Amid the escalating threats of a warming world, and with the latest annual United Nations global climate conference (COP28) behind us, there is one critical message that’s often left out of the climate change discourse. Halting overfishing is itself effective climate action.

This argument is the logical conclusion of a plethora of studies that unequivocally assert that stopping overfishing isn’t just a necessity, it’s a win-win for ocean vitality, climate robustness and the livelihoods reliant on sustainable fisheries.

The intricate relationship between climate change and ocean ecosystems was the subject of recent collaborative research — led by researchers at the University of British Columbia — that highlighted the crucial links between overfishing and climate change.

Finding the connections

Our collaborative team of international researchers applied a host of methodologies ranging from literature reviews to quantitative and quality analysis. The findings of this research illuminate eight key multifaceted impacts.

1 — Ending overfishing isn’t merely an ecological imperative but a vital climate action. Doing so would bolster marine life resilience in the face of climate shifts and reduce associate carbon emissions.

2 — Large subsidized fishing boat fleets can actually be a burden on small-scale fisheries, leaving them disproportionately vulnerable to shocks. In turn, overfishing not only depletes resources but also escalates carbon emissions, intensifying climate impacts on these fisheries and their communities, particularly women.

Additionally, the vulnerability of shellfish fisheries to climate stressors further underscores the importance of adaptive strategies tailored to local conditions.

3 — Success stories, like the recovery of European hake stocks, reveal a direct tie between stock recuperation and reduced emissions intensity from fisheries. We must champion and also learn from these successes.

4 — Ecosystem-based fisheries management reverses the “order of priorities so that management starts with ecosystem considerations rather than the maximum exploitation of several target species.”

Ecosystem-based fisheries management has considerable potential to enhance sustainable catches while fostering carbon sequestration. This is perhaps best exemplified by the successful implimentation of ecosystem-based fisheries management in the western Baltic Sea.

5 — Heavy metal pollution in the ocean — such as mercury or lead waste — intensifies the negative impacts of warming and overfishing. This pollution reinforces the need for developing multifaceted regulations based around ecosystem and ocean sustainability solutions.

6 — Overfishing exacerbates climate and biodiversity threats. Climate change contributes to less defined and predictable seasons and is causing reproductive challenges and the propagation of diseases in fish populations — among other issues.

Via Pixabay. .

Adding to these problems, overfishing itself is altering ecological dynamics, modifying habitats and opening new pathways for invasive species. These compounding crises further exacerbate the impacts of overfishing on marine ecosystems while at the same time making fish populations more vulnerable to climate change.

The above factors all combine to reduce the catch potential in any given ecosystem. In turn, fishers are forced to venture farther and deeper in the ocean to fish — increasing carbon emissions, personal risk factors to fishers and bycatch concerns.

7 — International fisheries management must play a central role in promoting biodiversity and retaining the ocean’s carbon sequestration potential. While 87 nations have signed the UN’s Biodiversity of Areas Beyond National Jurisdiction Treaty (also known as the High Seas Treaty), only one has ratified it. This treaty must be fully ratified and its effective implementation should be contingent upon the creation of marine protected areas that cover at least 30 per cent of the high seas.

8 — The ocean has huge carbon sequestration potential. Shifting from the generally accepted maximum of sustainable yield management to maximizing carbon sequestration in fisheries management could further advance climate goals.

Future regulations should allocate a percentage of the annual fish quota to maintain the carbon sequestration function of marine animals. Simply put, beyond just being food, fish stocks serve vital carbon sequestration and biodiversity services that directly benefit humanity. Future regulations should reflect this reality.

A simple goal

This joint collaborative research underscores the urgency of this issue. Ending overfishing isn’t just an ecological imperative but a linchpin for climate action. Furthermore, fisheries aren’t mere victims in these dynamics, but have real agency to play a pivotal role in either exacerbating or mitigating climate change.

An ideal governance framework would focus on managing ecosystems with considerations for their diverse benefits, based on the best evidence available. Regulation of fisheries, while controversial, is essential to not overly exploit such a valuable public resource.

As we gear up to the next COP, we would do well to remember these conclusions. Without nurturing ocean life, addressing climate change becomes an uphill battle. Sustainable fisheries management is not just an ecological necessity. It is also the cornerstone of a resilient, sustainable future.

Rashid Sumaila, Director & Professor, Fisheries Economics Research Unit, University of British Columbia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The health benefits of eating seafood are appreciated in many cultures which rely upon it to provide critical nutrients vital to our physical and mental development and health. Eating fish and shellfish provides significant benefits to neurological development and functioning and provides protection against the risks of coronary heart disease and Type 2 diabetes.

Over three billion people get at least 20 per cent of their daily animal protein from fish. In countries from Bangladesh to Cambodia, Gambia, Ghana, Indonesia, Sierra Leone and Sri Lanka, fish consumption accounts for 50 per cent or more of daily intake.

However, expansive growth of human populations globally puts immense pressure on the health of wild fish stocks. Fish catches peaked in 1996, and one-third are considered overexploited. With less fish available to still more people, the future of fish as an accessible source of nutritious food is at risk, particularly among low-income countries.

Seafood nutrient losses

Threats to seafood access aren’t just due to overharvesting. There is a growing body of research showing that higher water temperatures due to climate change can impact the presence and abundance of the catch, through shifts in species distribution and changes in the species caught. This impacts the amount that can be harvested, as well as the nutritional value of that harvest.

A new study (which Aaron MacNeil contributed to) quantified nutrient availability from seafood through time considering the twin impacts of overfishing and climate change.

