Merged Global Warming Discussion II: Heated Conversation

[macdoc]

Originally Posted by AlBell View Post
Sensitivity is what changes and by how much when CO2 does this or that.

My concern is that the CO2 sensitivity is not a magic parameter that contains all unknowns recognized or not. SFAIK there is yet no good consensus on warming/cooling of various cloud types.

This makes absolutely no sense. Either regarding CO2 or clouds.

Taking clouds - the general consensus comes down slightly on the positive feedback scale but not a lot. Here is some info
http://www.skepticalscience.com/clouds-negative-feedback-intermediate.htm

Here is a recent take on sensitivity and clouds

"When the processes are correct in the climate models the level of climate sensitivity is far higher.
Previously estimates of the sensitivity of global temperature to a doubling of carbon dioxide ranged from 1.5°C to 5°C.
This new research takes away the lower end of climate sensitivity estimates, meaning that global average temperatures will increase by 3°C to 5°C with a doubling of carbon dioxide,' according to lead-author Prof. Steven Sherwood from the University of New South Wales.

http://www.accuweather.com/en/weather-blogs/climatechange/climate-sensitivity-to-co2-sho/21841419

That's the higher end of the scale and we are approaching that pretty rapidly.

 

[aleCcowaN]

Sensitivity is what changes and by how much when CO2 does this or that.

My concern is that the CO2 sensitivity is not a magic parameter that contains all unknowns recognized or not. SFAIK there is yet no good consensus on warming/cooling of various cloud types.

Sorry, that makes no sense to me. You have to replace "what", "this" and "that" by something before I can make sense of it. And I have to tell you, your first phrase looked more like a deliberate attempt to make it unclear.

So, you're concerned about some unknown thing -there's no such thing as "CO2 sensitivity"- and from that point on nothing can be construed.

About the phrase you bolded, that means I'm not going to read your messages as tea leaves and reply to what I suppose you meant, like others do. Make yourself clear and I would be delighted to reply. It's not a matter of an assertion being right or wrong -everybody has the right to be wrong now and then-, it's a matter of an assertion making sense or not. You tried to say something in your first recent post. Now you should focus and add precision to that. Your "my objection..." diverges from that post, making the whole thing more confusing.

 

[a_unique_person]

Sensitivity is what changes and by how much when CO2 does this or that.

My concern is that the CO2 sensitivity is not a magic parameter that contains all unknowns recognized or not. SFAIK there is yet no good consensus on warming/cooling of various cloud types.

It's not a parameter, it's an output, the result of the calculations. That is, it is derived from what we know about how climate works.

I have had it explained to me by a climate modeler, clouds are a problem in the sense that they are hard to model. The resolution of models might be 100 sq KM. Clouds are smaller than that. The more capable hardware available now for computing should allow clouds to be modeled more accurately.

As I stated earlier. There seems to be a widespread attitude that if we can't determing exactly what the climate change will be, then we have nothing to worry about. It just makes me more worried, since we can't identify the risk as well as we would like to.

The consensus seems to be at least 2C for climate sensitivity, from what I have read, although it might take longer to get there than was first anticipated. Note that "climate sensititivty" is really "climate sensitivity for a doubling of CO2".

We are going to more than double CO2 concentration the way we are going at the moment. Especially when you consider that there are governments actively saying that we cannot afford to promote the use of renewables and reduce CO2 production, while at the same time they spend billions on actively subisidising and promoting the use of CO2 producing energy sources. Apparently this is OK, even if blatantly hypocritical.

 

[macdoc]

Some resources on the subject

A Bit More Sensitive…
Filed under: Climate modelling Climate Science Greenhouse gases — mike @ 2 January 2014

by Michael E. Mann and Gavin Schmidt

This time last year we gave an overview of what different methods of assessing climate sensitivity were giving in the most recent analyses. We discussed the three general methods that can be used:

The first is to focus on a time in the past when the climate was different and in quasi-equilibrium, and estimate the relationship between the relevant forcings and temperature response (paleo-constraints). The second is to find a metric in the present day climate that we think is coupled to the sensitivity and for which we have some empirical data (climatological constraints). Finally, there are constraints based on changes in forcing and response over the recent past (transient constraints).

All three constraints need to be reconciled to get a robust idea what the sensitivity really is.

