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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:

My 1975 'Cooling World' Story Doesn't Make Today's Climate Scientists Wrong

It's time for deniers of human-caused global warming to stop using an old magazine story against climate scientists.

by Peter Gwynne, Inside Science, May 21, 2014

Bob Loblaw at 10:00 AM on 25 March 2017

Elevator Pitches - Chapter 02 - Radiative Gases

Confusion in the third sentence is due to two interpretations of "33 degrees Celcius". A better phrasing, now rarely used, is "33 Celcius degrees".

33 degrees Celcius is a temperature, equal to about 91 degrees Fahrenheit.

33 Celcius degrees is a difference in temperature, about equal to 59 Fahrenheit degrees.

KojoKerr at 09:30 AM on 25 March 2017

Over 31,000 scientists signed the OISM Petition Project

The blog seems to attack common weaknesses of both realists and alarmists. The alarmist assertions, from ambiguous questions, are a commonality. I addition, the % of survey targets delivered a tiny number of respondants.

Consensus is irrelevant as all scientists should know however, it has been clearly assessed by Von Storche etc, that the relationship between alarmists, the media and consensus in the unqualified dogma of the masses, is a self perpetuating myth.

This blog, so far, contributes to the mythology.

Moderator Response:

[PS] Sloganeering snipped. Please read and abide by comments policy. This is not optional. Furthermore note that noone claims scientific consensus make the science right, only that the scientific consensus is the only rational basis for policy.

If you want dispute something, use appropriate language. Clearly state the claim (with a reference) you dispute so dont have any strawman arguments. Back your criticism with references/data preferably from the peer-reviewed literature. If you just want a rant there are plenty of other forums which welcome such contribution.

Tom Curtis at 08:37 AM on 25 March 2017

Global warming is increasing rainfall rates

With apologies to the moderators, Wake in a post deleted for sloganeering, did refer to some data at the World Bank in an attempt to disprove the contention that precipitation levels are rising. Looking at the data in detail, it becomes obvious that it shows precisely the same decadal average for all data in a given nation, for every decade in which there is data. That is, according to the World Bank data, not only is their no trend, but there is no natural variability. Somalia, for instance, shows no evidence in their data of the 1980s drought in the Horn of Africa.

Needless to say, this complete uniformity in the data is very suspicious. If checked against local weather agencies, in this case Australia's Bureau of Meteorology, it is also shown to be false as regards decadal variability and overall trend. I do not know how it comes about that the World Bank is generating such spurious data, but while they do it is appropriate that a comment should be made on it (even if the original commentor here "has now recused himself").

nigelj at 07:25 AM on 25 March 2017

Elevator Pitches - Chapter 02 - Radiative Gases

Interesting that Ozone is also a greenhouse gas, although a weak one. It's apparently that three atom structure again.

rkrolph at 03:27 AM on 25 March 2017

2017 SkS Weekly Climate Change & Global Warming Digest #11

I see Wake is on an alternative fact rant today. Now I understand where his climate change denial is coming from.

Moderator Response:

[JH] I have just deleted a bunch of Wake's most recent posts because they were nothing more than inflamatory sloganeering.

[DB] Due to his inability to adhere to the SKS Comments Policy, Wake has recused himself from further participation in this venue.

barry1487 at 02:19 AM on 25 March 2017

Elevator Pitches - Chapter 02 - Radiative Gases

The sentence is right. Average temp of the earth is about 15C (59F).

33C cooler than that is -18C. That's -0.04F, which, with rounding is 59F cooler.

Kal at 01:28 AM on 25 March 2017

Elevator Pitches - Chapter 02 - Radiative Gases

Confusion in the 3rd sentence.33 degrees C is not equivalent to 59 degrees F.

Tom Curtis at 07:59 AM on 24 March 2017

A Perfect (Twitter) Storm

JohnFornaro @42, the current rate of sea level rise, taking the average of the five teams determining it, is 3.34 +/- 0.44 mm per year (see side bar here). Taken over the 17 years todate since Jan 1st, 2000, that represents a sea level rise of 57.35 +/- 7.55 mm. Comparing visually to the the second graph @39, that is above the upper limit of the IPCC "likely" range (shaded in purple), but about 40 mm below the "upper limit". Unfortunately this does not preclude the upper limit as yet.

The difference between the upper end of the likely range in the upper limit will, if the IPCC is correct, come from significant collapse of ice sheets. That is likely to be an irregular process, with periods of slower sea level rise interspersed with periods of rapid rise when undermined maritime ice sheets break loose, and/or when glaciers increase their flow because the ice shelf that had been slowing the flow break up. As with many things with regards to AGW, it will be a decade or two before we can significantly resolve which projection/model combination is most accurate with respect to sea level rise. As it stands, however, the current best estimate from an empirical stance would be a near 1 meter sea level rise.

