The roles of water and ocean in preventing
global warming
Katsuya Yamaguchi
Suita city councilor
25-12 Toyotsu-cho
Suita-city Osaka Japan
Today I would like to talk about two things. First, about a massive undertaking to avert the melting of the Arctic ice, Bering, Strait dam. Then, about a new technology BHCS to capture carbon dioxide and store them under the sea. I know they are both controversial, but I will explain why we need to act in them right now.
Beginning of carbon cycle
First, I would like to show you a figure illustrating carbon cycle on the surface of the earth to make it easier for you to understand how these two methods work. I begin with the relatively simple carbon cycle of Archean eon of four billion years before. (Figure 1) At that age, the atmosphere was composed mostly of carbon dioxide and vapor. Temperature of the atmosphere was two to three hundred degrees centigrade and the pressure was several megapascal. You can see the oceans and continents that have been formed just before this age. Carbon dioxide absorbed in the ocean reacted with water under hydrothermal condition and produced a large amount of organic carbon. For this reason, the sea water of this age contained high amount of organic compound. In high-temperature areas such as around underwater volcanoes, carbon dioxide formed limestone by reacting with calcium. This process decreased the amount of carbon dioxide in the atmosphere as a result. Limestone formed in the ocean moved onto the continent by the convection of the mantle. Some of the limestone melted in magma and released carbon dioxide back to the atmosphere through the eruption of volcanoes. In other areas with high temperature and high pressure, limestone morphed into hydrocarbon and was stored in the lithosphere.
Carbon cycle after beginning of photosynthesis
After photosynthesis started on the earth, a large part of carbon dioxide in the atmosphere was captured by living organisms. (Figure 2）The formation of organic carbon through hydrothermal process and formation of limestone under high temperature and pressure stopped. Instead, creatures such as coral started fixation of carbon dioxide through formation of limestone. The dead bodies of creatures were dissolved into organic carbon and carbon dioxide emitted through the respiration of microbes, and some part of carbon was stored at the bottom of the cold sea or on the cold continent as methane hydrate. In this carbon cycle, the power to decrease carbon dioxide from the atmosphere exceeded the power to increase it. The earth lost global warming gas temporarily and started to experience severe cold climate. At times, all parts of the earth were covered with thick layers of ice. To recover from this situation, volcanoes had to work several million years to restore necessary amount of carbon dioxide in the atmosphere.
Carbon cycle after industlialization and global warming
Now we fast-forward to the modern age. (Figure 3) When the industrialization started, combustion of fossil fuels and incineration of wastes started. Carbon was released into the atmosphere from the hydrocarbon stored in the lithosphere. The power of increasing carbon dioxide in the atmosphere soared and the power of photosynthesis and carbon fixation and absorption decreased. As a result of the rising temperature, methane started being released from the permafrost in the recent decades. The diminishing polar ice may cause sudden increase of the temperature of Polar Circle and cause huge collapse of methane hydrate layer at the bottom of the sea.
Carbon cycle of the future earth
This next slide illustrates the carbon cycle of the future earth where we have averted the climate change disaster. (Figure 4) It shows important systems for abating global warming. Unfortunately, I don't have time to talk about energy conservation, renewable energy supply systems, forest restoration and Fossil Fuels Supply Control System, because of time limitations. So let me talk about the rest.
Ocean carbon storage system
In Figure 4, hydrocarbon in lithosphere is not used as fuel but used as materials. When the products made from hydrocarbon are disposed, in this chart, they are decomposed by BHCS with other waste, such as plants and sewage sludge, to some stabile and harmless organic carbon and dumped into the ocean. Carbon is stored in the ocean as organic carbon. Thus, in this circle, very small amount of carbon dioxide is emitted from human society to the atmosphere. The key part of the carbon ocean storage system is named BHCS, Blasting Hydrolysis Conversion System, by the company who holds this technology. Recently as a part of geo engineering, many researchers are trying to capture carbon dioxide before emitting and store it in deep lithosphere or ocean or as carbonate rock. The ocean carbon storage system is simpler, more convenient and certain in removing carbon dioxide from the atmosphere than other methods.
