Thinking from the Manabe's climate model

Summilux 1.4/50 ASPH, Leica M10P @Chinkokuji Temple, Munakata

Last weekend, I participated in the 8th Munakata International Environmental Conference in Munakata City, east of Hakata.

The venue of the conference, Munakata Taisha Shrine, is a special shrine with one of the longest histories in Japan as recorded in Kojiki and Nihonshoki (the oldest chronicles of Japan). The three palaces in a straight line are one huge divine realm. The three palaces are: Okitsuguu, where the entire island is a Shinto shrine and only priests are allowed to enter; Nakatsuguu on Oshima Island; and Hetsuguu on the mainland of Kyushu.

Munakata Taisha Shrine was the place where Admiral Heihachiro Togo, Commander-in-Chief of the Allied Fleet, prayed for victory during the Russo-Japanese War, which put the survival of modern Japan at stake, and it was also the place where Kukai (later Kobo Daishi) first took refuge after returning from Tang China in October 806. Many of you may recall that the main battlefield of the Russo-Japanese War was the Tsushima Strait, near Okinoshima, the island where God resides.

A very wide range of people involved in environmental activities in various fields participated in the event. I was stimulated by the multilayered and three-dimensional nature of the program, but what was particularly impressive was that Mr. Tokutaro Nakai, the vice-minister of the Ministry of the Environment, who participated in the entire program, clearly said, "We only have about 10 years left". What he meant was that the next ten years would determine whether or not the future would be settled within a level that we humans could manage to accept.


I was a member of the Digital Disaster Reduction (D-Disaster Reduction) Future Vision Team, which conducted an intensive study from the end of last year to the end of May under the supervision of Mr. Ryo Akazawa, Vice Minister of the Cabinet Office. The team consisted of disaster prevention experts Koji Ikeuchi of the University of Tokyo, Yuichiro Usuda of the National Research Institute for Earth Science and Disaster Prevention, Satoko Ohki of Keio SFC, author Tetsuo Takashima, who has written many prophetic works on natural disasters, Hiroaki Kitano of Sony Computer Science Laboratory (CSL), who is in charge of the national AI strategy and is also the head of the Cabinet Secretariat Covid Prediction Team as well as Sony AI, and myself*1.

While there was the D-Disaster Prevention and Social Implementation Team led by Professor Masaru Kitsuregawa of National Institute of Informatics, we, the Future Vision Team, were set up with the mission to think about what the country should really do to prepare for the future by utilizing the power of digital technology, regardless of whether it is possible now. Therefore, the members, while envisioning the largest disasters that could occur in the next 50 years, recognized the need to hastily create a pandemic-ready and disaster-ready society for the increasingly severe epidemics and natural disasters that are expected to occur.

In the past few years, many mysterious large craters with diameters of 25-50 meters have been appearing in the uninhabited permafrost regions, although they are rarely reported in the Japanese media. Needless to say, it is not because of the increasing number of meteorite falls, but because of the explosion of underground methane and other substances caused by global warming. If human efforts are slow and continue at this rate, the Arctic ice will melt within a few decades, accelerating the onset of global warming and pandemics. Cumulonimbus clouds are likely to become more massive than ever, and if the occurrence of linear precipitation belts becomes more frequent, there is a high possibility that damage beyond that of the Atami area will become commonplace. If the predictions of the Ministry of the Environment are correct, typhoons with instantaneous wind speeds of over 70 meters will start to arrive. In that case, not only would many towns and houses be destroyed, but they would have to be rebuilt from the infrastructure level up.

The era of carefree talk about ESG and SDGs is over. Human survival, survival as a human race, will be the most important theme. This is the future that the team needed to envision as an extension of the present, with the mission of envisioning the worst that is realistically possible without using wishful thinking (thinking that ignores probability and wants things to be this way).

I had never met anyone who was as aware of the issues as we were, or even more aware of them, so I had a very strong impression of Mr. Nakai and felt very encouraged by his presence.


As I have participated in this meeting, I have been able to connect various dots, and I think I have finally come to see the whole picture of measures to combat global warming. Here, I would like to share it with our readers.

It is clear from the following chart how rapidly global warming has been progressing.


The first thing we need to understand is how much solar energy that falls on the earth every day is greater than the energy we use. In other words, what is the ratio of solar energy falling on the earth compared to the sum of all of the above?

