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Crossing the line: Fossil fuels could soon displace Earth from its “safe operating space”

Written by Mongabay Published on   13 mins read

Earth teeters on the edge of unprecedented risks, intertwined with the extensive impacts of fossil fuel emissions on our planetary boundaries.
  • This exclusive three-part Mongabay mini-series explores how the oil, natural gas and coal industry are destabilizing nine vital Earth systems, which create a “safe operating space” for humanity and other life on the planet.
  • The first story in the series examined some of the direct detrimental impacts of fossil fuels, petroleum-based agrochemicals and petrochemicals (such as plastics) on climate change, biodiversity loss, nitrogen pollution of the world’s oceans and other forms of pollution.
  • This story looks at the direct and indirect impacts that hydrocarbon production is having as it destabilizes Earth’s freshwater systems, influences rapid land use change, pollutes air, land and water, potentially contributes to ozone layer decay, and ultimately impacts life on Earth.
  • Scientists say humanity’s actions—including burning fossil fuels and producing petrochemical and agrochemical products—have already pushed Earth into the danger zone, overshooting six of nine critical planetary boundaries. Unless we pull back from these violated thresholds, life as we know it is at risk.

In 2020, the worst drought in 40 years hit East Africa, as years of insufficient rainfall were followed by back-to-back rainy season failures. Water scarcity led to mass deaths of livestock, resource-based conflicts and a flux of destabilizing migration.

In 2023, researchers assessed the cause. “We found that the drought was made exceptionally severe by climate change,” said Joyce Kimutai with the World Weather Attribution Consortium.

2020’s East Africa drought directly impacted nearly 50 million people, and it’s just one example of how fossil fuel emissions, and the climate chaos they cause, is messing with the global hydrological cycle—threatening humanity’s water supply and in turn helping destabilize food security, worsening social and political conflict.

The latest UN Intergovernmental Panel on Climate Change (IPPC) report on climate and water charts a host of dangerous water-related impacts already being felt globally, including deepening droughts, worsening storms, reduced crop yields, shrinking glaciers and more.

“All components of the global water cycle have been modified due to climate change in recent decades,” the authors wrote, painting a “clear picture of human alteration of the global water cycle.”

Playing planetary boundary dominos

Fossil-fueled climate change is “one of the main causes of the increase in [hydrological cycle] variability, so we [now] get both more water and less water in different places,” said Lan Wang-Erlandsson, a PhD researcher at the Stockholm Resilience Centre.

This massively random water redistribution—like a dangerous game of musical chairs—directly affects the amount of water available to plants (called green water) and the water available to human societies (called blue water). Those two combined create what researchers have dubbed the freshwater change planetary boundary.

In 2022, scientists declared the freshwater change boundary “considerably” transgressed—with both green and blue water safe limits overshot by human actions—pushing Earth into an “unprecedented state” of risk.

To understand what that could mean, it’s important to realize that planetary boundaries don’t act in isolation. Each of the nine boundaries influences the others. Imbalance one, and others can be destabilized, like dominos falling into each other.

We know, for example, that fossil fuels are warming the world, adding huge amounts of heat energy to global weather systems. That increased energy makes those systems more chaotic, bringing greater weather extremes. Thus, the destabilizing climate planetary boundary domino falls into the freshwater change boundary domino, and so on. These instabilities in turn impact biomes across the Earth in complex ways.

Scientists warn, for example, that global climate change is driving alterations in the water cycle in the Amazon rainforest, with those shifts then being further intensified by land use change due to human-caused deforestation. Together, climate change, freshwater change, land use change (often carried out via the intentional lighting of wildfires), are increasing the chance the forest will soon transition to degraded savanna.

This so-called Amazon tipping point could in turn bring even more devastating global consequences, not only threatening extinction for countless tropical species but also bringing the mass release of the carbon once stored by the rainforest.

Research has clearly shown that climate change and deforestation are behind increasing drying in the Amazon. “Fossil fuels and deforestation can really work in concert to accelerate the existing loss of the rainforest by changing the hydrological cycle,” said Rong Fu, a climate scientist at the University of California, Los Angeles.

“If you reach a certain point, especially over the southeast Amazon, where the soil starts drying and the dry seasons increase, you basically reach this point where the climate is not able to sustain rainforest,” Fu said. Expansive droughts and fires, ripping through the forest, add to the pressure of a changing climate.