A new paper using the second ‘climatological’ approach by Steve Sherwood and colleagues was just published in Nature and like Fasullo and Trenberth (2012) (discussed here) suggests that models with an equilibrium climate sensitivity (ECS) of less than 3ºC do much worse at fitting the observations than other models.

- See more at: http://www.realclimate.org/index.php/archives/2014/01/a-bit-more-sensitive/#sthash.RyuRVrxg.dpuf

 

[aleCcowaN]

Fortunately those 3°C or more "use to be happening" by about 2800 a.d.

Please let me know when you have the chance to look at this more closely.

I got the reply I expected. In a nutshell, if fosil fuel related emissions ceased right now -CO2, methane from coal mining and fracking, sulphates- models show a drop of 6 to 8 ppmv of CO2 in a decade as calculated from their modules modelling natural sinks and sources. He thinks the final value will be a bit more, not as optimistic as me -10 to 12 ppm-. This comes from different reasons, including a concern we share which I'll explain below.

Those 6 to 8 (or more) ppmv during the first decade seem to drop slower than I expected for the following decades. This has little variation in spite of transient effects of previous emissions: the still-to-rise temperatures are not enough to induce great changes in sources and sinks.

A different picture comes if we wait until we reach 500 or 600 ppmv. In that case there is a change of the ocean as a sink and permafrost emissions activate as a consequence of the transient effects. In such cases, CO2 concentration drops slowly. Any inference about what happens with 850 or 1100 ppmv is pretty much useless.

The concern we share is about how different models do when they estimate the ocean mixed layer. Basically they can be either pretty bad, bad or worse at it. As the ocean mixed layer and the role of oceans as carbon and heat sinks are closely related, conclusions in the long term are to be taken with a pinch of salt.

A lesson comes from the paper by Yu Kosaka & Shang-Ping Xie that was mentioned before. The title says it all: "Recent global-warming hiatus tied to equatorial Pacific surface cooling" and the content, in a nutshell, refers they taking a coupled model and modifying it to get about 8% of the ocean surface to be a temperature input and not a state. The area chosen was all the equatorial Pacific from the American coasts to longitude 180°, that is, the ENSO area. As a result they got the "pause" pretty well [figure 1 - black line, observed global temperatures; purple line, global temperatures got with the original model; red line, global temperature got with the modified model]. But both models got similar results for ocean heat content [extended data figure 3] but they got more realistic values for the net radiative imbalance with the modified model.

In certain scientific website an interesting debate arose between a climatologist and a Finnish gentleman who objected both the blatant violation of conservation laws and the amount of OHC exceeding the real estimates for the period. The answer to that is both valid and revealing: the model understands what happens between the ocean surface and outer space, the differences in heat for that 8% of the global oceans is something that doesn't affect the outcome, and it's pretty valid because the area chosen is one of upwelling, so you have the heat difference temporarily ditched. Of course, it'll arrive the point that heat is gonna come back and haunt you, meaning, at some point in the timeline the model renders itself invalid, and by force that is to happen earlier than later.

For me this story makes easier to explain how a model is to be valued. Models are basically tools for research and control, and they give some orientation about what the future may hold. The fact that some items researched, like the equilibrium climate sensitivity, need models run for thousand of years doesn't make them a prediction tool.

 

[Trakar]

Fortunately those 3°C or more "use to be happening" by about 2800 a.d.



I got the reply I expected. In a nutshell, if fosil fuel related emissions ceased right now -CO2, methane from coal mining and fracking, sulphates- models show a drop of 6 to 8 ppmv of CO2 in a decade as calculated from their modules modelling natural sinks and sources. He thinks the final value will be a bit more, not as optimistic as me -10 to 12 ppm-. This comes from different reasons, including a concern we share which I'll explain below.

Those 6 to 8 (or more) ppmv during the first decade seem to drop slower than I expected for the following decades. This has little variation in spite of transient effects of previous emissions: the still-to-rise temperatures are not enough to induce great changes in sources and sinks.

A different picture comes if we wait until we reach 500 or 600 ppmv. In that case there is a change of the ocean as a sink and permafrost emissions activate as a consequence of the transient effects. In such cases, CO2 concentration drops slowly. Any inference about what happens with 850 or 1100 ppmv is pretty much useless.

