Tuesday, March 12, 2013

Lennart Bengtsson: Global climate change and its relevance for a global energy policy.

Lennart Bengtsson sent me this manuscript and asked for publication. Maybe a few words about who Lennart Bengtsson is are in order. He is a trained meteorologist, was head-of-research and later director of the ECMWF, the European Center for Medium Weather Forecast. Later he became one of the three directors ol the Max Planck Institute of Meteorology in Hamburg, where he was responsible for the development of the global atmospheric model ECHAM (and other scientific issues). After retirement he is active in Bern as Director Earth Sciences at the International Space Science Institute and professor at the Environmental Systems Science Center at the University of Reading.


Lennart Bengtsson: Global climate change and its relevance for a global energy policy

Background


The first in-depth discussion of the Earth’s climate and it possible change due to increasing greenhouse gases in the atmosphere started more than half a century ago but was restricted to a small numbers of leading atmospheric scientists. Since then the situation has changed beyond recognition. Over the last two decades climate change has evolved into a key worldwide issue with major involvement of media,the political community at different levels and the public at large not the least on Internet. The views vary widely but the dominant opinion is that climate change is genuine and a potential challenge to the world community at least in the longer perspective. This is also an opinion shared by a majority of leading scientists in the field. At the same time there is an increasing tendency towards a polarization in the opinion on climate change with on one hand a preference for dramatic and extreme consequences such as so called tipping points and on the other hand a tendency to even question basic aspects of the physics of climate change.

The relation between temperature and greenhouse gases in its very simplistic form has been known since the second half of the 19th century. The effect of the greenhouse gases can be seen as a warm overcoat preventing the surface in radiating away the heat to space. However, the warming is a complex process incorporating the dynamics of atmospheric and ocean flows and interactions of the many components of what is now called the Earth’s system. This includes in addition to the atmosphere, the oceans, the land surfaces and the land ices. Its study requires advanced computer models and other tools for its analysis and understanding.  It also requires accurate observations for validation and monitoring as well as special measurements for the development of many crucial aspects of the models. It is in fact an immensely complex undertaking that is virtually impossible to explain to the public in a readily understandable way. This has lead to a tendency towards oversimplification that has contributed more to confusion than to a thorough understanding. However, because of the strong public interest we are now facing a dilemma as the public and the political community have become too much involved in the climate change debate influencing the actual science and this not necessarily in a positive way as it implies an arbitrary selection of priorities and preferential issues.

Natural processes drive climate and practically all kinds of extreme weather have always been part of the climate and are practically unrelated to the modest warming we so far have had. The effect of increasing greenhouse gases is a slow but relentless process that will have to be dealt with but will require more time and better insight in key processes.Some events are seen as very dramatic as the reduced Arctic summer ice, others, even more puzzling, such as the surprising lack of warming in the tropical troposphere is hardly discussed.

The problem is that the global warming is mainly caused by the emission of carbon dioxide and thus directly related to energy production by fossil fuels that has dominated and still dominates the energy production by more than 80%. To significantly reduce or eliminate fossil fuel is not feasible on a time-scale shorter than several decades, as it requires fundamental technical breakthrough in energy generation or alternatively a major change in our life stile. As the second alternative is hardly possible to achieve in a world with mostly open societies, it is obvious that the world community is facing a gigantic challenge. Additionally many parts of the world are suffering because of a lack of suitable energy and the need is further underpinned by the fact that the world’s population will increase by another two billion humans in the next three decades.

Some comments on the present situation

Since the end of the 19th century the global warming amounts to about ¾ °C. This is a very modest increase in view of the fact that the greenhouse effect has increased by almost 80% or with about 3W/m2 as can be seen from Figure 1 below. If we translate this to an equivalent CO2-effect it corresponds to an increase from 280 ppm to ca. 490 ppm.


Figure 1. Correlation between the global temperature and the radiative forcing of the well-mixed greenhouse gases 1850-2012. The relation between the vertical and horizontal scale is 0.314°C/Wm2. (After S Schwartz). During this time the equivalent CO2 effect has increased from 280ppm to 490 ppm.
 
