Planetary boundaries and biodiversity

Planetary boundaries and biodiversity

• Biodiversity has been defined as one of nine planetary boundaries that help regulate the planet’s operating system.
• But humanity is crossing those boundaries, threatening life on Earth.
• The planetary boundary for biodiversity loss was initially measured by extinction rates, but this, as well as other measurements, have proved to be insufficient in determining a global threshold for biodiversity loss.
• While the planetary boundary framework provides one way of understanding biodiversity or biosphere integrity loss, there are many other measures of biodiversity loss — and all point toward the fact that we are continuing to dangerously destabilize life on Earth.

Planetary Boundary theory

• According to this theory, a theory that argues Earth has nine biophysical subsystems or processes with clear limits beyond which they cannot withstand anthropogenic pressure.
• These were described as climate change, the rate of biodiversity loss, interference with the nitrogen and phosphorus cycles, ozone depletion, ocean acidification, global freshwater use, land use changes, chemical and other pollution, and atmospheric aerosol loading.
• If humanity stays within the “safe operating space” of these boundaries, life can thrive, the theory suggests.
• If the thresholds are crossed, humanity can push Earth into a new, dangerous state that isn’t as accommodating to life as we know it.
• While it is difficult, if not impossible, to identify a global threshold for biosphere integrity, many researchers suggest that biodiversity boundaries can be defined at local or regional scales through something called “regime shifts,” also known as “tipping points.”
• A regime shift is an abrupt change that fundamentally alters the structure and function of an ecosystem, changing it from one state to another. In most cases, such shifts are irreversible.
• However, in most cases, regime shifts aren’t identified until after the process has occurred.
• Despite all these uncertainties, researchers argue that biosphere integrity acts as a core boundary in the planetary boundary framework, providing capacity for the planet to adjust to changes that occur in other boundaries, such as elevated levels of ocean acidification, and the onslaught of plastic pollution and other man-made chemicals.
• But if the biosphere becomes too compromised through anthropogenic pressures, other boundaries will weaken as a result.
• Despite the many uncertainties surrounding biosphere integrity and the approaches to measuring it, experts agree that biodiversity loss is happening now at unacceptable rates.