Monday, March 31, 2014

Bits From the Latest IPCC Report

(all quotes from the summary for policymakers)
In this report, the term impacts is used primarily to refer to the effects on natural and human systems of extreme weather and climate events and of climate change
Or in other words, they are lumping together costs associated with climate change due to human action, costs associated with climate change from other causes, and costs associated with extreme climate events, whether or not due to climate change.
In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. ... Evidence of climate change impacts is strongest and most comprehensive for natural systems.  ... See supplementary Table SPM.A1 for descriptions of the impacts (B) Average rates of change in distribution (km per d ecade) for marine taxonomic groups ... . Positive distribution changes are consistent with warming (moving into previously cooler waters, generally poleward).
"Impacts" sounds scary, but, as the quote shows, only means change.
While only a few recent species extinctions have been attributed as yet to climate change (high confidence), natural  global climate change at rates slower than current anthropogenic climate change caused significant ecosystem shifts and species extinctions during the past millions of years.
Warnings about large numbers of species being driven to extinction by anthropogenic climate change have morphed into the observation that species have gone extinct in the past for reasons unrelated to human action.
Some low-lying developing countries and small island states are expected to face very high impacts that, in some cases, could have associated damage and adaptation costs of several percentage points of GDP.
Compare costs of "several percentage points of GDP" in the places most at risk due to sea level rise with past rhetoric of hundreds of millions of climate refugees, drowned island chains, and the like.
Climate change has negatively affected wheat and maize yields for many regions and in the global aggregate (medium confidence). Effects on rice and soybean yield have been smaller in major production regions and globally, with a median change of zero across all available data
They don't actually say that yields have fallen, although that is what a careless reader is likely to think they are saying, only that they are lower than they would have been without climate change. A little searching finds a scholarly article on wheat yields, published in 2012, which reports that 
Wheat yields have increased approximately linearly since the mid-twentieth century across the globe, but stagnation of these trends has now been suggested for several nations. .... With the major exception of India, the majority of leveling in wheat yields occurs within developed nations—including the United Kingdom, France and Germany—whose policies appear to have disincentivized yield increases relative to other objectives. The effects of climate change and of yields nearing their maximum potential may also be important.

Near the time that leveling is generally observed, the European Union shifted away from a policy that rewarded high agricultural production through price guarantees to a policy that pays flat subsidies that do not increase with production and triggers taxes when production limits are exceeded
So what has actually happened is not that yields have decreased but that in some areas they have stopped increasing, at least in part due to changes in agricultural policy.
At present the world-wide burden of human ill-health from climate change is relatively small compared with effects of other stressors and is not well quantified. However, there has been increased heat-related mortality and decreased cold-related mortality in some regions as a result of warming ... .
The first sentence makes it sound as though climate change is making things worse. The second implies that there have been both costs and benefits and offers no estimate of their relative size.
People who are socially, economically, culturally, politically, institutionally, or otherwise marginalized are especially vulnerable to climate change.
One might conclude that keeping poor people poor, for instance by pressuring poor countries to produce less energy or produce it in more expensive ways in order to hold down CO2 output, will do more damage than good.
Impacts from recent climate-related extremes, such as heat waves, droughts, floods, cyclones, and wildfires, reveal significant vulnerability and exposure of some ecosystems and many human systems to current climate variability.
Note that the extremes are not limited to those due to climate change. Floods, cyclones, et. al. do damage...and always have. 
For the major crops (wheat, rice, and maize) in tropical and temperate regions, climate change without adaptation is projected to negatively impact production for local temperature increases of 2°C or more above late-20th-century levels, ...
Emphasis mine. If farmers ignore the implications of climate change on what crops they should grow how and continue to ignore them for the next sixty years or so, output is expected to decline.
With these recognized limitations, the incomplete estimates of global annual economic losses for additional temperature increases of ~2°C are between 0.2 and 2.0% of income (±1 standard deviation around the mean)
I have not yet gotten into the full report but, judging from accounts I have seen, 2°C of additional warming is about what it suggests we can expect by 2100 if we don't do much to prevent it. So if policies to prevent warming reduce the annual growth rate of world income from (say) 2% to 1.98%, the resulting loss will just about cancel the gain. Not a compelling argument for switching from fossil fuels to solar power.

All of these quotes are from the first half of the summary for policy makers—I have not yet tried to get into the full report. My conclusion is that the IPCC's estimates of the negative effects of climate change due to human action are much smaller than the rhetoric surrounding the subject suggests, a fact the report attempts to conceal as best it can by its presentation.

And a fact that does not come through in news stories about the report, at least those I have so far looked at.

How long before the more enthusiastic true believers start accusing the IPCC of having sold out to the oil industry?


T said...

Reading these quotes reminds me a lot of Fed speak.

Tibor said...

Though I agree with the other observations you made, I think you are a bit unfair to them with the extinction argument.