The concern we share is about how different models do when they estimate the ocean mixed layer. Basically they can be either pretty bad, bad or worse at it. As the ocean mixed layer and the role of oceans as carbon and heat sinks are closely related, conclusions in the long term are to be taken with a pinch of salt.

A lesson comes from the paper by Yu Kosaka & Shang-Ping Xie that was mentioned before. The title says it all: "Recent global-warming hiatus tied to equatorial Pacific surface cooling" and the content, in a nutshell, refers they taking a coupled model and modifying it to get about 8% of the ocean surface to be a temperature input and not a state. The area chosen was all the equatorial Pacific from the American coasts to longitude 180°, that is, the ENSO area. As a result they got the "pause" pretty well [figure 1 - black line, observed global temperatures; purple line, global temperatures got with the original model; red line, global temperature got with the modified model]. But both models got similar results for ocean heat content [extended data figure 3] but they got more realistic values for the net radiative imbalance with the modified model.

In certain scientific website an interesting debate arose between a climatologist and a Finnish gentleman who objected both the blatant violation of conservation laws and the amount of OHC exceeding the real estimates for the period. The answer to that is both valid and revealing: the model understands what happens between the ocean surface and outer space, the differences in heat for that 8% of the global oceans is something that doesn't affect the outcome, and it's pretty valid because the area chosen is one of upwelling, so you have the heat difference temporarily ditched. Of course, it'll arrive the point that heat is gonna come back and haunt you, meaning, at some point in the timeline the model renders itself invalid, and by force that is to happen earlier than later.

For me this story makes easier to explain how a model is to be valued. Models are basically tools for research and control, and they give some orientation about what the future may hold. The fact that some items researched, like the equilibrium climate sensitivity, need models run for thousand of years doesn't make them a prediction tool.

6-8ppmv, particularly at the lower end, does sound more reasonable, at least for the initial decade. Surface ocean absorption fraction of atmospheric CO2 is closely linked to concentration of atmospheric CO2. It is not a coincidence that as man's emissions have climbed, the ocean uptake of atmospheric CO2 has also increased (roughly in proportion to the increased excess of human CO2 contributions).

We are barely scratching the surface of this issue, especially with regards to what happens at higher concentrations and/or in later decades after more of the effects of higher atmospheric(/oceanic) concentrations of CO2 have manifested (for instance how warming waters and pH changes affect things like the Redfield ratio, and more importantly the solubility pump). If you are open to further discussion of the topic, we can keep it going in the background and explore some of the various aspects of it in more detail.

 

[aleCcowaN]

If you are open to further discussion of the topic, we can keep it going in the background and explore some of the various aspects of it in more detail.

I would love to.

 

[Trakar]

I would love to.

Excellent, there are more than a few holes in my understandings and your knowledge and understandings may be the complement needed to help me fill at least some of those deficits!

 

[Reality Check]

Is my understanding correct that CO2 sensitivity is not computed from first principals, but chosen from many model runs using different values for it, and the value selected for projections is the one that best ties historical data?

How sensitive is our climate?

Some global warming 'skeptics' argue that the Earth's climate sensitivity is so low that a doubling of atmospheric CO2 will result in a surface temperature change on the order of 1°C or less, and that therefore global warming is nothing to worry about. However, values this low are inconsistent with numerous studies using a wide variety of methods, including (i) paleoclimate data, (ii) recent empirical data, and (iii) generally accepted climate models.

My emphasis added.

 

[Reality Check]

My concern is that the CO2 sensitivity is not a magic parameter that contains all unknowns recognized or not.

How sensitive is our climate?

Climate sensitivity is not specific to CO2
It's important to note that the surface temperature change is proportional to the sensitivity and radiative forcing (in W m-2), regardless of the source of the energy imbalance. The climate sensitivity to different radiative forcings differs depending on the efficacy of the forcing, but the climate is not significantly more sensitive to other radiative forcings besides greenhouse gases.

 

[Trakar]

How sensitive is our climate?

Some global warming 'skeptics' argue that the Earth's climate sensitivity is so low that a doubling of atmospheric CO2 will result in a surface temperature change on the order of 1°C or less, and that therefore global warming is nothing to worry about. However, values this low are inconsistent with numerous studies using a wide variety of methods, including (i) paleoclimate data, (ii) recent empirical data, and (iii) generally accepted climate models.

