Transcription of a lecture “Living from the Air: How food and fuels arrive to the world” by Ron Milo, Associate Professor at the department of Plant Sciences at the Weizmann Institute of Science, on the new geological era we are living on: the Anthropocene.
I would like to ask you: in which Geological Period are we living in today? During the history of Earth, which has existed for 4.5 billion years, there have been many geological periods with many names; every million years a new name is given to the geological period usually according to the living creatures, which are found fossilized in rocks, of the period. In our current period the name is in the process of being changed. Every person who has had some interest in the matter knows the ‘Holocene Period’, which was the name given to the last geological period. However, in the last few years we understand that the time for a new geological period has arrived: ‘Anthropocene Period’, meaning ‘The Human Period’.
Every corner of The Earth is intensely influenced by human beings; this forces us to give a new name to the geological period we are living in, not only in terms of our personal understanding, but also because of how it affects the face of The Earth. Let’s take a look where is it visible: the graph we can see here starts in 1957 when exact measures started to be taken; Charles David Keeling took measurements of the Carbon Dioxide (CO2) levels found in the Atmosphere. The importance of his work was not comprehended when he started doing it. In 1957-58, which was declared the Geophysical year, different measurements of The Earth were taken. Keeling started to measure with precision the quantities of CO2 in the air; today his son, who is also a scientist, continues his father’s work. It could be seen in Keeling’s measurements for the first time that there is a direct connection between the passing of the years and the rise in CO2 found in the air. At the time when the measurements started being taken, the level of CO2 in the air was 300; today we have passed the 400.
It does not only happen next to power stations, which emit carbon, but in the composition of the Atmosphere around Earth. The quick pace in which we emit CO2 it’s due to the usage of fuels, petrol, carbon that we take from the earth. These minerals which were created in another geological period, two hundred million years ago, were given to us as a present from the Biosphere. The speed in which we are using these resources is such, that every year we are burning a present that took millions of years to become what it is.
The change can be seen in other examples as well. As the population of The Earth grows, seven billion today, and the needs rise, many cycles (nitrogen cycle, phosphate cycle) are changing drastically. It seems that we are even changing gravitation. An amazing thing can be seen: there are NASA satellites in space that measure and demonstrate that we are changing the gravitational force of The Earth. The place where this change is most visible is North India, in the regions of Punjab and Rajasthan. In those regions farmers use very intensively the aquifer of underground water. They are emptying the underground water reserve in such a pace that every few years they have to pump water from greater depths. The decrease in underground water levels changes the composition of the earth since the rocks become hollow, where water filled them. Thus, the satellites that measure the gravitational force show that the levels of water lost, changed the gravitational force on the face of The Earth. A similar effect can be seen in other places around the globe, but India’s case is the most noticeable.
We can ask: why do we need to use so much water? If we look at the ‘water footprint’, we can see that a lot of water is needed to provide food; for example, 1,000 liters of water are needed to get one kilogram of wheat. Think about one kilogram of flour. Now think about 1,000 liters of water. A huge amount of water is needed; therefore, water is pumped like in India.
Why is so much water needed to produce food? What is the main reason for which plants need to be watered so much? The main reason is that when CO2 enters the plant, water vapors escape. This is a crucial point to the human race, so it is worth understanding it better. Imagine a leaf, it is very thin: 200 millionths of a meter; there are places inside it in which supplied water flows and things leave the leaf. Nevertheless, the most interesting thing happens in small openings called pores. For the plant to be able to build itself, it needs to get CO2. The moment it opens the pore to get CO2 it releases water vapors. Because of that small opening that releases water when the plant get its CO2, so much water has to be invested for the watering.
For example, when looking at a Ficus leaf under a microscope the pores are visible. Sometimes, in some plants, with a little difficulty they are even visible to the naked eye. In every squared millimeter of the leaf there are between ten to a thousand pores that enable the plant to take from the air what it needs.
Why are these pores needed, what do we want from the air? We want the opportunity to use the raw material that will allow us to grow plants and accumulate energy. In simple words what we have here is nature’s creation of a battery. For the batteries that we invented, we have to dig the earth to find Lithium or Cadmium, which are rare metals. Nature found an elegant solution: it lives from the air. It found a way to make a battery from taking CO2 from the air. Nature’s battery is sugar; the same sugar we enjoy in our coffees and which is a link in the food chain.
