Editor’s note: “A new study in Science indicates that reforestation projects, which restore degraded or destroyed forests, are the most effective land-based method for carbon removal and biodiversity protection. Meanwhile, the authors found that afforestation, in which trees are added where they didn’t exist before, and bioenergy cropping, in which carbon-removing crops are planted to make biofuels, can have negative effects on wildlife, outweighing the benefits of carbon removal. The research highlights the importance of identifying the best places for reforestation projects, but the authors emphasize that reforestation is not a replacement for fossil-fuel reduction.”

Evidence suggests that allowing forests to regenerate of their own accord – a process known as “proforestation” – is a more effective, and perhaps more importantly, a more immediate way of sequestering carbon from the atmosphere than planting new forests. Coined by scientists William Moomaw and Susan Masino, the term basically means, in Moomaw’s words, “allow[ing] trees that are already planted, that are already growing, to continue growing to reach their full ecological potential, to store carbon, and develop a forest that has its full complement of environmental services.”

By Charles KOLOU / Mongabay

KARÈ, Togo — Under the hot sun of an April afternoon in northern Togo, we made our way by motorcycle across the impoverished prefecture of Kozah. It wasn’t a long journey, about 30 minutes, but threading between trucks and cars on National Highway No. 1, it was a treacherous one. When we arrived, we were greeted with a smile by “Dadja” Pékémassim Ali, the 57-year-old chief of the canton of Kouméa, where the village of Karè is located.

“We’re glad you’ve come to talk about this forest, whose restoration we’re delighted to see,” he told us. “Out of ignorance, and in a desire to satisfy our needs, our people set fire to the forest and cut down all the trees. And for years, we suffered from scarce rainfall, no timber, and even hotter temperatures. Our children no longer knew of the area’s birds and other animal species.”

Ali gave us his approval to climb Karè’s mountain and visit the sacred forest known as Titiyo forest. As we entered the forest, we were greeted by a cool breeze and the sound of birdsong.

Since the 1800s, the sacred forest of Titiyo has been the site of annual rituals that involve traditional dances and the celebration of various deities. People come from throughout the canton of Kouméa and the entire Kozah prefecture.

It’s also an area of biodiversity conservation. This ecosystem, vital for the Karè village community, has suffered severe degradation since 1992, in the wake of a political crisis in Togo. Pressure from a growing population led to its rapid destruction as trees were felled for charcoal, firewood and timber, reducing the forest to almost nothing.

“Ever since we destroyed this forest by cutting down the trees, and with bushfires, mainly for hunting, the rain stopped,” said Kossi Karani, a Karè villager. “And we suffer from that because it affects our agricultural yields. The animals had disappeared, as well as the birds. There was no more life in the forest.”

But today, this sacred forest persists and has even begun to recover, thanks to the determination of a son of Karè: Sylvain Tchoou Akati.

Akati said he remembers watching helplessly as Titiyo’s destruction began, when he was just 12 years old. The tragedy left such an indelible impression that it prompted him to start fighting to restore Togo’s forests.

“The destruction of our sacred forest of Titiyo is recent, it happened before my very eyes,” he told Mongabay. “It all started with a need for wood to put a roof on the village elementary school. The forest was gradually destroyed until 2005.”

Today, Akati is the executive director of an NGO based in the capital, Lomé, known as AJEDI, or Youth Action for Integral Development. Its mission is to support and coach local communities in sustainable development. Akati’s motivation for restoring his own village’s forest comes not just from his love of nature, but also from encouragement by his uncle, Anam, well known in Karè for his love of planting trees, notably teak and mango.

Although he left Karè in 1997 to pursue his secondary and university studies in Lomé, Akati never abandoned his love for Titiyo. He became an activist for the preservation of forest ecosystems and sustainable development, and founded AJEDI in 2008. A few years later, in 2015, he set about restoring his native village’s forest.