The global temperature has not increased steadily but in irregular intervals. Typical features are a distinct warming trend 1910-1940, a slight cooling trend 1945-1970 followed by the sharp warming trend until the end of the 20th century and finally the last 15 years without any clear warming trend. The lack of any significant warming in the tropical troposphere since the beginning of space observations in 1979 is particularly intriguing in particular as present models show a warming trend over the same time of 0.3-0.4°C in the average, figure 2. Such results, scientifically very puzzling as they are, have hardly received any media attention but instead the public has been overwhelmed in recent years by excessive reports of a rapid and threatening global warming very soon running out of control, unless the most drastic steps are taken to stop it. If there are no obvious global signals available, suitable arguments are created from an endless number of extreme weather events. The fact that similar extreme weather has been found to be a property of the present or undisturbed climate is not recognized. The global warming has been taken out of the hands of the meteorologists and traditional climatologists and is now run by professional media experts and different well-recognized members (political or otherwise) of the general public that have found the present climate hype to be a suitable way to remain or be obtain a place in the media limelight.

For some parts of the industry as well as for different NGOs such as Greenpeace and WWF a threatening climate warming have become a necessity and a source of extra income as it provides continued subventions for wind and solar energy as well as contributions from worried parents and grandparents that are anxious to protect their children and grandchildren from an approaching climate catastrophe.

In the very emotional climate debate today is it hardly possible to have a sensible and balanced exchange of views. If you do not support climate catastrophes as the one recently from the World bank, you are placed into a deniers box and accused to support the interest of the oil industry or alternatively that you are a man in a senior age and therefore unable to understand the concerns of the younger generations. Some of our colleagues are exposed to a powerful group pressure or that of a politically correct boss. The real genuine interest in climate and climate processes is fading away as the interest is confined to the concept of climate typical of the general public or rather I shall say the predominant or politically correct concept of climate.
Among meteorologists and well educated people the role of the greenhouse gases in the atmosphere is relatively well understood such that an increased concentration leads to higher temperatures at the surface and a cooling of the lower stratosphere. This has also been observed. The problem is not the direct effect of the greenhouse gases that is relatively minor, with about 1° warming for each doubling of the CO2 concentration, but the feedback processes in the climate system. Some of these are likely to be positive such as water vapour; others such as clouds are still not well understood. The feedbacks of the climate system dominate the outcome but are unfortunately so far not well handled by models. It is the main cause to the large differences between models.

However, the really important question is to know how much warmer it will be and how fast this is likely to happen as this determines a realistic and sensible cause of action. In spite of all research and modelling experimentation we are actually less sure what will happen than what might appear from all reassuring reports that dominates the media. Irrespective of all worrisome media report on the drama of climate change, climate is in fact warming much slower than anticipated. The very first climate simulations that were made almost a quarter of a century ago and at least according to the simulation by the MPI model in Hamburg, the global warming today should rather be 1.25°C than the present 0.75°C. And this is spite of a relatively large (cooling) aerosol effect of the Hamburg model that at the time was larger than the present view of IPCC today. The tropics are a crucial area as it is here where the greenhouse effect is largest. During the period 1979-2012 for which we have reliable observations, the warming of the lower tropical troposphere, 20°S – 20°N, has only got about a third of the warming compared to what is predicted by present climate models.

Figure 2. Tropical temperature changes at different pressure levels for 1979-2012 and for different observing systems and for a range of model experiments used in IPCC AR5 (courtesy J. Christy) The warming trend my the models is about 3 times larger than the observations. 

There is no simple explanation to this, except that the planet is capable to get rid of the heat more effectively than in the models. This can be due to errors in handling the clouds or that the water vapour effect is overestimated and that in reality the atmosphere is loosing heat to space in regions of very dry air that is not well represented in models. Alternatively more heat is effectively transported into the depth of the oceans. However, the observational records are clear and the global warming is proceeding much slower than generally is anticipated.