Focusing on four key nutrients important to human health — calcium, iron, omega-3 fatty acids and protein — the authors argue that nutrient availability in seafood has been declining since 1990 and will further decline by around 30 per cent by 2100 in predominately tropical, low-income countries with 4 C of warming.

These predicted losses are significant. While global famines are now relatively rare, some 50 million people suffer from “hidden hunger” — nutrient-deficient diets that are masked by being otherwise calorie-sufficient.

For animal-derived nutrients such as B12 and omega-3 fatty acids, nearly 20 per cent of the global population are at risk of becoming nutrient-deficient in coming decades due to reliance on wild-caught fish.

Climate change is also affecting natural cycles of nutrients in the ocean. For example, it has been predicted that increasing water temperatures will cause a decline in natural omega-3 availability from seafood by more than 50 per cent by 2100. At the bottom of the food chain, microalgae that naturally produce omega-3s are less productive at warmer temperatures and this cascades through marine and freshwater food chains resulting in fish having less omega-3s available to eat and store in their bodies.

These kinds of climate-caused losses are expected to disproportionately affect vulnerable populations, especially in inland Africa.

Challenges and strategies for nutritious seafood

Aquaculture can help supply some of these missing nutrients, but it is an industry also vulnerable to the effects of climate change. A recent study predicted that 90 per cent of aquaculture will be impacted by climate change, where warm waters increase disease outbreaks, harmful algal blooms and impact the availability of feed supplies.

Global disparities already exist in food security that will be exacerbated by climate change in the future. Yet the effects of warming waters on nutrient availability from seafood will compound these inequities among tropical and low-income countries.

These results suggest a major challenge to our future nutritional security that demands strong fisheries and aquaculture management to facilitate equitable distribution of nutritious seafoods.

Improvements are possible.

For example, redirecting nine per cent of Namibia’s fisheries toward its coastal population would alleviate the severe iron deficiencies experienced there. Policies that prioritize nutrient supply would help maintain diets as the climate warms.

The recent United Nations call to action for blue transformation emphasizes the need to provide sufficient aquatic food from fisheries and aquaculture for our growing population in a sustainable way.

To do this, strategies are needed to achieve healthy, equitable and resilient food systems that adequately deal with overfishing, strive for equal access to resources and markets and mitigate the environmental impacts of aquatic food production.

Ultimately, these strategies must support the nutritional security of vulnerable nations and consider global health equity and the cultural significance of seafood.

Stefanie Colombo, Canada Research Chair in Aquaculture Nutrition, Dalhousie University and Aaron MacNeil, Professor, Department of Biology, Dalhousie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Featured Image: (Pexels), CC BY

In early 2023, the Guardian published an article suggesting that more than 90% of rainforest carbon offsets are worthless. These credits are essentially a promise to protect forests and can be bought as a way to “offset” emissions elsewhere. Verra, the largest certifier of these offset credits, said the claims were “absolutely incorrect” but the story still shook confidence in the billion-dollar market. Soon after, Verra’s CEO stood down.

The claims in the Guardian article rested heavily on analysis which had been published as a preprint (before peer review). Now the research has been fully peer-reviewed and is published in the journal Science. It shows unequivocally that many projects which have sold what are known as REDD+ (reducing emissions from deforestation and degradation) credits have failed to reduce deforestation.

REDD+ projects aim to slow deforestation (for example, by supporting farmers to change their practices). They quantify the carbon saved through reducing deforestation relative to what would have happened without the project, and sell these emission reductions as credits.

Such REDD+ credits are widely used to “offset” (that is, cancel out) emissions from companies (who may use them to make claims that their operations are carbon neutral) or by people concerned about their carbon footprint. For example, if you were planning to fly from London to New York you might consider buying REDD+ credits that promise to conserve rainforest in the Congo Basin (with added benefits for forest elephants and bonobos). Offsetting your return flight would appear to cost a very affordable £16.44.

However, while previous analysis showed that some REDD+ projects have contributed to slowing deforestation and forest degradation, the central finding from the new study is that many projects have slowed deforestation much less than they have claimed and, consequently, have promised greater carbon savings than they have delivered. So that guilt-free flight to New York probably isn’t carbon neutral after all.

The finding that many REDD+ carbon credits have not delivered forest conservation is extremely worrying to anyone who cares about the future of tropical forests. We spoke to Sven Wunder, a forest economist and a co-author of the new study. He told us that: “To tackle climate change, tropical deforestation must be stopped. Forests also matter for other reasons: losing forests will result in loss of species, and will affect regional rainfall patterns. Despite the evidence that REDD+ has not been delivering additional conservation, we cannot afford to give up.”

Deforestation could simply move elsewhere

Carbon credits also face other challenges, one of the biggest being “leakage” or displacement of deforestation. Leakage may occur because the people who were cutting down the forest simply relocate to a different area. Alternatively, demand for food or timber that was fuelling deforestation in one place may be met by deforestation elsewhere – perhaps on the other side of the world. Another problem is ensuring that the forests are protected in perpetuity so that reduced deforestation represents permanent removal of carbon from the atmosphere.

Addressing these challenges is vital because selling carbon credits is an important source of finance for forest conservation. It is not too dramatic to say that unreliable REDD+ credits directly threaten forests.

However, this is an active research area and new approaches are increasingly available. Andrew Balmford is a professor of conservation science at the University of Cambridge who is actively developing methods to improve the credibility of forest carbon markets. He says the new study raises some important concerns but that more robust and transparent methods have been developed. Deploying these new methods, he told us, is “an urgent priority”.

