Cause and Effect | Interview: Science suggests multiple eco organs of Earth may be failing, says top scientist - Hindustan Times
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Cause and Effect | Interview: Science suggests multiple eco organs of Earth may be failing, says top scientist

May 13, 2024 09:01 PM IST

Johan Rockstrom, director of the Potsdam Institute for Climate Impact Research, warns that things are changing faster than expected and the risks are increasing

In September 2023, a team of scientists quantified the nine processes that regulate the stability of the Earth system. Called planetary boundaries — thresholds within which humanity can continue to develop and thrive — these processes were first proposed by Johan Rockstrom, former director of Sweden’s Stockholm Resilience Centre, and a group of 28 scientists in 2009.

Kenya is grappling with one of its worst floods in recent history, the latest in a string of weather catastrophes, following weeks of extreme rainfall scientists have linked to a changing climate. (Credit: AFP) PREMIUM
Kenya is grappling with one of its worst floods in recent history, the latest in a string of weather catastrophes, following weeks of extreme rainfall scientists have linked to a changing climate. (Credit: AFP)

In its Planetary Boundaries Framework, the Stockholm Resilience Centre outlined the nine key processes: climate change, biodiversity integrity (functional and genetic), freshwater use, land-system change, biogeochemical flows of nitrogen and phosphorus, the release of novel chemicals (including heavy metals, radioactive materials, plastics, and more), ocean acidification, depletion of the ozone layer and atmospheric aerosol pollution.

The 2023 update to the framework not only quantified the boundaries but also concluded that the first six of the nine boundaries have been transgressed due to the anthropogenic changes brought on by human actions.

"The 2023 update clearly depicts a patient that is unwell, as pressure on the planet increases and vital boundaries are being transgressed”, Rockstrom, who was recently awarded the 2024 Tyler Prize for Environmental Achievement, told HT in an interview.

The stability of these nine processes, all of which are inter-related, is essential to maintaining the Earth’s atmosphere, oceans and ecosystems in the delicate balance that has allowed modern human civilization to thrive, the Centre said.

Johan Rockstrom will receive the 2024 Tyler Prize for Environmental Achievement at a ceremony on May 17 in Germany. Credit: Jadranko Marjanovic
Johan Rockstrom will receive the 2024 Tyler Prize for Environmental Achievement at a ceremony on May 17 in Germany. Credit: Jadranko Marjanovic

The framework

Under human influence, crossing these boundaries increases the risk of generating large-scale abrupt or irreversible environmental changes, which in turn threaten the stability of the entire Earth System.

“The scientific work to develop the planetary boundary framework emerged from intensive international research work starting 2007, and was first published in the year 2009. The framework evolved quite naturally from a growing body of scientific evidence across the Earth system science, tipping point research, evidence that we have entered the Anthropocene, and paleo-climate research on the evolution of Earth over the past one million years,” Rockstrom, now the director of the Potsdam Institute for Climate Impact Research, said.

After the identification of the processes, scientists estimated the limit of how much human activities could exploit and alter each of them before the global system would pass a tipping point, a threshold beyond which the impact on the planet, and as a result civilisations and ecosystems, would be cascading and irreversible. The scientists say that these changes will not necessarily happen overnight.

“The understanding that the Earth system is a complex, self-regulating system, that there are tipping points which may undermine the life-support and stability of Earth, and the remarkable stability of the climate on Earth over the last 12,000 years, since we left the last Ice Age, together gave us the scientific basis. The planetary boundary framework takes into account all this science, and addresses the threats that humanity causes for the stability of the entire Earth system in a systematic way,” he explained.

A simple example of this self-regulation by the planet is natural carbon removal. Ecosystems like forests and wetlands absorb carbon from the atmosphere and sequester it in plants, soils and sediments. But the abundance of carbon in the atmosphere and drop in areas covered by forests has led to the weakening of such systems.

The research highlights that while a global focus on climate change is much needed, that alone is not sufficient for increased sustainability. Instead, understanding the interplay of boundaries, especially climate, and loss of biodiversity, is key in science and practice.

 

The 2023 update to the Planetary boundaries. Credit: Azote for Stockholm Resilience Centre, based on analysis in Richardson et al 2023
The 2023 update to the Planetary boundaries. Credit: Azote for Stockholm Resilience Centre, based on analysis in Richardson et al 2023

Health of the planet

According to the 2023 update to the framework, of the nine planetary boundaries humans have breached six: climate change, biosphere integrity, freshwater change, land system change, biogeochemical flows and novel entities.

While atmospheric aerosol loading and ozone depletion remain within the constraints, ocean acidification is close to being breached. Among concerning evaluations, the key was the overflow of nitrogen and phosphorus — the biogeochemical flow boundary — in the environment.

“The second major planetary boundaries update [the framework was first updated in 2015] is the first to provide a complete check-up of all nine processes… We don’t know how long we can keep breaching these key boundaries before combined pressures lead to irreversible change and harm. Science and the world at large are really concerned about the rising signs of dwindling planetary resilience, manifested by the transgression of planetary boundaries, which brings us closer to tipping points,” Rockstrom said.