There is a need to rethink

Instead of being grateful for this comforting result the reaction is rather the opposite. In the almost hysterical climate hype of today a less dramatic warming is not very well received as all political correct members of the public would prefer to hide this uncomfortable fact by following the popular maxim of letting the ends justify the means. From the standpoint of the green movement all political efforts, even extreme ones, are required as they wish to abandon fossil energy as well as nuclear energy and this at a time when the world population is increasing and where the lack of suitable energy is a primary obstacle towards a better life. To achieve this in a short period of time is like the squaring of the cube. Even Germany with its considerable economical and technical resources has been forced to build a number of fossil fuel power stations (using lignite) to replace nuclear power stations, as this is the only way to assure a steady supply of electricity in a time scale of a few decades. Renewable energy can only serve as complements as there is presently no way to store electricity effectively in the amounts required.

The global climate policy has unfortunately been a failure mainly because of an inconsistency in the carbon tax policy. A carbon tax is an effective way to reduce the emission of carbon dioxide. However, the effect of carbon tax in the EU has had the effect to transfer the production of goods that emit large amount of CO2 to countries that did not sign the Kyoto agreement such as the countries in the developing countries. Goods demanding use of fossil energy can therefore be produced outside the Europe and than be exported to Europe. The consequence is at best an unchanged amount of CO2 emission as it has only moved outside the EU. The consequence is loss of jobs and production capabilities in the EU with no effect at all on the global emission of CO2. As a minimum a corresponding import tax should be levied on relevant imported goods. As this has not been the case the Kyoto agreement has in this crucial aspect been a failure.

During the next 50 years the global primary energy must at least be increased by a factor of two that means that both fossil energy and nuclear energy will have to increase. The renewable energy is insufficient although not in theory but in practise. The reason is its low energy density and huge variation in time because of the weather. A central crucial factor is the insufficient capabilities of storing energy. The most positive development in recent years is the exploration of huge amounts of shale gas in the United States that is rapidly reducing the emission of CO2. A complete replacement of coal by gas will make it possible to half the CO2 emission. A similar possibility might be possible also in China that has huge amounts of shale gas as well.

We do not yet know how to best solve the Earth’s energy problems but many thing may happen in the next 100 years. A modest climate sensitivity that is supported by observations combined with a transition from coal to natural gas will provide the world with a waiting time of half a century or so but not very much longer. This will make it possible to avoid unnecessary and highly expensive panic-type subsidized investments driven by political whims and the expectations of quickly earned money and instead invest available means in a well thought through long- term energy research programs.

17 comments:

Jos said...

One technical remark.

"... the role of the greenhouse gases in the atmosphere is relatively well understood such that an increased concentration leads to higher temperatures at the surface and a cooling of the lower stratosphere. This has also been observed."

The current stratospheric cooling is by far not related to the increase in greehouse gases, but almost entirely attributed to the decrease in ozone. The change in stratospheric GHG has been too modest over the last 30 years to be able to explain the observed cooling over the same period.

There have been several papers on this, the most recent that comes to mind is this one:

Polvani, L. M., and S. Solomon (2012), The signature of ozone depletion on tropical temperature trends, as revealed by their seasonal cycle in model integrations with single forcings, J. Geophys. Res., 117, D17102, doi:10.1029/2012JD017719.

hvw said...

During the period 1979-2012 for which we have reliable observations, the warming of the lower tropical troposphere, 20°S – 20°N, has only got about a third of the warming compared to what is predicted by present climate models.

Hmm, I wonder whether that is backed by more than J. Christy's remarquable figure featuring model based temperature trends (1979-2012) from CMIP5 RCP8.5 runs. This CMIP5 experiment officially starts in 2006, and only CMCC-CESM (not in the figure, I believe) was run from 2000 on. Can we assume that this is just an illustrative plot, and one with a reasonable number of CMIP5 models and the "historical" or "AMIP" experiment would support the same statement?

Lars said...

the observational records are clear , really???

Po-Chedley, S. , Fu, Q., A bias in the midtropospheric channel warm target factor on the NOAA-9 microwave sounding unit, Journal of Atmospheric and Oceanic Technology Volume 29, Issue 5, 2012, Pages 646-652
This warm target factor bias directly affects the UAH lower tropospheric (TLT) product and tropospheric temperature trends derived from a combination of TMT and lower stratospheric (TLS) channels.


And what about the deep ocean? Could it explain why global warming is proceeding much slower than generally is anticipated?

