- A first of its kind Planetary Health Check by an international team of scientists indicates that six of nine planetary boundaries are not only transgressed, but are moving further into zones of risk. In addition, recent research shows that a seventh boundary, ocean acidification, is on the verge of transgression.
- Intensifying ocean acidification spells problems for marine life, fisheries and economies. Based on current human CO₂ emission trajectories, this boundary may be breached in a few years, say experts. Others argue this threshold may already have been crossed, with regional acidification above safe limits.
- Together, the nine planetary boundaries identify limits within which Earth systems can operate safely to maintain the planet’s habitability. Transgressing boundaries heightens risks of breaching tipping points that would bring about irreversible shifts to the planet, threatening humanity and life as we know it.
- This inaugural Planetary Health Check is the first of yearly scheduled reports on the wellbeing of Earth systems. Annual reports are now needed due to humanity’s rapid crossing of planetary boundaries, and due to the urgency of providing up to date scientific data to policymakers.
The first ever pulse check of the planet’s health shows that the Earth is far beyond it’s safe operating space for humanity. Six of nine key planetary boundaries are already transgressed, and continue moving deeper into risk zones that could threaten our planet’s habitability. A seventh boundary, ocean acidification, is on the verge of transgression and may exceed safe limits in a matter of years.
That’s according to the first-ever Planetary Health Check, a nearly 100 page report produced by the new Planetary Boundaries Science (PBScience) initiative led by Earth System scientist Johan Rockström and the Potsdam Institute for Climate Impact Research (PIK), and supported by the Planetary Guardians and other partners.
Boundaries for climate change, biosphere integrity, land system change, freshwater change, biogeochemical flows, and the introduction of novel entities (such as synthetic chemical pollutants) are all surpassed, as a study published last year found.
Worryingly, in this latest report, all those already transgressed are moving deeper into the red zone, says Levke Caesar, a report author and co-leader on planetary boundaries at the Potsdam Institute for Climate Impact. “Our updated diagnosis shows that vital organs of the Earth system are weakening, leading to a loss of resilience, and rising risks of crossing [irreversible] tipping points.
“We see it’s not changing [for the better]. It is actually getting worse,” she says.
The breach of planetary boundaries heightens the risk of permanently damaging Earth’s life support functions, with the report warning that the world is entering a “dangerous new era.” Symptoms of boundary transgression already being seen include the rapid extinction of species, extreme heat, drought and storms, record wildfires, reduced crop and fisheries productivity, and freshwater scarcity.
“We are really risking losing the planet as we know it, and this risk is increasing the further we go into the red zones,” Caesar adds.
Worse still, the health check found that the ocean acidification boundary is nearing transgression, and may pass its global “safe operating space” threshold in the next few years, says Caesar. Acidification — driven by climate change-fueling CO2 emissions — could severely impact marine ecosystems and the global economy.
Ocean health on the brink
For now, the ocean acidification boundary remains within the green safe operating space, according to scientists, but it is on the precipice. Studies show rising acidification could devastate fragile coral reefs and phytoplankton populations, considered the foundation of marine food webs. As acidification accelerates, global fisheries could degrade and even collapse, deepening human suffering and worsening hunger in vulnerable communities, and inflicting billions of dollars in global costs to economies.
Ocean acidification is driven by the same cause as climate change: rising atmospheric CO2 concentrations due to rampant fossil fuel emissions. The outlook for staying within the safe limit for this boundary appears bleak. “Looking at the current evolution, I’d say it’s really, really difficult to prevent that [boundary] crossing,” Caesar says.
The report uses surface aragonite saturation as an indicator for ocean acidification because it correlates to carbonate ion concentration. As atmospheric carbon dioxide is absorbed by the ocean, more-and-more carbonic acid is created, which releases hydrogen ions to lower pH and aragonite saturation. Declining pH in seawater means more ocean acidity and spells trouble for marine life that relies on calcium carbonate for shell formation.
The current safe operating limit is set at 2.75 aragonite saturation and is based on pre-industrial levels of 3.44. Levels below 3 can lead to some marine organisms becoming stressed, and if levels drop below 1 shells can begin to dissolve. Today, global aragonite saturation stands at 2.80. Passing that safe limit does not mean an immediate drop off a cliff, explains Caesar, but problems for marine life and the ocean’s food web will “definitely start to look more and more severe.”
For some, the acidification boundary may already have been crossed. That’s because aragonite saturation differs across the oceans, with levels of acidification not homogenous across the globe, and varying at regional levels; the polar region, for example, is already seeing worsening acidification effects as cooler waters absorb more carbon dioxide, making pH levels drops faster.
