Conversations on Climate: How geoengineering has been used in the past

PlanetIn The Planet Remade, Oliver Morton argues that geoengineering, the process by which Earth’s systems are manipulated, can be used in a positive way to address the problems caused by man-made climate change. Geoengineering is nothing new. Chapter 7 of The Planet Remade describes how it was used in the twentieth century to feed a growing population. A summary:

At the end of the nineteenth century it became apparent that the yield of wheat would soon fall short of the demand. Sir William Crookes, one of the leading chemists of the time, gave a speech in 1898 on the subject. The number of people who wanted to eat wheat was increasing, but by that point there was no more land on which to grow it. The solution? Increasing the amount of nitrogen in the soil to increase the amount of wheat that a given parcel of land could yield. If this wasn’t done, Crookes warned, the world would face starvation.

Nitrogen was fixed on as the key to a solution because it is a necessary component of photosynthesis. It exists in the air we breathe in the inert form of two identical atoms attached to one another. In order to aid in sustaining life, it must be detached and fixed to some other element. This happens when bacteria in plants twist nitrogen molecules and insert hydrogen molecules into the resulting spaces, turning the nitrogen into ammonia. Later, the nitrogen is returned to its inert form. The process by which nitrogen is fixed and then unfixed makes up the nitrogen cycle. As this process has proceeded uninterrupted by humans for billions of years, it has been one component in supporting increasingly more complex life forms on Earth.

Crookes was hopeful that the problem could be solved. He called on scientists to figure out a way to fix nitrogen industrially. Fritz Haber, a professor at the University of Freiburg, rose to the challenge. He and his laboratory technicians created a process by which fixed nitrogen was created by passing a continuous stream of nitrogen and hydrogen over a hot catalyst at very high pressure. His colleague Carl Bosch scaled the process up so that it could be used on an industrial scale. The process was quickly adopted globally to produce more food. By the end of the 1960s, the amount of nitrogen fixed by the Haber-Bosch process exceeded that fixed by all the microbes in the world’s soil. Both men won the Nobel Prize for their efforts. Their discoveries have had profound implications beyond the world of agriculture.

The problem identified by Crookes had been solved, but at a cost. One cost can be seen in the Gulf of Mexico every summer. Between the 1960s and 1990s, the flow of nitrogen out of America’s heartland, through the Mississippi and into the Gulf has doubled. This abundant supply of nitrogen makes ideal food for photosynthetic algae to flourish, resulting in colossal algal blooms. As they decompose, they consume all the oxygen in the water, leaving none to support other life forms. As a result, large swaths of the Gulf of Mexico become dead zones every summer.

Does this episode in history prove that humans can’t be trusted with geoengineering? Or can it be used more responsibly in the future to address the challenge of climate change? To answer that question, check out The Planet Remade here.

Toby Tyrrell, author of On Gaia, explains how he came to question the Gaia Hypothesis

We interviewed Toby Tyrrell about his new book “On Gaia” last week. This week, we’re proud to link to this article in which he details some of the research that led him to view the Gaia Hypothesis with a critical eye:

Nitrogen is exceptionally abundant in the environment, it makes up 78 per cent of air, as dinitrogen (N2). N2 is also much more plentiful in seawater than other dissolved forms of nitrogen. The problem is that only organisms possessing the enzyme nitrogenase (organisms known as nitrogen-fixers) can actually use N2, and there aren’t very many of them. This is obviously a less than ideal arrangement for most living things. It is also unnecessary. Nitrogen starvation wouldn’t happen if just a small fraction of the nitrogen locked up in N2 was available in other forms that can be used by all organisms; yet biological processes taking place in the sea keep nearly all that nitrogen as N2. If you think about what is best for life on Earth and what that life can theoretically accomplish, nitrogen starvation is wholly preventable.

This realisation led me to wonder what other aspects of the Earth environment might be less than perfect for life. What about temperature? We know that ice forming inside cells causes them to burst and that icy landscapes, although exquisite to the eye, are relatively devoid of life. We can also see that ice ages – the predominant climate state of the last few million years – are rather unfortunate for life as a whole. Much more land was covered by ice sheets, permafrost and tundra, all biologically impoverished habitats, during the ice ages, while the area of productive shelf seas was only about a quarter of what it is today. Global surveys of fossil pollen, leaves and other plant remains clearly show that vegetation and soil carbon more than doubled when the last ice age came to an end, primarily due to a great increase in the area covered by forests.

Although the cycle of ice ages and interglacials is beyond life’s control, the average temperature of our planet – and hence the coldness of the ice ages – is primarily determined by the amount of CO2 in the atmosphere. As this is potentially under biological control it looks like another example of a less than perfect outcome of the interactions between life on Earth and its environment.

Look further and you find still more examples. The scarcity of light at ground level in rainforests inhibits growth of all but the most shade-tolerant plants. There’s only really enough light for most plants at canopy height, often 20 to 40 metres up, or below temporary gaps in the canopy. The intensity of direct sunlight does not increase the higher you go, so having the bulk of photosynthesis taking place at such heights brings no great advantage to the forest as a whole. Rather the contrary, trees are forced to invest large amounts of resources in building tall enough trunks to have the chance of a place in the sun. This arrangement is hard to understand if you expect the environment to be arranged for biological convenience, but is easily understood as an outcome of plants competing for resources.

Source: “Not Quite Perfect”, Planet Earth Online:


Read a sample chapter from On Gaia: A Critical Investigation of the Relationship between Life and Earth [PDF].