These changes are rapidly closing “the window to have any chance of holding the planetary climate boundary of staying below 1.5°C”, he said.

“It could be that we are currently seeing the first signs that the capacity for self-regulation is losing strength: On land, in the rainforest and in the temperate forest zones, the absorption capacity for CO2 is decreasing,” Rockstrom said.

One of the most concerning evaluations is the overflow of nitrogen and phosphorus — the biogeochemical flow boundary — in the environment. Although nitrogen and phosphorus are essential for life, their widespread use as crop fertilisers is wreaking havoc by, for instance, triggering algal blooms (it can cause entire fish populations to leave an area or even die) and ocean dead zones (a reduced level of oxygen in the water).

Imagine Earth’s environment at present to be at an equilibrium based on nine distinct systems. One is biogeochemical flows of nitrogen and phosphorus -- these two elements constitute fundamental building blocks of life on Earth. What the scientists contend is that these systems must be seen as “boundaries” for the ecology to be the perfect mix of conditions that lets life bloom on the planet. A drastic change in one of them will lead to consequences for the others.

In the case of Nitrogen and Phosphorous, while they are essential for life, their widespread use as crop fertilisers is wreaking havoc by, for instance, triggering algal blooms (it can cause entire fish populations to leave an area or even die) and ocean dead zones (a reduced level of oxygen in the water).

The breach of these boundaries is directly tied to human pressures of overexploitation and pollution, Rockstrom said on the question of any observed order in the breach.

“The order they have been breached in the past is at least as much related to the degree of resilience in the system as to the degree of human pressure itself. Interactions between boundary processes and systems do play a role: for example, climate heating causes ecosystems to suffer, which on the other hand can play a vital role for climate if large biomes like the Amazon lose some of its carbon sink capacity,” he explained.

Prioritising justice

Building on the Planetary Boundaries Framework, scientists last year also assessed a “just” operating space for humans, defining justice as avoiding significant harm to people across the world. The team of over 50 scientists also included other species in their analysis.

For the study Safe and just Earth system boundaries, published in Nature on May 31, 2023, researchers explored five of the existing nine processes and quantified their justice implications: Climate, biodiversity, freshwater, nutrient cycles, and aerosol pollutants.

“Safe boundaries ensure stable and resilient conditions on Earth. Just boundaries set the thresholds for human exposure to significant harm,” Rockstrom said of the global assessment. “This new science will help develop science-based targets that can be adopted by cities, businesses and countries to address the systemic global crises of climate change, biodiversity loss, nutrient overloading, overuse of water, and air pollution.”

Focus on boundaries other than climate change

If these boundaries are respected, scientists hope the world will be able to sustain an environment like the Holocene, which began with the end of the last ice age and during which agriculture and modern civilisation evolved, and avoid more of the extreme environmental harm brought on during the Anthropocene.

While the Holocene was characterised by relatively stable and warm planetary conditions, the research has shown that maintaining these conditions calls for focus on boundaries other than climate change. And, Rockstrom says, there is a clear trend in the climate negotiations that recognises this need.

“…recognizing the need to manage also the biosphere boundaries of land, water, biodiversity, nutrients and air pollutants, and the only way to meet the Paris agreements limit of 1.5°C. We need a planetary boundary approach to solve even the climate crisis,” he said, adding: “Phasing out fossil-fuel alone will not do the job.”

“We have to understand that the Earth is a fragile system and that we have to coordinate our actions on a global scale,” he said.

Rockstrom recognized the “turbulent times” brought on by wars, misinformation and distrust that constantly undermine social resilience and amplify risks of displacement and conflict.

“Despite this turbulence, we are not losing ground on global climate policy. It is not going fast enough, for sure. But we are not turning back… the dice is thrown, the global economy is on a path towards phasing out fossil-fuels, and increasingly safeguarding water, land, biodiversity,” he said.

Underestimating risks

“In the past, we have constantly underestimated the risks and the speed of change. That is the quintessence of climate research over the past 20 years. Things are changing faster than expected and the risks are increasing,” Rockstrom said on the question of the unusual temperatures observed through most of 2023. The temperature trends are continuing this year as well, with ocean temperatures breaking records every day in the last one year.

“We don’t yet know why ocean temperatures are suddenly rising like this. The rise in ocean temperatures is only partly attributable to the ongoing El-Niño,” he said.

And in a year that several large economies, including India, are set to elect new governments, it is imperative to recognize these risks.

“If we see large economies in the world electing short-sighted, populist and climate skeptic governments, then we will lose pressure time. This is a key moment to use our democratic voices to express the need and huge benefits for all, to solve the climate and ecological crises that we are in the midst of,” Rockstrom said.

But, the question, according to Rockstrom, is whether “we will come back within safe Planetary Boundaries” before it is too late.

Tannu Jain, HT'ss deputy chief content producer, picks a piece of climate news from around the globe and analyses its impact using connected reports, research and expert speak

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