Fahrbach et al. (http://epic.awi.de/32485/1/BzPM_0569_2013.pdf , page 45)

Wenn diese Wärmemenge nicht vom Ozean aufgenommen worden wäre, wo sie über 3900 m Tiefe zur Erwärmung von 0,04 K geführt hat, hätte sie in der der darüber liegenden Atmosphäre eine Erwärmung von etwa 1°C über 24 Jahre bewirkt, bzw. hat die zu erwartende Erwärmung um etwa diesen Betrag gedämpft.

Anonymous said...

one question about this:


"Typical features are a distinct warming trend 1910-1940, a slight cooling trend 1945-1970 followed by the sharp warming trend until the end of the 20th century and finally the last 15 years without any clear warming trend."

why the distinction in language between the 'distinct' and 'sharp'

as the rate of warming in both periods would appear to be near identical?

Ie,given presumably the 'distinct' period is presumably natural, the obvious thought, that the same (possible poorly understood, or perhaps unnown) natural processes that drove this period, are also the same that perhaps predominantly drove the 'sharp' period.

ie all natural, as a null hypothesis, not to discount of course the possibility of a % of the sharp period could be cause by AGW.


Again a naive look at those trends would perhaps suggest, we might observe a similar 'slight cooling' trend as 1945-1970, over the next few decades, due to a similar cycle that we have observed.

Against a background of a long term warming trend of a decadal rate of ~0.07C per decade per century..

which will make the next 5-10-15 years worth of observed temperature very interesting to climate science. (as the world appear to be locked into a high CO2 emissions scenario, for at least that period)

Barry Woods

Anonymous said...

"the effect of carbon tax in the EU has had the effect to transfer the production of goods that emit large amount of CO2 to countries that did not sign the Kyoto agreement such as the countries in the developing countries. "

Ahem...as far as I know, developing countries are signatories of Kyoto Protocol for the very reason that the protocol does not require them to cut CO2 emissions.

Leonard Weinstein said...

The article has several good points, but makes the assumption that all of the recent net warming is due to the greenhouse gases. Since the temperature over the last 10,000 years has seen up and down variations at least as large many times before (based on the best overall sources including the polar glaciers and sea bed cores), and in fact the present high gobal temperature seems to be near the long term average over this period, there does not seem to be suitable justification for this assumption.

Volker Doormann said...

“Lennart Bengtsson: Global climate change and its relevance for a global energy policy
Background

Since the end of the 19th century the global warming amounts to about ¾ °C.

If we translate this to an equivalent CO2-effect it corresponds to an increase from 280 ppm to ca. 490 ppm.

The global temperature has not increased steadily but in irregular intervals.

. . finally the last 15 years without any clear warming trend.

There is no simple explanation to this, except that the planet is capable to get rid of the heat more effectively than in the models.

There is a need to rethink.”



Volker Doormann said:

Dear Lennart Bengtson,

I think the global climate change only can have relevance for a global energy policy, if the nature of the climate frequencies are understood. The coupling of CO2 to the global warming is an idea, and BTW, the actual value of CO2 in the atmosphere is 0.0395%.

Science is to look for coherence of functions, but as you say, there is no proper coupling of the CO2 content and the complex global temperature function in general, and not for the last 16 years.

I think it would be a great statement to say, ‘we are confused by facts. We do know nothing about the climate in the future.’

Simple comparisons of solar system functions with the well known global temperature reconstructions can help to bring light into the climate frequencies:

http://www.volker-doormann.org/images/16_year_stagnation_.gif
http://www.volker-doormann.org/images/ghi_23_ghi2_patzelt_sp1.jpg
http://www.volker-doormann.org/images/down3.gif
http://www.volker-doormann.org/images/sea_level_vs_solar_tide_1.gif
http://www.volker-doormann.org/images/uah_temps2013r.gif
http://www.volker-doormann.org/images/ippc_ar5draft14.jpg
http://www.volker-doormann.org/images/moberg_sonne.gif
http://www.volker-doormann.org/images/metoffice_model_4.jpg
http://www.volker-doormann.org/images/had4_minus_oni.gif
http://www.volker-doormann.org/images/ghi_11_vs_solar_neut5.gif
http://www.volker-doormann.org/images/solar_neutrino_vs_oni.gif
http://www.volker-doormann.org/images/cycles_10kb.gif
http://www.volker-doormann.org/images/ghi_11_had1960.gif
http://www.volker-doormann.org/images/solar_fig_3.gif
http://www.volker-doormann.org/images/ghi_23_edwards_2b.gif
http://www.volker-doormann.org/images/ghi_pub_fig2.gif

