Backing Biodiversity Will Lessen the Climate Crisis

The history of life on Earth has been marked five times by events of mass biodiversity loss caused by extreme natural phenomena. Today, a sixth mass extinction crisis is underway, this time almost entirely caused by human activities. In fact, one recent survey revealed that more species are threatened with extinction than we previously thought.

Unfortunately, even if global temperatures begin to decline after peaking this century because of climate change, the risks to biodiversity could persist for decades after. But there is good news, too. We’re continuing to find ways to institute climate-smart conservation strategies that transcend international borders. And an innovative “species stock market” might make more of us buy into them.

We’re learning that there are even some low-cost/low-energy measures we can take now to protect biodiversity: by allowing top predators to live, we can buffer the negative impacts of climate change on natural habitats. We’re also discovering that protected areas, such as national parks, can have a “mixed impact” on wildlife; for example, researchers have found that gene flow among giant pandas in a Chinese wildlife reserve is better in places that have gaps in the bamboo forest. Totally intact, pristine areas, therefore, may not be necessary to achieve conservation goals.

The sixth mass extinction is real: just ask a diverse group of experts

Drastically increased rates of species extinctions and declining abundances of many animal and plant populations are well documented, yet some still deny that these facts amount to mass extinction. But this denial is based on a biased view of the crisis, one that focuses on birds and mammals and that ignores invertebrates, which constitute the great majority of the planet’s biodiversity.

To address the naysayers, biologists from the University of Hawaii at Manoa and the Museum National d’Histoire Naturelle in Paris, France, conducted a comprehensive assessment of the evidence of the sixth mass extinction crisis and recently published their conclusions in the journal Biological Reviews.

They found that since the year 1500, Earth may have already lost between 7.5 and 13 percent of the 2 million known species on Earth—a staggering 150,000 to 260,000 species. Including invertebrates, such as land snails and slugs, was key to confirming that we, indeed, are witnessing the onset of the sixth mass extinction.

Another new survey, published in the journal Frontiers in Ecology and the Environment received 3,331 responses from scientists studying biodiversity in 187 countries, covering all major groups of ecosystems, habitats and species. Those experts estimated that about 30 percent of species have been globally threatened or driven extinct since the year 1500.

The survey also identified important demographic and geographic differences in experts’ estimates and perspectives. It included the viewpoints of a very wide range of specialists—some who, in the past, had been underrepresented in the global literature—and assessed the lesser-known taxa. It found that experts who identify as women and who are from the Global South provide significantly higher estimates for past biodiversity loss and its impacts. Also, those who identify as women disproportionately study the animals and plants that experts believe are most threatened.

The authors of the article published in Frontiers in Ecology and the Environment encourage biodiversity experts to use these results to learn how their own perspectives differ from those of other experts and to ensure that a range of viewpoints is included when conducting global biodiversity assessments, setting global biodiversity goals and targets, and making the new policies and other transformative changes needed to conserve biodiversity. They state that greatly increasing conservation efforts and investments now could remove the threat of extinction for one in three species that may otherwise be threatened or extinct by 2100.

Biodiversity risks will persist: they’ll go well beyond our future temperature peak

The Paris Agreement, signed in 2015, aimed to limit global warming to well below 2 degrees Celsius above preindustrial levels, preferably to 1.5 degrees C. However, as global greenhouse gas emissions continued to increase, many future climate scenarios started to feature a decades-long “overshoot” of the Paris Agreement limit. They then factor in the effects of potential carbon dioxide removal technology to reverse the dangerous temperature rise predicted by 2100.

But in a new paper published in the journal Philosophical Transactions of the Royal Society B: Biological Sciences, researchers modeled the potential impacts on global biodiversity if temperatures increase by more than 2 degrees C, before beginning to decline again. In other words, they investigated what will happen to global biodiversity if climate change is reined in only after a temporary overshoot of the agreed target, in order to provide evidence that has long been missing from climate change research.

What they found is that huge numbers of animal species will need to endure unsafe conditions for decades after the global temperature peak. Even if we collectively manage to reverse global warming before species are irreversibly lost from ecosystems, the ecological disruption caused by unsafe temperatures could well persist for an additional half century or more.

The study examined more than 30,000 species in locations around the world and found that for more than a quarter of the places studied, the chances of returning to a pre-overshoot “normal” are either uncertain or nonexistent.

The paper focuses on one interesting scenario, where CO2 emissions keep growing until 2040, then reverse their course and fall into negative territory after 2070—thanks to deep carbon cuts and massive deployment of carbon dioxide removal technology. This means that for several decades in this century, the global temperature rise will breach 2 degrees C but return to below this level around 2100. The researchers looked at when and how quickly the species in a particular location would get exposed to potentially dangerous temperatures, how long that exposure would last, how many species it would affect and whether they would ever get de-exposed and return to their thermal niche.