The easiest method for removing carbon dioxide from the atmosphere is utilizing plants, of course. However, the carbon stored in plants in decomposed by microbes and carbon dioxide is dispersed quickly when plants are dead. Wood can store carbon for a long time, but it takes place. I think the only place we can use for storing carbon on the earth is ocean. We can use sea water or bottom of the sea to store carbon for a long time, if we can dissolve organic waste by hydrothermal technology in harmless and stabile manner.
There is a technology called BHCS or Blasting Hydrolysis Conversion System. It is one of the best methods for decomposing organic wastes efficiently.
The flow chart of BHCS is as follows;
First, materials, such as city wastes, are grinded in the grinder. Then, materials and vapor of two hundred and forty centigrade at four mega pascal is injected to the reactor. Mechanical stirring is not necessary. Chemical change, such as separation of acetyl group, partial hydrolysis of hemicellulose, dissolution of lignin, occurs inside of the reactor. After the reaction time, contents of the reactor are blasted into blow tank.
Not only food waste or sewage sludge, but also branch of trees or plastics except rubber can be treated. After the hydrothermal reaction and blasting, the materials are changed to brownish or black grain. Originally this solid part was tried to use for fertilizer. Liquid fraction contains xylo-oligo-saccharide, phosphate and other minerals. Both solid and liquid fractions are not harmful to the plants, so are not harmful to the sea environment. Coastal drift of solid fraction never happens because it easily sinks into water. In the middle to deep part of the see, sea water contains abundant organic compounds and carbon dioxide. Thus, conditions of sea will not be largely changed by this carbon treatment. Several decades before, human waste was dumped into the ocean without any treatment in Japan. According to the record of the time, no accumulation of waste was found at the bottom of the sea. The product of BHCB, dumped into the sea, will disperse widely in the ocean. The life of BHCB product in the ocean is not examined yet, however, it seems that products remains as it is for fairly long period as is the case of other compound in the ocean.
Comparing organic carbon density of Atlantic Ocean deep sea and Pacific Ocean deep sea, Pacific Ocean has much higher density. This means the organic carbon produced in Atlantic Ocean flows into Pacific Ocean, which locates downstream of the deep sea convection. This means that organic carbon stays as it is for more than thousand years.
In addition to the city and industrial wastes which are incinerated today, much amount of agricultural and forest wastes, which decay and turn into carbon dioxide now, can be used in this carbon storage system. That is why, I believe, this carbon storage system, if this system is installed and used in all over the world, can reduce carbon dioxide in the atmosphere meaningfully.
A financial system, which compensate for carbon storage action is inevitable for BHCS to be installed in large scale. Until such financial system is established, BHCS should be chosen by other strong points in treating wastes. BHCS emits no methane or bad smell. In addition, when BHCS is used in city sewage sludge treatment, activated-sludge pool is not necessary. Thus, BHCS system can reduce consumption of electricity. I, as a city councilor of Suita, am trying to install this BHCS system for sewage water treatment.
Bering Strait Dam
The next is Bering Strait Dam, an earth cooling system. I think the situation we are facing is quite serious because studies show that the patterns of unexpected positive feedback are emerging on many parts of the earth. Descriptions concerning Arctic Ocean and oceanic warming have significantly increased between the fourth and fifth assessments of IPCC Working Group 1.
The fifth report says, in the latter half of this century, the sea ice area of Arctic Ocean diminishes to one third of that of preindustrialization in the summer time, even if the global warming gas emission is controlled very strictly. Without the strict emission control, the sea ice will vanish from Arctic Ocean in the 2030’s in the summer time in the worst case. Dr. Abe of University of Tokyo Center for Climate System Research simulated that, when there is no sea ice in the Arctic and Antarctic Oceans, the average temperature of the earth will increase by two degrees within fifteen years.
So, why is the ice in the Arctic Ocean disappearing? The team led by Dr. Koji Shimada of Tokyo University of Marine Science and Technology observed that warm sea water from the Pacific Ocean in the summer time flows through Bering Strait into the Arctic Ocean and caused the decrease of sea ice. This study was confirmed by Washington University group and the result was published in Chinese Journal of Polar Science.