From this results it can be drawn a new picture of global climate frequencies. The measured global temperatures are a mix of mainly three effects. One effect is the effect of the solar tide functions from all the relevant planets. This controls the ~900 year climate cycle as well as the high frequency cycles of years and several months. Superimposed to this is the ONI function, which is related to the ocean impedances and last the marginal effect of the CO2, which is of minor relevance to the climate. Strong stable phase correlations of the solar tide function of Mercury/Earth with the main sea level oscillation frequency suggest that there is a mechanism working between the Sun and the Earth. Fourier analyzed (FFT) spectra of the GISP2 sample do show a ~900 year power peak, which means, that this is a cycle repeated > 7 times over >10ky, and this power peak exhibit also in a FFT spectrum of the solar tide time interval of about 6ky. From this it is possible to calculate a climate forecast of about +1000 years.
A warm climate level has an effect on Earth AND a high CO2 level has an effect on the oceans etc. But what to learn is that there is no causality between.

V.

JamesG said...

Well I've known from the start that the models were not fit for purpose. It was always ridiculous to believe an extrapolation from 0.6K last century to 3K the next century based entirely on such models. However activist-scientists continue to do this. My question therefore is why are Earth scientists so unremittingly pessimistic? You cannot blame the media for jumping on the bandwagon. You cannot blame the deep green environmentalists either, as most seem anti-industry misanthropes anyway so they just needed an excuse. Alas it was headline-grabbing Earth scientists who started all this self-righteous, hypocritical, tribalist angst among the chattering classes about the fossil fuels that everyone relies on.

Of course the 70's ice-age scare was blamed on fossil fuels too. So it really seems to be some kind of institutional bias against fossil fuels? Again why? Use of fossil fuels has lifted people out of poverty and saved the forests.

Now ok, caring about the energy gap is important and yes alternative energies must be explored. I was doing this long before these faux-environmentalist thermageddon-believers came along and I am still doing it now. But the plain fact is that current climate policy has made this energy gap even worse by closing good plant and diverting resources from new plant to bad ideas. At the same time climate policy has unquestionably made fuel bills and food prices artificially higher and so is literally killing those who now have to face the choice between heating and eating. There is no moral high ground for the alarmists. But they live in the clouds and don't care to listen.

Please don't quote false hockey-sticks to support alarmism! Rather return to reasonable skepticism; ie what should be the natural state for both scientists and journalists.

Ed Caryl said...

We would like to invite Dr. Bentsson to the discussion here:
http://notrickszone.com/2013/03/17/warming-theory-doused-world-leading-meteorologist-climate-is-in-fact-warming-much-slower-than-anticipated/
We have a question.

G Howe said...

An informative, measured, and timely essay. I hope the good doctor will approach some other "skeptic" blogs, and ask for publication as well. The world needs more of this type of calm and thoughtful reasoning. A fine example of why one should respect one's elders! Thank you Dr. Bengtsson.

Mantram said...

ok, VERY good article, but... there is this BIG thing... that maybe COULD have SOMETHING rto do with temperature on erath. It´s called THE SUN! *caugh caugh*

policycritic said...

There is a typo. 490 ppm under Figure 1 should be 390 ppm.

Martin Stendel said...

Dear Lennart,

as we see it, there is ample evidence that a large part of the heat actually is going into the ocean (http://www.dmi.dk/dmi/nyt_tema_hvad_bliver_der_af_den_globale_opvarmning; in Danish).

Regards
Martin

Sylvain said...

Does Christy's figure come from a published article?

Following skepticalscience, "Most researchers believe this difference is likely due to instrument errors.":
http://www.skepticalscience.com/satellite-measurements-warming-troposphere-basic.htm

I am not an expert but I become always suspicious with figure not coming from a published paper.

Stickan said...

