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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.

Recent Comments

Comments 10101 to 10150:

Bob Loblaw at 11:26 AM on 31 July 2019

'No doubt left' about scientific consensus on global warming, say experts

For a less intense introduction to climate change, I often suggest the first IPCC report from 1990. It covers a lot more basics that are simply assumed in later reports.

https://www.ipcc.ch/report/ar1/wg1/

In the contents of the Executive Summary, the first section lists:

What factors determine global climate?
What natural factors are important?
How do we know that the natural greenhouse effect is real?
How might human activities change global climate?

In the main table of contents, Chapter 1 is titled "Greehouse gases and Aerosols". It covers five specific gases, plus ozone and related trace gases, and then aerosols.

Chapter 2 is titled "Radiative Forcing of Climate". Its sections cover greenhouse gases, solar radiation, direct aerosol effects, indirect aerosol effects, and surface characteristics.

So much for the idea that the IPCC does not consider other factors besides fossil fuel emissions. This is so easy to look up.

Daniel Bailey at 09:15 AM on 31 July 2019

Climate's changed before

"Thank you, scaddenp, Daniel Bailey and MA Rodger!"

For my small contributions, you are most welcome.

"i have looked at a lot of evidence from both sides of the argument"

If only there were actual sides. Because that would imply that both "sides" were roughly equal.

In the discussions around global warming and its anthropogenic causation, there are those who focus on the science using the scientific method and logic, seeking reproducible evidence that best explains what we can empirically measure. We call them scientists, the real skeptics.

Then there is everyone in the extremely small but vocal minority, those who ignore the above in favor of slander, innuendo, unsupported assertion and character assassination in favor of promulgating false equivalence to support the ephemeral facade of "debate" and "sides".

But it is not about the science, the bulk of the science was settled, decades ago. Deniers posing as skeptics set up a charade tableau of false equivalence to poison the well of public acceptance of that science.

A parsimonious harping at the font of stolen, out-of-context and context-less emails proven not germane to the science is continuing on in the prosecution of the agenda of denial.

Truth, science and reputable journalism all sacrificed to the unholy alter of false equivalence under the guise of promulgating a fallacious "debate".

There is no debate. All that remains is the informed and the uninformed.

Those professing the false equivalence of "both sides" are the journalist in this story.

Moral, dear readers: Don't be that journalist.

The discussion surrounding the science of climate change and its human-causation are a Möbius strip comprised of 170 years of evidence from hundreds of thousands of scientists from virtually every country on the planet. Meaning that from an evidence perspective, only one side exists, because only one side uses evidence.

Even the petroleum extraction companies researched the subject themselves and affirm the unassailable facts, physics and evidence of AGW.

Per the oil companies, which admitted it in court, under oath:

"The issue is not over science. All parties agree that fossil fuels have led to global warming and ocean rise and will continue to do so, and that eventually the navigable waters of the United States will intrude upon Oakland and San Francisco. "

The People of the State of California vs BP PLC et al (page 6, line 6).

nigelj at 08:39 AM on 31 July 2019

2019 SkS Weekly Climate Change & Global Warming Digest #30

OPOF @3, yes upper middle class and rich people could be called over consumers, often owning multiple cars and televisions, and having huge homes etc so some scope definitely exists for them to reduce consumption. I should have mentioned that, but didn't really have time.

I fall into that upper middle class category, and I choose to live reasonably modestly in terms of consumption. Similar to you in fact. However Im not prepared to live like a pauper, and we are nibbling away at the edges of the problem.

The rich also have most of their wealth invested or its on loaned to other people, so their over consumption of material resources is just their immediate posessions. This is a significant factor, but its the consumption of other classes of people which is largest. Virtually everyone owns basic technology and uses transport of some sort and the impacts add up, so the scope for working classes and lower middle classes to reduce consumpotion is limited. So population is a huge part of the issue and potential solution.

Daniel Bailey at 08:29 AM on 31 July 2019

'No doubt left' about scientific consensus on global warming, say experts

"all that concrete and pavement absorbs the sun rays, creating a giant heat sink"

While urban areas are undoubtedly warmer than surrounding rural areas, this has had little to no impact on warming trends.

"The Urban Heat Island effect is real. Berkeley’s analysis focused on the question of whether this effect biases the global land average. Our UHI paper analyzing this indicates that the urban heat island effect on our global estimate of land temperatures is indistinguishable from zero."

http://berkeleyearth.org/faq/#question-15

"Time series of the Earth’s average land temperature are estimated using the Berkeley Earth methodology applied to the full dataset and the rural subset; the difference of these is consistent with no urban heating effect over the period 1950 to 2010"

http://static.berkeleyearth.org/papers/UHI-GIGS-1-104.pdf

"The simple take-away is that while UHI and other urban-correlated biases are real (and can have a big effect), current methods of detecting and correcting localized breakpoints are generally effective in removing that bias. Blog claims that UHI explains any substantial fraction of the recent warming in the US are just not supported by the data."

