The Human Planet: How We Created the Anthropocene by Simon L. Lewis

Author:Simon L. Lewis [Lewis, Simon L.]
Language: eng
Format: epub
ISBN: 9780241280881
Google: dLyMEAAAQBAJ
Amazon: 0241280885
Goodreads: 33877058
Publisher: PELICAN
Published: 2018-06-07T03:00:00+00:00

Figure 7.1 — Rising global energy consumption, 1830–2010, in exajoules. The prefix exa- means adding 18 zeros to the number shown. Current energy use is about 550 exajoules, which is the same as 550 quintillion joules, or put another way 550 billion trillion joules. One joule is approximately the energy required to lift a 100 gram object vertically to one metre above the Earth’s surface.7

Other aspects of the human component of the Earth system also grew fast after 1945. Increased food production led to more freshwater and fertilizer use, while mass-produced goods such as the motor vehicle rapidly increased, numbering about 1.3 billion by 2015, as seen in Figure 7.2. These changes then altered the rest of the Earth system, including the atmosphere, shown in Figure 7.3, the oceans, depicted in Figure 7.4, and the land surface and wider biosphere, indicated in Figure 7.5. Collectively they illustrate increasingly large changes to our home planet; an ever-larger human fingerprint on the Earth system.

One way that energy, industrialization and the ability to feed ever-more people all came together is the fixing of nitrogen from the atmosphere to manufacture crop fertilizers. In the early twentieth century the invention of the Haber–Bosch process allowed the conversion of nitrogen to ammonia. Its inventors, German chemists Fritz Haber and Carl Bosch, developed the process by reacting atmospheric nitrogen with hydrogen under high temperatures and pressures with a metal catalyst. Initially, they wanted to create powerful explosives. Indeed, without the Haber–Bosch process the twentieth century would have been a lot less bloody. This process also had a second use, manufacturing nitrogen fertilizer.

Globally, the atmospheric nitrogen fixed for use as fertilizer is now 115 million tonnes per year, mostly in the form of anhydrous ammonia, ammonium nitrate and urea. In combination with high-yield crop varieties and pesticides, these fertilizers have quadrupled the productivity of agricultural land over the last century, allowing billions of additional people to live. To produce the same amount of food as is grown on croplands today, but without chemical fertilizers, would probably require three times the area. It is difficult to see how 7.5 billion people would be fed without them, given the unsuitability of much of the land that is not already planted with crops.

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