"sharp warming trend until the end of the 20th century and finally the last 15 years without any clear warming trend"

Really ?

http://www.woodfortrees.org/plot/gistemp/mean:12/from:1970/plot/gistemp/from:1970/to:1999/trend/plot/gistemp/from:1999/trend

Arno Arrak said...

You, Dr. Bengtsson, believe that science actually supports the existence of greenhouse warming. You say the right things about science, like pointing out the need for accurate observations, deploring lack of genuine interest in climate and climate processes by politically correct activists, and observing that opponents of catastrophic scenarios are either dropped into a deniers box or discounted as old fuddy-duddies who don't understand the younger generation. (The latter I had not heard of before!) But when it comes to climate science you are giving it a pass. To your credit, you do point out that AR5 model predictions for tropical warming are three times higher than observations, but you simply drop it there. Those predictions involved numerous labs equipped with supercomputers costing millions and their combined output is essentially worthless. To me, their contribution to climate science is negative - their results are completely misleading and the operation should be shut down to save the expenses involved. This is not the worst. AR4 also went into knowing the future and predicted that global warming in the twenty first century shall proceed at the rate of 0.2 degrees Celsius per decade. We are now in the second decade of this century and there is no sign whatsoever of their predicted warming. This is not a minor matter because huge expenditures for mitigation require knowledge of what there is to mitigate. There has been no warming now for the last fifteen years, nothing to mitigate, but the machinery set up to do it is totally unaware of it and moves forward at full speed. I looked at a preview of CMIP5 climate predictions and they totally ignore the current standstill of temperature and extrapolate the future from the nineties. And the nineties temperature itself is faked. They show a late twentieth century warming when in fact there was an 18 year warming pause in the eighties and nineties. I pointed that out in my book in 2010 and was simply ignored. But strangely enough, GISSTEMP, HadCRUT and NCDC all decided suddenly last fall to correct their eighties and nineties data and got rid of their phony warming there. Nice cross the pond cooperation - they knew quite well what they were doing, but nothing was said about it. You, in common with all professional climatists, have ignored the current warming pause that even Pachauri the railroad engineer admits has lasted 15 years. Fact is, there is more carbon dioxide in the air now than ever before but it is simply not doing its warming thing. Ferenc Miskolczi explains why. He is another person the "real" climate scientists are told to ignore. He published a full account of his theory in 2007. It is a Magnum Opus of 40 pages that most of his opponents don't understand even now. This does not prevent them from criticizing and denying him. In 2010 he followed it up with observations that confirm his predictions. Using NOAA weather balloon database that goes back to 1948 he showed that the atmospheric absorption of infrared radiation had been constant for 61 years. At the same time, carbon dioxide went up by 21.6 percent. The addition of this substantial amount of carbon dioxide to air had no effect upon the absorption of IR by the atmosphere. And no absorption means no greenhouse effect, case closed. This is an empirical observation, not derived from any theory, and it overrides any predictions from theory that do not agree with it. Specifically, it overrides any and all predictions that use the greenhouse effect to produce their warming. If that is not to your liking you have to prove Miskolczi's observations wrong. The databases he used are available to all and there is nothing to stop you from repeating his observations if you have to convince yourself and your cohorts of what the facts are. In the meantime, we must consider Miskolczi's observations correct and start implementing the logical consequences of a world not warmed by the greenhouse effect and free of AGW.

Arno Arrak

blouis79 said...

"The effect of the greenhouse gases can be seen as a warm overcoat preventing the surface in radiating away the heat to space."

Sorry, but that statement is the core misconception of climate scientists. I have not yet seen any experimental evidence demonstrating thermalization of IR by any "greenhouse" gas. IR absorbing/emitting gases are certainly able to absorb IR energy, they are also able to emit such IR energy. When in local thermodynamic equilibrium, emission = absorption and the best one can say is that there is "scattering" of IR. That is what Tyndall was able to demonstrate.

So called radiative transfer data collected within IR-reflective chambers has no validity in the study of thermodynamics.

A physicist could easily demonstrate thermalization or lack thereof in a laboratory. But if physicists think like Gerlich and Tscheuschner "Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics", then would not waste their time on such experiment.