Planetary Boundaries: Are We Making the Earth an Unsafe Space?

An article came out recently that suggested human activity has pushed earth beyond four of nine planetary boundaries. Planetary boundaries are identified environmental conditions that make earth a “safe operating space for humans” and a result of our human actions on the environment are shifting these boundaries. The journal, Science, published the findings of researchers from around the world that concluded the global environment is destabilizing with an urgency that should be handled immediately. The scientists are asserting the future of our planet may become less hospitable to humans as the environment responds. Why don’t we take a closer look at each of the nine planetary boundaries to see just how earth is doing.

The following are the four planetary boundaries we’ve already passed and are thus in uncharted territory:

Extinction rate

Our planet is currently in the midst of the 6th mass extinction. Extinction is not a new global phenomenon, yet, this current situation of a mass extinction is unique because it’s caused by humans. Prior to this, mass extinction’s were brought on by asteroids, volcanoes or even global climate shifts or changes. In the last 500 years, roughly 1,000 species have gone extinct.


At the current rate of deforestation, earth’s rainforests could completely vanish in 100 years. Forests are being clear-cut to provide land for agricultural uses – to grow food or to graze livestock. While deforestation has slowed in recent years, it’s critical to manage forests properly to ensure that they can remain intact.

Carbon dioxide in the atmosphere

The safe-planetary boundary of CO2 in the atmosphere has been identified at 350 ppm, but today Co2 is nearing 400 parts per million.  The level of co2 in the atmosphere increases by about 2 ppm per year.

Nitrogen and phosphorous entering the ocean

Chemical fertilizer run off (a byproduct of many forms of agriculture) often finds its way into the oceans. The increase in nutrients in the ocean cause algal blooms that consume all of the oxygen in an area and create a dead zone where no other organism can live. A growing human population needs more food, so this issue may only get worse if we don’t take measures now.

The following are the five planetary boundaries we remain within and have more complete knowledge of solutions:

Ozone depletion

A hole in the ozone layer was discovered in the 1970’s and governments quickly responded by banning substances that use chemicals causing the holes. Since then, the ozone layer has recovered, but not fully. If all nations participating in the Montreal Protocol fully comply, the ozone layer is expected to recover in total.

Freshwater use

Global freshwater use is increasing as the population increases – humans have altered the flow of rivers and manipulated water cycles to meet their demands. In some areas, deep underground aquifers have been all but depleted. The good news is that it is possible for aquifers to replenish themselves. The tricky part will be that humans must decrease or stop water extraction for this to happen.

Ocean acidification

Increases in CO2 alter the ocean’s chemistry and lower the pH of the water, causing ocean acidification. Many organisms can only handle a narrow range of pH in their environment and this acidification has caused the death of coral reefs and the rich biodiversity that relies on coral. Because the concentration of carbon dioxide in the atmosphere is the underlying cause of ocean acidification, human-created emissions have the power to slow or quicken the rate of acidification.

Introduction of exotic chemicals and modified organisms

The chronic use of chemicals and pollutants throughout the years have led to a build-up of particles in our atmosphere. This affects the health of not only our atmosphere and influences weather patterns, but also of humans and organisms throughout the planet.