For more info:

https://skepticalscience.com/urban-heat-island-effect-intermediate.htm

nigelj at 08:13 AM on 31 July 2019

'No doubt left' about scientific consensus on global warming, say experts

Hoipolloi.., cities are indeed absorbing some solar energy, but they are less than 0.1% of the earths area, so its just not enough energy to account for the vast warming seen in the oceans for example. This is basic stuff to calculate, and is not reliant on computer modelling.

william5331 at 07:38 AM on 31 July 2019

'No doubt left' about scientific consensus on global warming, say experts

Have you ever tried to argue a creationist out of his point of view. The most extreme case of cognitive dissonance I have come accross is a geologist I met who was a creationist and argued that a 500 plus series of gravel, sand, clay, gravel sand clay was the result of the great bibical flood. It is the same with climate change deniers. No amount of evidence short of a total disastrous flip of the climate is likely to convince them. The real problem, though, stoping effective action is the financial support of politicians by vested interest. Sort this one out and we will begin to gain traction on all the things we must do to avoid a disaster.

scaddenp at 07:19 AM on 31 July 2019

Models are unreliable

Strange comment. Models predict that climate is changing fast so I dont see how rapid change makes them wrong. However, no climate modellers is claiming that models are 100% accurate. Not even close. They have no skill at decadal level prediction but do at climate (30 year average) level. Climate sensitivity estimates are still too wide for comfort (2-4.5), however, they remain the best tools we have for predicting further climate.

Rob Honeycutt at 04:45 AM on 31 July 2019

'No doubt left' about scientific consensus on global warming, say experts

Hoipolloi... I get the idea that you've never read the IPCC reports because they most certainly do not claim that FF's are the "sole reason" for climate change. There are extensive sections on urbanization and deforestation as well as dozens of other related issues, including changes in solar forcing, volcanic influences, etc, etc.

You also seem to be under the mistaken assumption that the IPCC does computer modeling. They don't. The IPCC only does a report on all the published science related to climate change. The science cuts across a very wide range of fields of research and their purposes is to pull all that disperate information together into a single report.

My suggestion for you would be to spend at least an hour purusing through the IPCC reports. I don't even need to post a link. They're very easy to find and they've updated the website to make the reports very easy to navigate.

Have fun!

Hoipolloi at 03:43 AM on 31 July 2019

'No doubt left' about scientific consensus on global warming, say experts

Even if you believe in catastrophic climate change, no mention is made of the basis for this "consensus." Antropogenic warming of the earth may well be happening but for different reasons than what the IPCC would have us believe........

The Intergovernmental Panel on Climate Change (IPCC) would have us believe that fossil fuel emissions are the sole reason for climate change. But what about urbanization and deforestation? A study by the UN Department of Economic and Social Affairs states that the urban population rose from 750 million in 1950 to 4.2 billion in 2018. We don’t need the IPCC’S hugely complex computer models to know that cities are hotter. All we have to do is walk from a paved sun-heated street lined with concrete buildings to a grassy park. Rather than reflecting the sun’s rays back to outer space, all that concrete and pavement absorbs the sun rays, creating a giant heat sink. Likewise, deforestation is turning vast tracts of cool African and South American jungles into heat- absorbing barrens. The U. S. EPA summarizes the combined effect, “Processes such as deforestation and urbanization … contribute to changes in climate.” Trying to deal with any problem without considering all possible causes is both a foolish and dangerous strategy.

Moderator Response:

[DB] At Skeptical Science, the onus is on each person posting (in this case, you) to be able to support their statements and assertions with citations to the credible literature. Please read the Comments Policy and construct future comments to comport more fully with it.

"Trying to deal with any problem without considering all possible causes is both a foolish and dangerous strategy"

Scientists already have. Scientists have evaluated all natural forcings and factors capable of driving the Earth's climate to change and it is only when the anthropogenic forcing is included that the observed warming can be explained.

Natural vs Anthropogenic Climate Forcings, per the NCA4, Volume 2:

Forcings

Changes in the sun's output falling on the Earth from 1750-2011 are about 0.05 Watts/meter squared.

By comparison, human activities from 1750-2011 warm the Earth by about 2.83 Watts/meter squared (AR5, WG1, Chapter 8, section 8.3.2, p. 676).

What this means is that the warming driven by the GHGs coming from the human burning of fossil fuels since 1750 is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval.

It's not the Sun

Sloganeering and fake terms snipped.

One Planet Only Forever at 03:23 AM on 31 July 2019

2019 SkS Weekly Climate Change & Global Warming Digest #30

Another way to respond to concerns about total population is to point out that 'population' and climate change impacts are both included in the comprehensive Sustainable Development Goals. And all of the SDGs need to be achieved and improved on. And because of the lack of correction of the incorrect directions of development that have occurred, not just powerful resistance to climate change impact corrections, some developed perceptions of wealth or superiority relative to others will have to be given up to correct what has incorrectly developed.

The coal barons of today are poorer than they were thought to be. The same fate will need to be forced on the oil barons, the natural gas barons, and all the other pursuers of perceptions of superiority relative to others whose actions are not developing sustainable improvements for the future of humanity. Those people cannot all be expected to sacrifice their harmful and unsustainable pursuits of perceptions of success and superiority. In many cases the rule of law will have to be developed in ways that effectively correct them, just as it has developed to limit other harmful unsustainable human activities.

This also means the typical person will also have to be 'externally' encouraged to behave better, meaning having responsible leadership take actions like imposing carbon fees to correct their behavior.

Anyone wanting to believe that their developed perceptions of prosperity 'must be preserved' is destined to be disappointed (the future of humanity does have to win, the sooner the better), but those resisting correction will regrettably be able to be harmful until facing that deserved corrective disappointment.

