Eating the Sun: How Plants Power the Planet

Transitway station, Ottawa

Oliver Morton’s exploration of the nature and consequences of photosynthesis makes for a remarkable and informative book. It is divided into three sections: one covering the span of a human life and covering the scientific investigation of photosynthesis; one on a planetary timescale, describing the evolution of the climate, atmosphere, and life; and one on the timescale of a tree’s life, covering the changes humanity has induced in the carbon cycle, and the ways through which the climate change crisis can be overcome. The book is strongest when it comes to putting scientific information into a poignant and comprehensible form that is almost poetic. Arguably, it is weakest in terms of its analysis of what needs to be done in response to climate change.

Eating the Sun contains many sections that are highly technical: descriptions of the biochemistry of photosynthesis, the geological and climatological processes that have taken place over billions of years, the scientific methods through which both have been explored, and more. It can also be quirky, philosophical, and personal. For instance, there are asides in which the author explains his aesthetic preference for one or another scientific theory, such as how photosystems I and II in plants came to be integrated. The combination is not unlike that found in Michael Pollan’s work, where an educated non-expert with a talent for writing adopts the task of explaining technical issues and making their significance clearly felt.

The book features a great deal of discussion of the Earth as an integrated chemical and energy system, including consideration for many different forms of ‘Gaia hypotheses’ – most of them far less teleological than James Lovelock’s earliest work, which (probably wrongly) attributed a kind of agency to the planet as a whole. Of particular interest, among the non-telelogical variants, is combination of the anthropic principle with the idea of systems that self-regulate. It may well be that there are planets where physical and chemical processes do not remain constrained between life-compatible bounds over the long term. Of course, there are no living and intelligent observers on these planets to make note of them.

On climate change, Morton fails to appreciate the rapidity with which mitigation must occur. He contemplates what would be necessary to stabilize greenhouse gas emissions by 2050, whereas we will actually need to make great strides towards stabilizing concentrations by then. Rather than the seven Pacala-Socolow wedges required to produce a flat emissions profile, many more will be needed to begin the decline towards zero net emissions. His calm descriptions of global concentrations of carbon dioxide passing 500 parts per million (ppm), with associated temperature increases of up to four degrees Celsius, fails to portray what a catastrophic outcome this would be. These days, those committed to avoiding change of more than two degrees are advocating concentration targets around 350 ppm.

Morton’s discussion of mitigation technologies also offers scope for criticism; in particular, his discussion of nuclear fusion, fission, and hydrogen fuel cells is fairly superficial and fails to take into consideration some of the major limitations associated with each technology. In particular, he fails to consider the practical and economic issues associated with hydrogen as a fuel. That being said, he strongly makes the point that, in the long run, it will be necessary to move from an economy powered by the built-up solar reserves in fossil fuels to one largely powered by the current energy available in sunlight: whether that energy is directed towards the production of electricity, biomass, or fuels.

At times, the level of detail in Eating the Sun can be overwhelming. In particular, I found that some of the passages about biosphere-atmosphere interaction or long-term geological trends required close and repeated reading to be understood. For the non-practitioners at whom this book is aimed, such knowledge is not likely to be long-lasting. At the same time, by providing such clear and vivid detail, Morton grants a worthwhile understanding of the history and nature of the scientific processes through which we have uncovered so much about the world. As with the very best scientific writing, this book makes you feel both awed about the complexity and power of the world and impressed with the ingenuity that has gone into better understanding it. The book is highly recommended to anyone with an interest in the history of the planet, the nature of the carbon cycle, or science generally.

Author: Milan

In the spring of 2005, I graduated from the University of British Columbia with a degree in International Relations and a general focus in the area of environmental politics. In the fall of 2005, I began reading for an M.Phil in IR at Wadham College, Oxford. Outside school, I am very interested in photography, writing, and the outdoors. I am writing this blog to keep in touch with friends and family around the world, provide a more personal view of graduate student life in Oxford, and pass on some lessons I've learned here.