Change is also needed to how certification operates. At present, there are incentives for verifiers to inflate estimates of the amount of deforestation that would have happened without the project, and therefore the number of credits that can be issued. Sven Wunder explains: “We need to move beyond vested interest towards independent governance employing scientifically informed, cutting-edge methods.”

Reasons to be cautious

Even if these problems can be solved, there are still reasons to be cautious about the role of carbon offsets in combating climate change. First, there is the risk that offsetting actually increases emissions because people or companies might feel more comfortable emitting carbon if they believe they can undo any damage by simply buying carbon credits. For this reason, some argue that offsets must only ever be a last resort, after all non-essential emissions have been cut (the problem being of course: who decides which emissions are essential?).

Second, keeping warming within 2°C will require most deforestation to be stopped and major reductions in fossil fuel emissions. There is a limit to which one can be used to balance out the other.

REDD+ projects mustn’t harm local farmers.

Finally, there are serious equity concerns with some forest carbon offsets. If forest conservation is achieved by stopping farmers in low-income countries from clearing land for agriculture, REDD+ may exacerbate poverty: your long haul flight would come at the expense of others being able to feed their families.

We don’t know how much it would cost to achieve genuinely additional offsets which avoid leakage and ensure equity but it is likely to be considerably more expensive than forest carbon credits currently sell for. A higher price would reduce the perception that offsetting is an easy option and should encourage more focus on reducing emissions.

So, should you buy those cheap forest carbon offsets when taking a flight? Unfortunately, there’s currently little evidence that doing so will really make your journey carbon neutral. If you want to contribute to tackling climate change, perhaps the only real option is to not take the flight.

Julia P G Jones, Professor of Conservation Science, Bangor University and Neal Hockley, Senior Lecturer in Environmental Economics & Policy, Bangor University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Like the heat waves on land we have all grown familiar with, marine heat waves are being amplified by climate change. These extreme warm water events have ushered in some of the most catastrophic impacts of climate change and are now a major threat to ocean life.

Coral reefs, which are home to a quarter of all life in the ocean, are the most vulnerable.
This is a dire situation, given the vast number of people who depend on coral reefs for their sustenance and livelihoods.

As climate change pushes corals beyond their limits, a key question is why different corals vary in their sensitivity to warm waters.

In our new study in Science Advances, we examined the genetics of hundreds of individual corals during the 2015-16 El Niño-driven heat wave. Our results suggest that heat waves have hidden impacts on the genetic composition of reef-building corals. Understanding this could help scientists bolster reef resilience to future heat waves.

Pushing corals out of their comfort zones

Corals are highly adapted to the temperature of their local waters, with temperatures even 1 C warmer than normal pushing them out of their comfort zone.

Unusually warm water disrupts the vital relationship between stony corals (the reef-builders) and their symbiotic partners, microscopic algae that provide food to the corals. This causes coral bleaching, and in many cases mortality.

The tropical heat wave at our study site in the central Pacific Ocean, Kiritimati (Christmas Island), lasted for ten months, a world record. This led to extensive coral bleaching, presenting an opportunity to determine why some corals died and others survived.

Cryptic diversity within a widespread coral species

We focused on the widespread lobed coral (Porites lobata). This species is amongst the most heat-tolerant corals, and despite almost 90 per cent of all coral cover being lost on Kiritimati, over half of lobed corals survived.

In fact, some Porites colonies didn’t bleach at all.

Why?

Using genomic tools, we identified three distinct types of Porites lobata on Kiritimati. These lineages, which may represent distinct species, are indistinguishable by eye but genetically different.

Such biodiversity is known as “cryptic diversity” or “hidden diversity.” Although cryptic diversity is widespread across corals, its ecological implications remain unclear.

Marine heat waves threaten cryptic diversity

We found that one genetic lineage of Porites was highly sensitive to the heat wave: only 15 per cent of its colonies survived compared to 50-60 per cent in the other lineages. Thus, even in a coral widely considered to be stress tolerant, heat waves can have hidden impacts, threatening diversity that is invisible to the naked eye.

If future marine heat waves continue to have similar effects, eventually sensitive genotypes like this one could be completely lost, reducing the genetic diversity of coral reefs.

Because interbreeding between cryptic lineages and species can offer a potential avenue for future adaptation, losses of genetic diversity could make a bad problem even worse by limiting future adaptation to changing environments.

A forced breakup

So why did Porites lineages on Kiritimati differ in survival?

One hypothesis is that they house symbiotic partners with different heat sensitivities. Using metabarcoding, a technique that attempts to identify everything found living in the coral tissue, we identified which symbionts were partnered with which corals before, during and after the heat wave.

We found that the distinct Porites lineages had different partnerships before the heat wave. Porites species pass on their symbionts from one generation to the next and so these relationships likely arose over many generations.

By the end of the heat wave, however, one of Porites’ unique algal partners had been virtually eliminated. The survivors of all lineages had similar symbionts, suggesting specialized relationships between the partners had been lost under extreme temperatures.

Thus, not only was a cryptic coral lineage left teetering on the edge of local extinction, but its specialized symbiotic relationship had also been forcefully broken up.

Implications for conserving coral reefs

Due to climate change and other threats, we are currently experiencing a biodiversity crisis. Our findings underscore that this crisis extends beyond what the eye can see.

Cryptic species often occupy unique ecological niches and play specific roles within ecosystems. Discovering these hidden differences can enhance our understanding of how ecosystems function. But worryingly, we may be losing this critical diversity before it is even discovered.

Continued study of cryptic diversity could prove essential to building climate resilient ecosystems. Using heat tolerant cryptic lineages in restoration approaches, for example, could help make reefs more tolerant to future warming.

