A good share of my classes this semester has begun the same way -- with what is now known by the students in my program as "the graph of death." The graph is deathly for both its implications and the outrageous number of times it has appeared before my eyes from lectures and guest speakers.

The graph depicts the growth of global capture fisheries and aquaculture, the controlled cultivation of aquatic organisms. Production of seafood is depicted on the x-axis along with time on the y-axis. The output from capture fisheries begins to plateau in the 1980s as fish stocks become chronically depleted but global seafood production continues to grow, with the difference filled by aquaculture.

The implications of the figure are clear -- once humans exploit one resource, they move onto the next best alternative. And this lesson isn't just confined to fisheries management. Every scientific field has its own "graph of death," whether it be an oil reserves graph for energy, the famous "hockey stick" graph in climate science, or a species extinction curve in conservation biology. All the graphs tell essentially the same story: Things are going quite poorly for the environment and humans are at fault.

This narrative is the core element of the "tragedy of the commons," a theory stating that individuals acting in their own self-interest will deplete a public resource. While the tragedy of the commons is certainly experienced in societies around the world, its simplistic explanation of environmental problems serves as an intellectual crutch that impedes scientists from analyzing our greatest challenges more critically and holistically. We need to reach beyond the tragedy of the commons to develop sustainable solutions that can be adapted to the needs of communities and the unique ways in which they interact with the environment.

The tragedy of the commons was popularized by ecologist Garrett Hardin who used the metaphor of sheep grazing on a common pasture to convey how natural resources are depleted. If each herd is allowed to graze on the meadow as much as they want, then soon the field will become completely denuded of vegetation, thus rendering it useless for all parties involved. Though an individual sheep cannot destroy the field alone, the cumulative impact of all the sheep exploiting the same resource ultimately destroys it. In the same way, even if one person's emissions do not significantly impact climate change, the aggregate emissions of humanity have major consequences.

Hardin's theory took off because it was elegant, broadly applicable and easy to understand. The tragedy of the commons paradigm initiated a 50-year research spree on the study of common pool resources, a topic that was previously ignored by academics. The appeal of this framework is that it provides a standardized depiction of the status quo to which researchers can apply their ideas, just like how builders need to flatten the ground before they can construct a house. However, the simplicity that made the theory so successful is also what disconnects it from reality. Resource dilemmas are not like flat land, so to speak; each situation is unique.

Hardin assumes that humans, when acting in their own self-interest, will take actions that harm or deplete the environment. But what if self-serving desires end up improving environmental conditions?

For example, take renewable energy development. The primary goal of any solar and wind company is to maximize profit. In the process of doing so, they are displacing fossil fuel generation, which is instrumental in mitigating climate change. The same can be said for many other activities, such as beekeeping, shellfish aquaculture and teaching. Individuals acting their own self-interest partake in these activities and even make careers out of them. In doing so, they provide environmental benefits such as pollination, water purification and increased awareness about the environment. Self-interested motives do not always equal environmental destruction.

Unfortunately, environmental science has become a field defined by pessimism. The tragedy of the commons only adds to this sentiment while ignoring many successful attempts at managing common resources without resorting to privatization. Though we must be candid about the immense challenges facing our environment, we also must not underestimate our ability to solve these challenges.