“I think the warming is pushing the system closer and closer to the breaking point,” Fu concludes.

If the Amazon Rainforest turns into a net carbon source within the next decade or two, Wang-Erlandsson said, it will make it “much tougher [for humanity] to limit climate change.”

“On a positive note,” policymakers could step up to the challenge of stopping deforestation and restoring damaged land,” she added. “A faster phaseout of fossil fuel globally would also help prevent a further deepening of this crisis.”

High-altitude transformations

Fossil fuel-driven changes to the Amazon, while complex, are clearly visible in the dying of water-loving trees. But high above, in the upper reaches of Earth’s atmosphere, other invisible fossil fuel-driven changes may be getting underway.

In 2020, devastating forest fires tore across Australia. Since then, a series of studies have found that smoke from this “megafire” reached high altitudes, triggering chemical reactions that depleted stratospheric ozone. That’s bad news, because the weakening and collapse of the ozone layer (another planetary boundary)—allowing the penetration of deadly ultraviolet solar radiation—could threaten life on Earth.

Watching that Australian smoke sweep around the globe, scientists “saw some ozone depletion and some record low ozone values in the mid latitudes,” said Kane Stone, a research scientist at the Massachusetts Institute of Technology. That’s because the smoke’s presence in the stratosphere led to chemical reactions that activated chlorine molecules able to destroy ozone, he added.

Studies indicate Australia’s 2020 fires depleted mid-latitude ozone by around 3–5% and may have expanded the Antarctic ozone hole by around 10%. It’s unclear whether, or to what extent, other fires—such as this year’s Canadian fires, which burned an estimated 1 billion trees and added 2 billion tons of CO2 to the atmosphere—may have on ozone depletion, as not all smoke may reach the stratosphere, experts said. Researchers are working to understand how wildfire scale, intensity and even the species of tree burned, might influence chlorine activation.

At the global level, the ozone layer is forecasted to recover within the next four decades due to the phaseout of chlorofluorocarbons—the primary culprits of ozone depletion and also powerful greenhouse gases—under the Montreal Protocol. As such, the stratospheric ozone depletion planetary boundary is considered still well within safe limits.

These wildfire findings, however, are concerning, especially in a warming world with the potential for far more frequent megafires. “If wildfires become more extreme and more frequent in the future, this type of chemistry could happen more often,” said Stone. “If that happens, then it could delay the recovery of the ozone layer.”

“It’s sort of a logical conclusion that if you have lots of fires, and they are decreasing ozone, then that will delay recovery,” said Peter Bernath, a professor at Old Dominion University in Virginia, whose lab is tracking the effects of fires on ozone depletion. “But that’s all very speculative right now.”

Other stratospheric alterations?

Fossil fuel-driven climate change is causing other changes in the stratosphere. Projections are that, with increasing greenhouse gas emissions in the troposphere, water vapor in the stratosphere will increase—a process dubbed “stratospheric moistening.” Some models suggest high levels of stratospheric water vapor could lead to a substantial delay in ozone recovery.

However, a recent paper ruled out such worst-case scenarios, findings that are “good news,” according to study author Peer Nowack, a professor in climate and environmental sciences at Karlsruhe Institute of Technology in Germany.

Climate change is also altering stratospheric temperatures. A study published earlier this year found that the mid to upper stratosphere cooled by 1.8–2.2 degrees Celsius (3.24–3.96 degrees Fahrenheit) between 1986 and 2022. For the authors, this is a clear human-induced climate “fingerprint.” At the global level, this cooling could drive a “super recovery” of the ozone layer, researchers said, by slowing the reactions that cause depletion.

However, these high-altitude temperature changes could also lead to a shift in distribution of ozone across the Earth’s latitudes. “That would have different implications,” said Nowack, as it may mean more ozone than human beings are accustomed to at certain latitudes far into the future.

The conflicting findings of these studies play up just how little we know about the ultimate results of humanity’s planet-wide fossil fuel-burning experiment. Big uncertainties remain about interactions between emissions, a changing climate and effects in the troposphere and stratosphere. A 2019 modeling study found that fossil fuel-driven changes in climate and clouds could lead to a cataclysmic 8 degrees Celsius (14.4 degress Fahrenheit) temperature increase on Earth.