Ultimately, greenhouse gas emissions must be rapidly reduced to curb planetary warming. While targeted efforts to bolster coral reefs against climate change may buy limited time, the current heat waves blanketing the world’s oceans underscore that the ocean is simply becoming too hot for corals and we need to act rapidly to mitigate the damage.

Samuel Starko, Forrest Research Fellow, The University of Western Australia and Julia K. Baum, Professor of Biology, University of Victoria

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Featured image: A healthy reef on Kiritimati (Christmas Island, Republic of Kiribati).
(Danielle Claar), Author provided

When asked to situate the world’s most iconic rainforest on a map, most people will pinpoint Brazil. And given the intense media coverage of the country’s deforestation and fires – concerns reached a peak under former president Jair Bolsonaro and his free-for-all approach – they might also imagine a thick black soot clinging to the remaining trees. While newly re-elected president Lula da Silva has vowed to prioritize the Amazon forest and sparked hope among environmentalists, deforestation in the Brazilian section of Amazon remains of deep concern.

That interest is only set to grow as Brazil gets ready to host a high-level meeting to renew the Amazon Cooperation Treaty Organization (ACTO) in the northern town of Belem on 8 and 9 August. Bringing together the eight countries containing the Amazon forest – Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname, and Venezuela – along with senior officials from the United States and France, the event will enable them to discuss how to attract investment, fight deforestation, protect indigenous communities and encourage sustainable development.

The meeting will also be the occasion for sustainability scientists such as ourselves to draw attention to one of the Amazonian ecosystems that will be just as vital to protect if we are to limit global warming to the safer threshold of 1.5C above pre-industrial levels: Bolivia.

One of the highest carbon-emitting countries per capita

I have studied the flows that contribute to deforestation in the Amazon for more than five years. Earlier this year, I met with academics, environmental NGOs, smallholder farmers, and multilateral development banks in Bolivia to learn more about their work to protect the Bolivian Amazon.

Bolivia is not only at the centre of the current international rush for lithium. It is also one of the world leaders in deforestation. According to Global Forest Watch, the country lost more than 3,3 million hectares of humid primary forest from 2002 to 2021 to deforestation, or the equivalent of 4 million soccer fields, with an exponential growth in deforestation rates of more than 5.5% per year over the last two decades.

Bolivia’s forests have also increasingly been forced to cope with a combination of drought and large wildfires. In 2020 alone, 4,5 million hectares were affected by such fires, of which more than 1 million hectares took place in protected areas (data from Fundación Amigos de la Naturaleza) – and the deforestation trend is worsening (see Figure 1). As a result, Bolivia has placed itself at the top of carbon-emitting countries per capita, with emissions of 25 tCO2eq per person per year – more than five times higher than the global average, ahead of large economies like the United States and the United Arab Emirates.

Accelerated deforestation might seem paradoxical in a country known internationally for its commitment to the “Rights of Mother Earth”. But it seems that the government has chosen to prioritize economic development based on natural resources over its promises to become stewards of Nature.

The accelerated loss of tropical rainforest is the result of destructive and familiar combination: increased global demand for commodities such as soy and cattle, and extractive national and regional policies with the explicit ambition to boost economic growth with little consideration on its environmental impact.

Soybean production has accelerated from negligible levels in 1970 to almost 1.4 million hectares in 2020, and 5 million hectares deforested since 2001 is mainly used for cattle. A similar trend can be observed for the export of beef in the last years, as well as for mining.

Between 2015 and 2021, the number of mining concessions in the country’s Amazon regions (La Paz, Beni and Pando) has increased from 88 to 341 while the mining area (cuadriculas in Spanish) have increased from 3,789 to 15,710 (+414%). According to Bolivian mining law, a cuadricula is a square of 500 meters per side, with a total surface area of 25 hectares, according to the Study Center for Labor and Agrarian Development (CEDLA). The rapid expansion of illegal gold mining in the Amazon powers one of the country’s largest export industries. As global gold prices have increased, the industry is creating massive social and environmental challenges as well as severe health threats to indigenous communities.

This expansion is fuelled in part by generous fossil-fuel subsidies, which in turn finance the growth of the soy, cattle and mineral sector. According to 2021 data from the International Monetary Fund fossil-fuel subsidies consume 6,7% of Bolivia’s GDP. In addition, illegal settlements in the lowlands feed from these larger economic changes as communities transform forests into agricultural production lands through destructive slash-and-burn techniques, which increase wildfire risks.

How to save the Amazon

Regional collaboration to protect the Amazon took a serious hit during the presidency of Jair Bolsonaro in Brazil. The announced revitalization of cooperation in the Amazon basin and surrounding forests through the Amazon Cooperation Treaty Organization offers a unique window of opportunity to end deforestation. But this opportunity will be wasted unless the following key issues are addressed.

• Pan-continental regulation: It is no secret that countries that enforce strict forest-conservation laws tend to see the most ruthless industries emigrate to less-regulated countries; experts call this phenomenon “deforestation leakage”. To protect the Amazon in Brazil, the international community therefore has every interest in ensuring that Bolivia is not forgotten. World Bank data shows that Bolivia is a perfect destination for its neighbours’ predatory sectors, with much of the state’s regulation rolled back in the past 10 years.

  To counter this, the Amazon Cooperation Treaty Organization should form a task force that directly addresses such cross-border leakage risks to protect the forests of the region, and the people who depend on them for their livelihoods. Lessons from studies of the effects of previous zero-deforestation policies] will offer useful guidance in these ambitions. Countries should ramp up their support for cross-border supply chain transparency, provide enough resources to enforce environmental legislation on the ground, and make sure indigenous rights are properly protected.

