This article first appeared in The Edge Malaysia Weekly on December 25, 2023 - January 7, 2024

The concept of planetary boundaries was first introduced in 2009 and it defined nine natural limits within which humanity can thrive. But those limits have been breached, according to new scientific studies published this year, posing significant risks to humanity going forward.

“[Earth is now] well outside of the safe operating space for humanity,” said the 24 scientists who published a study in the Science Advances journal in September. They found that six of nine planetary boundaries have been breached, namely those for climate change, biosphere integrity, land-system change, freshwater change, biogeochemical flows and novel entities.

“Imagine Earth as a spaceship with a control panel of nine big red buttons. Each button represents a ‘do not press’ limit on how much we can change the environment before bad things start happening,” says Dr Ricky Anak Kemarau, research fellow and lecturer at the Earth Observation Centre, Institute of Climate Change, at  Universiti Kebangsaan Malaysia.

These buttons, Ricky explains, are the planetary boundaries. The climate change boundary, for instance, is crossed when global warming exceeds a certain level, while biosphere integrity is exceeded when there has been too much loss of plants and animals.

The biogeochemical flows boundary is transgressed when too much nitrogen and phosphorus is released into natural systems from excessive fertiliser use.

“Scientists have just reported that we’ve already pressed six of these buttons. This is a big deal because it means we’re risking the ship’s stability or our planet’s ability to support life as we know it,” says Ricky.

When these boundaries are crossed, it can trigger abrupt environmental changes with severe consequences for humanity, such as a decrease in food security, more extreme weather events and the loss of biodiversity, which is critical for maintaining a stable environment.

A study published in the renown journal Nature in May included “justice” when assessing the boundaries, which also considers fairness since not everyone will suffer from the impact of climate change equally.

What should be done with this information? “For one, countries and companies that have contributed more to problems like climate change might need to work harder to fix them. It also means recognising that some people are hit harder by environmental problems, even though they did the least to cause them.”

The consequences of crossed boundaries are already felt. The latest Intergovernmental Panel on Climate Change reports have noted an increase in heavy rainfall events in many regions of the world, while changes in atmospheric circulation patterns have exacerbated drought in some regions.

The rate of combined mass loss from the Greenland and Antarctic ice sheets is accelerating as well, which results in sea level rise.

A key point to understand is that the boundaries are interconnected. For instance, climate change is caused by a higher concentration of greenhouse gases, with deforestation being one culprit. But deforestation also exacerbates biodiversity loss, which then affects food security and ecosystem services provided by natural systems, such as clean air and water.

A crucial question to consider is whether it’s too late for humanity to take action. It’s complicated, says Ricky.

Climate change can be mitigated by reducing greenhouse gas emissions, but changes like melting glaciers might be irreversible within human timescales, explains Ricky. This is the same for species extinction, although habitat restoration can halt further loss of species.

Completely reversing the impact of biogeochemical flows would be difficult because nitrogen and phosphorus from fertiliser use are already widespread in the environment. Too much of these elements in water causes algae to bloom and reduces the oxygen needed for fish and other aquatic life to survive. It also produces toxins that can make people sick.

Meanwhile, reversing the impact of the introduction of novel entities, which include pollutants such as microplastics, heavy metals and synthetic chemicals, is challenging due to their persistent nature and accumulation in the environment.

The impact from land-use change can be reversed via reforestation and sustainable land management, while reducing carbon emissions can mitigate ocean acidification, says Ricky. However, for the latter, restoring the pH levels of oceans is a slow process.

As for the boundaries of freshwater use, Ricky says sustainable water management is effective, but in some areas where overuse of water has led to long-term depletion of aquifers, it might not be reversible.

There is one piece of good news. The stratospheric ozone depletion boundary was successfully restored and the major ozone hole over Antarctica is on track to recover within four decades, according to a United Nations-backed panel of experts in January. This is thanks to the Montreal Protocol of 1987, which banned the production and consumption of chemicals that destroyed the ozone layer.

This demonstrates that collective global action can reverse environmental harm, says Ricky. “Katherine Richardson, a professor in biological oceanography, likens the Earth to a human body and planetary boundaries to blood pressure. Exceeding the ‘safe’ level doesn’t guarantee a crisis (like a heart attack), but it does raise the risk, which is why efforts to reduce these pressures are crucial.”

It is crucial for the public to understand the severity of the problem and the interconnectedness of Earth’s systems, says Ricky, and take action, whether it’s by reducing energy consumption or adopting a sustainable lifestyle like recycling and reducing waste.

Businesses, meanwhile, should play their part by taking up green practices like using renewable energy and conducting climate risk assessments. The government must play its part by introducing policies and regulations, he says. “[The government] should develop a national adaptation plan to address the impact of climate change. This plan could cover areas such as water, coastal zones, agriculture, infrastructure, health and forestry,” he adds.

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