The transition to a world with zero CO2 balance is surely the biggest challenge humanity has ever faced. It requires a complete transformation of the way we produce, consume and get around, replacing the polluting energy from coal, gas and oil with energy from renewable sources.


We owe the concept of man’s interconnection with nature to Francis of Assisi

Francis of Assisi, one of the most recognized saints of Christianity, left us an important teaching in the 11th century: the concept of the interconnection of humankind with the natural world. Humanity has never assumed that idea, however, and has treated nature from a purely utilitarian point of view.

To cite two examples, deforestation to create arable land and provide construction wood and firewood, and mining and smelting operations with all kinds of toxic discharges to the environment have been common throughout history. The Industrial Revolution was initially based on the exploitation of coal and iron, but the next stages of this revolution were incorporating new energy sources, mainly oil and gas, and new minerals, with the development of a powerful chemical industry. The breakdown of harmony between humans and nature became more evident in the form of air, water, and soil pollution. The damage became more and more visible, with the creation of unbreathable atmospheres in the most industrialized cities, fish dying in the rivers, the acid rain that destroys the landscape, and so many other issues. And, although there have always been voices raised against this environmental deterioration, they have been systematically silenced by the interests involved. In fact, prior to the 1960s, there were no significant environmental regulations.

Rachel Carson, the woman who moved public opinion

In the 1950s, large numbers of dead birds were observed in numerous places, something for which no one had an answer. In 1961, marine biologist Rachel Carson solved the question, which she detailed in her book Silent Spring. In it, she unequivocally identified the bird killers: potent synthetic insecticides, such as DDT, which were poisoning food chains, from insects upwards. The clear message of the book was that everything in Nature is related to everything else. She rediscovered and disseminated the thinking of Francis of Assisi, although she reached her conclusion through scientific reasoning, while Francis did so under the consideration that everything on Earth is the work of God.

The impact of Silent Spring, which sold two million copies,[1] was incredible. President John F. Kennedy ordered an investigation into the use of pesticides, which concluded the need for residues of these products to be tracked and monitored in the air, water, soil, fish, wildlife, and humans, with the goal of eliminating the use of persistent toxic pesticides.[2]

Carson, without doubt, has the merit of having awakened popular ecological awareness in the United States and Europe. Her biographer Linda Lear wrote that “[h]er courage in sounding the alarm and her ecological vision of the oneness of all life indelibly shaped the contemporary environmental movement.”[3] Friends of the Earth and Greenpeace originate directly from Silent Spring.

In the 1960s and ‘70s, the environmental movement focused its attention on pollution in all its forms, and successfully lobbied different governments to pass measures aimed at promoting cleaner air and water and the disposal of toxic waste. Nature was gaining a place in the normative order of modern societies.

The mechanism that allows the Earth to enjoy a temperature suitable for life

The greenhouse effect – a natural process that warms the Earth – is necessary to sustain life on the planet. It is produced when certain gases in our atmosphere trap the heat emitted by the Earth and act as the planet’s own greenhouse. These gases, including carbon dioxide (CO2), methane and nitrous oxide, are required to keep the Earth’s surface temperature warm. If the Earth had no atmosphere and this mechanism was not present, the surface temperature of our planet would be -18°C, but thanks to the effect of these gases, it is +15°C. For thousands of years, nature had regulated the concentration of these gases well.

This effect has been known since it was discovered in the 19th century by French mathematician Joseph Fourier, although the influence of man’s action in altering that effect would not be verified until much later, since this required measurements of the composition and temperature of the atmosphere for long periods. This is what paleoclimatic scientists have achieved in the last 20 years. According to the latest techniques,[4] the composition of the atmosphere can be determined by precise measurements of the air bubbles trapped in the ice of glaciers, which extends to the last 800,000 years. In order to delve further into the CO2 content in the past, we need to use indirect methods. Thus, for example, the changing CO2 values affect the pH of the ocean, and this has various effects on plankton fossils; accordingly, the study of these fossils allows us to reproduce the CO2 content in the atmosphere going back tens of millions of years.

Similarly, we have to use indirect methods to determine the temperature, as records of thermometric measurements have only been available for 160 years. The slight differences in the weight of the oxygen isotopes present in the water make them behave differently in processes such as evaporation and condensation. The lighter isotope (16O) evaporates more easily than the heavier isotope (18O) in the oceans. Therefore, the amount of the lighter isotope (16O) in rain is higher, which is why glacial ice also contains a higher concentration of 16O. Because of this, the highest concentration of the heavier isotope (18O) remains in ocean water. As the ice in the polar ice caps and glaciers accumulates light isotopes (16O) and the ocean becomes rich in heavy isotopes (18O) during glaciations, seafloor sediments allow us to know when there has been more or less ice on the planet.

