By Jon Lamson | Illustration by Jubilee Hernandez

On April 22, 1970, 20 million Americans gathered in great masses to celebrate our common home, and protest its maltreatment, in the first iteration of the now-annual Earth Day. Months later, Richard Nixon (far from an environmentalist himself) proposed and helped pass the legislation to create the Environmental Protection Agency (EPA). But few among these 20 million had a clear view of the serious environmental issues ahead, aside from a small number of researchers, and the upper echelon of the American Petroleum Institute, who were well aware of the impending crisis by the mid-1960s. Fifty years later, we are currently on course for around eight degrees Fahrenheit of warming by the end of the century, or in the “optimistic policies scenario,” four and a half degrees Fahrenheit, according to the Climate Action Tracker.

Today, all well informed citizens are aware that human activity is causing serious issues with the earth’s climate system. But what is less understood, among college students, the working public, and in certain circumstances, the scientists themselves, are the complex processes of the earth’s systems that accompany and fuel dramatic shifts in the earth’s climate. There are a number of positive feedback loops that, if we do not quickly and drastically decrease human-caused greenhouse gas emissions, will only hasten the most dire, looming consequences.

The first, and perhaps easiest to visualize, has to do with a phenomenon called the albedo effect, relating to the melting of the ice that currently covers large portions of the earth’s surface. The most severe warming resulting from human emissions is occurring at the poles. As demonstrated in the endless stream of videos of starving polar bears, the ice that covers the poles is rapidly melting. As this ice melts, less of the sun’s radiation is reflected back into space, increasing the amount of heat absorbed by the earth. In turn, this increases the melting of the ice and heat being absorbed, and our first positive feedback loop is born.

Staying in the Arctic, the next positive feedback loop has to do with the permafrost, a layer of frozen, dead organic matter that covers the upper-most land masses in the northern hemisphere. As these regions warm, the permafrost thaws, and decomposes. As it decomposes, the carbon contained is released as a mixture of carbon dioxide and methane. These greenhouse gases then help accelerate the warming, which in turn increases the warming pressure on the permafrost, giving us feedback loop number two.

Along with melting ice at the poles, a warming climate also affects the amount of water vapor that the atmosphere can contain. Warmer air can hold more water vapor, so as our climate heats up, the atmosphere can contain greater amounts of vapor, which is itself a greenhouse gas. As this vapor traps even more heat, the warming causes more water to vaporize, presenting us with our third positive feedback loop.

Moving towards the equator, the Amazon Rainforest takes in a quarter of all carbon that is sequestered by forests each year. However, through a combination of intentional burning and logging, and projected drying of the climate as a result of climate change, the rainforest is rapidly shrinking.

According to a study published in Theoretical and Applied Climatology, if the rainforest is deforested another 20%, a “dieback” could be triggered, during which the rainforest would turn from a carbon sink to a carbon source, and would begin releasing vast amounts of greenhouse gases. Increasing warming, in conjunction with increased wildfires, could lead the entire region to transition from a rainforest to a dry savanna, containing only a fraction of the 140 billion tons of carbon that it stores today.

This type of biosphere carbon release isn’t simply limited to the Amazon. Earlier this month, a review paper was published in Science Magazine that concluded that climate change is resulting in widespread forest declines, due to increasing drought-related stress. The paper found that the negative effects of drought have outweighed any anticipated benefits of increased atmospheric carbon dioxide, a key component in photosynthesis. As climate change increases desertification and drought across the globe, forest fires and die offs will increase, resulting in even more carbon dioxide entering the atmosphere, increased warming, and our final positive feedback loop.

While it all seems to shake up to a thoroughly depressing spectacle, these positive feedback loops are a huge part of the reason that immediate, drastic action is necessary. Once we reach a certain tipping point, even if we stop all of our direct emissions, there will be very little that we can do to stop these processes. While the 50th anniversary of Earth Day may have been a disappointment, with COVID-19 sidelining even the smallest of public gatherings, now is not time to lose hope. If Richard Nixon could be pushed by an engaged public to enact meaningful environmental legislation, then perhaps we too can have some impact. If by nothing else, this could be done by mobilizing the vote against an administration of climate-deniers. With the clock ticking there are few other options.

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