• Phasing out forest-hungry policies and industries: The case of Bolivia also highlights a general challenge that countries in the region are facing: the need to not only “scale up” green financial innovations, but also actively phase out unsustainable economic activities, harmful subsidies and policies that increase inequality.

  Don’t get us wrong: saying goodbye to industries like unchecked cattle ranching, and incentives such as fossil-fuel subsidies will take strong political will. But the world abounds with examples to draw inspiration from. Two include the Just Energy Transition Partnership that was concluded at the annual climate summit in Glasgow, COP26 and the international support to help decarbonize coal retirement in Indonesia. They show it is possible to move away from harmful industries while making sure local communities aren’t left behind.

• Cleaning up the finance industry: In today’s globalized economy, large companies often rely on capital from financial institutions to conduct their operations. The financial sector has made progress in mobilizing its influence as owners and lenders to put pressure on industries associated with deforestation risks in the Brazilian Amazon. The sector must now mobilize to help protect the enlarged Bolivian Amazon.

Cascading negative changes resulting from deforestation, such as disrupted hydrological cycles, negative health impacts, and biodiversity loss will eventually impact negatively on investments. The financial sector thus needs to support national legislation and financial regulation that shift investments away from extractive economic practices that amplify social inequalities, toward new ways of protecting forests while simultaneously promoting education, health, sanitation, employment, and other development goals. Major initiatives like the United Nations’ Principles for Responsible Investment, pension funds in the Global North, and international development banks must work closely with countries around the Amazon basin to make sure deforestation and climate ambitions are translated into action.

Bolivia’s forests, and the communities that depend on their resilience for their livelihoods, are facing a perfect deforestation storm. Swift national and international action is of the essence.

This article was co-written with Guido Meruvia Schween, a programme officer at the Swedish Embassy in La Paz, Bolivia.

Victor Galaz, Deputy Director and Associate Professor, Stockholm Resilience Centre, Stockholm University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Featured Image: Deforestation in Santa Cruz, Bolivia (2021). Photo courtesy of Overview.
https://www.over-view.com/, CC BY-NC

Across the world, rainforests are becoming savanna or farmland, savanna is drying out and turning into desert, and icy tundra is thawing. Indeed, scientific studies have now recorded “regime shifts” like these in more than 20 different types of ecosystem where tipping points have been passed. Across the world, more than 20% of ecosystems are in danger of shifting or collapsing into something different.

These collapses might happen sooner than you’d think. Humans are already putting ecosystems under pressure in many different ways – what we refer to as stresses. And when you combine these stresses with an increase in climate-driven extreme weather, the date these tipping points are crossed could be brought forward by as much as 80%.

This means an ecosystem collapse that we might previously have expected to avoid until late this century could happen as soon as in the next few decades. That’s the gloomy conclusion of our latest research, published in Nature Sustainability.

Human population growth, increased economic demands, and greenhouse gas concentrations put pressures on ecosystems and landscapes to supply food and maintain key services such as clean water. The number of extreme climate events is also increasing and will only get worse.

What really worries us is that climate extremes could hit already stressed ecosystems, which in turn transfer new or heightened stresses to some other ecosystem, and so on. This means one collapsing ecosystem could have a knock-on effect on neighbouring ecosystems through successive feedback loops: an “ecological doom-loop” scenario, with catastrophic consequences.

How long until a collapse?

In our new research, we wanted to get a sense of the amount of stress that ecosystems can take before collapsing. We did this using models – computer programs that simulate how an ecosystem will work in future, and how it will react to changes in circumstance.

We used two general ecological models representing forests and lake water quality, and two location-specific models representing the Chilika lagoon fishery in the eastern Indian state of Odisha and Easter Island (Rapa Nui) in the Pacific Ocean. These latter two models both explicitly include interactions between human activities and the natural environment.

The key characteristic of each model is the presence of feedback mechanisms, which help to keep the system balanced and stable when stresses are sufficiently weak to be absorbed. For example, fishers on Lake Chilika tend to prefer catching adult fish while the fish stock is abundant. So long as enough adults are left to breed, this can be stable.

Image by ANIL GOPI from Pixabay

However, when stresses can no longer be absorbed, the ecosystem abruptly passes a point of no return – the tipping point – and collapses. In Chilika, this might occur when fishers increase the catch of juvenile fish during shortages, which further undermines the renewal of the fish stock.

We used the software to model more than 70,000 different simulations. Across all four models, the combinations of stress and extreme events brought forward the date of a predicted tipping point by between 30% and 80%.

This means an ecosystem predicted to collapse in the 2090s owing to the creeping rise of a single source of stress, such as global temperatures, could, in a worst-case scenario, collapse in the 2030s once we factor in other issues like extreme rainfall, pollution, or a sudden spike in natural resource use.

Importantly, around 15% of ecosystem collapses in our simulations occurred as a result of new stresses or extreme events, while the main stress was kept constant. In other words, even if we believe we are managing ecosystems sustainably by keeping the main stress levels constant – for example, by regulating fish catches – we had better keep an eye out for new stresses and extreme events.

There are no ecological bailouts

Previous studies have suggested significant costs from going past tipping points in large ecosystems will kick in from the second half of this century onwards. But our findings suggest these costs could occur much sooner.

We found the speed at which stress is applied is vital to understanding system collapse, which is probably relevant to non-ecological systems too. Indeed, the increased speed of both news coverage and mobile banking processes has recently been invoked as raising the risk of bank collapse. As the journalist Gillian Tett has observed:

The collapse of Silicon Valley Bank provided one horrifying lesson in how tech innovation can unexpectedly change finance (in this case by intensifying digital herding). Recent flash crashes offer another. However, these are probably a small foretaste of the future of viral feedback loops.