Global understanding that needs to be developed for sustainable development to happen is that everyone's actions can impact the future of humanity, and everyone is a part of global humanity and are only free to do as they please if what pleases them helps develop a sustainable improvement of the future of humanity. Tribalism is fine Within That Limit. However, diversity of people within that limit needs to be encouraged (acceptance of that diversity is another required correction that some people resist and they can be seen to partner up politically with those who want to powerfully resist the economic corrections that climate science has exposed are required - resisting improved understanding and resisting the related corrections of developed perceptions that are required to achieve sustainable development beneficial to the future of humanity is what they have in common).

One Planet Only Forever at 02:37 AM on 31 July 2019

2019 SkS Weekly Climate Change & Global Warming Digest #30

The proper description of the concern is this sustainability of how humans are living and whether sustainable improvements are being developed.

And the undeniable understanding based on abductive reasoning in pursuit of the best explanation of what is going on is that competition for perceptions of superiority relative to others with popularity and profit as measures of merit has developed unsustainable human activity that is detrimental to the future of humanity and has developed powerful resistance to correction.

Growth of the total population is a concern. But the real concern is the total impacts of the total population. And everyone should be expected to aspire to being deserving of merit and living like the perceived leaders/winners.

With that understanding it is clear that the problem is the example being set by the perceived winners. The developed competitions are rewarding unsustainable and harmful behavior.

What is required is for the winners to be required to be proven to be deserving based on the helpfulness and sustainability of that helpfulness to the future if humanity. What is currently developed as methods of evaluating the merit of actions, and the people doing the actions, is failing to properly determine what is deserving of merit (popularity or profit).

The growth of consumption and harmful results of human actions is what needs to be curtailed, not just the growth of the population. And the highest consuming and highest impacting people are what needs to be targeted for correction. Reducing total population while allowing total consumption and impact to continue to grow is No Solution.

The developed ways of living of the highest impacting and consuming among the more fortunate today can only be understood as harmfully unsustainable. Significant incorrect overdevelopment has occurred. Correcting it is challenging. It requires people to accept a sacrifice of their developed perceptions of merit and ways of living.

It would be nice if sustainable alternatives existed that were as easy and cheap for those benefiting from them as the currently developed activity is. But that is not likely a reality. That is likely a tragic fantasy.

As for what I do. I drive as little as possible and drive a hybrid (because the power generation in Alberta is so bad that there is more impact from an all electric than there is from a hybrid, lots of coal burning to produce the electricity). I also consume very little that is not food or water. I also seek out Fair Trade goods or sustainably produced goods.

MA Rodger at 01:18 AM on 31 July 2019

Greenland is gaining ice

Molsen @40,

You say that "it seems that a little more than 99.99 per cent of it does not melt in even a bad year." That is actually wrong. It is about 99.93% that annually "does not melt." The ice sheet averages something like 1,500m in depth and the melt is about 1m of that. What you appear to ignore is the annual +800mm precipitation of snowfall which must be added to the net Ice Mass figures to give the total annual melt.

However, I will assume you are interested in net Ice Mass as that has been your interest up-thread and that would be roughly equal annually to 0.01% of the total ice mass. The statistical significance of the net ice loss is not in any way dependent on the total mass of ice suffering the loss. Rather it is a matter of whether the measurement of Ice Mass is noisy enough that the negative trend could be purely a product of the noise. This can be determined statistically.

In the case of the GRACE data of total Greenland Ice Mass graphed repeatedly on this web-page, the negative trend is a long long way from being statistically insignificance. A quick linear regression through the data with the annaul cycle removed (2003-2015, the data which was readily available) gave a trend of -273.4Gt/yr +/-7.3Gt/yr(2sd). So the Confidence interval would be -266 to -281, all a long way from zero.

Rob Honeycutt at 23:46 PM on 30 July 2019

'No doubt left' about scientific consensus on global warming, say experts

Kuidaskassikaeb... This would just be yet another hockey stick. The first hockey stick was done by Mann, Bradley and Hughes back in 1998/99. It was merely a collection of local and regional temperature data series all combined that stretched back over the past 1000 years to show the changes in global temperature. Since then there have been lots of newer studies with refinements and the same answer comes back: human activities are rapidly warming the planet. And all that is merely a confirmation for what scientists already expected going back through 100+ years of science.

SirCharles at 23:32 PM on 30 July 2019

'No doubt left' about scientific consensus on global warming, say experts

The Consensus on Anthropogenic Global Warming Matters

http://journals.sagepub.com/doi/abs/10.1177/0270467617707079?journalCode=bsta

Kuidaskassikaeb at 23:26 PM on 30 July 2019

'No doubt left' about scientific consensus on global warming, say experts

This is just a question. How is this different from the famous hocky stick?

richieb1234 at 23:18 PM on 30 July 2019

How could global warming accelerate if CO2 is 'logarithmic'?

MA Rodger: Great stuff! Thanks

Evan at 23:01 PM on 30 July 2019

'No doubt left' about scientific consensus on global warming, say experts

"This paper should finally stop climate change deniers claiming that the recent observed coherent global warming is part of a natural climate cycle."

I doubt this will silence the critics. When have credible facts ever guided POTUS? I expect the only thing that will move the deniers is evidence outside their windows.

But hopefully it will move some of the fence sitters into greener pastures.