How does it happen? Energy comes from the sun; the light flux is very impressive if you take into account the amount of energy that the sun generates. The topic of energy is very present in matters of discussion nowadays due to the depletion of fuel sources. If the energy that comes from the sun every hour of the day could be stored without loss, this energy would be enough for all of humankind’s use of energy for a whole year! The use of the sun’s energy is a great and complicated challenge, but the fact stated before makes it optimistic. Although Earth is poor in terms of energy in many ways, and every year humankind uses resources of coal that have been created during millions of years, there is still the option of using the sun as a source of energy. The main problem is that the path that will lead us to the use of the sun’s energy is long; moreover, we do not yet know how to use this energy in the most efficient way in terms of engineering and economy.
How do plants know the most efficient way to use the sun’s energy? A big amount of energy comes from the sun, and the plant needs to solve the problem of how to take advantage of this energy. Inside the cells of every leaf there is an organelle called Chloroplast. The Chloroplast is the one that receives the energy, and inside it the process of Photosynthesis takes place. The sun’s energy stimulates Electrons which make a chemical reaction that enables the storage of this type of energy. The plant stores this energy in a molecule called ATP which works as a coin of energy. However, these coins can be used for small purchases and for short periods of time only. To store energy for long periods of time, to build bigger things, the plant has to use what it is available to it constantly, and this is the air.
In air we can finds CO2, not in big quantities, less than a thousandth. The Carbon is the chemical basis for the plant to store energy for long periods, and to build with it many different things, so the plant must take the Carbon as little quantities as there are. There is a cycle which nature created, The Calvin Cycle, in which Carbon Dioxide enters, and through the use of energy it becomes sugar. With sugar as a point of departure, Nature knows how to make any kind of metabolic changes, like human’s metabolism. The metabolic change is the chemical process in which something, like Carbon from the air, changes into something else, like the body of a human being or a plant. Bacteria and plants are wizards in their capacity to do this, much more than humans. It is Nature’s great invention. In this subject is the greatest interaction between humankind and Planet Earth in many aspects. When looking at the usage of water, 70% of sweet water humankind uses is related to the watering of plants, which are connected to the Carbon taken from the Atmosphere, and it is used to produce sugar that turns into food and fuel. Although water is not the only resource humankind takes from The Earth. Let’s take a look at other resources from The Earth that humankind uses. These are not neighborhoods, shopping malls and highways, but in agriculture which is made of the process we have explained before. If we will be able to make this process more efficient, without cutting down any more forests, it will be of great help because the process itself is the reason why humankind uses the water and the soil. It affects the composition of the Atmosphere as well, which has a dramatic impact in terms of weather and global-warming. Humankind should be acquainted with this process and think about the way to make it more efficient. The real challenge is to get more out of the same resources humankind already has; finding the way to provide a good life standard for seven billiard people without using more of Nature’s resources since we have only one Planet Earth.
How do we approach the subject? In our research group at Weizmann Institute we are about fifteen researchers who come from different fields such as: physics, engineering, biology, biochemistry, chemistry, zoology, mathematics, and also from computer science. Each one of them is looking at the questions from different angles and perspectives. We try to approach the subject by mixing as many different knowledge domains as needed. The main question that we ask ourselves is: what is the most efficient way for us to take Carbon from the air? We want to learn from Nature how to take Carbon Dioxide from the air, and turn it into sugar. The first thing we had to ask ourselves was: how does Nature approach the process? We learned from watching molecular players that know how to work inside the cells and are able to turn one substance into another. When looking at bacteria or plants those same players are called ‘enzymes’. These enzymes know how to take a molecule and turn it into a different chemical substance; then another enzyme takes another type of substance to turn it into something else. Thanks to the fact that scientists have been studying biochemistry for more than a hundred years, we now know that there is a good infrastructure for the changes that might happen in each organism. The question that we are asking ourselves is: how can we take these enzymes that are found in large scales in so many organisms, and try to make a new connection between them that will help us cope with our challenge?
How big will the damage be if we do not change the way humankind uses Earth’s resources? This is the leading question. To answer this properly a group of experts with different perspectives is needed. The answer comprises knowledge of the cycles of The Earth, climate and more. It could be very bad even if we take into account that there were other periods in which the Carbon levels were as high as they are today or even higher. Although being on Earth was not always a pleasure, in many geological periods humankind would not have been able to live on Earth. Allegedly – Planet Earth will continue to revolve around the sun, and the bacteria in the lab will be fine, but us human beings will see a different world that the one we grew-up in and enjoy living in today. The question is: in which kind of world do we want to live in?