With regard to Larsen C, it is an ice shelf, not an ice sheet. The difference is that an ice shelf is not grounded, ie, it floats. Consequently the break up of an ice shelf has a minimal direct effect on sea level rise; and no more direct effect than the melting of a similar volume of sea ice. The break up of an ice shelf can have a significant indirect effect in allowing the more rapid motion of the glaciers behind it. Given the location of Larson C on the Antarctic Peninsular, however, such glaciers will be of short length and limited mass. The effect on sea level rise is therefore likely to be, if anything, less than the similar break up of ice shelves on Greenland.

nomorewoo at 06:37 AM on 24 March 2017

How Green is My EV?

greg_laden@ 14

"EVs have no known depreciation function." This is nonsense, any mechanical technology has some sort of depreciation as all machine experience wear and tear.

:the market hasn't come close to making up its mind." This is also nonsense; the market is making up its mind every minute of everyday. Type in 'used electric vehicle for sale' into google and you will find what the market has decided the market depreciation on a EV is in your area at that moment.

nigelj@15

The only thing i "need" to do is breath, but here you go anyway

https://cleantechnica.com/2016/08/14/stunning-deals-used-electric-cars-expense-1st-owners/

I am making the suggestion that an article investigating the depreciation costs of EVs vs ICEs would be great.

Moderator Response:

[PS] Fixed link

nomorewoo at 06:17 AM on 24 March 2017

Global warming is increasing rainfall rates

I remember reading a figure of only 1 to 3% increase in precipitation per degree C in average global temperature in Gavin Schmidt's book Climate Change: Picturing The Science. The guardian has written a much higher figure of "between 5 and 10% for every degree C increase".

Is this referring to in increase in average peak temperature or average temperature? Anyone have a source for this statement?

Moderator Response:

[PS] Fixed formatting. Use the tools in the editor for formatting and embedding link.

michael sweet at 05:55 AM on 24 March 2017

A Perfect (Twitter) Storm

John,

As I understand it, every year a lot more is learned about the melting ice sheets. This new information changes the opinions of experts somewhat over 10 years or so. It is not really possible for amateurs to determine which model is the best fit right now.

In addition, if the nations of the world really start to work hard on carbon emissions it will change the trajectory that is followed. We must hope that China successfully invests in renewable energy and the rest of the world follows. Parts of Europe are putting in a good effort and demonstrating what is possible. If wind and solar energy continue to go down in price it may happen.

william5331 at 05:10 AM on 24 March 2017

Global warming is increasing rainfall rates

With more precipitation and with the precipitation more often occuring in strong downpours rather than gentle rain and with more of the precipitation falling as rain instead of feeding snow packs, our problem is to keep this water on the land, direct it underground and spread it timewise from times of rainfall (often the winter) to times of drought (usually the summer). We could create zillions of little concrete dams in all catchments but what a waste of money. Nature can do it for us.

https://www.youtube.com/watch?v=wI5AjJd00cM

http://mtkass.blogspot.co.nz/2011/05/erics-beavers.html

JohnFornaro at 01:11 AM on 24 March 2017

A Perfect (Twitter) Storm

Tom Curtis @39 and Michael Sweet @40:

Thanks for those graphs.

My question is pretty simply stated:

At what point can we measure sea level rise and point to that rise as incontrovertible evidence that one or more of these models is accurately predicting sea level rise?

I printed the graph provided by Michael to fit an 8.5 x 11 sheet of paper, and manually graphed the minimum and maximum sea level rise for the years 2017 to 2020. The minimum level rise can't be seen readily at this scale, but the maximum level rise would indicate a sea level rise of about 4 cm over the next three years.

I quite understand that I have arbitrarily selected the highest predicted rise.

Is there a better selection from among the eleven possibilities suggested in the graph?

When can the models be tested against reality? Is 4 cm good enough proof?

Michael Sweet: "Apparently they use the high value that 80% of experts think is the lowest high value."

I saw that too. Scott Adams' Twainian hammer is persuasion, and he rants, there's no other term for it, about how <b>all</b> things are about persuasion. Of course he's broadly wrong about that, but still, it is the case that people are trying to <b>persuade</b> policy makers to change policy regarding the climate, with tax policy being the tool of choice.

A graph such as this, with eleven scenarios and various percentages of confidence does not persuade well.

I saw Tom Curtis @ 41, quoting IPCC AR5:

"Based on current understanding, only the collapse of marine-based sectors of the Antarctic ice sheet, if initiated, could cause global mean sea level to rise substantially above the likely range during the 21st century. This potential additional contribution cannot be precisely quantified but there is medium confidence that it would not exceed several tenths of a meter of sea level rise during the 21st century."

Clearly, Larson C is in play and it seems that higher rates of sea level rise can be expected by current modeling.

pattimer at 22:38 PM on 23 March 2017

Global warming is increasing rainfall rates

The result is a shift such that more intense precipitation occurs at higher temperatures in future, while the drop-off moves to even higher temperatures.

