What does it mean to be influential? What does a person have to do to leave a lasting legacy? There have been many exceptional people throughout history that have carved their spot in humanity’s memory — from cunning politicians like Julius Caesar to brilliant scientists like Albert Einstein or Isaac Newton. However, every once in a while, there comes a person so remarkable that their influence and legacy carry on long after their name is uttered for the last time.

One such person happened to be a scientist in the early twentieth century: Thomas Midgley Jr. His story is a cautionary tale, but also a story of hope. It is a story that showcases that humans are capable of coming together to solve problems and prevent a large disaster. Perhaps we could take a lesson or two from those who came before us to apply to the challenges of the climate crisis facing us today.

The invention of the climate crisis

At the turn of the twentieth century, as the Industrial Revolution continued to spread over the world, its negative environmental effects began to show. A lot of them were caused by the carbon emissions from factories as more and more of our everyday products were being mass produced. A lot of it also came from cars, which would become ubiquitous in urban areas. One thing that many people didn’t realize, however, was that the products they were using — and not just the production of those products — were contributing to large emissions of greenhouse gases.

One man, however, has had more impact on the environment than any other single organism in Earth’s history: Thomas Midgley Jr., a chemical engineer and inventor in the early twentieth century. His inventions went on to become one of the primary causes of the depletion of the ozone layer of the Earth’s atmosphere.

Midgley was a highly celebrated mechanical and chemical engineer in the 1920s and 1930s. He is best known for introducing a compound called tetraethyl lead (TEL) as an additive for gasoline to prevent engine knocking in cars — the premature ignition of fuel outside of an engine’s regular cycle. Leaded gasoline was considered a huge breakthrough, and in 1922, the American Chemical Society awarded Midgley the William H. Nichols Medal for it.

Another one of Midgley’s big contributions was synthesizing one of the first chlorofluorocarbons (CFCs), a series of molecules that are composed only of carbon, chlorine, and fluorine, in various combinations. CFCs were created as safer alternatives to the toxic compounds that were being used at the time as refrigerants in air conditioners and refrigerators. For his creations, Midgley was awarded the 1937 Perkin medal by the American Chemical Society.

Suffering from success

As groundbreaking as Midgley’s discoveries seemed at the time — even gaining him medals and prestige in the scientific community — they all ended up causing harm in one way or another.

As leaded gasoline became commonplace in 1923, factory workers started getting fatal lead poisoning, which led to a moratorium on TEL production until 1926. The moratorium was lifted and production continued when scientists at the time reached the consensus that only exposure to high concentrations of TEL were toxic and that it wasn’t harmful to the atmosphere. However, later studies showed that exposure to lead, even at low levels through the atmosphere, could lead to a decrease in children’s cognitive abilities. Lead exposure could also lead to physical health effects such as reproductive dysfunction and toxicity to the kidneys and blood.

Midgley’s other invention, CFCs, were so useful that they became ubiquitous in many industrial and consumer products. In addition to being used as refrigerants, they were also used as propellants for aerosol spray cans such as hairspray products and asthma inhalers, and even in the making of styrofoam. As a result of their many use cases, tons of CFCs were being pumped into the atmosphere every year.

The ozone layer, as its name suggests, is primarily composed of ozone molecules, which is a molecule made of three oxygen atoms. When a CFC reaches the ozone layer, it is broken down by radiation from the sun, leaving chlorine atoms to bond with the ozone to create oxygen and chlorine monoxide. This creates a chain reaction where loose oxygen atoms bump out the chlorine atoms, which frees them to bond with more ozone molecules and weaken the ozone layer in the process.

While there was evidence circulating in the 1970s that CFCs could be harmful to the atmosphere, by the time people realized the magnitude of the threat in 1985, there was already a giant hole in the ozone over Antarctica. If they didn’t take steps to fix the problem very soon, the ozone layer was going to be depleted enough that its protection against ultraviolet (UV) rays from space would have been weakened, which would have led to extreme UV radiation. UV radiation causes skin cancer in humans and is also harmful to plants and animals.

Disaster was on the horizon and all hope seemed to be lost, but in an unprecedented move, the world’s countries came together to ban CFCs and many other chemicals that were contributing to the depletion of the ozone layer in an agreement called the Montreal Protocol.

Saving the world, one signature at a time

The Montreal Protocol is a global agreement, finalized in 1987, to protect the ozone layer by phasing out the production of ozone-depleting substances. It is the first climate agreement to be ratified by every single country in the world, and the most successful environmental agreement in history.

A large part of the agreement’s success was the result of a widespread campaign led by scientists and environmental activists to effectively communicate the scale of the threat and its effects to the public. One of the leading scientists in the campaign to save the ozone was atmospheric scientist Susan Solomon. She and her colleagues went on two expeditions to Antarctica, in 1986 and 1987, to observe the hole in the ozone and gather data. Their observations showed high levels of chlorine monoxide being released into the atmosphere by the breakdown of CFCs, confirming theories that had been circulating since the 70s.

If not for the effort of countless scientists and environmental activists, we would have already seen large-scale depletion of the ozone layer, a disaster from which recovery might have been impossible. Current United Nations estimates say that the ozone in northern latitudes will recover by the 2030s, and the damage in the southern hemisphere over Antarctica is on track to heal by the 2050s.

What have we learned?

The story of the ozone layer shows us that given enough determination and cooperation, it is possible to overcome a situation that is thought to be hopeless. Even though we’ve successfully avoided the ozone disaster, we still have the climate crisis threatening life on Earth as we know it. While stories like this provide hope, they aren’t enough to solve the problem. In time, we’ll see if we will be able to follow in the footsteps of those that came before us.

Midgley had one more invention that would prove to be the most disastrous — at least for him. In 1940, he contracted polio, which left him bedridden, so he created a system of pulleys and harnesses to help him get in and out of bed. One day, he accidentally got tangled in the ropes and was strangled to death.

Midgley’s life took up a tiny fraction of human history, and yet his impact on the Earth will last much longer than that. He was unfortunate enough to die by his own invention, but we don’t have to let humanity meet the same fate. Will we learn a lesson from his story and the story of those that came together to prevent the disaster he caused, or will we let humanity die by its own hands?