There is a lot of research on this, but it is not well known to most people. When I asked this question in my university class, even if there were more than 100 people, they basically said no idea. The answer is roughly 7,000 to 10,000.

The answer is roughly 7,000 to 10,000 times.

I can't believe my eyes, can you? We use so many air conditioners and computers, buy so many things, drive so many cars, and even the night landscape of the earth as seen from space is shining brightly.


The next thing I want to share is the climate model by Dr. Shukuro Manabe of Princeton University, who was awarded the Nobel Prize in Physics a few days before this conference. Needless to say, Dr. Manabe won the prize for proposing and clarifying the greenhouse gas effect of CO2.


This is a chart from a historic paper by Dr. Manabe in 1967, which showed that CO2 concentration affects temperature. The results are remarkably consistent with current measurements. (© Johan Jarnestad/The Royal Swedish Academy of Sciences ; Press release: The Nobel Prize in Physics 2021 -

Based on this finding, the model proposed by Dr. Manabe is as follows.

(© Johan Jarnestad/The Royal Swedish Academy of Sciences ; Press release: The Nobel Prize in Physics 2021 -

In a nutshell, it is a very simple and powerful model that says that a certain percentage of the energy that falls from the sun is stored as heat energy by the greenhouse gases in the atmosphere. To put it in my own way, the equation is

Heat on Earth = Input - Output

Input = energy coming from the sun x transmittance

Out = Radiation to space × (1- Shielding effect by greenhouse gases)

In principle, radiation to space ≒ input


These two pieces of information together show that although we often talk about saving energy, it is not the amount of energy we consume or the exhaust heat from our activities that is really troublesome, but the fact that the energy that falls on us is not escaping into space at just the right level (that is, the radiation into space is slightly collapsed). Considering that the total amount of radiation is so huge, the difference in balance is very small. The main reason for this discrepancy is greenhouse gases.

In fact, the Nobel Committee's presentation material describes Dr. Manabe as "the first person to explore the interaction between radiation balance and the vertical transport of air masses".


Let's also briefly recap the concept of radiation. As we learned in elementary and junior high school, there are three ways of transferring heat: convection, conduction, and radiation. Convection is easy to understand, as we experience it every day in our rooms and bathrooms. It is a phenomenon in which warm air and water are transported in a flow where their density decreases and they go upward, while cold ones go downward. Conduction is also something that we experience every day. If you touch a cold object, heat is transferred from you to it, and if you hold a warm person's hand, that person's heat is transferred to your hand.

Only radiation may be hard to understand, but this is the same thing that makes you warm when you are facing the stove, even though you are away from it. This is also the same thing that makes you feel warm when you are facing the sun, which is more than 8 minutes away, even at the speed of light. This is because energy is carried in the form of electromagnetic waves (light), and some of it is converted into heat when it hits.

There is a wide range of greenhouse gases such as CO2, CH4, and CFCs. Of these, CO2 has only a few tenths of the greenhouse effect of CH4 and only a few thousandths of that of CFCs per volume, but it plays a particularly large role among the greenhouse gases because of the large volume of emissions by humans.


Based on this understanding, the following is a summary of the spread of efforts needed to curb global warming.


  1. Stop using C in the ground
  2. Reduce the generation of CH4 and other strong greenhouse gases from the earth's surface.
  3. Reduce direct intake of greenhouse gases from the atmosphere.
  4. Increase reflection and radiation (albedo)
  5. Reduce direct intake of greenhouse gases from the atmosphere.

Let's look at them one by one.


(1) Stop using C in the ground

When it comes to curbing global warming, most people think of (1)-i, curbing the use of fossil fuels, which is fair if you look at the following.


This is because most of the human-derived CO2 (which would not increase without humans) comes from fossil fuels. Fossil fuels are the result of the conversion of solar energy into chemically bonded energy that has been stored underground for hundreds of millions of years, and we burn them at a very high rate every day, extracting large amounts of energy and producing large amounts of CO2.

This is the background to the argument for promoting biofuels*2. This is because plants grow on the basis of the CO2 that was originally in the ground, and then burn it, so CO2 will almost never increase (as long as we plant the next plant).

There is also a considerable amount of CO2 generated from the use of mineral resources such as cement. For example, it is estimated that about 6-8% of human-derived CO2 comes from the production of cement. Most of the so-called hard buildings and civil engineering around us depend on cement, and

Limestone (CaCO3) + heat over 900°C → raw cement (CaO) + CO2

The reason is that we exhale almost half of the weight of limestone (100 -> 56+44 in terms of equation) and use fossil fuels (including power generation) in many cases to generate heat.