This makes intuitive sense. In an existaing world state if a region gets too hot then the precipitaion will likley occur somewhere else. If the world on average is getting warmer then this turning point will have to occur at a higher temperature for it to go somewhere else.

Paul D at 21:46 PM on 23 March 2017

Global warming is increasing rainfall rates

On a practical note. About two years ago I upgraded the rain guttering on our house so that it could handle about 3 or 4 times more water. Previously it was beginning to overflow when there was a heavy rainfall, the new guttering can now handle the climate change induced heavier downpours, at least for now! Trouble is, I am not sure the soak away and the ground will be able to handle the greater amounts of water in the future.

Not sure if new homes in the UK are designed to handle increased rainfall?! Developers/builders seem to be still using the standard sized guttering they have always used.

Doug_C at 15:14 PM on 23 March 2017

In-depth: What Donald Trump’s budget means for US spending on climate change

This is obviously a politically motivated budget, not a practical one. And while climate change denial is used as a political football to kick around to motivate support in certain sectors of the US, as this piece states at the very start, there is so much evidence that supports catastrophic human forced climate that defunding research to the level the Trump Whitehouse would like is highly unlikely.

This is just going to add gasoline to the fires that are going to start this year as the US gears up for the mid terms next year.

There's no way that climate change is ever going to be a forgotten issue in any nation as the catastrophic impacts become progressively severe. Climate change denial is an exercise in idiocy, it doesn't banish the physical processes we're pushing into overdrive as the heat budget of the planet grows every second. Many Hiroshima bombs worth of heat were added to Earth's oceans and atmosphere as I composed this brief comment.

SemiChemE at 13:39 PM on 23 March 2017

Models are unreliable

Tom Curtis @1034, Thanks for understanding the point I was trying to make and giving a better explanation than I could have (see post #1035) for why paleoclimate data from >30million years ago may not be useful for predicting the earth's climate sensitivity to CO2 in modern times.

As for my conclusion, your post suggests I was not clear in stating my conclusion, since your argument appears to be about the likely range of climate sensitivities. I did cite a paper (or papers) that reflect a lower climate sensitivity, but my point in doing so was to highlight potential flaws in the models that might cause them to make improper predictions about future climate trends.

My intended conclusion was that climate models are still quite crude and unreliable for predicting the future climate. I do have hope that the models will get better over time, especially in light of modern data collection techniques (eg. Satellites, Argo sensors, etc...), which will enable modellers to reduce the acceptable ranges of the parameters that are currently used to adjust the model outputs.

I also argued that paleoclimate data is not sufficient to completely validate any given model due to
1. Limitted accuracy and precision
2. Poor temporal resolution
3. Significant gaps in global coverage
4. Limited visibility to important historical factors, including cloud behavior, aerosol and particulate variations, Ocean Currents, etc...

Finally, while I believe my statements about Paleoclimate data to be true, I am certain there is a literal army of climate scientists working to address these shortcomings and I would welcome any suggestions for a good summary on the latest state of the art in understanding our planet's climate history.

Tom Curtis at 13:07 PM on 23 March 2017

Models are unreliable

SemiChemE @1035, the three papers you cite all deal with the Transient Climate Response, formally defined as the temperature achieved at 70 years after a 1% increase in CO2 per annum over the 70 year period. The Equilibrium Climate Sensitivity (ECS) is the condition that obtains when quasi equilibrium between energy in and energy out is obtained at the Top Of the Atmosphere. The difference between the two is a function of how much energy must be stored at the Earth's surface (primarilly in the oceans) for the temperature to rise sufficiently to obtain an energy balance. Because of this, the three papers have no bearing on the value of the ECS except in that the TOA energy imbalance is used in energy balance estimates of ECS to change an estimate of the TCR to an estimate of the ECS. (That wording may be confusing, for which I apologise. If necessary I shall explain more clearly later when I have more time.) The papers certainly have no bearing on the issue of estimating the ECS from paleo data.

SemiChemE at 12:50 PM on 23 March 2017

Models are unreliable

DB inline @1030, I appologize for letting another poster pull me into an off topic discussion. My interest is in modelling and I will try to constrain my posts to that topic.

nigelj at 12:41 PM on 23 March 2017

Global warming is increasing rainfall rates

Peru is currently experiencing some record floods, in the sense of their intensity over very short periods, and are causing a lot of damage. The basic cause appears to be an unusual local el nino like phenomenon, that sometimes happens.

The high intensity would seem to be consistent with higher atmospheric moisture from a warming climate, possibly in combination with the local el nino generated weather phenomenon, which may or may not itself be influenced by global warming.

It also appears there's also a 50 / 50 chance of another full scale el nino later this year.

I agree with the concept of having a robust military, but I would have thought the USA spends ample already on it's military. It's hard to see how spending more will resolve the sorts of threats in the current global situation, and agreements with countries, and linkages by way of free trade would seem a better way of reducing tensions.