MA Rodger at 22:56 PM on 30 July 2019

Climate's changed before

TVC15 @770,
Well, let that be a lesson for you!!
Denialism isn't logical. It turns folk into swivel-eyed loons.

To correct his nonsense-
♣ It was 3 million years ago (not 2) that North & South America collided and joined up, a process that did kick off the Arctic glaciation which then resulted in c3 million years of ice ages. And over tha last 1 million years the ice ages were significantly bigger. Presumably the present warming that is bringing this 3-million-year-period to an end can be blamed on the collision of the USSR and the Republic of China with the United States of America, these all constituting significantly large land masses.
♣ You probaly could argue the Arctic was ice-free 100,000 years ago but only through the peak of the summer melt season (as in the Arctic Ocean having the levels of summer ice we would declare today to be ice-free).
♣ 15,000 years ago we were still coming out of the last ice age. We were out nearer 10,000 years ago (as the graphed ice core data clearly shows).
Ice Core Temperatures
♣ The extreme global temperature changes since the Last Glacial Maximum were nothing like "10-15 degrees C" except at a regional level (ie Greenland). And the period over which these increases occurred (the data graphed shows two large sudden Greenland increases in the last 20,000 years - +12ºC at 14.5kybp & +9ºC at 11.5kypb - which were not 10-year periods of increase but 200-year periods. I don't think the ice cap volumes exist in the northern hemisphere to achieve a repeat performance today.
♣ The relative temperature of different interglacials has been discussed in this thread before and so we know the swivel-eyed loon is having difficulty hearing this particular message. So, yes, we do think he is "just being crazy" and that craziness is why he has such difficulty accepting the science and its implications.
♣ With regard to emisions controls, we can, of course, treat all people on Earth equally as the denialist wishes. The science says that anthropogenic CO2 emissions of more than 700Gt(C) will be bad and with 7.7 billion folk living on the planet, that would be an allowance of 91t(C) per head(historical) ('historical' as your allowance-use is handed down from previous generations).
So let's calculate that allowance using Global Carbon Project figures and present-day population. Note these GCP territorial emission data only go back to 1959. Getting full historical figures would be possible (& correcting for increasing population could be factored in) but the general result will not change. That would mean that China still had an outstanding carbon allowance of 54t(C) per head, India 82t(C)/head while the good old USA has exceded its allowance and so has to pay back 238t(C)/head into the collective kitty. If full historical emissions were included, the US pay-back would be greater still, not qute as great as the UK pay-back if taken to the beginning of the Industrial Revolution. (From 1959 the UK pay-back is a trifling 47t(C)/head). Luxembourg from 1959 has a pay-bacl 0f 199t(C)/head but would be the country facing the biggest carbon-emissions pay-back with full historic figures.

Denial is a sad thing to behold. Denialist folk become happy to dismiss the evidence witout any assessment of what they are ignoring. It is simply done. "The IPCC assessment reports? A complete pack of lies!!"
More telling is the misuse of the remiaining information that you do accept. As you are ignoring whole swathes of actual data, your sources tend to be limited and adjusting the findings beyond that limited evidence becomes a necessity. So some, no all previous ice ages were warmer, golly, 10 degrees warmer, 20, 100 degrees warmer. We should be grateful we live now and not then!!!!
And how does the following rate on the scale of untruthfulness given it comes from a real climatologist, abet a retired one. It's from Lindzen's seminar at the UK House of Commons in 2012. (@ 32.20mins in the first videoed part of his talk linked here. (You-tube link here)

"Does it [20th century temperature increase] matter?"
"Okay so some points to take away from the global mean temperature anomaly record. Changes are small. They are in the order of several tenths of a degree. Changes are not causal but rather the residue of regional changes. Changes in the order of several tenths of a degree are always present at virtually all time-scales. And obsessing on the details of this record is more akin to a spectator sport or tea-leaf reading than a serious contributor to scientific efforts."
"Say, at least so far. I mean if some day I shoud see the changes are twenty times what I've seen so far, that would be certainly remarkable but nothing so far looks that way."

The implication is that we have here a retired climatologist who considers a gobal average temperature increase of less than (0.7 x 20=) 14ºC to be unremarkable. Are we then supposed to take such a retired climatologist as a serious authority on climate?

What perhaps we cannot judge is how much a denier knows he is misrepresenting the data he presents, that he is effectively lying. I suppose gross exageration can be justified because the denialist message is to them the correct message and, and denialists don't have the resources to counter all the lies that you climate alarmists generate with all your fake IPCC science.

Molsen at 22:27 PM on 30 July 2019

Greenland is gaining ice

To clarify: is the percentage that melts (i.e., the 0.01 per cent - at worst -statistically different from zero?

Moderator Response:

[DB] Annual losses from the Greenland Ice Sheet are 286 Gt/year. Pretty statistically significant, even relative to the Empire State Building:

Annual Greenland Ice Sheet Mass losses

Molsen at 21:56 PM on 30 July 2019

Greenland is gaining ice

Given the total volume of ice in the Greenland ice sheet, it seems that a little more than 99.99 per cent of it does not melt in even a bad year. Is that statistically significant from zero?

Eclectic at 20:39 PM on 30 July 2019

In 1982, Exxon accurately predicted global warming

MsG @15 ,

If you seek some audiovisual presentations, then you may like the Youtube videos by Potholer54 (a science journalist by the name of Hadfield). Excerpts permissible, I'm sure !