Likewise, when we use bauxite underground to obtain aluminum*3, or iron ore to obtain iron, a fair amount of it is spit out (depending on the quality of the electricity and the method of refining). However, there is news that Apple, a company that loves machined aluminum bodies, is converting to a process that does not produce CO2 (but emits O2) with Alcoa, so there is still hope.

In general, most of the C (carbon) is pumped out of the ground for the burning of fossil fuels and the production of cement and metals, and a large amount of CO2 is produced. It is hoped that the amount of carbon brought in from underground, not only from fossil fuels, will be as close to zero as possible.

Incidentally, the breakdown of CO2 emissions from fossil fuels (①-i) in Japan at present is as follows.


Excluding "other sectors (over 10%)" in order of frequency

  1. Electric power (about 40%)
  2. Combustion in other industries (about 20%)
  3. Transportation (less than 20%)
  4. Buildings (about 10%)

The easiest way to reduce CO2 emissions from the power generation side, which is the largest factor, is to eliminate CO2 emissions from power generation. This includes saving electricity since the source of electricity still depends on fossil fuels (which will become unnecessary if we can completely eliminate CO2 emissions).

CO2 emissions from energy production = Σ (amount of energy × CO2 production/energy produced)

The figure in parentheses changes depending on how the energy is produced. Of course, natural energy (hydro, solar, wind, geothermal, etc.) and nuclear energy are close to zero.

It should be noted, however, that not only does solar power not work at night, but also the supply of many renewables is uneven, as a few millimeters of snow can reduce the amount of power generated to almost zero, making it difficult to achieve a stable supply (no blackout) for power distribution.

While electric vehicle batteries can be used to store and utilize electricity at the household level, the only reliable way to store electricity on a large scale, such as on a city scale, is through "potential energy conversion" (potential energy depends on the scale, but in the case of hydropower, more than 90% can be converted to electricity if designed well). In the future, we will probably see the development of energy storage methods such as moving large amounts of water or heavy objects (such as iron sand) up and down tall buildings.

One of the fastest growing trends is to replace the internal combustion engine (ICE) as the power source with an electric motor, but do you know why?


Internal combustion engine engines have a conversion efficiency of 40-45% at the highest level, but as you can see from the diagram above, for a means of transportation like a car, the actual efficiency is less than 20%, and most of the energy produced is dissipated as heat. In other words, about five times the amount of CO2 is emitted when all the energy is converted into propulsion. On the other hand, with electric motors, more than 90% of the input is converted into propulsion energy. This is a half-physical limit, and as long as there is such a difference, it is inevitable that gasoline-powered cars will be replaced by electric cars, just as trains were replaced by electric cars in the past.

This is the background to the argument that regardless of the percentage of electricity generated by thermal power plants, it is better to switch to electric vehicles whenever possible in terms of necessary power (output) and energy capacity. Incidentally, in large cities such as Shanghai, China, all buses and scooters were converted to electric vehicles 3-4 years ago. (Especially in sparsely populated areas where it is difficult to maintain gas stations, all other means of transportation will soon disappear, and gas station operators will be required to transform themselves into businesses with chargers everywhere.)

In addition, I have recently heard of the idea of using electricity to make hydrogen H2 to run internal combustion engines. Although this has the advantage of the strong power of an internal combustion engine and does not produce CO2, it is not energy efficient because most of the input (the energy produced by the combustion of hydrogen) is still dissipated as heat. This would be fine if all the electricity used to produce the hydrogen came from renewable sources, but there is no denying that there is a great deal of waste.

Even gas stations in urban areas are rapidly dwindling, and it is unlikely that there will be hydrogen stations everywhere, even in Japan.

The issue of energy capacity is extremely important. Even if a motor has five times the energy conversion efficiency of an internal combustion engine, it would have to carry about seven times as many batteries as a tank of gasoline to generate the same driving distance. Incidentally, long-haul trucks are generally designed to run more than 1,000 kilometers on a single refueling.

Of the transportation applications, tankers and airplanes will probably be the last ones to use fossil fuels in terms of the amount of power and energy capacity required. However, in the case of tankers, there is an almost ignored trick to turn them into nuclear-powered ships, which would allow them to keep running for many years.