While countries owe a duty to their own citizens first, global connections would come a reasonably close second, I would have thought. Todays problems are global scale, and so require some degree of cooperation.

SemiChemE at 12:27 PM on 23 March 2017

Models are unreliable

Here are a few references, discussing the importance of Ocean-effects on global Climate Sensitivity.

Balmaseda, Magdalena A., Kevin E. Trenberth, and Erland Källén. "Distinctive climate signals in reanalysis of global ocean heat content." Geophysical Research Letters 40.9 (2013): 1754-1759.

Meehl, Gerald A., et al. "Model-based evidence of deep-ocean heat uptake during surface-temperature hiatus periods." Nature Climate Change 1.7 (2011): 360-364.

Raper, Sarah CB, Jonathan M. Gregory, and Ronald J. Stouffer. "The role of climate sensitivity and ocean heat uptake on AOGCM transient temperature response." Journal of Climate 15.1 (2002): 124-130.

There are many, many more such papers. Clearly, the oceans are very important to climate Sensitivity.

As for the evolution of Ocean Currents over time, here's a nice summary:

https://earth.usc.edu/~stott/Catalina/Oceans.html

As you can see, prior to ~30 million years ago, the arrangement of the continents was different, which had a dramatic impact on ocean circulation patterns. The Atlantic Ocean was much smaller and the isthmus of Panama had not formed. Given that Atmospheric-Ocean coupling is a major factor in determining climate sensitivity (see references above) and that due to geological changes in the configuration of the continents the Ocean circulation patterns were different, it is entirely reasonable to believe that climate sensitivities prior to 30 million years ago may have been different from those today. Thus, as I stated before, I would be very skeptical of the relevancy of paleoclimate data from >30 million years ago for predicting the modern climate.

Moderator Response:

[PS] Fixed link

Johnboy at 11:03 AM on 23 March 2017

In-depth: What Donald Trump’s budget means for US spending on climate change

For what it's worth, my past experience in a Government agency was that President's budgets, assembled by the Office of Management & Budget, are not much more than an "exercise" for the administration to mostly display its philosophy with a general 10-year budget plan including spending and anticipated revenues. Our agency's budget office folks used to laugh that when it gets to Congress its given a glance and tossed under the desk and then they try to agree on Congressional Budget resolution, another 10-year "plan"which may or may not have much resemblance to the Presidents.

After all this, the real work goes to the Appropriations Commitees to knock appropriations to each of the agencies For the upcoming fiscal year. Lots of horse trading and "bringing home the bacon" back to the Congresspersons home District.

Borrowing from a phrase from the golf world, we used to joke, "Budget for show, appropriate for dough"

Tom Curtis at 10:08 AM on 23 March 2017

Models are unreliable

PS inline @1029, SemiChemE's speculation is, I think, fairly obvious. Examples of changes in ocean circulation that would effect climate sensitivity include the opening of the Drake Passage between Antarctica and North America, the opening of the gap between Australia and Antarctica, the closure of the Central American Seaway between North and South Americas (with consequent strengthening of the Gulf Stream), and even the northward drift of Africa which is slowly strengthening the leakage of warm, saline water from the Indian ocean to the Atlantic Ocean, which leakage may have a significant effect on deglaciations. The extent of the effect on climate of these events is disputed in each case, but that they have some effect is, I think, incontrovertible. Each may have some role in the onset and/or intensity of recent glacial cycles; a sign that they have increased climate sensitivity over the geological average.

Nor are they the only geological changes that can impact climate sensitivity. Geological evidence shows that in periods with glacial caps climate sensitivity is greater. It follows that geological events that significantly increase or decrease CO2 concentrations will, respectively, decrease or increase climate sensitivity. The draw down of CO2 concentrations that resulted from the formation of the himalayas, therefore, has also likely increased climate sensitivity.

Despite agreeing with SemiChemE's speculation, however, I do not agree with his conclusion. We have climate sensitivity estimates across a very wide range of continental positions and glacial conditions. While the estimate of climate sensitivity from paleo data for one particular time may not be a reasonable analog of the modern Earth, we can expect the range of climate sensitivities across all times to constrain likely climate sensitivities today. In particular, we can expect modern climate sensitivity to be above within the range of climate sensitivities found in glacial conditions (as we are in a glacial condition).

Moderator Response:

[PS] Understodd. Thank Tom, and apologies to SCE for not following his line of reasoning.

Tom Curtis at 09:22 AM on 23 March 2017

2017 SkS Weekly Climate Change & Global Warming Digest #11

Wol @15, you are correct. My statement was over general, and was not believed by me in its over general interpretation. I should more correctly have said that conservative parties are the enemies of science, and restricted that claim to the English speaking nations in the Americas and Australasia.

michael sweet at 07:16 AM on 23 March 2017

Models are unreliable

SCE,

Here is a more suitable thread to continue this discussion.