The IPCC basically says:"The past data show that increasing the temperature leads (in the long run) to species extinction even at lower temperature increase rates and so even though we do not observe much extinction related to warming yet, the evidence suggests that in the long run it will be present." That seems like a valid argument to me.

Of course, one could argue that the effect is logarithmic and so it will not be significantly higher if you increase the temperature by 2 degrees compared to when you increase it by half a degree and so you might as well have to diminish the warming way beyond the anthropogenic part to make a significant difference. I don't know if that is true or not.

As for the hurricanes, again my question from the previous post:

Are there reasons to believe the warming is/is not (spatially) uniform? If it is not uniform, what is the distribution and why?

Anonymous said...

The IPCC are funded by governments. Guess who else is often subsidized by governments? Big oil. Coincidence? You decide!

Anonymous said...

This is a good post, but I have to quibble with one part of it. You say:

I have not yet gotten into the full report but, judging from accounts I have seen, 2°C of additional warming is about what it suggests we can expect by 2100 if we don't do much to prevent it.

I don't think that's right. The Working Group I report includes a number of different forecasts based on different possible paths for greenhouse gas concentrations over the coming century. RCP2.6 assumes that CO2 concentrations will be basically flat at 400 ppm; RCP4.5 assumes that CO2 will rise to 500 ppm by 2100; RCP6.5 assumes that CO2 will rise to around 600 ppm, and RCP8.5 assumes CO2 will rise to 900 ppm.

On page 20 of the WGI SFP, it says:

Global surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to 1850 to 1900 for all RCP scenarios except RCP2.6. It is
likely to exceed 2°C for RCP6.0 and RCP8.5, and more likely than not to exceed 2°C for RCP4.5.

The report defines "likely" as >66% and "more likely than not" as >50%. So with the exception of RCP2.6 (which would require some kind of action to prevent climate change), all of the scenario imply a greater than 50% chance temperatures will rise by more than 2°C.

Bob Murphy said...

I really like your recent posts on these matters, David, and encourage you to keep at it. I think it helps tremendously when people who are experts in other fields come in and give their "smell test" reaction.

Obviously the peer-reviewed climate scientists are free to correct your (alleged) misunderstandings, but (as the case with your showdown with Cook) I think more often than not the public will see that the climate scientist who is defending the alarmist position is grasping at straws.

Josiah Neeley is right that it's nuanced, but I think it is defensible to say the AR5 says we likely won't get 2C of additional warming until the year 2090 or so. I have a forthcoming post on IER that walks through it.

Bob Murphy said...

Josiah be careful: The "0.2% to 2.0% of income" for 2C of warming refers to *additional* warming, not to warming since 1900.

Anonymous said...

Anthony Watts presents crop yield data (from USDA) here:

Josiah Neeley said...

Fair enough, Bob. The ranges for RCP4.5, RCP6.5, and RCP8.5 do go over 2C even with a 1985-2005 baseline, but the most likely estimate is under 2C for RCP4.5, and not much more than 2C for RCP6.5. I regret the error.

Mac Muir said...

Bob Murphy commented on smell tests. here is mine:
‘The Scientific Smell Test.’

This test has several parts:

- Is there sufficient detail given so that the conclusions become obvious?

- Are the assertions plausible?

- Are key parts of the story missing?

- Do those parts of the presentation where I do have expertise match my understanding?

- Are the arguments so much arm waving?

- Are the arguments logically consistent?

- Is superposition and/or other properties of linear systems claimed for what is a significantly non-linear system?

- Is the claim made that: “Everybody knows or Everybody agrees?”

- Are their clear overreaches in the presentation?

- Willingness or lack thereof in sharing raw data and details of methodology.

- Willingness to address questions / ideas / explanations posed by others who do not hold your view.

- Are “Straw man” games being played? (Claiming that those you see as opponents have said things they haven’t and then demolishing those arguments.)

- Does what is being presented appear to be “Good science.” Good science does not have an agenda, political or otherwise. It lets the chips fall where they may.

- Really good science includes discussions of what you don’t know as well as what you do. It also gives facts which weaken its case.

This list is far from complete but I’m sure you are getting the idea.

This is not part of the scientific smell test but a smell test of its own: Follow the money.

As I continued to research this material I was somewhat surprised by the extent that the pro AGW material was not passing my smell tests and also to the extent the skeptics material was passing it.

One area that really smells to me is the claims made about the results of climate models. We have a name for instantaneous climate: its called weather. Weather prediction programs do not have a good track record at predicting more than a few days ahead. There are significant non-linearities and phase change phenomena (Two are extremely important and neither are well understood or well modeled: cloud formation and precipitation.) involved such that any claim that it would be possible to get the details wrong and the trends right is just not plausible. Yet climate models are routinely trotted out as proof of impending doom.

Mac Muir said...

Carbon not causing warming.