Informative & often amusing & encouraging of critical thinking. The videos now number 50 (fifty!) but are mostly short (though some over 20 minutes).

Potholer54 avoids political partisanship, and is careful to give facts based on the scientific papers published in reputable peer-reviewed journals i.e. based on the actual science. Many of his videos are given with a humorous facet or two ~ which is (IMO) bound to appeal to you and your students.

Always , always , he emphasizes the importance of careful critical thinking wherever one encounters "facts" / information / hysteria / blogs / newspaper articles . . . and the need always to check the sources, find the original sources and evaluate their reliability, and be skeptical of the headlines.

# Be careful with the numerical label of each video ~ Youtube nowadays numbers the videos 1 - 50 , but the main video screen prominently displays an older numerical notation.

All are worth seeing (as fresh info for the climate science novice, and as humorous chuckles for the climate Old Hands . . . especially the five videos under the Monckton Bunkum heading ! )

If I may suggest a few :-

the 1st : "1- Climate Change - the scientific debate" [ 10 minutes]

the 23rd : "21- "Earth facing a mini-ice age!" [ 6 minutes]

the 25th : "23- Medieval Warm Period - fact vs. fiction" [ 20 minutes]

the 28th : "26- Science vs. the Feelies" [ 16 minutes]

the 29th : "27- The evidence for climate change WITHOUT computer models" [ 16 minutes]

the 31st : "28- The consequences of climate change (in our lifetimes)" [ 18 minutes]

the 40th : "A conservative solution to climate change - part 2" [ 21 min]

(The videos range in date from about 2009 'til 2019. None obsolete ! )

michael sweet at 19:34 PM on 30 July 2019

In 1982, Exxon accurately predicted global warming

MsG,

You should have a section on Greta Thunberg. She is the same age as your students. She is the most successful climate campainer in the world. Perhaps your students will want to start a group to support her or school strike on Fridays.

When I taught AP Chemistry I used several data sites to introduce AGW. If you want to use denier information you will only confuse your students, they cannot evaluate data very well. Most are familiar with the denier side since Exxxon's propaganda arm is so strong. If you choose to use denier data I think you should view this sketch from John Oliver first:

John Oliver 97%

I find that students like to see the data themselves and did not care about what I thought. I used the NSIDC web site for the retreat of Arctic Sea Ice. The minimum is around September 15 and the NSIDC October report around October 5 will cover sea ice in detail. It is written at a level AP students can read. This year is very low. If you look at the NSIDC site the first week of school you can follow to see what the final result will be.

The NOAA annual climate report (2018 linked) describes the global temperature. They have a USA only report and have monthly reports also. I only used the annual reports. The annual report comes out around January 15. I like this graph linked at the start of their global report: There is a similar US only graph.

It is possible to find data for the city you live in but that data is often very noisy and hard to interpret.

My students did not like the IPCC reports because they wanted to only see US data. The Fourth National Climate Report, issued by the Trump Admministration, has many sections that describe most of the expected affects already measured and expected in the USA. I recommend you focus on this report since it is so authorative and is USA based. Since this report is so long you could make your unit as long or short as you like by reading more of it. I had students choose a section and write a report on the affects expected for the area they were most interested in.

All of these data sets are accepted by everyone. There is no need to offer the "other side" since only one set of data exists. If you view the Michals video you will only be indoctrinating vunerable students with false propaganda. Perhaps at the very end of your unit you could view it and point out his mistakes. Time how long you view it and only give 1% of your time to it (the scientific consensus is now 99% and not 97% so more than 1% for deniers means you are pushing their points). There is not really a denier position, they all disagree with each other and change their arguments every sentence to suit the wind.

Ask here for more information. If you describe in more detail what you want we can be more specific in reply.

MA Rodger at 18:46 PM on 30 July 2019

How could global warming accelerate if CO2 is 'logarithmic'?

richieb1234 @13,
It's an interesting thought. Although for me the answer below doesn't really need calculating, let's do it.

The forcing from a doubling of CO2 is 3.7Wm*-2, enough to raise a body at a theoretical temperature of 255K by 1K. This then kicks off feedbacks that raise the temperatures by something like a further 2K. For sake of argument, let us assume this ECS=1K+2K = 3K.

We know that a further doubling of CO2 will require twice as much CO2 as the first doubling and that will raise that theoretical body from the double-CO2's 258K, but by a little less than 1K due to the S-B fourth-power relationship. So theoretically it would be 0.966K or 3.4% less than the first doubling.
And if we went for a third doubling to raise that theoretical body from the quadruple-CO2's 261K, the CO2 would provide a further 3.7Wm^-2 of forcing** and raise temperatures by a theoretical 0.933K or 6.7% less than the first doubling. And compounded with the reduced second doubling, that would amount to 10% less warming over the third doubling or an average reduction of 4.5% over all three doublings. But with global temperatures now +9ºC and the uncertainty with ECS=3K (It could well be significantly higher through three doublings), I would be surprised if a 10% discount for being such a loyal customer of CO2-powered AGW is going to feature in anybody's decision making.

[** With a third doubling, CO2 atmospheric levels would be reaching 2,200ppm so now well above the 1,300ppm that my memory tells me is the top of the range over which the logarithmic relationship should be used. The forcing relationship then increases somewhat due to the compound CO2 absorption band at 10 microns starting to kick in.]