Airplanes currently fly with 20-40% of their weight in fuel, but the energy density of fossil fuels and batteries is so different that it is impossible to carry the necessary energy in batteries (they are too heavy to fly). It will also take some time to be able to produce enough homogeneous biofuel for airplanes that will carry the lives of many people (and to bring the price down to an economically reasonable level). We will probably have to give up on this for a while, and offset it with approaches from (3) onward.

(2) Suppressing the generation of CH4 and other strong greenhouse gases from the earth's surface

This is an issue represented by the cow burping problem that is often mentioned these days.

Originally, C contained in the air and grasses on the earth's surface is not a big problem because it is circulating even if it is emitted as CO2. However, when the C is converted to a gas with a greenhouse effect tens of times greater than CO2, such as CH4 (methane), it begins to cause visible harm. This can be cut down considerably when vegetarian-based meat and cultured meat become cheaper. There is no denying the possibility that one day individual meat (the meat we eat now) will become a luxury that we can eat only once a month.

The same can be said of the case where, as a result of human activities, parts of the swamp begin to decay and CH4, not CO2, starts to spew out (②-ii). If the impact is large enough, we will need to take engineering measures and guidelines for creating green infrastructure and other spaces.

(3) Direct capture and reduction of greenhouse gases in the atmosphere

This means directly capturing CO2, CH4, CFCs, etc. from the air. This includes not only the byproduct effects of tree planting campaigns*9 but also Direct air carbon capture (DACC) or artificial photosynthesis, a technology being researched by RIKEN and others. Although there is talk about the inefficiency of DACC and artificial photosynthesis technologies, it is presumed that a large part of the progress will be made through technological innovation. Rather, the challenge for this approach is how to scale it up.

On a global scale, we human beings emit 51 gigatons (51 billion tons) of CO2 per year (the normal value before Covid), and even if we confine our emissions to Japan, if we assume that our emissions account for 5% of the world's GDP, we would be emitting 2.5 gigatons. It is almost certain that a lot of ingenuity will be required to capture even 1% of these emissions, whether at the emission stage or at the stage of targeting those scattered in the air.

(4) Increase reflection and radiation (albedo)

This is a critically important element in the Manabe model, but one that has not been sufficiently addressed.

Heat on earth = (energy coming down from the sun × transmittance) - {radiation to space × (1- shielding effect by greenhouse gases)}

The study that I have been conducting with dozens of volunteers and members of the Keio SFC Ataka Lab, with the aim of creating alternatives to the urban-intensive society, includes quite senior members of related major government functions. Immediately after returning from Munakata, I mentioned this to the energy study team and was told that this was indeed not a major consideration at the global level or in Japan until now.

The word "albedo" is familiar to readers of my book "Shin Nihon", but I think it is unfamiliar to many people. In a nutshell, it is the ratio of reflected light to incident light from the outside of a celestial body. It can also be translated as "reflectance," but the point here is that it is not necessarily reflection, as described later, so I will refer to it as albedo.


Thus, fresh snow reflects more than 80% of the sunlight. In the case of soil, 90% is absorbed.

In Tokyo, 22% of the city is covered with roads, most of which are asphalt and black. As you can see above, about 90% of the sunlight is absorbed, and changing this albedo is of great value. The same is true for the rooftops and walls of buildings and the roofs of houses and cars.

However, roads only account for about 3% of Japan's total land area (according to the Ministry of Land, Infrastructure, Transport and Tourism's Current Status of Land Use), so it is important to consider what to do with the overwhelmingly large forest area and how to deal with albedo in territorial waters, while not destroying the ecosystem. This is an area where there is considerable room for innovation.


From the data above, it can be estimated that thinning many of the man-made forests that are no longer absorbing CO2 but have been neglected and planting new young trees will improve albedo and activate CO2 absorption. In the case of Japan, 70% of the planted forests are single-storied cedar or cypress forests, which are not suitable for making paper. However, thinned wood can be used as a raw material for plywood and cross-laminated timbers (CLT), as biofuel (including firewood), and as a road strengthening agent for unpaved roads.

There is a start-up company called Radicool that is doing something very interesting from this perspective. The company, chaired by Akira Matsumoto, is developing and selling a Radicool material that converts incoming light into infrared light and radiates it back. When this material is applied, greenhouses, which would normally be a scorching hell, can be kept at an appropriate temperature, and if it is applied to windows, it will keep them cool in the summer, and in the winter it will reflect and radiate heating inside, making it more effective than mirror film. Incidentally, when the same wavelength as the incoming light is bounced back, it is called "reflection," and when blue is bounced back at a longer wavelength, such as green, it is called "fluorescence." In the case of RADICOOL, it is an extremely interesting material that bounces back at a longer wavelength than fluorescent materials.