The scientists discovered that, for most regions, exposure to unsafe temperatures will arrive suddenly, pushing many species beyond their thermal niche limits. However, the return of these species to conditions comfortably within their thermal niches will be gradual and will lag the global temperature decline, due to continually volatile climatic conditions within local sites and lasting changes to ecosystems. The effective overshoot for biodiversity risks is projected to be between 100 and 130 years, about twice as long as the actual temperature overshoot of about 60 years.

Tropical regions will be most affected by these risks, with more than 90 percent of species for many locations in the Central Indian Ocean, Indo-Pacific, northern Australia and northern sub-Saharan Africa being ousted from their thermal niches. And in the Amazon, one of the most species-rich regions of the world, more than half of the species will be exposed to potentially dangerous climate conditions.

Concerningly, for about 19 percent of the total number of sites studied, including the Amazon, it is uncertain whether the share of exposed species will ever return to pre-overshoot levels. And a further 8 percent of sites are projected to never return to those levels at all. This means that the overshoot can cause irreversible impacts to nature due to radical transformations of ecosystems and species extinctions.

This study underscores the importance of looking at the complete picture of the damage that could be caused in overshoot scenarios, rather than focusing only on making sure we stay within the agreed temperature limits, which could underplay the need for deep and rapid emissions reductions. Moreover, the authors note that carbon dioxide removal technology itself is also likely to have negative impacts on ecosystems: for instance, large-scale forest planting or biofuels production require a lot of land and water and may even have secondary effects on the climate system.

Climate-smart conservation strategies could work: roads for re-envisioning

Under a scenario of 2-degrees-C warming, climate conditions are expected to change in more than a quarter of the current land-based global network of protected areas, such as national parks, nature reserves and designated wildernesses.

This means that some species currently in protected areas may have to cross international boundaries to find more suitable climate conditions. As they move, they may face physical barriers, such as border fences; and nonphysical barriers, such as inconsistent conservation policies across different countries.

Now, new research published in the journal Environmental Research Letters provides insights for developing climate-smart conservation strategies that transcend international borders. Scientists looked at the global network of protected areas and evaluated the potential shifts animals and plants may have to make due to climate change. Understanding these shifts away from known to new climate conditions within protected areas will help international conservationists and governments forecast planning needs and make more strategic investment decisions for limited conservation funding.

In another new effort to protect biodiversity amid the current extinction crisis, scientists conceptualized a species “stock market” to put a price tag on actions posing risks to biodiversity.

Species have intrinsic value, but they also provide ecosystem services of major economic value; for example, bees pollinate our crops. Such services are hard to translate into figures, so they’re easy to dismiss and deem worthless. As a result, humanity has been quick to justify actions that diminish animal populations and even imperil biodiversity at large.

Now, a team of Estonian and Swedish scientists propose to formalize the value of all species through a conceptual species “stock market” (SSM), orchestrated by international associations of economists and taxonomists. Publishing their ideas in the journal Research Ideas and Outcomes, the scientists say that by using digitized information from museums, occurrence data and DNA sequence databases, we could quantify our knowledge of each species from economic, scientific and societal points of view. Much like the regular stock market, the SSM would act as a unified basis for instantaneous valuation of all items in its “holdings.”

However, other aspects of the SSM would be starkly different from the regular stock market. Ownership, transactions and trading would take new forms. Species would have no owners, and “trade” would not be about the transfer of ownership rights among shareholders. Instead, the concept of “selling” would comprise processes that erase species from specific areas—such as deforestation, pollution or war.

The SSM would be able to put a price tag on such transactions, and the price could be thought of as an invoice that the seller needs to settle in some way that benefits global biodiversity. Conversely, taking some action that benefits biodiversity would be akin to “buying” on the species stock market.

Buying, too, would have a price tag on it, but this cost should be thought of in goodwill terms. Here, “money” represents an investment towards increased biodiversity. By rooting such actions in a unified valuation system, say the scientists, it is hoped that goodwill actions will become increasingly difficult to dodge.

Interestingly, the SSM revolves around the notion of digital species. These are representations of described and undescribed species concluded to exist based on DNA sequences and elaborated by including all we know about their ecology, distribution, habitat, interactions with other species and traits—sourced from global scientific and societal resources, including life science data portals, natural history collections and sequence databases. Non-sequenced individuals could be included by using observations, older material in collections and information from publications.

The most realistic and tangible way out of the looming biodiversity crisis, state the creators of the SSM, is to put a price tag on species and assign a cost to actions that compromise them.

Another weapon in the arsenal to mitigate climate change impacts is predators.