Moderator Response:

[PS] Thank you

HK at 05:14 AM on 23 March 2017

CO2 effect is saturated

Nahle's incompetence isn't confined to how the greenhouse effect actually works.
He has claimed (nearly halfway down this page) that this sequence of pictures proves that Mars was warming between 1995 and 2005 because the polar caps were shrinking, implying that it must be the sun.
He apparently didn't understand (or forgot to tell his readers!) that each picture was taken a little more than one Martian year after the previous one, and that the changes in the polar caps are almost entirely due to seasons! (more on that in the thread Mars is warming)
A similar sequence at 13 months intervals of the Arctic from September 2005 to March 2012 would seemingly show a nearly 3-fold increase in sea ice extent, but we know what really happened in September 2012, don't we?

Mal Adapted at 04:17 AM on 23 March 2017

Global warming is increasing rainfall rates

I'll call SkS readers' attention to a germane US National Academy of Sciences report, Attribution of Extreme Weather Events in the Context of Climate Change. You can order a printed copy for $71.10, but you can download the PDFs for free.

michael sweet at 03:10 AM on 23 March 2017

Models are unreliable

SCE,

Simply repeating a false claim that you read on the internet does not make it an argument. Your claim that "the social costs of planning for an overly pessimistic ECS would also be tremendous" is simply false.

The US Academy of Science warned President Johnson in 1965 that AGW would be a crisis for mankind in the future. How long do you want to wait?? Scientists have been sure since the 1990's that this is a critical issue that must be addressed immediately and you want to wait?

Let us look at the worst case . We start to seriously build out renewable energy (WWS). After 10 years it is more expensive than we expected and the consequences of AGW are less than we expected. We stop the build. We end up wasting a few hundred billion dollars on the energy build. The money goes to pay workers who spend it and improve the economy. It is a wash overall.

Since every time the IPCC puts out a new report it increases the damage already caused it is extremely unlikely the worst case will happen. The report I linked above (which you do not appear to have read) documents billions of dollars damage that are being caused already. To mention only today's newspaper, wildfires caused by AGW have caused several hundred million dollars damage already and the fire season has barely begun. The 11 million people who will lose their homes from sea level rise in Florida alone can go live in your house.

We wasted over two trillion dollars unsuccessfully trying to steal Iraq's oil. If we switch to WWS we will not need half the military we currently have. Jacobson estimates that WWS will cost less than conventional energy. The cost of solar and wind have plummeted since Jacobson made these estimates so his cost estimates are too high. You must support your claim that fossil fuels have a comparable cost to WWS. I have not seen any serious analysis that suggest fossil fuels are as cheap as WWS when all costs are included.

The cost of wind and solar have plummetted the last few years and they are now the cheapest form of energy period. You are arguing to preserve more expensive energy sources for what?? Jacobson identified the need for alternate materials for the turbine magnets years ago. Iron nitride magnets are one alternative. Others are being developed. Where are you going to get the beryllium you need for all those nuclear power plants?

No mater what is done, fossil fuels will run out in a few decades. When do you think we should start the switch to WWS?

You are skeptical of WWS. Perhaps if you read more about them you would be less skeptical. Read the Jacobson 2015 article I linked above.

Several hundred thousand people per year die from air pollution in the USA alone from your preferred energy source. All these people will live longer if we switch to WWS. The cost of medical care caused by coal pollution alone is over $40 billion per year. We will save all that money.

I am amazed that you claim (without any supporting data or citations) that WWS is a risky choice and then you are in favor on Nuclear. Toshiba is on the verge of bankruptcy from its nuclear adventures. No market economy will build any nuclear for decades. Raw materials (like beryllium and uranium) do not exist for a widespread nuclear effort.

Moderator Response:

[PS] This is wandering completely offtopic. Unless there is comment on modelling, please use the search box to find a more appropriate thread and continue there.

SCE - please avoid stating opinions and hand-wavey arguments without providing the data/sources which form the basis of your opinion. And stick to topic.

vmarletto at 00:58 AM on 23 March 2017

Global warming is increasing rainfall rates

Is the first letter of this article missing?

Rob Painting at 18:19 PM on 22 March 2017

Models are unreliable

Latest climate model vs observations update - courtesy of Zeke Hausfather @ Berkley Earth:

SemiChemE at 15:26 PM on 22 March 2017

Models are unreliable

michael sweet @1024

Why should I cite a peer reviewed report to back a claim that I never made? I never said that changing to renewable energy will be bad for the economy.

I stated that, "the social costs of planning for an overly pessimistic ECS would also be tremendous."

So, let's go for a worst-case IPCC ECS estimate of 6degC/doubling. How much would the U.S. need to cut it's CO2 emissions to avoid a 2degC increase in global temperatures? What would such a reduction cost?