18 thoughts on “Eating the Sun: How Plants Power the Planet

  1. On climate change, Morton fails to appreciate the rapidity with which mitigation must occur. He contemplates what would be necessary to stabilize greenhouse gas emissions by 2050, whereas we will actually need to make great strides towards stabilizing concentrations by then.

    For instance, in his latest book, Andrew Weaver spells out a global emissions scenario with a 66% chance of avoiding warming of more than two degrees. It is based on a climate sensitivity of 4.5 degrees.

    In this scenario, humanity emits a total of 484 billion tonnes of carbon between 2007 and the point when carbon neutrality is reached. Total global emissions rise from the current level of about seven billion tonnes per year until it peaks in 2020 at 8.8 billion tonnes.

    By 2050, it has declined somewhat below current levels and by 2100 it has reached zero.

    Emissions in North America, Australia, and Western Europe start declining immediately. Those in Africa peak around 2040, though at a level far, far lower than North American emissions today.

    Note that if James Hansen is right, and climate sensitivity is significantly higher than 4.5 degrees, a much more aggressive pathway is required to make a change of more than two degrees unlikely.

  2. Is Quantum Mechanics Controlling Your Thoughts?

    Science’s weirdest realm may be responsible for photosynthesis, our sense of smell, and even consciousness itself.
    by Mark Anderson

    From the February 2009 issue, published online January 13, 2009

    Peering deep into these proteins, Fleming and his colleagues at the University of California at Berkeley and at Washington University in St. Louis have discovered the driving engine of a key step in photosynthesis, the process by which plants and some microorganisms convert water, carbon dioxide, and sunlight into oxygen and carbohydrates. More efficient by far in its ability to convert energy than any operation devised by man, this cascade helps drive almost all life on earth. Remarkably, photosynthesis appears to derive its ferocious efficiency not from the familiar physical laws that govern the visible world but from the seemingly exotic rules of quantum mechanics, the physics of the subatomic world. Somehow, in every green plant or photosynthetic bacterium, the two disparate realms of physics not only meet but mesh harmoniously. Welcome to the strange new world of quantum biology.

  3. In Heat, George Monbiot argues that emissions must be reduced from about seven gigatonnes, at present, to 2.7 gigatonnes in 2030.

    In his scheme, rich countries need to undertake the biggest reductions by 2030: an 87% cut for the UK, 88% for Germany, 83% for France, and 94% cuts for the United States, Canada, and Australia.

  4. Nature 446, 782-786 (12 April 2007) | doi:10.1038/nature05678; Received 13 October 2006; Accepted 14 February 2007

    Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems

    Photosynthetic complexes are exquisitely tuned to capture solar light efficiently, and then transmit the excitation energy to reaction centres, where long term energy storage is initiated. The energy transfer mechanism is often described by semiclassical models that invoke ‘hopping’ of excited-state populations along discrete energy levels.

  5. Solar cells that imitate plants

    By David Pescovitz on High Energy

    Every year, approximately 2.5 million exajoules of solar energy reach the Earth. That’s about 5,000 times the amount of energy consumed by people each year. The trick is collecting it and converting it into electricity cheaply and efficiently. Plants do a good job of that. Turns out scientists have been working on ways to imitate nature’s photosynthesis since 1912. And they’re still at it. This week, the scientific journal Chemical & Engineering News posted two deep articles on the subject. The first is about the molecular mysteries of photosynthesis, including whether it’s as efficient as one would expect from a process that has more than a couple billion years of evolution behind it. From the article, “Harnessing Light”:

    “Water-splitting is key to the renewable production of hydrogen gas and other energy fuels, and doing so with inexpensive catalysts, as plants do a billion times per day, would be a huge step forward for solar power research. But the photosynthetic process has some other secrets, too, that scientists are only just figuring out, such as how photosynthetic organisms can tame light without suffering too much radiation damage, the plant equivalent of a sunburn…”