“I cannot allow Titiyo, this sacred forest, to disappear without me doing something about it, especially given climate change. So in 2015, I visited my father, who was still alive, to tell him of my intention to restore the forest that our grandfather was responsible for preserving,” he said.

Raising public awareness

But Akati said he knew he couldn’t do it alone. Through his NGO, he began rallying the members of his community.

“We organized a meeting in the public square, which was attended by people from the surrounding villages. I explained to them the environmental, cultural, economic and social importance of restoring our forest, which is part of our shared heritage,” Akati said.

“During the training, we were made aware of how restoring the forest can contribute to good rainfall and improve agricultural production,” Tchilalo Pitekelabou, a member of the project’s monitoring committee, told Mongabay. She was one of six people appointed to the committee by the community’s members after the meeting. “We were also made aware of how forest resources can make our lives easier. That’s why we became involved, both men and women, in the restoration of Titiyo.”

The awareness-raising campaign prompted the Karè villagers, especially its women, to commit to the restoration of the forest. “In the early years, we sometimes watered the seedlings in the dry season to ensure their growth,” Pitekelabou said.

People who owned land within the forest’s perimeter agreed to give up their plots for reforestation.

A helping hand from the government

In 2019, Akati presented his project to Togo’s Ministry of Environment and Forest Resources, receiving positive feedback.

“The forest had become highly degraded and consisted of just a few trees,” said Yawo Kansiwoe, the Kozah prefectural official responsible for water, forests and the environment. “The local population and authorities were desperate to find ways of restoring it. This is what caught the attention of the NGO, which held discussions with local officials to jointly determine how the forest could be restored. Sylvain Akati’s determination encouraged us to give our full support to the NGO in all its awareness-raising and reforestation activities.”

In 2019, the first year of reforestation, the environment ministry provided technical and financial support worth $5,702 to support the reforestation of around 3 hectares (7 acres), allowing the planting of 3,500 seedlings, including Khaya senegalensis, earleaf acacia (Acacia auriculiformis), melina (Gmelina arborea), African locust bean (Parkia biglobosa), baobab (Adansonia digitata), kapok (Ceiba pentandra) and neem (Azadirachta indica) trees.

“We chose these species because they are sacred. The baobab, kapok and African locust bean are sacred in this forest,” said Koudjabalo Ayouguele, AJEDI’s local representative for the Kara region, where Kozah prefecture is located. “But beyond that, we have also planted trees such as Khaya senegalensis, which will enable us to restore the forest quickly.”

After this first year, the rest of the reforestation work fell to Akati. But he was able to draw on the commitment of local authorities eager to see Titiyo restored.

New life makes the birds sing

“We are grateful to our son Tchoou, who had the idea of enlisting us to help restore this forest,” said Ali, the Kouméa canton chief who also serves as the primary guardian of the area’s traditions and customs. “In the beginning, there were a lot of us, but along the way some became demotivated because there was no money to be made straight away. But others like us, who understood the wider importance, remained determined. And we’ll never give up.

“Before, children didn’t know about the birds in this area, but with the restoration of the forest, we can show them all the types of birds here,” he added. “And we ourselves are happy, because the birds are singing in our ears again, something we haven’t experienced here for years with the disappearance of the forest.”

As well as birds, other animals have also found refuge in the Titiyo forest. “Thanks to this forest, a fresh breeze now blows through the village of Karè,” Akati said. “It’s like a microclimate. And there are monkeys, cane rats [Thryonomys swinderianus], reptiles like the boa [sic, boa constrictors are not native to Africa], the eastern green mamba [Dendroaspis angusticeps], vipers and snakes that have returned to the forest.”

On top of this, from a cultural perspective, the local people can now once more perform traditional rites with joy.

Kansiwoe, the prefectural official, said seeing the forest’s recovery is a source of great satisfaction: “We are delighted with the encouraging results of the restoration and recovery of this forest, which at its core is a sacred place, and preserves this sacred forest tradition.”

Now that the forest has begun to be restored, it’s time to consider how to maintain it.