Now don't forget that in the U.S. we don't make the best choice, rather we make the most politically expedient choice. So, how would we likely make up the difference? Probably by expanding fracking of natural gas (basically, what we've already been doing) and by expanding our subsidy to the Corn industry for ethanol-based fuels. Of course, the latter is especially troublesome, since it would cause food prices to spike, which would hit the most vulnerable in our society and because of the intensive use of hydrocarbons in agriculture, it would probably do little to reduce CO2 emissions.

It's important to get the science right and make reasonable attempts to adapt on reasonable time-scales.

As for renewable energy, it has it's place, but I'm skeptical it can be implemented at sufficient scale to replace our existing infrastructure in a timely manner. Large-scale adoption of wind and solar will also run into vital material shortages (eg. niobium for generator magnets). Finally, government subsidies to encourage adoption of renewables are tricky and can lead to unintended consequences (see Arizona's attempt at encouraging alternative fuels: http://www.sfgate.com/politics/article/Arizona-Taxpayers-Fuming-Over-200-Million-2720374.php)

Finally, with respect to renewables, I think we'd be better off investing in Nuclear as it's a proven technology with scale sufficient to meet our electricity needs, but that's a debate for another time.

Moderator Response:

[DB] Off-topic snipped. Please post on the topic of the OP of this thread. Other topics and threads can be found using the Search function.

Please note that posting comments here at SkS is a privilege, not a right. This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

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SemiChemE at 13:42 PM on 22 March 2017

Models are unreliable

Glenn Tamblyn @1021 & 1023 and scaddenp @1028

The paleoclimate data is interesting, but I have concerns about how relevant it is for our world today and for predicting climate dynamics into the future. My biggest concern is that climate sensitivity is likely highly dependent on the prevailing ocean circulation patterns, since these dominate the heat exchange between the atmosphere and the oceans, thus amplifying or moderating greenhouse gas effects. For this reason I would be very skeptical of any conclusions based on data older than ~30 million years, since at that time the modern continents were still forming and ocean circulation must have been different. Presumably, there are other such factors that would make even more recent data of questionable value, though I'm no expert on the topic and would be interest to hear from anyone with such knowledge. Specifically, how relevant is paleoclimate data to today's world and how far back do we still have a modern climate system (eg. modern ocean and jetstream circulation patterns)?

My next concern is the accuracy and precision of the available climate record. During the instrument era (~200 years), we have daily, monthly, and yearly data, accurate to within tenths of a degree. By contrast, the error bars for paleo reconstructions are surely much larger, probably on the order of degrees or even tens of degrees. Furthermore, depending on the particular proxies, they often represent annual or at best seasonal averages. Thus, it becomes hard to distinguish a short-term period of extreme temperatures from a longer bout of moderate temperatures.

Finally, as I mentioned before, the paleo data is somewhat geographically sparse. So, what is interpreted as a large gobal climate shift may simply be a local, temporary abberation.

Now, I'll shift back to the topic at hand, which is"How reliable are climate models?". The problem is that if the data set against which you are validating the model has large error bars, significant uncertainties in the temporal resolution, and large spacial gaps, it becomes too easy to tweak the model such that it fits the data, but for the wrong reasons. For example, one of the biggest challenges for the models is handling cloud coverage. The unit cells are often much larger than individual clouds, so parameterizations must be used to represent cloud coverage. This means the entire cell has some "average cloud effect", which may or may not reflect reality. The result is that the model includes a "fudge factor" of cloud coverage, which cannot be independently verified.

Another such factor involves aerosols and particulates (think Sea-spray or Dust storms). In these cases, you need to know both the variation in the particle and aerosol densities, as well as the sensitivity of the climate to these densities. Clouds, particulates, and aerosols are important phenomena, which are known to impact global temperature and climate, so you can't ignore them, but we are just beginning to understand the factors that drive them, so by necessity our current models are quite crude. This means, we can probably "fit" many models to match paleo data, but it doesn't mean we are doing it correctly or that those models will be able to predict the future climate.

Only in the satellite era are we beginning to get the proper instrumentation, so that we can monitor cloud, aerosol, and particulate densities so as to verify that the assumptions that are put into the models are reasonable. Because of this, I would say that our current models are not very reliable, but there is hope that within the coming decades they will become much better.

Moderator Response:

[PS] You make the assertion "My biggest concern is that climate sensitivity is likely highly dependent on the prevailing ocean circulation patterns, since these dominate the heat exchange between the atmosphere and the oceans, thus amplifying or moderating greenhouse gas effects", implying unmodelled feedback effects. To me this looks like hand-waving in extreme so please provide some sources for supporting that opinion.

Wol at 11:07 AM on 22 March 2017

2017 SkS Weekly Climate Change & Global Warming Digest #11

Tom Curtis @ 5:

>>It is also fairly clear that conservatives are enemies of science.<<

Don't fall into the same paradigm as deniers, Tom, by implying that ALL Xs are Ys.

Because one is of a conservative disposition does not automatically mean that one's brain is offline. As a conservative I am perfectly capable of assessing the arguments and coming to the conclusion that the science is correct.