But there the comparison between ecological and economic systems runs out. Banks can be saved as long as governments provide sufficient financial capital in bailouts. In contrast, no government can provide the immediate natural capital needed to restore a collapsed ecosystem.

There is no way to restore collapsed ecosystems within any reasonable timeframe. There are no ecological bailouts. In the financial vernacular, we will just have to take the hit.

Don’t have time to read about climate change as much as you’d like?

Get a weekly roundup in your inbox instead. Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. Join the 20,000+ readers who’ve subscribed so far.

John Dearing, Professor of Physical Geography, University of Southampton; Gregory Cooper, Postdoctoral Research Fellow in Social-Ecological Resilience, University of Sheffield, and Simon Willcock, Professor of Sustainability, Bangor University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The ocean holds 60 times more carbon than the atmosphere and absorbs almost 30% of carbon dioxide (CO₂) emissions from human activities. This means the ocean is key to understanding the global carbon cycle and thus our future climate.

The Intergovernmental Panel on Climate Change (IPCC) uses earth system models to project climate change. These projections inform critical political, social and technological decisions. However, if we can’t accurately model the marine carbon cycle then we cannot truly understand how Earth’s climate will respond to different emission scenarios.

In research published today, we show that zooplankton, tiny animals near the base of the ocean food chain, are likely to be the biggest source of uncertainty in how we model the marine carbon cycle. Getting their impact on the cycle right could add an extra 2 billion tonnes to current models’ assumptions about annual carbon uptake by the ocean. That’s more carbon than the entire global transportation sector emits.

Marine carbon cycling is a $3 trillion thermostat

Roughly 10 billion tonnes of carbon are being released into the atmosphere each year. But the ocean quickly absorbs about 3 billion tonnes of these emissions, leaving our climate cooler and more hospitable. If we price carbon at the rate the IPCC believes is needed to limit warming to 1.5℃, this adds up to over A$3 trillion worth of emission reductions accomplished naturally by the ocean every year.

However, we know the size of the ocean carbon sink has changed in the past, and even small changes can lead to big changes in the atmosphere’s temperature. Thus, we understand the ocean acts as a thermostat for our climate. But what controls the dial?

Extensive geological evidence suggests microscopic marine life could be in control. Phytoplankton photosynthesise and consume as much CO₂ as all land plants.

When phytoplankton die, they sink and trap much of their carbon deep in the ocean. It can remain there for centuries to millennia, locked away safely out of contact with the atmosphere.

Any changes to the strength of this biological carbon pump will be felt in the atmosphere and will change our climate. Some have even proposed enhancing this biological pump by artificially fertilising the ocean with iron to stimulate phytoplankton. It’s possible this could sequester as much as an extra 20% of our annual CO₂ emissions.

Right for the wrong reasons

Despite its importance for the global climate and food production, there are large gaps in our understanding of how the marine carbon cycle is expected to change. Most earth system models differ in how the cycle’s major components will respond to a changing climate. Models simply can’t agree on what will happen to:

• net primary production – the carbon consumed by phytoplankton resulting in growth of marine plants at the base of the food web

• secondary production – zooplankton growth, which is an indicator for fisheries, since fish eat zooplankton

• export production – the biological pump of carbon transferred to the deep sea.

To diagnose what might be going wrong, we compared the marine carbon cycle in 11 IPCC earth system models. We found the largest source of uncertainty is how fast zooplankton consume their phytoplankton prey, known as grazing pressure.

Models differ hugely in their assumptions about this grazing pressure. Even if zooplankton were exposed to the exact same amount of phytoplankton, the highest assumed grazing rate would be almost 100 times as fast as the slowest rate.

This is because some models effectively assume the ocean is filled entirely with slow-grazing shrimp. Others assume it is teeming exclusively with microscopic, but rapidly grazing ciliates. In reality, neither is true.

Models must make up for such large differences in zooplankton grazing by making additional assumptions about how fast phytoplankton grow and how quickly zooplankton die. Together, these differences can be balanced in a way that allows most models to simulate the present-day amount of carbon consumed by phytoplankton and transferred to the deep sea.

However, that is only because we can observe what those values should be. We can then tune models until we ensure they get the right answer.

Yet, even though our best models can admirably recreate the present-day ocean, they do so for different reasons and with dramatically different assumptions about the role of zooplankton. This means these models are built with fundamentally different machinery. When used to test future emissions scenarios, they will project fundamentally different outcomes.

We cannot know which projections are correct unless we know the true role of zooplankton.

Tiny plankton with a big impact

We ran a sensitivity experiment to show how small changes in zooplankton grazing can dramatically alter marine carbon cycling. We considered two sets of experiments, one control and one in which we increased both zooplankton grazing rates and phytoplankton growth rates, such that both were tuned to the exact same total carbon consumption by phytoplankton.

This increase in how fast zooplankton can graze was only a fraction of the difference between assumed grazing rates seen across IPCC models. Despite this, we found even this small increase led to a huge difference in the percentage of carbon consumed by phytoplankton that was eventually exported to depth and transferred up the food chain.

Ocean carbon storage increased by 2 billion tonnes per year. Zooplankton carbon consumption increased by 5 billion tonnes.

From a climate perspective, that is double the maximum theoretical potential of iron fertilisation. From a fisheries perspective, that leads to a 50% increase in the size of the global zooplankton population on which many fish feed. This matters for global food supply as the ocean feeds 10% of the global population.