“When you start to think of the nuances of how the ocean works and the importance of some regions over others, I don’t necessarily agree that we’re still in a safe place,” says Helen Findlay, a biological oceanographer at the Plymouth Marine Laboratory who was not involved in the report. By averaging the planetwide threat, “I think it puts at risk [fully] understating the impacts because the polar regions have potentially more weight in terms of their contribution to climate cycles, feedbacks and to the climate system in general.”
Hans-Otto Pörtner, a senior scientist with the Alfred Wegener Institute and former co-chair of IPCC Working Group II, underlines that acidification is just one part of the ocean health picture. Climate change is driving extreme heat and deoxygenation (also called hypoxia), which add to pressures on marine ecosystems. A group of scientists recently called for aquatic deoxygenation to be added as an additional tenth planetary boundary.
“I think we need to bring [ocean acidification] together with the other climate change drivers in the ocean to fully understand [all the] implications,” Pörtner, who was not involved in the report, adds. “We are seeing, certainly that the combination of warming, acidification and hypoxia is really where things are becoming detrimental for marine organisms.”
An annual planetary health checkup
The time for action is limited: A reversal of planetary boundary trends is needed in the next five years, with 50% cuts in climate emissions required by 2030, the report authors emphasized in a statement.
Researchers hope that taking a holistic planetary systems view — understanding the complex interactions between vital Earth systems — will leverage solutions to address these deeply intertwined problems, says Caesar.
“We’re already committed to a certain amount of acidification… We’re already committed to a certain amount of warming, we’re already committed to a certain amount of ice loss,” says Findlay, “But I think we do, just by the tip of our fingers, have time [to stave off irreversible change] but we need to be moving forward now, pretty rapidly.”
The 2024 Planetary Health Check is intended as the first in a series of regular reports by the newly organized Planetary Boundaries Science (PBScience) initiative. PBScience will track Earth system trends and publish an annual Planetary Health Check, offering policymakers an up to date diagnostic tool to help combat the environmental degradation now posing a growing risk to national and global security.
The research team aims to develop a far flung science partnership, bringing together comprehensive data gathered via satellites and AI, multiple scientific disciplines, and Indigenous knowledge to help create an integrated view of planetary health.
The researchers note that while the destabilization of one Earth system can magnify the disfunction of other Earth systems, the reverse is true; with the solutions implemented to improve the health of one system, simultaneously benefiting the health of others.
The report emphasizes, for example, how the global food system is the “single largest driver behind the transgression of multiple planetary boundaries.” Radically transforming food systems by tackling biodiversity hotspot encroachment, reducing water use, limiting fertilizer applications, and cutting agricultural CO2 emissions could reverse negative trends for the climate change, freshwater, biodiversity, and ocean acidification boundaries.
Increasing data collection capabilities via a global collaboration will be key to producing accurate timely reports, says Caesar, who notes that for some boundaries (such as biosphere integrity, and freshwater use) researchers are working with decades-old data.
Developing detailed data sets that can drill down to detect regional trends, and mapping of potential biome tipping points is also critical. The 2024 report is the first ever to include global maps indicating estimates of regional planetary boundary pressures. Refined regional analysis could especially help policymaking at the national level.
“Having this holistic Earth System approach in mind shows that [Earth] really is an interconnected system,” says Caesar. “It’s not enough to just look at the ocean, or just look at atmospheric circulation, or just look at biosphere integrity. We really [need] to stress the interconnections between those different disciplines.”
Banner image: A jellyfish swims in the sun in the mangroves. The just published Planetary Health Check report finds that transgression of six planetary boundaries — climate change, biosphere integrity, land system change, freshwater change, biogeochemical flows, and the introduction of novel entities — is worsening, while the ocean acidification boundary is close to entering the red zone. Image by Chris Rohner / Ocean Image Bank.
Citation:
Caesar, L., Sakschewski, B., Andersen, L S., Beringer, T., Braun, J., Dennis, D., Gerten, D., Heilemann,. A., Kaiser, J., Kitzmann, N.H., Loriani, S., Lucht., W Ludescher, J., Martin, M., Mathesius, S., Paolucci, A., te Wierik, S., & Rockström, J. (2024), Planetary Health Check Report 2024. Potsdam Institute for Climate Impact Research, Potsdam, Germany.
As waterbodies lose oxygen, are we breaching a potential planetary boundary?
FEEDBACK: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.
Credits