Leto at 09:16 AM on 22 March 2017

CO2 effect is saturated

Considering the rebuttals by Tom Curtis @447 and by Walter Hannah at MA Rodger's link @448, the paper linked by Wake appears to be incredibly poorly conceived... But even if its flaws were more difficult to spot, it should be clear that any valid paper disproving the greenhouse effect would make its author both rich and famous. Not only would the author become the new darling of the Koch Bros, touring the world giving triumphant defences of BAU fossil-fuel policy, the author would collect the Nobel Prize and all the other accolades befitting a genuine Galileo who had successfully overturned decades of understanding. Instead, the paper remains deservedly unpublished and largely obscure, and not even the denialists have bothered funding a round of much-needed editing for this paper. Thus, even for those unable or unwilling to follow the scientific rebuttal, there are ample clues that this is nonsense. Wake might want to consider what it is about his own world views that made him miss those clues.

MA Rodger at 08:41 AM on 22 March 2017

CO2 effect is saturated

Wake @445,

The denialist paper you link to is actually five years old now, one of a number of crazy climatological ideas promulgated by Nasif Nahle. Concerning that particular paper, Walter Hannah of the Lawrence Livermore National Lab addressed Nasif Nahle’s Shaky Math last year.

Tom Curtis at 08:10 AM on 22 March 2017

CO2 effect is saturated

Wake @445:

1) If you are going to say "actual measurements are a lot more indicative of the real world than computer modeling" you should at least point me to actual measurements rather than just a crude mathematical model (which is what Nahle's calculations amount to).

2) Nahle uses surface values for CO2 and H2O concentration. Therefore, even if calculated correctly, he would only be calculating relative emissivity for back radiation at the surface - not the effective emissivity for radiation to space which is the basis of the greenhouse effect. Therefore, the best that can be said for Nahle's calculations is that he simply does not understand the theory of the greenhouse effect.

3) Nahle uses the formula for the emissivity of a 128.2:1 H2O/CO2 isothermal gas mixture. Therefore, at best all he shows is that if the an isothermal gas in a container was 100% water vapour, adding 0.78% CO2 would reduce the emissivity of the gas mixture relative to the 100% water vapour. He goes on to demonstrate that adding oxygen to the H2O/CO2 mixture would further reduce emissivity. The obvious point is that if adding oxygen to a H2O/CO2 mix decreases emissivity, adding a H2O/CO2 mix to an oxygen atmosphere will increase emissivity. That is, it will induce a greenhouse effect. For a more detailed exposition of this point, go here.

To summarize, Nahle's calculations do not apply to the atmosphere as a whole because it is not isothermal; do not calculate the strength of the greenhouse effect because they apply to the surface layer only, and cannot calculate the effect of the change in outgoing radiation due to the presence or absense of a gas; and are incorrectly applied in any event. Worse, they are not observations and do not produce an observationally testable hypothesis with regard to atmospheric radiation. In contrast, the theory he wishes to rebut is based on models that apply the type of formula he is using radiation band by radiation band, layer by layer across a large number of layers in the atmosphere, each of which is small enough to be approximately isothermal. Those models produce observationally testable predictions which have been compared to actual observations as with this example from 1969:

Those detailed, band by band, layer by layer models also predict a greenhouse effect from CO2.

Leto at 07:24 AM on 22 March 2017

CO2 effect is saturated

Wake, your link points to a non-peer reviewed article with questionable conclusions, not to raw data as implied by your description of it as "actual measurements".

I will let more knowledgeable people comment on the alleged science in the article, but the article has not even been edited by someone who speaks English as their first language. If an article is to be taken seriously, proof-reading it is a minimum first step, followed by peer review.

Tom Curtis at 07:15 AM on 22 March 2017

A Perfect (Twitter) Storm

michael sweet @40, it is helpful to put the results of Horton et al (2014), ie the paper on which the Real Climate article is based, into some context.

First, while the IPCC AR5 projected a 0.52 to 0.98 likely range for sea level rise in RCP 8.5, they add the significant qualifier that:

"We have considered the evidence for higher projections and have concluded that there is currently insufficient evidence to evaluate the probability of specific levels above the assessed likely range. Based on current understanding, only the collapse of marine-based sectors of the Antarctic ice sheet, if initiated, could cause global mean sea level to rise substantially above the likely range during the 21st century. This potential additional contribution cannot be precisely quantified but there is medium confidence that it would not exceed several tenths of a meter of sea level rise
during the 21st century."

Therefore, according to the IPCC, the probability of a result exceeding the likely range is greater than the probability of it being below that range, but that the extent to which this is so is unquantifiable. To the extent that it does exceed it, according to the IPCC, it will be due to a partial collapse of the Antarctic Ice Sheet. Those experts who think the IPCC assessment is too low tend to think that the increased sea level rise will come from just such a collapse, and differ from the IPCC primarilly in their willingness to quantify the probality of the likelihood and extent of such a collapse in the 21st century.

