The authors of “The Limits to Growth” argued that growing economies eventually devour finite supplies of natural resources. Moreover, the authors claimed that aggregate demand for such resources as oil, wood and copper will rise until prices send a scarcity signal. Economists, however, often rely on optimistic assumptions that for-profit firms can constantly design goods with smaller environmental footprints.

Deforestation

Forests are the natural habitat of many animals and plants, and they help regulate the Earth’s climate. But deforestation can have negative effects on the environment as well, such as soil erosion and loss of biodiversity. In some cases, people may also clear forests to make way for agriculture or housing.

The world’s population has never been so large, and the global demand for food is rising rapidly. In order to meet this need, there needs to be enough land to grow crops and provide space for livestock. This requires clearing forests to create fields, which means that trees and shrubbery are removed and burned.

In addition to providing food, forests also contain valuable resources such as timber, oil and minerals. These can be extracted from cleared forests, boosting the local economy.

However, the positive reasons for deforestation need to be weighed against the negative consequences. For example, the destruction of forests can cause climate change by removing a significant amount of carbon dioxide from the atmosphere. It can also contribute to flooding, as fewer trees mean less water vapour in the air, resulting in less rain.

Furthermore, forests are vital in preventing the spread of disease and reducing the risk of fire. In areas where there are few trees, a lot of fires can break out, and the smoke from these can harm human health. Forests can also act as a firebreak, protecting the surrounding area from damage or destruction.

Moreover, clearing forests can lead to the loss of species, as well as the loss of important ecosystems such as wetlands, coral reefs and dry tropical forests. These losses can have a direct impact on human health and the quality of life.

The number of trees on the planet is constantly decreasing due to deforestation. However, the rate of tree loss can be slowed with the help of international markets and improvements in agricultural productivity.

The world has a long way to go in terms of conservation efforts. As of 2020, the world has lost an estimated 26 million hectares of forest cover, which is roughly the size of Oregon. This is a significant amount of forest, but the good news is that countries are starting to move from Stage 1 to Stage 2 of the deforestation transition. Countries that are in Stage 1 lose some forest each year, but the losses are relatively small.

Water

While Earth is full of water, only a tiny fraction of it is salt-free—fresh—and even that fraction is rapidly depleting because the world’s population continues to grow at an exponential rate. Freshwater supplies come from rain, rivers, lakes, streams, springs, and groundwater reservoirs known as aquifers (rock formations that store, transport, and yield groundwater to wells). Countries with less than 1,000 cubic meters of renewable fresh water per person per year are considered water-scarce. In the MENA region, high household demand for water is compounded by a growing population and harsher weather conditions that affect water supply. Water scarcity is expected to worsen in the future. (Learn more in the Teacher Guide.)

A related lesson, “Water: Our Most Precious Resource,” includes a water activity and student worksheets.

Energy

The MIT researchers behind Limits to Growth claimed that global economic growth would eventually eat up finite supplies of natural resources such as wood, oil and copper. They extrapolated that if developing nations catch up to per capita income levels of the United States by 2035, they will consume the same amount of these natural resources as Americans do today.

When the book first came out in 1972, it was widely denounced and dismissed by business leaders and economists. The premise that there are limits to global economic growth was considered blasphemous and unscientific. But as it turns out, the authors were right.

Using the World3 computer model from The Limits to Growth, Meadows and Randers present an updated look at the global trends of population growth, resource consumption, and pollution. Despite aggressive attacks and denial by some, the results of the new World3 simulations appear to be tracking very closely with the standard-run scenarios from The Limits to Growth. This 30-year update is a timely reminder that if aggregate consumption continues at current rates, overshoot will occur and global society will have to shrink significantly in order to avoid collapse. The System Dynamics Society receives affiliate compensation for purchases of this book from Amazon.