Thanks to these indirect measurements, we know the Earth’s climate going back millions of years and we have ascertained that, in its 4.5 billion years of history, planet Earth has experienced periods of greater and lesser heat. However, these have always been slow changes in temperature in cycles of the order of 100,000 years caused by variations in the Earth’s orbit around the Sun.

Global warming is discovered

The use of fossil fuels, coal, oil, and natural gas has done nothing but increase exponentially since the first industrial revolution. It is estimated that in this time, we have discharged 1.5 trillion tons of CO2 into the atmosphere, increasing the proportion of this greenhouse gas in it by 50%. And this has had consequences.

In 1967, an accurate computer model of Earth’s changing climate was developed for the first time, corroborating that doubling CO2 concentrations could increase the global temperature by 2°C. Syukuro Manabe was awarded the Nobel Prize in Physics 2021 for this work. Measurements from the pre-Industrial Revolution to the present day fit this prediction perfectly: CO2 has risen by about 50% and temperatures have risen by 1.1°C.[5] It represents a brutal change compared to the stability observed over thousands of years.

In 1988, the scientific confirmation of warming became official in the United States Congress. This was how it was reported by the New York Times: “Until now, scientists have been cautious about attributing rising global temperatures of recent years to the predicted global warming caused by pollutants in the atmosphere, known as the ‘greenhouse effect’. But today, Dr. James E. Hansen of the National Aeronautics and Space Administration told a congressional committee that it was 99 percent certain that the warming trend was not a natural variation but was caused by a buildup of carbon dioxide and other artificial gases in the atmosphere.”[6]

The relationship between extreme weather events and climate change was demonstrated in 2004 in a paper published in the journal Nature,[7] authored by several professors from the University of Oxford and the UK Meteorological Office, in which they demonstrated that climate change had doubled the risk of the 2003 European heat wave that killed tens of thousands of people. Today, scientists are able to calculate the impact of global warming on droughts, heat waves, and floods with remarkable accuracy.

Climate-related disasters accounted for about 90% of the more than 7,000 major disasters that occurred between 1998 and 2017, most of them floods and storms. Economic losses amounted to nearly $2.3 billion, according to a report by the United Nations Office. The Earth’s climate system is complex and chaotic, so the effects of the changes are different in different places. An estimated 3.5 billion people live in areas that are highly vulnerable to climate change.

The Paris Agreement: a good agreement that simply limits the problem

Countries have been debating how to combat climate change since the early 1990s. They agree on the scientific basis of the phenomenon posed by the threat and, therefore, on the possible solution. Notwithstanding, the transition to a world with zero CO2 balance is surely the biggest challenge humanity has ever faced. It requires a complete transformation of the way we produce, consume and get around, replacing the polluting energy from coal, gas and oil with energy from renewable sources.

Reaching agreements has proved difficult, because there has been disagreement over who is most responsible, how to track emission reduction targets and whether the countries most affected should be compensated. Finally, however, in 2015, the Paris Agreement was signed by 196 countries. It legally requires countries to reduce their carbon emissions to limit global warming to 1.5°C compared to pre-industrial levels. Emissions must be reduced by 45% by 2030 and reach zero by 2050.

As the then-UN Secretary-General Ban Ki-moon said, “[t]he Paris Agreement provides a viable blueprint to mitigate the serious threats to our planet. It sets clear targets to restrict rising temperatures, limit greenhouse gas emissions, and facilitate climate-resilient development and green growth.”[8] The agreement puts a limit on the problems that we will have to experience, although for a long period we will endure harms caused by climate change.

There is no doubt that, apart from ethical reasons, economic considerations have helped to achieve such a comprehensive agreement. Researchers at the Potsdam Institute for Climate Impact Research concluded that the politically motivated Paris Agreement also represents the economically favorable pathway.[9]

Finally, great news

Very recently, changes are being considered in the way we see the problem of global warming; these have to do fundamentally with the cost of green energies, which are being dramatically reduced.

This paradigm shift is reflected very well in the rapid change of opinion of David Wallace-Wells, a journalist specializing in climate issues. Just four years ago, he wrote a book, a bestseller entitled The Uninhabitable Earth, in which he presented some of the worst-case scenarios of what life on Earth might be like as a result of global warming. Just three years later, however, after a process of dialogue with numerous scientists and economists in the sector, he published an article entitled “Beyond catastrophe: A new climate reality is coming into view” in The New York Times Magazine, in which he refers to this new way of seeing the processes around climate change.[10]

We have been debating how costly the energy transition is for so many years that we have barely noticed the rapid decline in prices that has already occurred. Since 2010, the cost of solar power and lithium battery technology has been reduced by 88% and the cost of wind power by 70%.[11] Furthermore, over that same period of time, fossil fuels have not come down in price at all, meaning that many renewables are now much cheaper than their unclean alternatives.