My emphasis added.

In isolation, an atmospheric CO₂ doubling from pre-industrial concentrations (ppmv ~280) actually does produce a bit over 1°C. But, de facto, nothing occurs in complete isolation in complex systems like planetary surface climate. A temp rise of a bit over 1°C means that the resulting atmosphere will equilibrate with sufficient water vapor for that temp. The amount of water vapor (which is an acknowledged, more powerful than CO₂ GHG) in the atmosphere, is directly proportional at standard surface conditions to the average temperature of the atmosphere. A rise of a bit more than 1°C sucks enough additional water vapor into the atmosphere to raise the temps an additional bit more than 2°C, the real questions that are at all legitimately debatable are how much above 3°C/doubling we are talking about. There are not inconsiderable long-term and potential natural cascade feedback system questions at the upper end of the scale (especially in the long-term, fully equilibrated, surface environment) and very few question marks in the factors that eliminate <3°C sensitivities in the assessments of known positive/negative feedbacks. The geologic record increasingly, and with overwhelming predominance, supports and provides minimal-maximal bounds for a range of CO₂ppmv.

(ironically, their primary error is in using too simple a model and expecting it to perfectly reflect a much more complex and messy reality).

 

[Kestrel]

The latest claim from climate change deniers is that the data is being altered to hide the truth.

The scandal of fiddled global warming data

Goddard shows how, in recent years, NOAA’s US Historical Climatology Network (USHCN) has been “adjusting” its record by replacing real temperatures with data “fabricated” by computer models. The effect of this has been to downgrade earlier temperatures and to exaggerate those from recent decades, to give the impression that the Earth has been warming up much more than is justified by the actual data.

http://www.telegraph.co.uk/earth/en...e-scandal-of-fiddled-global-warming-data.html

The detailed explanation for the adjustments to historical data is documented in this paper:

THE U.S. HISTORICAL CLIMATOLOGY NETWORK MONTHLY TEMPERATURE DATA, VERSION 2

ftp://ftp.ncdc.noaa.gov/pub/data/ushcn/v2/monthly/menne-etal2009.pdf

What Goddard didn't mention is the reason for the adjustments. These turn out to be things like stations that changed the times when they measured temperature data.

 

[Trakar]

The latest claim from climate change deniers is that the data is being altered to hide the truth.

The scandal of fiddled global warming data


http://www.telegraph.co.uk/earth/en...e-scandal-of-fiddled-global-warming-data.html

The detailed explanation for the adjustments to historical data is documented in this paper:

THE U.S. HISTORICAL CLIMATOLOGY NETWORK MONTHLY TEMPERATURE DATA, VERSION 2

ftp://ftp.ncdc.noaa.gov/pub/data/ushcn/v2/monthly/menne-etal2009.pdf

What Goddard didn't mention is the reason for the adjustments. These turn out to be things like stations that changed the times when they measured temperature data.

Promoting conspiracy theories does not equal compelling support of their assertions.

 

[aleCcowaN]

Today's denialist "objections" (a fancy word for "I don't like what I see") don't amount to a hill of beans. They are just refitting and overhauling a few old memes.

In those ancient times when we debated here with denialists of a better quality the same topic was discussed and analysed several measurements and papers. Basically most of the corrected data fall in one of these categories: temperatures were taken in different times; weather station was moved; weather station was in a rural area that became urbanized; weather station was originally built in a rural area, the area became urbanized, the station was consequently moved. Hundreds among the thousands of weather stations all around the 48 contiguous states continue to be in a rural location and weren't moved. When temperature trends are collected just gathering data from those stations and compared with the corrected data, there are no significant differences.

More about this in the thread: 89% of U.S. temperature stations are biased by +1-5 °C (any resemblance with Days of Our Lives is a coincidence)

 

[CapelDodger]

The latest claim from climate change deniers is that the data is being altered to hide the truth.

Not so much the latest claim as their earliest claim, repeated yet again by one of the same old names in one of the same old newspapers.

What strikes me is Booker's (dubious) claim that the 1930's were "the warmest in US records". Is the Telegraph's main audience now US Americans? I wouldn't be at all surprised, but it may simply reflect the fact that the engine-room of AGW denial lies across the Pond.