Second, IPCC assessments represent an review of the evidence by a group of experts. It differs from a review paper in a journal primarilly in the far greater extensiveness of the peer (and non-peer) review of that results. As a review of the evidence, we should not expect the results to precisely match the results of a survey of expert opinion, although would should expect some similarity. Even if it were a survey of expert opinion, we would expect the upper bound to be set at "a value that 80% of experts think is the highest possible value" but rather at the median or mean estimate of the upper value by experts. That value would more closely approximate to the 95th percentile of a Probability Density Function (PDF) generated by averaging the PDF's of the experts. The box plots of expert opinion of the 5th, 17th, 83rd and 95th percentiles of expected sea level rise is shown in Figure 2 of the paper. Here is that part of Figure 2 relating to RCP 8.5 and 2100:

As an aside, I made a mistake in the text in that it should be Fig 2 b. In any event, by your of criteria expert opinion the upper limit should be above 2 meters, whereas by mine it is about 1.6 meters. For the 5th percentile, the lower limit should be below 0.5 meters by your criteria, and just above 0.5 meters by mine. In either case the IPCC underestimates the range of plausible outcomes.

Third, while the IPCC understates the likely consensus projection of sea level rise, it is a much better fit to the consensus projection of the most expert experts, ie, those with a h-index of 40 or above, whose likely range for RCP 8.5 is approximately 0.62 to 1 meter sea level rise by 2100 (see Figure 3 B). Again, this fits with the IPCC report being a review of the evidence rather than a statement of the consensus of the experts. Presumably the most expert of the experts will have a better grasp of the evidence, and certainly those with a higher h-index will have contributed more of the evidence that is being reviewed by the IPCC. This disparity of the most expert opinion, along with the significantly increased knowledge of the potential of Ice Sheet collapse that became available after the IPCC cut off period may be sufficient to explain the relatively optimistic position of the IPCC on sea level rise.

Wake at 06:35 AM on 22 March 2017

CO2 effect is saturated

Tom Curtis - Thought you may not have seen this and since actual measurements are a lot more indicative of the real world than computer modeling it could be of interest.

http://www.biocab.org/Overlapping_Absorption_Bands.pdf

Moderator Response:

[PS] Fixed link please learn to do this yourself using the link tool in the comment editor. Discussions here could be more fruitful if you tried applying some of your skepticism to your own sources.

nigelj at 06:34 AM on 22 March 2017

In-depth: What Donald Trump’s budget means for US spending on climate change

Excellent summation. None of the cost cuts make any sense, and they will have a difficult time getting through congress, unless congress throws caution to the wind, and completely loose their minds. There's a risk of that. Anything seems possible these days.

There is no hard evidence of any inefficiencies at NASA, and the same cost cutting efficiency logic should apply to the military and border patrols anyway.

Trump wants to cut the very climate related spending associated with determing the exact areas of climate science that need more clarification like particulate emissions, clouds, etc. This looks calculated and cynical to disrupt the science as much as possible.

We are addicted to oil. It is like a drug that hits the same dopamine receptors in the brain as cocaine or sugar etc, with the same feel good factors and growing dependence. People are attached to big V8 cars or SUV's. It's a society wide, and global scale addiction.

william5331 at 06:11 AM on 22 March 2017

19 House Republicans call on their party to do something about climate change

These 19 must have kids and grandchildren. It tends to focus your attention.

michael sweet at 01:38 AM on 22 March 2017

A Perfect (Twitter) Storm

JohnFornaro @38: Unfortunately, most scientists who study sea level rise consider the IPCC projections to be minimum sea level rise. According to RealClimate, a survey of sea level rise experts produced this graph:

Figure 2: Sea level rise over the period 2000-2100 for two warming scenarios (red RCP8.5, blue RCP3). The ranges show the average numbers given across all the experts. The inner (darker) range shows the 17 to 83 percentile values, the outer range the 5 to 95th percentiles. For comparison we see the NOAA projections of December 2012 (dashed lines) and the new IPCC projections (bars on the right).

For RCP 2.6 the difference is not that much, but for RCP 8.5 the low projection of experts is similar to the high projection from the IPCC. Because the IPCC always uses consensus numbers it ends up with low values for sea level rise.

It seems to me that while a low value that 80% of experts agree on is OK, for the high end they should use a value that 80% of experts think is the highest possible value. Apparently they use the high value that 80% of experts think is the lowest high value.

As side comment, when I searched on Bing for "Real Climate Sea Level Rise" Stephen Goddard was the first hit and several more hits from his blog were present. On Google the Real Climate article was the first hit. Where does Goddard get the money to buy the first place on Bing?

Mal Adapted at 12:09 PM on 21 March 2017

19 House Republicans call on their party to do something about climate change

For those not wholly despairing of the GOP, this is a hopeful sign. Wouldn't it be great if it signals a general turning away from irrationality by the party? Nah, that's too much to hope.

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