Bodies radiate energy in the form of electromagnetic waves. The spectrum of this energy is determined by the temperature of the radiating surface. The surface of the Sun is at a temperature such that most of its radiation is in the frequency band we call visible light with some in the near infrared (which we sense as radiant heat) and some in the ultraviolet. Most of the UV is blocked high in the atmosphere. The visible (0.4-0.8 micron) and near infrared (0.75-1.4 micron) largely makes it to the earth’s surface.

The Earth having a much lower surface temperature will radiate energy back into space in the far infrared wavelengths (1-30 microns. Peaking around 10 microns. Most of the energy is in the 9-13 micron range.). Carbon dioxide and the other so called “greenhouse gasses” tend to absorb and re-radiate radiation in the far infrared and thus trap heat on the Earth.

Each vibrational mode of a particular type of molecule will act as a narrow band reject filter taking out one particular wavelength. This is based in quantum physics. The energy of a photon is inversely proportional to wavelength and only photons with the correct energy are absorbed. For CO2 these are 2.7, 4.3 and 15 microns.

For an explanation of this see:

Scientists like to assume things are linear, even when they are not. It makes modeling much easier. I suspect that many scientists involved in this modeling just assumed that the energy absorption was linear without checking.

I tried to research this. Starting in 2001. I googled every form of the question I could think of for years without result. Finally I found the answer on my own bookshelf. The fifth edition of “Reference Data for Radio Engineers” (H.W. Sams & co. 1968) has a graph on page 26-28 showing the transmission of 300 meters (about 1000 feet) of air in the far infrared. The transmission of all three wavelengths affected by CO2 are already zero. The atmosphere is far thicker than 300 meters. Therefore it is safe to assume that almost no radiation at the wavelengths affected by CO2 was making it into space when the data for this graph was taken.

This says that CO2 has already done all the warming it can.

Case closed.

Jim Rose said...

the report of the IPCC was a one-day media wonder in the country where I live.

Not a single story today in the local paper, which is the paper for the political capital of the country.

Anonymous said...

Yes, but wouldn't more CO2 mean that the transmission distance is shorter, and therefore the temperature nearer to the surface of the earth would be hotter? Humans, plants, animals, and thermometers are generally close to the surface, not 300 meters up in the air.

Mac Muir said...

“Anonymous said:
Yes, but wouldn't more CO2 mean that the transmission distance is shorter, and therefore the temperature nearer to the surface of the earth would be hotter? Humans, plants, animals, and thermometers are generally close to the surface, not 300 meters up in the air.”

Actually I think not because all of the energy is making its way back to the Earth’s surface anyway. (Otherwise the atmosphere would continue to heat).

This brings up a second point. If the planet is being warmed by ANY greenhouse effect then the Troposphere (lower atmosphere) should be warming faster than the surface. Years of balloon and later satellite data do not show this. [This claim is widely made but I do not have hard data to reference.]

Likewise I should point out that the chart I referenced represents an upper bound on the distance to opaqueness. 300 meters is fully opaque but shorter distances may be also. I remember reading someplace that one of the CO2 absorbing wavelengths is opaque in 30 feet but I cannot point to that data and 300 meters is adequate to my case.

A second point: The modelers like to assume that the weak warming caused by CO2 is amplified by water in the atmosphere. This assumes a positive feedback with a loop gain near one.

As far as I can tell the modelers are making this as an assumption rather than basing it on data. The actions of water n the atmosphere is quite complex, complete with numerous non linear effects (cloud formation, precipitation etc.). I propose a simple observation to indicate the sign of this feedback. Is the day to night temperature swing larger or smaller with high humidity or with low humidity. This is quite unequivocal : Temperature swings are smaller with higher humidity and therefore the net feedback is negative and therefore water in the atmosphere is attenuating not amplifying other greenhouse gas effects.

Anonymous said...

Mac Muir said...

"Actually I think not because all of the energy is making its way back to the Earth’s surface anyway. (Otherwise the atmosphere would continue to heat). "

No, that's not the final destination.

Short term, the infrared photons are absorbed by the CO2 and then re-emitted in a random direction. Some reheat the earth's surface and some go further up in the atmosphere.

Ultimately, a large share of infrared radiation radiates up out of the atmosphere each night (that is why it gets colder).

However, it stands to reason that increased CO2 in the atmosphere slows down this "radiation up and out" process making the earth hotter.

Mac Muir said...

Keep in mind CO2 affects only two or three very narrow bands within the part of the spectrum which cools the Earth. My point is that within those bands the transmivity is so low that virtually no energy is making it into space. Outside of those bands CO2 has no effect, just as nitrogen and oxygen have no effect.

Put another way: Half of zero is stil zero.

Outside of those bands yes energy radiates into space.

That radiation is affected by other greenhouse gasses, principally water (as vapor, liquid droplets, clouds and ice crystals). Water effects a wide range of wavelengths in this part of the spectrum as we are dealing with high harmonics of the basic water vibrations.