“The closer we stay to the climate as it originally was, the more likely that ozone recovery will return to levels we are accustomed to, and where we want them to be,” Nowack concluded.

Dirtying the sky: Aerosol pollution

Smokestacks and tail pipes aren’t only supercharging climate change—they are also polluting the air we breathe. When gasoline is burned, for example, it releases not only carbon dioxide, but also carbon monoxide, nitrogen oxides, particulate matter and unburned hydrocarbons, contributing to air pollution.

Almost all of the global population is exposed to polluted air above safe guideline limits at times, according to the World Health Organization, with an estimated 4.2 million premature deaths resulting annually. Harvard researchers, meanwhile, estimated that more than 8 million people died due to fossil fuel pollution in 2018 alone.

“We talk about climate change, and we talk about air pollution—but we really need to think of them together as one, in a holistic way,” said Frederica Perera, founding director of the Columbia Center for Children’s Environmental Health.

Air pollution poses a particular risk to the most vulnerable, including children: “We’re seeing preterm births, asthma, impacts on early brain development and almost 2 million infant and child deaths each year, linked to pollution and other environmental risks,” Perera said. Climate change-linked heat waves and extreme weather events are exacerbating these effects and incurring an additional mental health toll.

Phasing out fossil fuels could reduce atmospheric aerosols, and thereby these health impacts, along with premature mortality to “a very large degree,” said Jos Lelieveld, director of the Max Planck Institute for Chemistry, in Germany.

But health impacts are just one consequence of fossil fuel-derived aerosols. Though the global aerosol loading planetary boundary currently remains within safe limits, transgressions of regional boundaries may already have occurred in India and China, where fossil fuel pollutants have been historically intense: “These are regions where we identified that the regional water cycle may have been affected by large local aerosol loading,” said Govindasamy Bala, a professor with the Indian Institute of Science.

Aerosol pollution in Asia—primarily in the form of black carbon, commonly known as soot, and sulfates emitted by burning coal and biomass, mixed with automotive exhaust—interacts with solar radiation to disrupt rainfall patterns and has possibly resulted in a weakening of Asia’s monsoon. “Aerosol emissions … could basically decrease the monsoon rainfall in the northern hemisphere monsoon domain, particularly the Indian monsoon, and the North African monsoon,” Bala added.

Aerosols can also exert an overall cooling effect by “masking” global warming caused by long-lived greenhouse gases such as CO2—a cause for concern to some researchers because making deep air pollution cuts could worsen climate change impacts.

“That means you need to do even more to prevent overall warming, because by reducing fossil fuels, you’re taking out some of the cooling effect of the aerosols,” Lelieveld said. “The bottom line is that we need to phase out fossil fuels as quickly as possible to prevent this from exceeding the 2 degrees Celsius (3.6 degrees Fahrenheit) target.”

The benefits of doing so extend to improved air quality, reduced health impacts, potential restoration of altered rainfall patterns—all while curbing climate change, he added. Thus, while increases in fossil fuel use can further destabilize several planetary boundaries, conversely, a decrease in use could positively impact multiple boundaries.

Fossil fuel extraction on land and at sea

Once completed, the controversial East African Crude Oil Pipeline will link up oil fields in Western Uganda’s Lake Albert region to the port of Tanga on the Tanzanian coast. Opponents say the pipeline’s development threatens protected areas, including forests, rivers and wetlands as well as charismatic endangered species such as African savanna elephants and eastern chimpanzees.

The potential environmental and social footprint is “huge,” said Diana Nabiruma, senior communications officer with the Africa Institute for Energy Governance. “So much so that some people have said it was as if the pipeline was designed to affect as many environmentally sensitive resources and biodiverse places as possible.”

“There are huge implications for conservation,” added Tutilo Mudumba, an ecologist with the Center for Agriculture and Bioscience International. His research indicates oil and gas activities in Murchison Falls—Uganda’s largest national park—can impact the movement patterns of elephants, with potential to heighten human-wildlife conflict and disrupt predator-prey dynamics. “Even if the pipeline didn’t come through, we are already battling changes in the environment beyond our control [due to climate change].”

Localized impacts of oil and gas extraction and distribution can reverberate over great distances, with clear global implications on land use change (a planetary boundary), while also triggering more climate change, experts say. The East African Crude Oil Pipeline project has been described as a “climate bomb” due to the CO2 it will emit as the fossil fuel it transports is burned—multiple other oil and gas projects under development across the globe have been similarly described.