 

[CapelDodger]

Today's denialist "objections" (a fancy word for "I don't like what I see") don't amount to a hill of beans. They are just refitting and overhauling a few old memes.

It's very noticeable, isn't it? Same names, same claims - it's as if the last twenty years have been a dream.

 

[Kestrel]

Not so much the latest claim as their earliest claim, repeated yet again by one of the same old names in one of the same old newspapers.

What strikes me is Booker's (dubious) claim that the 1930's were "the warmest in US records". Is the Telegraph's main audience now US Americans? I wouldn't be at all surprised, but it may simply reflect the fact that the engine-room of AGW denial lies across the Pond.

Climate change deniers tend to fall back on the argument that man's actions are too small to have an effect on the climate. But the dust bowl of the 1930s is clearly traceable to the agriculture practices of the time.

You are correct, the engine room and financial hub of climate change denial is in the US and tied to the fossil fuel industry. A propaganda effort that echoes the how the tobacco industry denied the heath effects of their products and delayed regulation as long as possible.

 

[aleCcowaN]

Is the Telegraph's main audience now US Americans? I wouldn't be at all surprised, but it may simply reflect the fact that the engine-room of AGW denial lies across the Pond.

According to Alexa, 26.8% of telegraph.co.uk's visitors come from the UK (ranked 19th in the country) and 24.1%, 2.4% and 2.0% come from USA, Canada and Australia, respectively (ranked 248th, 200th and 153th), so that is somewhat true.

By reading the comment sections in that telegraph's article one can confirm how rotten meat attracts flies. The Telegraph is just selling controversy, a product always in high demand. And selling stereotypes, the highly valued ones: though the article theoretically refers to global temperatures, it ends talking about those of the 48 contiguous, representing 1.6% of the real planet, but 10 to 50% of it in the public's hubris, so it must be relevant in some way to qualify the remainder (that 98.4% left).

 

[Red Baron Farms]

AlBell, I think that Megalodon is overstating things with "the huge amount of freak weather events occurring".
It is more that there is a increasing trend of outlying weather events (droughts, floods, storms, ice breakups) happening which is what is expected from global warming. Have a look at the WMO report, The Global Climate 2001-2010, A Decade of Climate Extremes (a bit overwhelming at 100 pages though!).

There is plenty of discussion on Skeptical Science, e.g. New Research Shows Humans Causing More Strong Hurricanes.

That's a really interesting read. I did see one glaring problem though.

Climate change refers to long-term changes in
the average state of the climate and can also
be due to natural factors. The rapid changes
that have occurred since the middle of the past
century, however, have been caused largely
by humanity’s emissions of greenhouse gases
into the atmosphere. Other human activities
also affect the climate system, including
emissions of pollutants and other aerosols,
and changes to the land surface, such as
urbanization and deforestation. link

No mention of cropland. Maybe the single greatest factor besides emissions. Primarily due to the fact that the great "bread baskets" of the world used to be the primary driver of global cooling. [1] Now that those biomes are largely eliminated or highly degraded and no longer functioning due to agriculture[2][3], glossing over that factor seems like missing the forest for the tree. Or more precisely, looking up, watching the air, and missing the soil you are standing on!

 

[r-j]

The latest claim from climate change deniers is that the data is being altered to hide the truth.

I brought that up here and my posts vanished. Shucks, I can even prove it is happening, but what's the point? There is always moving of the goal posts, rationalizations or worse. Nobody here who believes in warming is the least bit skeptical of anything that makes it seem like there is more warming.

That's a really interesting read. I did see one glaring problem though.

That's what you think the problem is? Not that with one fell swoop the NCDC just changed the entire climate history of the US?

And every bit of it was to make the present seem warmer, and the past colder?

That doesn't make you skeptical at all?

The claim is "they measured things different back then", but it seems they just figured this out in 2014. So now we are supposed to believe the records are correct. But last year, the records were all wrong.

In fact, according to this logic, up until a few months ago, the entire climate history the NCDC showed the world was actually wrong.

But now it's OK.

Also, they already changed it years ago, supposedly for the same reason. This is the second time they changed the records.

But it certainly shows that the warming is due to humans.