This work shows we must improve both our understanding and modelling of zooplankton. With limited resources and an immense ocean, we will never have enough observations to build perfect models. However, new technologies for measuring zooplankton are making it easier to make autonomous, high-resolution measurements of many important variables.

We must make a concerted effort to leverage these new technologies to better understand the role of zooplankton in the marine carbon cycle. We will then be able to reduce uncertainties about future climate states, advance our ability to assess marine-based CO₂ removal, and improve global fisheries projections.

Tyler Rohr, Lecturer in Southern Ocean Biogeochemical Modelling, IMAS, University of Tasmania; Anthony Richardson, Professor, The University of Queensland, and Elizabeth Shadwick, Team Leader, Oceans & Atmosphere, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Featured image: Julian Uribe-Palomino/IMOS-CSIRO, Author provided

(The Conversation) – People once believed the planet could always accommodate us. That the resilience of the Earth system meant nature would always provide. But we now know this is not necessarily the case. As big as the world is, our impact is bigger.

In research released today, an international team of scientists from the Earth Commission, of which we were part, identified eight “safe” and “just” boundaries spanning five vital planetary systems: climate change, the biosphere, freshwater, nutrient use in fertilisers and air pollution. This is the first time an assessment of boundaries has quantified the harms to people from changes to the Earth system.

“Safe” means boundaries maintaining stability and resilience of our planetary systems on which we rely. “Just”, in this work, means boundaries which minimise significant harm to people. Together, they’re a health barometer for the planet.

Assessing our planet’s health is a big task. It took the expertise of 51 world-leading researchers from natural and social sciences. Our methods included modelling, literature reviews and expert judgement. We assessed factors such as tipping point risks, declines in Earth system functions, historical variability and effects on people.

Alarmingly, we found humanity has exceeded the safe and just limits for four of five systems. Aerosol pollution is the sole exception. Urgent action, based on the best available science, is now needed.

So, what did we find?

Our work builds on the influential concepts of planetary boundaries by finding ways to quantify what just systems look like alongside safety.

Importantly, the safe and just boundaries are defined at local to global spatial scales appropriate for assessing and managing planetary systems – as small as one square kilometre in the case of biodiversity. This is crucial because many natural functions act at local scales.

Here are the boundaries:

1. Climate boundary – keep warming to 1℃

We know the Paris Agreement goal of 1.5℃ avoids a high risk of triggering dangerous climate tipping points.

But even now, with warming at 1.2℃, many people around the world are being hit hard by climate-linked disasters, such as the recent extreme heat in China, fires in Canada, severe floods in Pakistan and droughts in the United States and the Horn of Africa.

At 1.5℃, hundreds of millions of people could be exposed to average annual temperatures over 29℃, which is outside the human climate niche and can be fatal. That means a just boundary for climate is nearer to 1°C. This makes the need to halt further carbon emissions even more urgent.

2. Biosphere boundaries: Expand intact ecosystems to cover 50-60% of the earth

A healthy biosphere ensures a safe and just planet by storing carbon, maintaining global water cycles and soil quality, protecting pollinators and many other ecosystem services. To safeguard these services, we need 50 to 60% of the world’s land to have largely intact natural ecosystems.

Recent research puts the current figure at between 45% and 50%, which includes vast areas of land with relatively low populations, including parts of Australia and the Amazon rainforest. These areas are already under pressure from climate change and other human activity.

Image by Rosina Kaiser from Pixabay

Locally, we need about 20-25% of each square kilometre of farms, towns, cities or other human-dominated landscapes to contain largely intact natural ecosystems. At present, only a third of our human-dominated landscapes meet this threshold.

3. Freshwater boundaries: Keep groundwater levels up and don’t suck rivers dry

Too much freshwater is a problem, as unprecedented floods in Australia and Pakistan show. And too little is also a problem, with unprecedented droughts taking their toll on food production.

To bring fresh water systems back into balance, a rule of thumb is to avoid taking or adding more than 20% of a river or stream’s water in any one month, in the absence of local knowledge of environmental flows.

At present, 66% of the world’s land area meets this boundary, when flows are averaged over the year. But human settlement has a major impact: less than half of the world’s population lives in these areas. Groundwater, too, is overused. At present, almost half the world’s land is subject to groundwater overextraction.

4. Fertiliser and nutrient boundaries: Halve the runoff from fertilisers

When farmers overuse fertilisers on their fields, rain washes nitrogen and phosphorus runoff into rivers and oceans. These nutrients can trigger algal blooms, damage ecosystems and worsen drinking water quality.

Yet many farming regions in poorer countries don’t have enough fertiliser, which is unjust.

Worldwide, our nitrogen and phosphorus use are up to double their safe and just boundaries. While this needs to be reduced in many countries, in other parts of the world fertiliser use can safely increase.

5. Aerosol pollution boundary: Sharply reduce dangerous air pollution and reduce regional differences

New research shows differences in concentration of aerosol pollutants between Northern and Southern hemispheres could disrupt wind patterns and monsoons if pollutant levels keep increasing. That is, air pollution could actually upend weather systems.

At present, aerosol concentrations have not yet reached weather-changing levels. But much of the world is exposed to dangerous levels of fine particle pollution (known as PM 2.5) in the air, causing an estimated 4.2 million deaths a year.

We must significantly reduce these pollutants to safer levels – under 15 micrograms per cubic metre of air.

We must act

We must urgently navigate towards a safe and just future, and strive to return our planetary systems back within safe and just boundaries through just means.

To stop human civilisation from pushing the Earths’s systems out of balance, we will have to tackle the many ways we damage the planet.

To work towards a world compatible with the Earth’s limits means setting and achieving science-based targets. To translate these boundaries to actions will require urgent support from government to create regulatory and incentive-based systems to drive the changes needed.