MsGteacher at 17:06 PM on 30 July 2019

In 1982, Exxon accurately predicted global warming

Hi fellow posters :)

I wonder if you might help me find respected resources on the topic of global warming. I know this is a huge ask and I know I can Google, but I have collected a plethora of resources and want to make sure I'm not missing something obvious/recent.

My dilemma is that I teach an AP English course to 17-year-old students. I want my opening unit to be focused on whether or not global warming is happening in 2019. My goal is to always give students both sides (I have NASA data to compare with a Fox News interview with Patrick Michals from the Koch-funded Cato Institute). I try, hard as it is, to step aside and have students think critically and ask Socratic-type questions of one another during class to provote "out of the box" thinking while remaining open to changing their opinion (which is often related to what their parents have fed them).

I truly appreciate any help in advance in terms of guidance toward resoures, videos, documentaries, etc. that show BOTH sides of this issue and are easily digestable by young minds and not scientists with PhDs.

Fun fact: I wrote an 80-page research paper in 1997 about the effects of global warming on our world's forests. I went to university in San Francisco, so it was a topic that was heavily discussed back then in our college classes. Crazy to think, 20+ years later, I am a lot like Exxon...we both knew decades ago.

tjarlz at 15:29 PM on 30 July 2019

2019 SkS Weekly Climate Change & Global Warming Digest #30

Yes, I have been wondering about this too. If people in the global north decided to reduce their consumption to meet planetary boundaries, then how much expenditure would that represent per annum (based on a notional basket of goods/services)? What would people do with the(ir) surplus "unspendable" income? Would we all work less? Would the economy be able to adapt?

emmawilliam11 at 15:17 PM on 30 July 2019

Models are unreliable

the climate is changing very fast, so these models can not be 100% accurate.

richieb1234 at 11:06 AM on 30 July 2019

How could global warming accelerate if CO2 is 'logarithmic'?

scaddenp - Thank you. I think your response to my comment would be a good addition to the article, because I am probably not the only reader who wondered about how Stephan-Boltzmann fits into the picture.

TVC15 at 09:12 AM on 30 July 2019

Climate's changed before

Thank you, scaddenp, Daniel Bailey and MA Rodger!

I'm with scaddeep's statement: "If someone isnt prepared to let data inform their opinion, then it isnt worth arguing".

I realize how utterly useless my efforts are in trying to help the "deniers" understand the science that supports human caused climate change.

I have learned so much from you all when I post the denier claims. I thoroughly appreciate the responses as you provide me with insights that I would not have been able to discover myself.

However I've grown tired of dealing with the deniers. If they can't understand what they are seeing all over the globe right now as I type this there is no amount of science that will open up their minds.

Here is just another sample of the type of denier minds out there.

i have looked at a lot of evidence from both sides of the argument, and i dont need someone to tell me what my conclusions should be. and there is PLENTY of geological evidence that this round of warming is nothing more than a natural event, one that had been going on for the last 2 million years, ever since the north and south american continents collided. 100,000 years ago the arctic was ice free. and as has been noted many times by many people in many ways, here are a few truths you need to take into account;

1: we are out of the last period of glaciation by only 15,000 years roughly
2: the AGW crowd is complaining about an increase of 1 degree C over 150 years, but there is geological evidence that 15,000 years ago the temperature went up by something more like 10-15 degrees C in TEN years.(i didnt know there are that many SUVs back then, who knew?)
3: we are still ten degrees COOLER than at this same time during the last intergalciation period, and the one before that, and the one before that for the last 2 million years. and its funny how the AGW crowd FAILS to take into account previous interglaciation periods, and what was NATURAL warming.

and if you think that i am just being crazy, then why is the IPCC scientists solution always more regulations and more taxes and redistributing the wealth of the developed nations to those nations that are still developing? and why is it that all the so called climate change protocols penalize the developed nations, mostly western europe and the US, and ignore the rest of the world? why is china given a pass, along with india? two of the highest CO2 emitters in the world?

if the AGW message was more consistent, and required ALL countries to stick to the climate change protocols, then perhaps their message might be more acceptable, and more people might actually listen to them.
in the end these protocols are nothing more than a way for the UN to control the worlds population, and to work to usher in one world government with the UN running things, and no national sovereignty of any kind.

now you claim i am a science denier, but that isnt the truth here. i suppose you also consider the science settled, and that is NEVER the case. the science is NEVER settled, except in the case of the closed minded, non scientific lemmings.

I see no point in spinning my wheels on a mind such this.

scaddenp at 08:31 AM on 30 July 2019

How could global warming accelerate if CO2 is 'logarithmic'?

richieb1234 - while the Stephan-Boltzmann law gives you relation between radiative power to 4 power of temperate (so the doubling CO2 would raise temp by 1.1C), it is less useful than you might think for estimating actual surface temperature. You cannot raise (or lower) temperature without other feedbacks coming in. These operate on very wide timescales from very fast (water vapour increase), through decadal scale of albedo change from less ice, to century/millenia feedbacks in carbon cycle. Add in the complexity of cloud feedbacks (both +ve and -ve), and you get the wide range of estimates on climate sensitivity.

richieb1234 at 05:56 AM on 30 July 2019

How could global warming accelerate if CO2 is 'logarithmic'?

