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The other energy crisis
Arthur Dahl's blog
Energy powers all systems from machines and cities to the planetary biosphere and all of life, including our own. Recent events have underlined how dependent we are on energy supplies and how vulnerable to price rises and shortfalls. And this is on top of the fossil fuel energy crisis due to the release of fossil carbon causing climate change. Yet there is little awareness of the other energy crisis that also threatens our future. Almost all our useful energy comes from the sun, whether directly received as solar radiation or through ancient solar energy stored in fossil organic matter.
Solar energy supports and powers planetary systems in two ways: one is the thermal heating that maintains the global environment within a temperature range suitable for life, that creates convection currents that power winds and weather, and that drives the water cycle of evaporation and precipitation. Today rising greenhouse gas concentrations threaten that thermal equilibrium, causing global heating and climate change. That energy crisis is well documented, even if our response is inadequate.
The other solar energy system is photosynthetic, where plant and microbial life use solar energy to build the carbon chains of organic compounds. These energy-rich materials flow through the extensive food chains that power all life, including our own. For hundreds of millions of years, the biosphere has evolved an ever-greater capacity to support life with increasingly complex ecosystems including forests, savannas, coral reefs, ocean plankton, and many other marvels of efficient energy capture. Only in a few remote and extreme places, such as hydrothermal vents in the deep ocean, are there communities of life that do not depend on solar energy. Before there were significant human impacts on the planet, much of the land was covered in lush vegetation, forests and prairies, supporting in turn abundant animal life. Many indigenous peoples learned to live in respectful balance with nature, drawing what they needed while preserving the richness that nature provided. The sea was similarly full of marine plants and phytoplankton at the base of rich food chains all the way up to abundant whales.
Today, our economic drive for endless growth by exploiting natural resources for profit without regard for the future is rapidly degrading the biosphere, its rich biodiversity, and the ecosystem services it provides, including all the energy to support life. The rapid destruction of tropical rainforests, the demise of coral reefs around the world, soil degradation and erosion, and the conversion of much of the land surface to human uses, with many other impacts, are destroying the photosynthetic capacity of the planet. I have not seen anyone calculate how close we may be to tipping points where the energy captured by plant life on the planet may no longer be sufficient to support the needs of all living things, including human society. We worry about food shortages and rising prices leading to famine, without looking beyond that to the biological capacity of the planet to feed us all, animals, microbes and humans alike. We need urgently to measure the rapid decline in ecosystem services like photosynthesis, and the speed with which we may be approaching an energy catastrophe even more fundamental than that precipitated by global heating and climate change.
Consider the difference in total productivity and standing stock of organic matter between a lush tropical rainforest and a field of soybeans plowed and left bare much of the year, producing feed for livestock with only a tiny fraction of the energy captured by a single crop arriving on your plate. Yet we only value the steak and not all that has been lost in the process of producing it.
Biodiversity conservation and restoration are certainly critical to preserve the fantastic diversity and efficiency with which evolution has endowed the planet, and the wonders of nature with all its beauties and benefits. Losing parts of these complex systems will trigger many other failures and cascading impacts. However, beyond this it is essential to maintain our continuing access to enough food energy and other organic matter to support our still-growing human population. This can only be done by protecting what still exists of the natural world and restoring much of what has been degraded, along with all the ecosystem services that nature has provided for millions of years. We need to rethink agriculture and fisheries to again become part of complex ecosystems with continuing high productivity and resilience. Only then can we ensure an adequate photosynthetic solar energy system to maintain the sustainability of the biosphere and its component ecosystems long into the future, and thus guarantee our own survival.
This issue, and the threat to global photosynthesis from geoengineering in space to reduce solar radiation at the surface and thus global heating was published in my letter to New Scientist on 4 February 2023.
Last updated 22 February 2023