“Protecting this forest remains a major challenge, and it is something we are working on,” Akati said. “For the time being, the watch committee is carrying out its mission well, which consists of monitoring the forest, making fire patrols, and continuing to raise awareness so we avoid bush fires and tree cutting. So far, thanks to their work, no bush fires have been recorded. We hope, thanks to their commitment and that of the population, to continue in this way.”

Beyond that, he pointed out a practice carried out by his grandparents, which could be a crucial asset.

“What we also want to do to help preserve the forest is to reinstate an old practice or law, which prohibited entering the forest in the rainy season and which everyone respected without question. This rule also prohibited entry into the sacred forest without authorization,” he said.

In search of support

To safeguard the Titiyo community forest, Akati also needs financial and technical support. He said establishing some income-generating activities linked to the forest should increase the chances of its preservation.

“Now, we need to find ways to preserve what we’ve achieved. We’re thinking of promoting beekeeping and market gardening, and building a multipurpose facility with a solar energy system. In the long term, in addition to beekeeping, we’re also thinking of developing nontimber forest products, given the species planted in the forest.”

With his commitment to restoring forest ecosystems, Akati is also looking for support to enable him to restore other sacred forests across Kozah prefecture. Now in his 40s, he’s already hard at work restoring the sacred forest of Landa, about 5 kilometers (3 miles) from Titiyo.

“It’s not just Titiyo that was threatened with extinction,” he said. “Our experience here can now help us restore all of Kozah’s sacred forests.”

Banner image: Red-throated bee-eaters (Merops bulocki), Pehonko, Benin. Image by Yves Bas via iNaturalist(CC BY 4.0).

Editor’s note: “In recent years, the Southeast Asian country of Vietnam experienced a boom in renewable energy investments driven by generous feed-in tariffs, under which the state committed to buying electricity for 20 years at above-market prices. However, the high tariffs increased losses for Vietnam’s state-owned power utility EVN, the only buyer of the generated electricity, and led to an increase in power prices for households and factories. Authorities have repeatedly tried to reduce the high tariffs. Now they are considering a retroactive review of the criteria set for accessing the feed-in tariffs.”

“It’s really hard to build wind farms in Arizona, and if you put this into place, it’s just pretty much wiping you out,” said Troy Rule, a professor of law at Arizona State University and a published expert on renewable energy systems. “It’s like you’re trying to kill Arizona’s wind farm industry.”

United States Congressional House Republicans are seeking to prevent the use of taxpayer dollars to incentivize what they describe as “green energy boondoggles” on agricultural lands, citing subsidies that could cost taxpayers hundreds of billions of dollars over the next decade.

They are expensive to build, just finding their footing on this side of the Atlantic, and have faced backlash from parties as varied as beachfront property owners and fishermen to coastal businesses and fossil fuel backers(most of the developers have fossil fuel ties).

The future of Humboldt County’s offshore wind industry appears increasingly uncertain following mass layoffs at RWE and Vineyard Offshore, the multinational energy companies leading efforts to develop commercial-scale floating wind farms on the North Coast. The job cuts come in response to widespread market uncertainty following President Donald Trump’s efforts to ban offshore wind development in the United States.

A critical permit for an offshore wind farm planned near the New Jersey Shore has been invalidated by an administrative appeals board.

By Malaka Rodrigo / Mongabay

COLOMBO — In a dramatic turn of events, Indian tycoon Gautam Adani’s Green Energy Limited (AGEL) has withdrawn from the second phase of a proposed wind power project in northern Sri Lanka. The project, which was planned to generate 250 MW through the installation of 52 wind turbines in Mannar in the island’s north, faced strong opposition since the beginning due to serious environmental implications and allegations of financial irregularities.

While renewable energy is a crucial need in the era of climate change, Sri Lankan environmentalists opposed the project, citing potential ecological damage to the sensitive Mannar region. Additionally, concerns arose over the way the contract was awarded, without a competitive bidding process.