Once the temperature of the Arctic Ocean increased, the edge of the sea ice which fixed sea ice to the coast was lost. The sea ice started to move freely. The speed of sea ice movement doubled. The movement fostered summer Pacific sea water to enter Atrctic Ocean even more. Each sea ice lost thickness because the speed of melting exceeded the speed of growing. The connection of ices was lost and crack spread all over the sea ice field accelerating the sea ice movement furthermore.
To prevent Arctic ice from disappearing, we have to focus on Bering Strait. The width of Bering Strait is around eighty-six kilometers, and the depth is around thirty to fifty meters. The climate change on the global scale is being caused by the Pacific warm sea water going through this narrow channel. This is fortunate for us because it will be feasible for us to build a dam to control the flow from the Pacific Ocean. The project will be extremely difficult because of budget, resources and political reasons, and currently there is not enough researches going on. However, to stop the accelerating loss of Arctic ice, we have to start serious studies and planning immediately.
What will the Bering Strait Dam look like? The sea level of Pacific Ocean is higher than Arctic Ocean only by fifty centimeters. The current form Pacific Ocean to Arctic Ocean is not fast, sometimes flowing backward. Thus, water pressure of the dam is not strong as that of conventional dams constructed on the river. However, in the winter season, huge amount of ice arrives at this Strait from the north and the dam would have to stand for ice pressure. The dam will look like a sixty-meter tall wall sticking ten meters above water. The dam also should have the function of closing the strait partially based on the temperature of the current. So, the middle to bottom part of the dam should have a structure like a roll-up blind or a roll-screen.
How much will it cost? We can compare it to other construction projects to get an idea. A conventional river dam is much more expensive for its size because it has to withstand high pressure. I simulated the cost of Bering Strait Dam based on cost of tsunami barrier walls located alongside the Tohoku coast of Japan, and Isahaya bank and water gate in Kyusyu region. Considering the cost of delivering materials from distant locations, the cost of the Bering Strait Dam will come up to two hundred billion dollars. It costs about 2.3 billion dollars per kilometer, which is about seven times of the cost of the Channel Tunnel.
Regarding the idea of controlling Pacific water inflow, there have been two criticisms. One was written by Dr. Ito of Japan Agency for Marine-Earth Science and Technology (JAMSTEC). She says if there is no Pacific water in Arctic Ocean, fresher light sea water, which is formed by the mixture of sea water and fresh water from the rivers and freeze on the surface of the sea, touches directly to the warmer, saltier and heavier sea water which derives from Atlantic Ocean.
It is a valid concern. To address this issue, the Bering Strait Dam should stop only warm part of the water and pass usual sea water.
The other argument comes from the international study led by scientists at the National Center for Atmospheric Research (NCAR). They found that Bering Strait has strong influence on climate pattern of North America and Greenland in the one hundred thousand year timeframe. Their thesis says closing Bering Strait leads to the warming of North Atlantic Ocean and finally the whole world in the long run. This finding is not something which makes closing Bering Strait impossible. The effects of Bering Strait dam, which they found out, emerge slowly through thousand years and sea ice on Arctic Ocean has much stronger influence on the climate. So, we should first control warm Pacific sea water inflow to recover sea ice.
From those who have agreed with controlling summer Pacific sea water, an idea of fence, which closes upper side of Bering Strait to stop only the surface flow of the sea, is proposed. The design of the fence is published. I believe scientists and designers will succeed in producing efficient and stable structure of the dam or fence. At the same time, researchers should work on simulations of Bering Strait closure concerning sea currents, sea ice and ecosystem. Researches for the construction of the dam, such as geological research, should be started. The financial scheme to fund this dam also should be worked out.
It is true that unanticipated risk exists under such large-scale geoengineering projects. This project should be carried out with the keenest attention and methods for fail-safe. However, we know from the earth history that stable and cool climate with the closed Bering Strait existed in the near past. I would like to stress that we are in dire need to initiate the Bering Strait Dam project even though it could be the hardest project the humankind has ever experienced.