Setting boundaries and targets is vital. The Paris Agreement galvanised faster action on climate. But we need similar boundaries to ensure the future holds fresh water, clean air, a planet still full of life and a good life for humans.

We would like to acknowledge support from the Earth Commission, which is hosted by Future Earth, and is the science component of the Global Commons Alliance

Steven J Lade, Resilience researcher at Australian National University, Australian National University; Ben Stewart-Koster, Senior research fellow, Griffith University; Stuart Bunn, Professor, Australian Rivers Institute, Griffith University; Syezlin Hasan, Research fellow, Griffith University, and Xuemei Bai, Distinguished Professor, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The climate and biodiversity crises we have been experiencing for the past few decades are inseparable. The scientific research presented at the back-to-back international summits on climate and biodiversity held in Sharm El-Sheikh in Egypt and in Montréal, Canada, respectively, has made this abundantly clear.

Addressing these crises requires real transformative action and commitments — including plans that call for the conservation of 30 per cent of global land and sea areas within the decade — have been made to halt biodiversity loss by 2030. But where do we start implementing these targets?

At the 7th Summit for Subnational Governments and Cities, an official parallel event to the COP15 biodiversity conference, cities were brought to the forefront of conversations on how to protect life on Earth.

As a researcher of terrestrial ecosystems, I believe that we cannot think of nature as something set aside in wildernesses, far from human activity. We need to conserve some elements of nature everywhere, including in the cities we live in.

Conserving nature in cities can help protect the biodiversity within them. (Unsplash)

Cities need nature

Cities are growing rapidly and covering more and more land. They are often built on the most fertile land, near rivers or coastlines. This is also where most of the biodiversity lives. It is, therefore, crucial to conserve nature in cities.

To add to this, some ecosystem services that humans rely on only operate within short geographical limits. Healthy soils and wetlands absorb rainwater and snowmelt to buffer floods, while trees filter pollutants from the air and alleviate heat waves. All these services are most effective when nature is close to where people live, making it crucial for cities to preserve their nature.

In Canada, the richest ecosystems and the highest numbers of species are found in the south, and this is also where most of the cities and farms are, leaving little land available for wilderness.

To protect healthy population sizes of species native to this region, we need to preserve green spaces in cities. Research has shown that small protected areas can have disproportionately large effects in protecting biodiversity.

Contact with nature also brings tremendous physical and mental health benefits as seen during the pandemic when spending time outdoors became very valuable to people suffering from stress and isolation.

Equitable distribution of natural areas around a city is also important. Public green spaces can be especially valuable to people who do not own country cottages or backyards.

Montréal leads the way

Montréal, the host city of the COP15 biodiversity conference, is a perfect case in point for how cities are both succeeding at and struggling with conserving nature.

The City of Montréal committed to protecting 10 per cent of its territory in November 2022. This commitment was reaffirmed at COP15, along with the launch of the Montréal Pledge, which called on cities around the world to protect biodiversity on their territories and provided practical steps on how to do so. So far, 47 cities from all five continents have committed to the pledge.

Meeting this target includes the creation of new parks like Montréal’s Falaise St-Jacques escarpment and Champ des Possibles.

The Falaise St-Jacques, long used as a dumping ground by businesses nearby was revitalized by a community group. They organized clean-ups, removed hundreds of tires and other debris, built trails and transformed the site into an urban oasis enjoyed by local residents, human, feathered and furry. Home to 83 bird species, including two species at risk, the Chimney Swift and the Wood Thrush, Falaise St-Jacques has become an important habitat for migratory birds.

The Champ des Possibles — a railway triage site turned industrial wasteland — was saved by a group of local residents, who planted gardens, installed beehives and held concerts, creating a de-facto park that is now co-managed by the community organization and the city. This area now boasts of a wealth of biodiversity too.

However, the island of Montréal continues to include many other unprotected green spaces, including the Technoparc and Parc-Nature Mercier Hochelaga Maisonneuve, which are threatened by industrial expansion.

The Technoparc, which comprises a mature forest, marshes and meadows and is a birding hotspot in Montréal (216 birds including 14 species-at-risk), is attracting thousands of nature enthusiasts to document the ecological value of the site, to tag endangered Monarch butterflies and to chart the cooling effects of the meadows and forests in the surrounding industrial heat island.

Despite numerous pressures exerted on the space, efforts like citizen-science documentation, gained notably through iNaturalist observations and City Nature Challenge bioblitzes, have succeeded in dissuading developers from moving into the site so far.

Politicians at all levels of government — from the municipal to the provincial to the federal — have now started to call for the site’s protection.

Researchers here have also mapped remaining green spaces around the island of Montréal and calculated the ecosystem services they can provide to help communities better plan for the future.

Community efforts can go a long way

Researchers and students at Concordia University have been working with community organizations to study and educate about biodiversity in these spaces.

We use citizen-science tools like iNaturalist.ca to welcome people from all walks of life to the community of biodiversity scientists, help them identify the fauna and flora around them and share the collected data with scientists around the world.

Building a relationship with nature around us can help foster human engagement with the natural world and a desire to learn more and to protect, restore and steward the living ecosystems around us.

At the COP27 climate summit in Egypt last month, UN Secretary-General António Guterres called for “all hands on deck” to address the climate and biodiversity crises. He said, “Making peace with nature is the defining task of the 21st century. It must be the top, top priority for everyone, everywhere”.

What better place to start than in a park or green space near our homes?

Emma Despland, Professor, Biology Department, Concordia University

This article is republished from The Conversation under a Creative Commons license. Read the original article.