The former government, led by President Ranil Wickremesinghe, had inked an agreement with AGEL, setting the power purchase price at $0.82 per unit for 20 years. This rate was significantly higher than rates typically offered by local companies. “This is an increase of about 70%, a scandalous deal that should be investigated,” said Rohan Pethiyagoda, a globally recognized taxonomist and former deputy chair of the IUCN’s Species Survival Commission.

Legal battles

Five lawsuits were filed against this project by local environmental organizations, including the Wildlife and Nature Protection Society, the Centre for Environmental Justice and the Environmental Foundation Ltd. In January, the newly elected government expressed its desire to cancel the initial agreement and to renegotiate its terms and conditions, citing the high electricity tariff. Environmentalists welcomed the decision, believing the project would be scrapped entirely. However, their relief was short-lived when AGEL clarified that the project itself was not canceled, only the tariff agreement.

Government spokesperson Nalinda Jayatissa later confirmed that the project would proceed after renegotiating a lower power purchase rate. However, two weeks later, AGEL announced its complete withdrawal from the project, a decision widely believed to be influenced by the government’s stance.

Wind energy potential 

Sri Lanka has been exploring wind energy potential for more than two decades, with the first large-scale wind farm in Mannar named Thambapavani commissioned in 2020. This facility, comprising 30 wind turbines, currently generates 100 MW of power. With an additional 20 turbines planned, the Mannar wind sector would have surpassed 100 towers.

The Adani Group had pledged an investment totaling $442 million, and already, $5 million has been spent in predevelopment activities. On Feb. 15, the Adani Group formally announced its decision to leave the project. In a statement, the group stated: “We would respectfully withdraw from the said project. As we bow out, we wish to reaffirm that we would always be available for the Sri Lankan government to have us undertake any development opportunity.”

Environmentalists argue that Mannar, a fragile peninsula connected to the mainland by a narrow land strip, cannot sustain such extensive development. “If built, this project would exceed the carrying capacity of the island,” Pethiyagoda noted.

Mannar is not only a growing tourism hub, known for its pristine beaches and archaeological sites, but also Sri Lanka’s most important bird migration corridor. As the last landmass along the Central Asian Flyway, the region hosts millions of migratory birds, including 20 globally threatened species, he added.

Sampath Seneviratne of the University of Colombo, who has conducted satellite tracking research on migratory birds, highlighted the global importance of Mannar. “Some birds that winter here have home ranges as far as the Arctic Circle,” he said. His research has shown how extensively these birds rely on the Mannar Peninsula.

Although mitigation measures such as bird monitoring radar have been proposed to reduce turbine collisions, power lines distributing electricity remain a significant threat, particularly to species like flamingos, a major attraction in Mannar. The power lines distributing electricity from the already established wind farm near the Vankalai Ramsar Wetland and are already proven to be a death trap for unsuspecting feathered kind.

Nature-based tourism

Given Mannar’s ecological significance, conservationists say the region has greater potential as a destination for ecotourism rather than large-scale industrial projects. “Mannar’s rich biodiversity and historical value make it ideal for nature-friendly tourism, which would also benefit the local community,” Pethiyagoda added.

With AGEL’s withdrawal, Sri Lanka now faces the challenge of balancing its renewable energy ambitions with environmental conservation. However, there are other sites in Sri Lanka having more wind power potential, and Sri Lankan environmentalists hope ecologically rich Mannar will be spared from unsustainable wind farms projects.

Photo by Dattatreya Patra on Unsplash

Editor’s note: “I think hope is really harmful for several reasons. False hopes bind us to unlivable situations, and they blind us to real possibilities. Does anybody really think that Weyerhaeuser is going to stop deforesting because we ask nicely? Does anybody really think that if a democrat would have gotten into the White House that things would be ok? Does anybody think that vivisectors will stop torturing animals just because we stand outside with a sign?