“The East African Crude Oil Pipeline is a great example of where there is currently no meaningful production today, but there is a potential for an enormous amount of oil to come online,” said Bart Wickel, science and research director at the nonprofit Earth Insight. “Such [fossil fuel infrastructure] investments are really pushing us over the climate change edge, much further than we would be based on existing production.”

According to Earth Insight, more than 135 million hectares (333.6 million acres) of undisturbed tropical forest overlap with current and future oil and gas blocks in the Amazon and Congo. Drilling in these native forests would further destabilize the already transgressed land use boundary while also greatly damaging global biodiversity (another boundary).

Ecological and social consequences of such projects can cause a ripple effect through natural areas, said experts such as Wickel, but have received far less attention compared with major land use drivers, such as agricultural expansion. “What is often ignored is the massive impact of fossil fuel exploration, exploitation and infrastructure development on water resources, biodiversity and local people,” he noted.

Almost every stage of oil and gas production can leave an outsized environmental and social footprint. A review paper examining 31 studies published earlier this year states that “terrestrial wildlife were generally negatively impacted by oil extraction through road development, seismic surveys, hydraulic fracturing, installation of oil wells, contamination and other extraction disturbances.”

More challenges are introduced when oil production is shifted to the world’s oceans, where the 2010 Deep Horizon US Gulf Coast disaster serves as a warning. While that event received months of news coverage, smaller ocean spills are ongoing, with some lasting for years.

A 2021 report, for example, detailed how the amount of oil spilled in the Gulf of Guinea between 2002 and 2012—much of it coming from small spills connected to shipping and offshore activities—may have exceeded the volume of the Deepwater incident. Another report published earlier this year found that an estimated 273 tons of oil leaked into marine protected areas in UK waters—the majority of spills were the result of “small” and “chronic” leaks of around 1 ton. Across UK waters as a whole, nearly 13,000 tons of oil leaked from offshore extraction activities in the past five years, according to NGO Oceana.

Fossil fuels and biodiversity

The planetary boundary framework—with its nine boundaries—has a bottom line: Its focus on not transgressing eight of the nine boundaries is ultimately intended as a means of protecting the most critical boundary: biosphere integrity.

But here, too, fossil fuel exploitation and pollution are leaving an outsized mark, worsening the global biodiversity crisis.

For billions of years, climate and biodiversity have interacted to create the conditions for life on Earth, said Katherine Richardson, a professor at the University of Copenhagen and a planetary boundaries expert. Now, in the midst of a sixth mass extinction, the biosphere integrity boundary’s safe operating space has been overshot.

“During the last 100 years or so, humanity’s activities have had such a global impact that we are altering [natural] interactions,” Richardson said. Fossil fuel consumption is shredding the web of life—compounding impacts including pollution and habitat loss—with consequences for species and entire ecosystems, maybe soon devastating entire biomes.

The current pace of climate change is creating “big issues” with biodiversity loss, said Ingo Fetzer, a researcher at the Stockholm Resilience Centre: “It means you have large areas where the biosphere has no possibility to adapt to these rapid environmental changes.”

Ecosystems and species are feeling the heat: From the Amazon, approaching a degraded savanna tipping point to ocean corals facing “catastrophic” losses with just 1.5 degrees Celsius (2.7 degrees Fahrenheit) of warming, a rapidly changing Arctic losing sea ice en masse, African wild dog populations risking collapse, rapid disease spread among amphibians and ocean heat waves triggering phytoplankton decline, undermining ocean food webs.

Experts interviewed for this mini-series underlined again and again that drastically reducing emissions, phasing out fossil fuels, and intensifying conservation efforts are the only way to address the dual challenges posed by climate change and biodiversity loss.

“We need to reduce emissions in order to protect natural systems. These natural systems will then help us to stabilize the climate in the long term,” said Hans Otto Portner, a research scientist with the Alfred-Wegener Institut and former co-chair of IPCC Working Group II. “If we let climate change go beyond what we have set as targets based on the IPCC assessment reports, then we are challenging planetary health.”

This article first appeared on Mongabay and was originally written by Sean Mowbray, a Mongabay contributor. It has been republished here under the Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0) Creative Commons license.


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