive scale, this may give a boost to the worldwide economy … resulting in a higher demand for fossil fuels."

That would only happen if renewable energy was developed and spread widely and was very affordable, and there was no carbon tax or other control on fossil fuels. Nobody is suggesting that scenario. If renewable energy becomes cheap, and a huge general boost for the economy, and fossil fules are taxed, demand for fossil fuels will be pretty low.

And it is absolutely senseless having a carbon tax on fossil fuels, if there is no viable alternative, like renewable energy, so this fuel source must be encouraged. A carbon tax will partly do this by making it more attractive to purchase, however I don't think a carbon tax would go far enough to do this, and you also need to subsidise renewable energy to some extent (which happens right now anyway). Or it may be a case of just needing to subsidise things like recharging stations.

I agree the bottom line is the best solution is a carbon tax combined with indirect measures.

nigelj at 06:41 AM on 26 June 2017

2017 SkS Weekly Climate Change & Global Warming Digest #25

Some great articles, however the main reason the aral sea has receded is rivers feeding the sea were diverted for agriculture, starting right back in the 1960s (notably before the modern global warming era). If climate change is a factor, it should be stated as a "contributory factor" .

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