That doesn’t mean that we shouldn’t stand out there with that sign. What it means is, do we really believe that they will stop because we do that? And if you don’t believe that, what does that mean? The book I have just recently completed is really centered around this question. Do you believe that the culture will undergo a voluntary transformation to obtain a sustainable way of living? If you don’t, what does that mean for our strategy and for our tactics? We don’t know. The reason we don’t know is that we don’t ask that question. The reason we don’t ask that question is that we’re so busy pretending that we have hope.” – Derrick Jensen December 1st, 2004

“Biosphere Collapse: We Are in a Terminal Phase

The Sixth Mass Extinction is not a future risk—it is happening now, and human activity is the sole cause.

Extinction Rates: Current rates are 100–1,000 times higher than the “background” rate of the Cenozoic era. While the oft-cited “250–300 species per day” figure is debated (due to undercounting invertebrates and microbes), conservative estimates still suggest ~150 species lost daily. For context, the Permian-Triassic extinction (“The Great Dying”) wiped out 90% of species over 60,000 years. We’re matching that pace in decades.

Habitat Destruction: 75% of Earth’s land surface is degraded by human activity. Forests (critical carbon sinks) are vanishing at 10 million hectares/year. Oceanic dead zones (hypoxic regions) have quadrupled since 1950.

Food Web Collapse: Phytoplankton (the base of marine food chains) have declined 40% since 1950. Insect biomass is dropping 2.5% annually, threatening pollination and soil health.

Conclusion: The biosphere is unravelling faster than evolution can adapt. Humans are not exempt—we are apex predators in a collapsing food web.”

Editor’s note: Water, as well as forests, do not need to be managed. They just need to be left alone.

By Petro Kotzé / Mangabay

Water seems deceptively simple and is easy to take for granted. It has no color, taste or smell and is one of the most plentiful chemical compounds on Earth. Recycled endlessly through the biosphere in its various forms, it is fundamental to keeping our planet’s operating system intact, and has done so for millions of years.

Water is life. Earth’s oceans are where life likely originated, and freshwater is essential for plants and animals to persist and thrive. It is basic to all human development. But as our 21^st-century world gallops ahead, we are vastly manipulating the water cycle at an unprecedented rate and scale to meet the ever-growing needs of an exploding population.

By 2030, we will have built enough dams to alter 93% of the world’s rivers. Estimates vary, but we already use around 90% of the planet’s freshwater to grow our food. More than half of us now live in cities, but by 2050 a projected 68% of the world’s nearly 8 billion people will reside in urban areas. That metropolitan lifestyle will require astronomical amounts of water — extracted, treated, and piped over large distances. Humanity also prevents much rainwater from easily infiltrating underground, reducing aquifers, as we pave over immense areas with impermeable concrete and asphalt.

But these easily visible changes are only the proverbial tip of the iceberg. Researchers are shining new light on sweeping human alterations to Earth’s water cycle, many playing out in processes largely unseen. In the Anthropocene — the unofficial name for the current human-influenced unit of geologic time — we are already pushing one of Earth’s most fundamental and foundational systems, the hydrological cycle, toward the breaking point.

Trouble is, we don’t yet know when this threshold may be reached, or what the precise consequences will be. Scientists are resolutely seeking answers.

Water cycle basics

The hydrological cycle is powered by the sun and flows through eternal inhalations and exhalations of water in different states, as it is exchanged between the atmosphere and the planet. Liquid water from oceans, lakes and rivers rises via evaporation into the sky, to form water vapor, an important greenhouse gas that, like carbon dioxide, helps insulate the planet to maintain that “just right” temperature to maintain life as we know it.

Atmospheric water vapor then changes to liquid, falling to earth as precipitation. It then flows as runoff again across the landscape, and what doesn’t go back into waterbodies, settles into soils, to be taken up by plants and released via transpiration as vapor skyward. A large amount of freshwater is also locked in glaciers and icecaps.

Within this cycle, there are constant complex interactions between what scientists call blue and green water. Blue water includes rivers, lakes, reservoirs and renewable groundwater stores. Green water is defined as terrestrial precipitation, evaporation and soil moisture.