In the international science journal Global Change Biology, a research team led by scientists at Japan’s Hokkaido University and Trinity College Dublin published the results of a study that emphasize the importance of conserving biodiversity—top predators, in particular—and that highlight the potential for species extinctions to worsen the effects of climate change on ecosystems.

The researchers assembled communities of freshwater organisms in streams at the Tomakomai Experimental Forest in northern Japan. Algal (plant) communities are important in streams because they form the energy base for all other organisms. Some of the stream communities also included a dominant predator (a sculpin fish), while others did not. The communities were then exposed to realistic heat waves.

The researchers found that the heat waves destabilized the algal communities in the streams such that the differences normally found among them disappeared, and they resembled each other much more closely—equating to a loss of biodiversity—but this only happened when the predator was absent from the community.

Additionally, the scientists discovered that important heat wave effects—such as shifts in total algal biomass—only emerged after the heat wave had passed, underlining that even catastrophic impacts may not be immediately obvious. Predator species help to buffer such impacts, acting as allies in the fight against climate change.

As plans to formally protect 30 percent of the Earth’s surface by 2030 gather pace, the authors of a study published in the journal Nature say this alone will not guarantee the preservation of biodiversity. They argue that targets need to be set for the quality of protected areas, not just the quantity.

The study published in Nature focused on waterbirds because they are well researched and found in many locations worldwide. Also, their mobility means that they can quickly colonize or leave a location based on the quality of the conditions.

Examining 1,500 protected areas (in 68 countries) with more than 27,000 waterbird populations, the scientists used a “before-after-control-intervention” method: they compared waterbird population trends before protected areas were established with trends afterwards, and they also related the trends of similar waterbird populations inside and outside of protected areas. This provided a much more accurate and detailed picture than previous studies had.

What they found was that while many protected areas are working well, many others are failing to have a positive effect. Their impacts widely varied, with the biggest dependent factor being whether they were managed to benefit biodiversity.

While we know that protected areas can prevent habitat loss, especially in terms of stopping deforestation, we have less understanding of how protected areas help wildlife. This study shows that we can’t just expect protected areas to work without appropriate management in place. So, rather than focusing solely on the total global area protected, we need more attention placed on how they’re operated.

Giant pandas are a case in point. Scientists studying the animals in the mountainous bamboo forests of central China say a close look at the genetic profiles of pandas there suggests that the axiom that the “more habitat the better” is not always true.

The charismatic black-and-white bears dwell only in the bamboo forests of central China, where hunting and deforestation have driven populations down to approximately 2,000 animals. While their numbers are on the rebound, giant pandas are still considered vulnerable due to habitat fragmentation and the threat that climate change poses to the forests.

To see if they could trace how gene flow was influenced by variations in habitat conditions in China’s 772-square-mile Wolong National Nature Reserve, a team of scientists spent two years scouring the forest for fresh panda scat. By studying the DNA in the feces, the scientists identified 142 individual pandas, traced how they were related to each other and looked for signs of inbreeding. The researchers then overlaid this genetic map on a detailed computer model of the habitat conditions in the reserve. A subsequent statistical analysis delved into how the amount of panda habitat and different landscape features—such as farmlands, roads, rugged cliffs, villages and other breaks in the forest—were correlated with how DNA varied from one bear to another.

Surprisingly, the results, published in September 2021 in the journal Conservation Biology, showed that the greatest genetic diversity didn’t occur where the bamboo forest was entirely intact and continuous. Rather, gene flow among the bears appeared to peak in places where approximately only 80 percent of an area was prime bear habitat.

The findings didn’t answer why this is happening. But the researchers suspect that bears in uninterrupted habitats might have such comfortable lives that there is little incentive to wander. These stay-at-home bears would be less likely to go looking for other habitats and encounter mates along the way.

The researchers concluded by cautioning that the habitat conditions that maximize gene flow won’t be the same for different species, or even for other populations of panda bears. But they do think their results could mean that a variety of species—not just pandas—can thrive even with some damaged habitat.

That, to me, is a very hopeful thought.

The loss equation: hotter temperatures equal less biodiversity plus a lesser quality of life

If we overshoot the 2-degrees-C global warming target, we could pay an astronomical cost in terms of biodiversity loss, compromising the ecosystem services that we all rely on. Urgent action is needed to ensure that we never approach, let alone exceed, the 2-degrees-C limit.

We’ve learned that there is no silver-bullet-solution for mitigating the impacts of the climate change that we created. Unproven negative-emission technologies cannot simply reverse what’s done and could come with potential negative impacts. It comes down to this: we must rapidly reduce greenhouse gas emissions.

Luckily, measures such as placing a priority on protecting predators and creating a species stock market could equate to a two-crises solution.

Here’s to finding your true places and natural habitats,

Candy