  6. NASA satellite detects red glow to map global ocean plant health

    Published: Thursday, May 28, 2009 – 16:24 in Earth & Climate

    Researchers have conducted the first global analysis of the health and productivity of ocean plants, as revealed by a unique signal detected by a NASA satellite. Ocean scientists can now remotely measure the amount of fluorescent red light emitted by ocean phytoplankton and assess how efficiently the microscopic plants are turning sunlight and nutrients into food through photosynthesis. They can also study how changes in the global environment alter these processes, which are at the center of the ocean food web. Single-celled phytoplankton fuel nearly all ocean ecosystems, serving as the most basic food source for marine animals from zooplankton to fish to shellfish. In fact, phytoplankton account for half of all photosynthetic activity on Earth. The health of these marine plants affects commercial fisheries, the amount of carbon dioxide the ocean can absorb, and how the ocean responds to climate change.

  7. June 23, 2009, 10:00 pm
    Guest Column: Building a Better Biosphere?
    By Oliver Morton

    After looking at the relationship between atmospheres and life a few dozen light years away, a billion years or so in the future and three billion years or more in the past, it’s time to look at the one in your lungs at the moment. Given that humans are changing the atmosphere at an unprecedented rate, what responses should we expect from the biosphere? And is there anything that we can do to make those responses work to human benefit?

    For those in a hurry, the answers in brief: a) complicated ones; b) yes, at least a bit.

    Human influence on the atmosphere takes many forms, but the most dramatic is the recent build-up of carbon dioxide, produced mostly by burning fossil fuels. Before the Industrial Revolution, the carbon dioxide level in the atmosphere was about 280 parts per million. Today, it is about 387 parts per million. Action to limit emissions might see the eventual level even off at 450 p.p.m., a target popular with greens and like-minded politicians – but only if such action were far more dramatic than any seen so far. While stressing that they would like to see such a plateau, or ideally, a lower one, few climate scientists see a stable 450 p.p.m. world as very likely. A world in which the pre-industrial level is doubled is a more likely one – and higher levels are far from out of the question.

  8. “Every two hundred years, every atom of carbon that is not congealed in materials by now stable (such as, precisely, limestone, or coal, or diamond, or certain plastics) enters and reenters the cycle of life, through the narrow door of photosynthesis.”

    Levi, Primo. The Periodic Table p. 231 (paperback)

  9. Ancient seaweed is living fossil
    By Matt Walker
    Editor, Earth News

    Ancient seaweed that have been found growing in the deep sea are “living fossils”, researchers have reported.

    The two types of seaweed, which grow more than 200m underwater, represent previously unrecognised ancient forms of algae, say the scientists.

    As such, the algae could belong to the earliest of all known green plants, diverging up to one billion years ago from the ancestor of all such plants.

    Details of the discovery are published in the Journal of Phycology.

    “The algae occur in relatively deep marine waters – 210m, which is certainly deep for a photosynthetic organism,” Professor Frederick Zechman told the BBC.

    “They can be found in shallower water but typically under ledges in low light.

  10. Azolla hardly looks like a typical fern and, as an aquatic rather than a terrestrial plant, does not behave much like one either. But it is probably the most economically important fern on the planet—and it may also once have been responsible for changing the climate.

    Azolla’s significance comes from its partnership with several species of bacteria that can manage a trick no plant finds possible by itself: extracting nitrogen from the air and “fixing” it into chemicals such as ammonia, so that it is available to make proteins. Asian rice farmers have known of Azolla’s fertilising properties for at least 1,500 years, and in many places the fern is encouraged to grow alongside rice in paddies—a sort of aquatic version of alfalfa. Dr Pryer’s primary pitch, therefore, is that understanding the genomes of Azolla and its associated bacteria (which she proposes to sequence at the same time) might assist the improvement of this process, and maybe aid its transfer to other plants.

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