A fully functioning hydrological cycle, with balanced supplies and flows of blue and green water, is essential to terrestrial and aquatic ecosystems, human food availability and production, and our energy security.

It also regulates Earth’s weather and influences climate. Atmospheric temperature, for example, is dependent on evaporation and condensation. That’s because as water evaporates, it absorbs energy and cools the local environment, and as it condenses, it releases energy and warms the world. Throughout the Holocene geological epoch, a relatively stable water cycle helped maintain balanced temperatures and conditions able to support civilization.

However, in the Anthropocene, human activity has impacted the water cycle, the climate and ecosystems. For one, as more human-produced CO₂ and methane build up in the atmosphere, more solar energy is held by the planet, causing global warming. And the hotter the air, the greater the quantity of water vapor the atmosphere can hold. That’s bad news because water vapor is itself a powerful greenhouse gas, greatly increasing the warming.

Measuring hydrological cycle change: ‘It’s complicated’

As our anthropogenic manipulation of the water cycle escalates on a global scale, we urgently need a holistic way to monitor these modifications and understand their impacts. Yet, the topic has not received the urgent scientific attention it requires. “To the best of our knowledge, there is no study comprehensively investigating whether human modifications of the water cycle have led, could be leading, or will lead to planetary‐scale regime shifts in the Earth system,” researchers noted in a 2020 paper on the role of the water cycle in maintaining fundamental Earth functioning.

One key concern of scientists: If severe hydrological shifts occur in too many regions, or in key regions that greatly influence the water cycle or water availability (such as the Amazon), then that could provoke shifts in other regions, in a global chain reaction, says study co-author Dieter Gerten, working group leader and Earth modeling coordinator at the Potsdam Institute for Climate Impact Research in Germany.

“Conceptually we know that there must be a limit for how much we can disturb the [hydrological] system before we start feeling serious impacts on the Earth system and then, by extension, to humanity,” says one of the paper’s other co-authors, Miina Porkka, a postdoctoral researcher at the Water and Development Group at Aalto University in Finland.

International researchers under the auspices of the Stockholm Resilience Centre have been hammering away at answering these questions. They had to start with the basics. One big problem to date has been scientists’ lack of a metric for quantifying serious water cycle alterations. How do we even measure changes to the water cycle?

“It gets complicated,” says Gerten, who has been involved in the research to bring a global perspective to local water management since 2009, as conducted under the Planetary Boundaries Framework; Gerten is also a professor of global change climatology and hydrology at Humboldt University of Berlin.

Measuring change: Blue water

The Planetary Boundaries Framework defines a safe operating space for humanity as represented by nine natural global processes that, if severely destabilized, could disrupt Earth’s operating system and threaten life and civilization. The freshwater planetary boundary presents one such threshold, and scientists are working to define a global limit to anthropogenic water cycle modifications.

Initially, in 2009, river flow was used to try and measure the boundary threshold, Gerten explains, because blue water in all its forms was seen to integrate the three largest anthropogenic manipulations of the water cycle: human impacts on precipitation patterns, modifications of soil moisture by land use and land cover; and water withdrawals for human use.

This research used a simple calculation of the global sum of the average annual surface water flow in rivers, with an assumed 30% of that accessible water needing to be protected. This “freshwater use” boundary was set at 4,000 cubic kilometers (960 cubic miles) per year of blue water consumption. This is at the lower limit of a 4,000-6,000 km3 (960-1,440 mi3) annual range designated as a danger zone that takes us “too close to the risk of blue and green water-induced thresholds that could have deleterious or even catastrophic impacts on the Earth System,” researchers wrote in a 2020 paper that evaluated the water planetary boundary.

With only an estimated 2,600 km3 (624 mi3) of water withdrawn annually at the time of the study, scientists concluded we were still in the safe zone. However, “That [conclusion] was immediately criticized,” Gerten says, in part because scientists were already seeing ample regional water-related problems. Another criticism argued that the measure of blue water alone did not reflect all types of human interference with the water cycle and Earth system.

