Plants should be considered the link between the sun and the Earth. Without plants, the sun’s energy would not be transformed into the chemical energy that sustains life. But that’s not all. Every living being needs to obtain the energy required for survival from some source.
The energy present on planet Earth comes from three main sources: the sun, the primordial heat from the Earth’s formation, and the heat generated by the radioactive decay of certain materials in the Earth’s crust and core. For practical purposes, we can disregard the contributions from geothermal energy and focus on solar energy, the true life-sustaining source on Earth.
Even the energy we obtain from burning coal or oil is merely solar energy originally captured by plants (broadly defined to include all photosynthetic organisms). Likewise, the energy that drives the wind, ocean currents, or waves also originates from solar energy. In short, we can approximate that, with negligible exceptions, all the energy on the planet comes from the sun.
Having simplified the issue to its fundamental terms, we can return to plants and the central role they play in ensuring the survival of species. Through photosynthesis, and with the help of solar energy, plants capture atmospheric carbon dioxide, forming sugars—highly energetic molecules—while producing oxygen as a byproduct.
The average amount of energy produced by photosynthesis on a planetary scale is about 130 terawatts, approximately six times greater than the current energy consumption of human civilization. As Primo Levi writes about the carbon cycle in The Periodic Table, “if the organic conversion of carbon did not take place daily around us, on the scale of billions of tons per week, wherever the green of a leaf appears, it would fully deserve the name of miracle.”
Thanks to this miraculous process, life has been able to spread and thrive. Photosynthesis is essentially the sole driver of the entire production of organic matter through biochemical means, the so-called primary production.
Once produced by plants, this chemical energy—whether we think of it as food, coal, or oil—is used as fuel by the rest of the animal kingdom to sustain survival. Humans, however, use it excessively, relying on it as the primary source of energy for their development. When this fuel burns, it inevitably produces byproducts that disrupt the environment’s balance and cause pollution. CO2, for instance, is emitted whenever combustion occurs—whether it’s the burning of sugars and fats to power our bodies or the burning of oil, gas, coal, wood, or any other fuel originally produced through photosynthesis.
Human activities emit approximately 29 billion tons of CO2 annually. By comparison, volcanoes release 100 times less—only 200 to 300 million tons. The CO2 that accumulates in the atmosphere is the primary driver of the greenhouse effect and the resulting increase in global temperatures. Through activities like fossil fuel combustion and deforestation, humans have raised the average annual atmospheric CO2 concentration from 280 ppm (parts per million), where it had remained stable for around 10,000 years before the Industrial Revolution, to 421 ppm as of 2022.
The last time Earth experienced such high atmospheric CO2 concentrations was during the Pliocene epoch, around three million years ago. At that time, the planet’s average temperature was 4°C higher, large parts of the Antarctic continent were covered by forests, and sea levels were 20 to 25 meters higher than today due to melting ice.
Of course, the carbon cycle is far more complex than outlined here and involves numerous variables tied to life on Earth. For instance, not all CO2 emitted by human activities ends up in the atmosphere; about 30% dissolves into the oceans, forming carbonic acid, bicarbonate, and carbonate. While this oceanic absorption is vital because it prevents even more CO2 from entering the atmosphere, it also causes ocean acidification. This phenomenon is responsible for the destruction of coral reefs and profoundly affects the lives of calcifying organisms such as coccolithophores, corals, echinoderms, foraminifera, crustaceans, and mollusks, ultimately impacting the entire food chain.
In essence, the core issue is that, until recently, the carbon cycle functioned effectively. CO2 was released into the atmosphere through processes like combustion, digestion, and fermentation, and then reabsorbed by plants via photosynthesis—a balanced cycle capable of handling significant fluctuations in carbon dioxide levels without disrupting equilibrium. For millions of years, this system worked like clockwork. However, with the advent of the Industrial Revolution, the sheer volume of CO2 released into the atmosphere through fossil fuel use has become so immense that plants can no longer fully reabsorb it.
Today, everyone is called to reduce their carbon dioxide emissions as much as possible. This is not something we can delay: from individuals to businesses to nations, the time to act is now. Solutions exist and are effective. If adopted by significant portions of the global population, they could ensure a sustainable future. Many of these solutions are brought together in the concept of an Energy Park.
What I find most fascinating about this idea is that, whether through solar panels powered by human technology or through plants developed by evolution, the ultimate goal is the same: transforming the sun’s light energy into a form usable by humans. Whether the end result is the sugars in plants or electricity from solar panels, designing a park where humanity collaborates—for once—with nature to minimize its planetary impact is heartwarming and instills hope for a better future.