This is such a good article. I keep coming back to it. If there is one thing that might improve it, I might suggest a discussion of the mathematical relationship between forcing function and temperature. If I remember my Physics correctly, radiative energy goes as the fourth power of temperature. So a small temperature change can make up for a relatively large deficit in radiative energy. Whether or not I am right about that, it would be interesting to see a discussion of that relationship.

knaugle at 03:55 AM on 30 July 2019

2019 SkS Weekly Climate Change & Global Warming News Roundup #30

This may interest you. It's a story of the effect of "Dzud winters" on the nomadic lives of people in the Mongolian Steppes. Climate change appears to have hit them hard.

Deadly Winters ... For Herders In Mongolia

Daniel Bailey at 03:36 AM on 30 July 2019

Wind energy is a key climate change solution

"what about all the bird and bat deaths it's causing"

Wind turbines kill orders of magnitudes fewer birds than do fossil fuel energy generation sources. Where's the outcry against those?

In reality, cars kill 2,800 birds for every 1 killed by a wind turbine.

And cars kill more pedestrians than windmills kill birds. Is it time to ban cars yet?

The leading causes of Raptor deaths in the Altamont study:

1. Shooting
2. Poison
3. Cars

But pretend-skeptics aren't interested in facts that disagree with their desired outcome.

Per Erickson 2005:

Table 2–Summary of predicted annual avian mortality.

Buildings_______________ 550 million
Power lines_____________ 130 million
Cats___________________ 100 million
Automobiles_____________ 80 million
Pesticides_______________ 67 million
Communications towers___ 4.5 million
Wind turbines___________ 28.5 thousand
Airplanes________________ 25 thousand

Cat's out of the proverbial bag. Per Loss et al 2013, feral cats kill most of the 87,000 times as many birds (in the US alone) than do all of the wind turbines in the world do, combined. That's 3.7 BILLION bird deaths per year, by cats alone...in the US. Or about 10 MILLION per day, as compared to about 2 per day per wind turbine.

Seems the bird holocaust is getting out of...paw. Meow. :)

"Why have these people forsaken nature's physical grandeur for an often ineffective power source?"

Grandeur like this?

As for the environmental impacts of wind power:

"Most estimates of wind turbine life-cycle global warming emissions are between 0.02 and 0.04 pounds of carbon dioxide equivalent per kilowatt-hour. To put this into context, estimates of life-cycle global warming emissions for natural gas generated electricity are between 0.6 and 2 pounds of carbon dioxide equivalent per kilowatt-hour and estimates for coal-generated electricity are 1.4 and 3.6 pounds of carbon dioxide equivalent per kilowatt-hour"

And

"building and running new renewable energy is now cheaper than just running existing coal and nuclear plants...the full-lifecycle costs of building and operating renewables-based projects have dropped below the operating costs alone of conventional generation technologies such as coal or nuclear"

And

"its cheaper to tear down three-quarters of American coal plants and replace them with renewables than to let them continue operating"

Both utility solar and wind are cheaper than gas:

"alternative energy costs have decreased to the point that they are now at or below the marginal cost of conventional generation"

Unsubsidised wind and solar are now the cheapest form of bulk energy:

"The unsubsidised cost of wind and solar now beats coal as the cheapest form of bulk generation in all major economies except Japan, according to the latest levellised cost of electricity analysis by leading energy analyst BloombergNEF.
The latest report says the biggest news comes in the two fastest growing energy markets, China and India, where it notes that “not so long ago coal was king”. Not any more.
“In India, best-in-class solar and wind plants are now half the cost of new coal plants,” the report says, and this is despite the recent imposition of import tariffs on solar cells and modules.
The China experience is also significant. While local authorities have put a brake on local installations, causing the domestic market to slump by one third in 2018, this has created a “global wave of cheap equipment” that has more than compensated for increased financing costs caused by rising interest rates.
The cost of battery storage is also falling – so much so that in countries like Australia and India, pairing unsubsidised wind and solar with four hours of battery storage can be cost competitive with new coal or gas plants."

Fancy that, renewables are already cheaper than 75% of the US coal fleet of power generation facilities.

Whodathunkit, the carbon benefits of wind and solar far outweigh their carbon footprints.

Harking back to that picture of that lovely tableau of the open pit coal mine:

"Coal’s carbon footprint is almost 90 times larger than that of wind energy, and the footprint of natural gas is more than 40 times larger"

To wrap this up and stick a wooden stake through the undead heart of this meme, fossil fuels are less efficient than earlier estimates and are essentially uneconomical, now.

This means that the levelized cost of electricity estimates put fossil fuels at even more of a disadvantage vs renewables than previously demonstrated.

Yes, without subisidies.

Brockway et al 2019 - Estimation of global final-stage energy-return-on-investment for fossil fuels with comparison to renewable energy sources

Eclectic at 00:34 AM on 30 July 2019

Models are unreliable

MA Rodger @1121 ,

thank you for the link to McKitrick & Christy 2018. The paper suffers from major logical non-sequitur in arguing from the status of the high altitude Upper Troposphere (which he elsewhere misrepresents as the lower troposphere "TLT" ) instead of examining the planetary surface temperature and (even more important) the ocean heat content. Severe cherry-picking . . . as well as poor logic.