Gerten later led work that proposed quantifying the boundary by assessing the amount of streamflow needed to maintain environmental flow requirements in all river basins on Earth. This approach had the advantage of recognizing regionally transgressed limits and thereby deduced a global value.

According to this newer calculation, the freshwater use planetary boundary should be set much lower, at about 2,800 km3 (672 mi3), Gerten says, which means humanity is already much closer to the danger zone than previously thought. “Water is more limited on Planet Earth than we think,” Gerten cautions.

Redefining the freshwater boundary: Green water

Over time, a consortium of researchers was formed to deeply scrutinize the freshwater boundary. This resulted in follow-up work in 2019 and 2020 proposing that the freshwater boundary be divided into sub-boundaries related to major stores of freshwater: namely atmospheric water, frozen water, groundwater, soil moisture, and surface water.

Since then, scientists simplified their approach further. “Even though we are talking about very complex matters,” Porkka says, the boundary definition, to be useful as a metric, needed to stay “relatively simple.”

The most recent and sweeping reassessment of the freshwater planetary boundary was published in 2022. “Our suggestion is to … change the name from ‘freshwater use planetary boundary’ to ‘freshwater change planetary boundary,’” says study lead author Lan Wang-Erlandsson from the Stockholm Resilience Centre. “Then, to have two components,” she adds, “One for green water, and one for blue water.”

“Water has so many functions in the Earth system, and many of them happen invisibly via green water,” Gerten explains. “We don’t see it and we don’t feel it. That’s why [green water] has been neglected over decades. The focus has been on river flows and groundwater because we can see it, feel it, use it, and touch it. But [as a result] a big share of the water cycle has been overlooked.”

The newly accepted metric for tracking green water: The soil moisture in the root zone of plants, or more technically: “the percentage of ice-free land area on which root-zone soil moisture anomalies exit the local bounds of baseline variability in any month of the year.”

This new proxy is appealing because it is directly influenced by human pressures with change over time measurable. In turn, soil moisture directly impacts a range of large-scale ecological, climatic, biogeochemical and hydrological dynamics.

Using this novel green water boundary transgression criteria, scientists detected a major hydrological departure from the baseline set during the Holocene. And the evidence for such a departure is overwhelming: Researchers found “unprecedented areas [of Earth] with root-zone soil moisture anomalies,” indicating an exit from the so-called “safe zone.”

A second criteria, Earth Systems Resilience, was also instituted. Researchers evaluated the state of regional climate systems (ranging from monsoons to land carbon sinks and large biomes) to see which have seen enhanced changes in their process rates, resulting in ripple effects that could destabilize the Earth system, Wang-Erlandsson explains.

A transgressed freshwater change boundary

Unfortunately, examples of compromised Earth System Resilience transgressions are rife across the planet.

Take the Amazon Rainforest, for instance. It is now understood that carbon uptake likely peaked there in the 1990s, with a sequestration decline since then driven by escalating climate change and fires, along with global demand for agricultural commodities, which spurred extensive Amazon forest clearing, bringing major land-use change. More recently, African tropical forests have passed their carbon uptake peak.

When these vast biomes and natural systems are put under extreme multiple stressors, the effects can self-amplify and lead to greater, more rapid, rates of change, Wang-Erlandsson says: In South America, this combination of stressors, particularly deforestation and climate change, is inducing intensifying drought, which is now leading to cascading perturbations in living systems. Scientists now think the rainforest biome, stable for thousands of years, is reaching a tipping point, and could quickly transition to seasonal forest, or even a degraded savanna. This shift could lead to the transformation of the South American monsoon system, and a permanent state of reduced rainfall and impoverished biodiversity.

But what starts in the Amazon won’t likely stay there: The rainforest’s destruction will release massive amounts of carbon, intensifying climate change, potentially leading to climate and ecological tipping points in other biomes.