Some are talking about surprising drops in the cost of renewable energy, although it should be said that scientists and economists have long predicted these reductions. In 1936, an aeronautical engineer, Theodore Wright, while studying the costs of aircraft manufacturing, observed what we call the learning curve in new technologies, and formulated the law that bears his name (Wright’s law): that the cost of each unit produced decreases as a function of the cumulative number of units produced. Analysis of the experience curve has already provided accurate forecasts in renewable technologies. In 2011, researchers at MINES ParisTech predicted a 67% drop in the price of solar modules by 2020,[12] which has been far exceeded. In a recent study, researchers at the University of Oxford[13] developed an approach based on probabilistic methods of cost forecasting, which have been statistically validated by retrospective tests of more than 50 technologies. Using this, they have generated cost forecasts for solar energy, wind energy, batteries and electrolyzers, with a time frame of up to 20 years. And the results suggest that a rapid transition to green energy is beneficial, even if climate change were not an issue. When climate change is taken into account, i.e. the effects avoided by preventing warming, the benefits of rapid transition become staggering.

“There is a pervasive misconception that switching to clean, green energy will be painful, costly and mean sacrifices for us all – but that’s just wrong,” says Professor Doyne Farmer, co-author of the cited paper. “Renewable costs have been trending down for decades. They are already cheaper than fossil fuels in many situations, and our research shows that they will become cheaper than fossil fuels across almost all applications in the years to come. And if we accelerate the transition, they will become cheaper faster. Completely replacing fossil fuels with clean energy by around 2050 will save us trillions.”[14]

The certainty provided by the new studies on renewable energy price forecasts opens the door to optimism, an optimism that is already present in official bodies, as indicated by these words of Fabio Panetta, member of the Executive Board of the European Central Bank: “The green transition is often presented as a threat to fundamental aspects of our daily lives, including growth opportunities or purchasing power. This negative narrative is unjustified. The divine coincidence is not a pipe dream: greener can mean cheaper.”[15]

The divine coincidence of which Fabio Panetta speaks has shaken off perhaps the greatest environmental concern that has so far assailed mankind, but we must not forget the teachings of Francis of Assisi: the interconnection of the human being with the natural world manifests itself in all our activities, forcing us to maintain ecological balance as a means of survival.

Manuel Ribes

Bioethics Observatory – Institute of Life Sciences

Catholic University of Valencia


[1] Eliza Griswold How ‘Silent Spring’ Ignited the Environmental Movement  The New York Times Magazine  Sept. 21, 2012

[2] Manu Mediavilla  Rachel Carson, pionera y referente en la lucha contra el cambio climático Amnistía internacional  2022

[3] Robin McKie Rachel Carson and the legacy of Silent Spring The Observer 27 May 2012

[4] Caitlin Keating-Bitonti & Lucy Chang  Here’s How Scientists Reconstruct Earth’s Past Climates    Smithsonian Magazine  23 March 2018

[5] UKRI (UK Research and Innovation) Corporate report  A brief history of climate change discoveries 21 October 2021

[6] Philip Shabecoff Global Warming Has Begun, Expert Tells Senate Special To the New York Times, 24 June 1988

[7] Stott, P., Stone, D. & Allen, M. Human contribution to the European heatwave of 2003 Nature 432, 610–614 (2004)

[8]  The Explainer: The Paris Agreement | UNFCCC (United Nations Framework Convention on Climate Change) 26 February 2021

[9] Nicole Glanemann, SvenN.Willner & Anders Levermann Paris Climate Agreement passes the cost-benefit test | Nature Communications 27 January 2020

[10] Dave Davies A new climate reality is taking shape as renewables become widespread : NPR 10 November 2022

[11] Data taken from “Our World in Data.Org ” and “Borates Today”

[12] Arnaud de La Tour, Matthieu Glachant & Yann Ménière Predicting the costs of photovoltaic solar modules in 2020 using experience curve models – ScienceDirect  10 October 2013

[13]  J.Doyne Farmer et al. Empirically grounded technology forecasts and the energy transition – ScienceDirect 13 September 2022

[14] Decarbonising the energy system by 2050 could save trillions – Renewable Carbon News 22 September 2022

[15] Fabio Panetta Greener and cheaper: could the transition away from fossil fuels generate a divine coincidence? Rome, 16 November 2022


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