In the future, I hope that various materials and technologies with albedo control capabilities will be developed, and that the world's first legislation for albedo control will be enacted. I think there is a possibility that this will become a very large market.

In addition to albedo itself, there is another important mission that has not yet been tackled in terms of radiation balance. This is the acceleration of the radiation of heat accumulated in the oceans to space, which I showed you at the beginning of this article. Water is about 800 times denser than air and has four times the specific heat of air, so it stores much of the heat that cannot escape into space. As a result of this increase in sea surface temperature, updrafts are more likely to occur, increasing the probability of cumulonimbus clouds and typhoons. Taiwan is known to be hit by more intense rainstorms than Japan at times, and this is largely due to the difference in sea surface temperature of about 2 degrees Celsius. On the other hand, in the Sea of Japan alone, the sea surface temperature has risen by more than 1.7 degrees Celsius over the past 100 years. If we can find a way to increase this radiation to space, it will directly lead to the curbing of natural disasters and will be a big step forward for the earth and humanity.

(5) Reduce input

This is the first step in terms of the energy balance of the planet, and if we can cut it down appropriately here, we can say that the global warming problem is halfway over.

Heat on earth = (energy coming down from the sun × transmittance) - {radiation to space × (1- shielding effect by greenhouse gases)}

The energy coming down from the sun itself is virtually uncontrollable because it requires manipulation of the sun itself or control of the distance between the sun and the earth. This is because about 10% of the earth's surface is covered by clouds, and if the clouds were slightly thicker or slightly larger, the amount of energy reaching the earth's surface could be optimized. However, it is quite difficult to determine how much is appropriate, and just like the brakes on a car, it is necessary to be able to control them at will. We have to face the fact that human beings have been suffering from famine and starvation due to cold rather than global warming.

It has been a long time since there has been any research on the creation or removal of clouds, although it is not that major. These 3), 4), and 5) are in the realm of what is scientifically called geo-engineering, but as a potential endeavor, it is highly worthwhile to further research on them as humanity's ultimate weapon, while doing as much as possible in (1) and (2).


Finally, a few things to keep in mind.

First, the manipulation of albedo and sunlight transmittance is quite powerful medicine.

Once the snow melts, the albedo drops rapidly, and because of the positive feedback, the snow tends to melt at once. This is called ice-albedo feedback. As a result, during a very short period of time during the ice age, the temperature rose rapidly by about 10 degrees Celsius, and when it started to freeze again, the temperature cooled rapidly again because of the downward feedback. This is probably why Homo sapiens was always on the verge of extinction until a few thousand years ago, when the temperature stabilized. Therefore, we must make sure that our efforts are sensitive, controllable and reversible. This is the same way that braking performance is more important than anything else in driving a car.


Also, there are those who casually say that if we can no longer live on Earth, why don't we move to Mars or the Moon?

I'd like to believe it's a joke, but I'll briefly mention that these planets are not habitable for humans or any other life on earth that could be used as food. It is inevitable that transporting a single person to Mars would incur a tremendous amount of money and environmental burden, including technological development.

In addition, if the destination is Mars, it is estimated that the amount of radiation exposure from the spacecraft would be enormous, and even if we could move there without getting sick, it would probably be difficult to survive there for a long time. In other words, it is unlikely that these neighboring planets will become Noah's ark for the entire human race. And we only have about 20~30 years left to change the future.

In reality, we only have the Earth. How we can protect this planet with care and coexist with it will be one of the greatest challenges for humanity for the foreseeable future.

ps. I would like to add that this is based on my current understanding and may change as discoveries and understanding progress.

(This is an English translation of the original entry below, written in Japanese. )

Translated with (free version)

*1:I am not an expert in disaster management at all, but I am relatively familiar with the situation in the world of data x AI, and as a long-time strategist with a strong awareness of the issues related to future disasters, I was asked by Vice Minister Akazawa to chair this team.

*2:Biomass ethanol, biogas, biocoke, greenbug fuel, and others. Wood pellets and firewood are also considered to be of this type.

*3:As of 2018, 53% of Japan's aluminum production is recycled, so production from natural raw materials is less than half of the total requirement