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On the Verge of Vanishment by Ali Wilt

The International Union of Conservation of Nature keeps a running tab of the global extinction risk of thousands of animal, fungus and plant species in what it calls the "Red List," and the most recent numbers for 2020 are in. Of the over 128,500 species assessed and categorized by the IUCN, about 28% are threatened with extinction.

And thus, the biodiversity of our planet appears to be in grave danger. A few scientists have even proclaimed the current period the "Sixth Mass Extinction."

Data source: https://www.iucnredlist.org

The year of 2020 is, as evidenced above, no exception. The number of species on the IUCN Red List has increased every year for which data is available, beginning with the year 1996. While it is true that the IUCN's capacity for research has increased and its accuracy refined over time, the organization's website states with certainty that biodiversity is declining, regardless of the effect these variables might have on the above data.

Specifically, the IUCN's assessments categorize species into one of several risk categories. The nine categories, which each have varying criteria, include Not Evaluated, Data Deficient, Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild, and Extinct. The latter six of those categories (all but Not Evaluated, Data Deficient, and Least Concern) represent species which are facing a documented and legitimate risk.

Perhaps, for some reason, one of these categories has skyrocketed in number over the years, accounting for the positive trend we saw in the first graph. In order to investigate, the data can be broken down by IUCN categories to see how the number of species in each category has changed over time.

Data source: https://www.iucnredlist.org

As we can see, there is no one status with an extreme increase in number of species. Certain status groups grow more than others, but there must be some other reason for this gradual increase in the number of species on the Red List, and thus, a gradual decrease in biodiversity.

Creatures great and small, including the Eastern Gorilla (left) and the Rusty Patched Bumble Bee (right), are critically endangered. (Left: Richard Ruggiero/USFWS; Right: Kim Mitchell/USFWS)

So, who or what is to blame for this plummeting of global biodiversity? Recent research points to many factors. In 2017, David Tilman of the University of Minnesota, St. Paul and colleagues published an article in Nature detailing current and future threats to the planet's biodiversity. They found significant ecological implications from threats such as agricultural development, unlawful hunting and grazing, invasive species, water pollution, and exotic diseases.

According to Tilman and colleagues, habitat loss and degradation pose the most frequent, direct threats to terrestrial mammals and birds by reducing the size of the area that a species can occupy and fragmenting populations into isolated clusters. While some habitat loss and degradation is caused by logging, mining, and urbanization, much of it is driven by agricultural development. "About 80% of all threatened terrestrial bird and mammal species are imperiled by agriculturally driven habitat loss," reads the research. And the problem only becomes more complex from there.

"About 80% of all threatened terrestrial bird and mammal species are imperiled by agriculturally driven habitat loss." - Tilman et. al

The need for this land for agricultural development is only becoming increasingly important to human survival as the population steadily increases and our planet becomes more crowded. And when it comes down to either satisfying the consumption habits of an ever-growing population or saving the habitats of plants, animals, and fungi...it seems that human need takes precedence.

Data source: https://ourworldindata.org/world-population-growth

What's more, there are no signs of population growth significantly decreasing any time soon, spelling even more bad news for biodiversity. "With the human population worldwide now 25 times greater than 3,000 years ago and projected to increase by about 4 billion people by the end of the twenty-first century, extinction rates will accelerate in the absence of large-scale conservation actions," according to the research.

"With the human population worldwide now 25 times greater than 3,000 years ago and projected to increase by about 4 billion people by the end of the twenty-first century, extinction rates will accelerate in the absence of large-scale conservation actions." - Tilman et. al

Another potentially significant threat to biodiversity is climate change, which is only intensifying over time as greenhouse gases continue to be emitted into the atmosphere at alarming rates, as shown below.

Data source: https://data.giss.nasa.gov/gistemp/

While climate change has caused range shifts and local destruction of species, Tilman and his colleagues, as well as the greater scientific community are still uncertain about how many species and which species will be affected as anthropogenic climate change progresses.

Research indicates that species have survived past fluctuations in climate through migration. However, Tilman and colleagues importantly note that "the velocity of the projected changes in climate is unprecedented, and habitat fragmentation will limit migration pathways."

While it may sound crass, a logical next question is, "Why does it matter?" What's the impact of having fewer creatures roaming our planet and fewer plants growing in our soils? A lot actually, as it turns out.

Economics research has found that the costs associated with declining biodiversity are immense; processes like pollination and soil reclamation, which are driven by various species, would have to be engineered and paid for in the event that those species vanished.

Our food security is threatened as well. Foreign breeds of cattle are being imported around the world and pushing out native populations; thus, livestock are becoming less and less genetically diverse, increasing vulnerability to disease and other factors, which in turn threatens the food supply.

Yet another implication of decreasing biodiversity is an increased risk of coming in contact with zoonotic diseases, or those transmitted from animals to humans-- a perhaps gut-wrenching reality in the wake of the one-year anniversary of the global Covid-19 pandemic. Research has shown that the species best adapted to survive critically fragmented habitats are also the most prolific carriers of pathogens.

The implications are grim, but ramping up conservation efforts can turn things around, at least to some degree, according to Tilman and colleagues. One specific approach of proactive conservation could combat the issue of habitat loss. The research reads, "Land is a limiting resource for both humans and nature, so reducing human demand for land and changing the pattern of land clearing to minimize habitat fragmentation is crucial for proactive conservation."

"Land is a limiting resource for both humans and nature, so reducing human demand for land and changing the pattern of land clearing to minimize habitat fragmentation is crucial for proactive conservation." - Tilman et. al

Focusing on agriculture seems a promising approach to researchers as well. Agriculture contributes to around 30% of greenhouse gas emissions worldwide, mainly through land clearing, the application of nitrogen fertilizers and methane production by cows and other livestock. Thus, Tilman and colleagues predict that greater agricultural efficiencies and a reduced demand for beef would therefore help to slow climate change and afford significant biodiversity benefits.

As the number of economically developed countries continues to increase, natural resources will become even more disproportionately consumed, placing an onus on these countries to make significant contributions toward conservation efforts both inside and outside of their borders. Tilman and colleagues suggest "directing funds strategically to regions with the greatest current, or future, threats or the largest potential return on investment."

In the United States, the newly ushered in Biden Administration may be poised to make such efforts, as the administration is already making swift moves toward facing the climate crisis. Wherever it may be, nations will likely be required to step up sooner rather than later if we are to preserve much of our planet's life.

Credits:

Cover photo:  Susanne Miller/USFWS Data visualizations:  Ali Wilt