Thank you also for the link to Dr Christy's talk at the GWPF (actually given in May 2019, not in June). Much of the earlier part, as well as the middle part, must have been as clear as mud to most of the audience !

The talk contained the same logical fault as the McK & C 2018 paper . . . and then expanded into a great deal of waffle. And then finalized with poor analysis of storms and Californian wildfires . . . and with much irrelevant but emotion-charged rhetoric (including how Christy's Californian land-holder neighbour had dishonestly moved Christy's property-boundary marker peg ~ ??possibly a metaphor for all those dishonest mainstream scientists at the IPCC?? )

Irrelevancies, poor science, and demagogic rhetoric ~ just another ordinary day at the GWPF.

Considering that Dr Christy makes similar misleading presentations at senate/congressional committee hearings . . . it comes as no surprise that he was "uninvited" to return to contributing to the IPCC.

knaugle at 00:17 AM on 30 July 2019

'No doubt left' about scientific consensus on global warming, say experts

Wow! I occasionally peruse Roy Spencer's blog, and he definitely is not on board with the consensus. His latest post is still beating the "urban heat island" and "it's always cold somewhere else" drums. I wonder if he and John Christy are all that remains of the "3%"? It's no surprise the political think tanks like CEI are pushing to not even mention this topic. As I recall it was one of their key talking points 20 years ago, that scientists are all over the map on AGW.

MA Rodger at 22:05 PM on 29 July 2019

Models are unreliable

rupisnark @1120,
We discuss the serious error in John Christy's June 2019 GWPF talk. I could start running through the points @1120 and setting the record straight but as #1120 was the outcome of a previous record-straightening exercise @1119, I don't think a further round of record-straightening would achieve anything more than add to the length of this comment thread.

Perhaps then, rather than demonstrate the utter incomeptence engendered within the grand denialist presentation set out in John Christy's June 2019 GWPF talk (my original idea), perhaps it would be best to describe the nub of his theorising and why it is failing to establish itself. Note that this will be a little more technical than simple identification of gross error within his talk (error which was not of itself fundamental to Chrisity's argument).

Happily, this will be on-topic for this thread as Christy does attempt to refute the reliability of climate models.

Climate models have developed in complexity through the dacades. They all (simple and complex) show the same basic result from AGW. This result is disputed by Christy using a rather narrow argument. Christy first dismisses the performance of these various models at reproducing the global average surface temperature (GAST) increase. He insists "models are often adjusted to broadly match its (GAST's) evolution over time." GAST is thus, according to Christy, not an independent measure and thus should not be used to test the models (McKitrick & Christy 2018).

This argument is repeated by Christy in his June 2019 GWPF talk:-

"We cannot use the surface temperature, because the surface temperature record was used in the development of the model. That’s just as if I gave all the answers out to my students on Monday, I gave them the final on Friday, and they all did spectacularly well. Well, because I gave them the answers ahead of time! You cannot use surface temperature as a metric to test your model because that was used to tune the model, and you are not doing a legitimate scientific test."

(The actual abilities through the decades of the various models at projecting GAST is briefly reviewed by CarbonBrief.)

Instead of GAST, Christy uses specifically "the temperature of the atmosphere between 30,000 and 40,000 feet in the tropics, 20oN to 20oS." Given his insistence on not testing on 'Friday' what had been shown on 'Monday', Christy's choice is particulalry poor. His choice coincides with the long contentious "tropical hotspot" which has been argued over for decades. (So Christy is effectively testing on 'Friday' what had been shown on 'Monday'). And the "tropical hotspot" isn't a marker of AGW but of warming generally. I don't think Christy disputes that is happening. And as for measuring it to check whether it is there and to what extent, that introduces yet another layer of great uncertainty. (See this SkS post of 2009. And Christy in not addressing uncertainty plus other failings is considered by this 2016 post at RealClimate.)

So it is true that our present measurements suggest the "tropical hotspot" isn't as vigourous as expected, at its upper altitudes (although present at its lower altitudes).

Christy attempts to use the uncooperative "tropical hotspot" as some sort of essential failing of CMIP5 models and by implication as an essential failing of all models. As set out above, such attempts are poorly contrived and to-date even a corrected argument is far from unconvincing.

nigelj at 15:55 PM on 29 July 2019

2019 SkS Weekly Climate Change & Global Warming Digest #30

"Earth Overshoot Day falling on July 29th means that humanity is currently using nature 1.75 times faster than our planet’s ecosystems can regenerate."

To solve this very real problem would require quite large cuts to consumption of everything really. If you own a television, even an average sized home in a western country, a car, eat large meals, etc you are part of the problem but how many of us would give those things up? Hoping people will reduce their consumption significantly is a fantasy dream.

Recycling and better farming systems would help, but much of the solution will have to come from smaller global population. If anyone disagrees with me, I would be interested in how much you have cut your personal levels of consumption.

This is not an attempt to blame problems on high population countries like Africa. The consumption problem is mainly a western problem, but poor countries are also getting richer as well. Neither am I a huge consumer by western world standards. It is looking at the big picture, and facing reality, and making hard choices.

Rob Honeycutt at 14:31 PM on 29 July 2019

Wind energy is a key climate change solution

False Progress... Clearly, from your website, it seems you strongly object to the look of wind turbines, but what's your alternative? Personally, it seems to me wind turbines are infinitely more preferable to things like mountain top removal to get at coal seams.