Another concerning example (although debated) of an Earth system shift is the suggestion of a weakening carbon fertilization process, in which higher atmospheric carbon concentrations result in speeded-up photosynthesis as plants try to improve water efficiency in the face of drought. It is thought that this effect is happening already, brought on by limitations in nutrient and soil moisture availability.

In drylands, climate change and ecosystem degradation are triggering vicious cycles of infiltration capacity loss — a decrease in soil moisture and moisture recycling, resulting in increasing desertification and biodiversity loss. In polar permafrost regions, soil moisture saturation could accelerate thawing, generating dangerous methane emissions. Methane is a greenhouse gas far more powerful than carbon dioxide.

Alarmed by the water cycle’s departure from the Holocene baseline, and noting “worrying” signs of low Earth System Resilience, researchers early in 2022 declared the green water boundary to be “considerably transgressed.” The situation, they said, will likely worsen before any reversals in the trend will be observed. “Green water modifications are now causing rising Earth system risks at a scale that modern civilizations might not have ever faced,” the study states.

We don’t yet know what the planetary-scale impacts will ultimately be, but, Porkka says, we have an idea of how impacts could be felt in different parts of the world.

Disastrous extreme weather events

Regional extreme events, including floods and mega droughts, are already occurring, Porkka notes. Examples are to be found on every continent.

On Africa’s southeast coast, as just one example: the World Weather Attribution (WWA) network of scientists has found that human-induced climate change has increased the likelihood and intensity of heavy rainfall associated with tropical cyclones. The group based their findings on an analysis of tropical storms Ana and Batisrai, which battered parts of Madagascar, Mozambique, Malawi and Zimbabwe in early 2022. Both cyclonic systems brought devastating floods that caused severe humanitarian impacts, including many deaths and injuries and large-scale damage to infrastructure. These sorts of extreme weather events put great pressure on socioeconomic and political institutions, and could easily destabilize struggling developing nations.

And the situation is worsening. The number of disasters related to weather, climate or water hazards has increased fivefold over the past 50 years, according to the World Meteorological Organization. An assessment from 1970 to 2019 found more than 11,000 reported disasters attributed to such hazards globally, resulting in more than 2 million deaths and $3.64 trillion in losses. All are indicative of a careening hydrological cycle.

Of the top 10 climate disasters, those causing the largest human losses during that period were droughts (650,000 deaths), storms (577,232), floods (58,700), and extreme temperature (55,736 deaths). In economic terms, the top 10 events included storms (costing $521 billion) and floods ($115 billion).

Porkka points out, however, that freshwater system destabilization impacts can be more subtle than extreme events. Widespread irrigation of croplands, for example, can increase evaporation to such a high degree that even distant precipitation patterns are altered. Part of the problem is that we do not know if consequences like these are negative or positive.

“[W]e know that we’re changing the [hydrological] system in fundamental ways and, once we do, we don’t really know how the impacts accumulate,” says Porkka.

While many riddles remain, scientists now feel they have a reliable metric for accurately tracking transgressions of the freshwater change boundary. “The prime question was what the key variables are, and I think that is relatively solid now with soil moisture [green water] and river flows [blue water],” Gerten says. “The next questions are, where exactly to put the boundaries, and what happens if they are transgressed?”

Based on these findings, researchers are calling for urgent action: “The current global trends and trajectories of increasing water use, deforestation, land degradation, soil erosion, atmospheric pollution, and climate change need to be promptly halted and reversed to increase the chances of remaining in [Earth’s] safe operating space.”

That’s a tall order, and no matter humanity’s actions, we don’t know how things will play out. “Water is so fundamental and elemental, and at the same time, so varied,” Gerten says, and there is no silver bullet for solving our hydrological problems.

Banner image: Farmers tending to their agricultural land in Uzbekistan. Image by Petro Kotzé.

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Photo by Leslie Lopez Holder on Unsplash