Billions of dollars are lost every year due to disease, crop destruction and other costs caused by invasive species, according to new ecology research.
(CN) — The ecological devastation that invasive species can wreak is well documented, and now new research finds that species invasions cost the world at least $1.28 trillion between 1970 and 2017.
That’s an average of $26.8 billion lost annually as a result of reduced agricultural yields, damaged infrastructure, hazards to human health and the resources that have been spent on costly management services and pest-control projects.
“This trillion-dollar bill doesn’t show any sign of slowing down, with a consistent threefold increase per decade,” said lead author Christophe Diagne, an ecologist at Université Paris-Saclay, in a statement. “Our annual global estimates signify the huge economic burden, with the average cost exceeding the gross domestic product of 50 countries on the African continent in 2017, and it’s more than 20 times higher than the total funds available for the World Health Organization and U.N. combined.”
When a species native to one portion of the globe is transported outside its usual range, it might flounder and fail, or establish a foothold in its new environs — frequently to the detriment of the species, agriculture and other systems native to its new home.
When a species’ introduction to a new environment negatively impacts that area, the organism is called an invasive species, and they are everywhere. House sparrows, originally native to the Mediterranean basin, can be found bullying native birds from food and evicting local species from shelter in nearly every corner of the world. European rabbits have wrought havoc on crops and sped soil erosion across Australia and in portions of Africa and South America.
Some of these invasions are purposeful. Famously, European starlings took over North America after an amateur ornithologist named Eugene Schieffelin let 60 free in New York City’s Central Park, purportedly because he was party to a project that aimed to bring every bird mentioned in William Shakespeare’s corpus to North America.
Other invasions are wholly accidental, as when a weed’s seeds hitch a ride in imported plant material, or when rats stow away in international merchants’ ships.
The study, published Wednesday in the prestigious, peer-reviewed scientific journal Nature, took Diagne and his colleagues more than five years to complete.
Critical to the group’s estimates was the comprehensive InvaCost database, which catalogues the economic costs of invasive species by surveying the conservative estimates offered by 850 studies and more than 2,400 cost estimates that Diagne and his team standardized and used to filter the data according to more than 40 variables, such as habitats affected, economic sectors impact and species responsible for damages.
“The global costs of invasive alien species are so massive that we spent months verifying our models and this overall estimate, to ensure we were not exaggerating,” continued Diagne. “As it turns out, our very conservative approach is in fact a massive underestimation of the actual economic costs.”
As invasive species’ populations continue to grow and international trade and travel grows more voluminous, those costs have grown as well.
“We found that costs roughly doubled every six years, a pattern that mimics the continuous increase in the number of alien species worldwide,” ecologist Corey Bradshaw of Flinders University in Australia said in a statement. “We’re calling for international policy agreements that aim to reduce the burden of invasive species.”
The scientists estimate that the three costliest invasive species are the yellow fever mosquito, which is a primary vector for dengue, Zika and other viruses in tropical areas across the world; crop-devastating rats; and the domestic cat, whose millions of feral counterparts’ predation on birds alone costs the U.S. billions every year.
But these costs are widely and unevenly distributed, such that they are almost totally hidden from policymakers and taxpayers.
The researchers stress that these costs aren’t merely financial in nature.
“These economic losses are only part of the full aggregate of effects that are incurred from invasive alien species. Indeed, the ecological and health impacts of invasions are at least as important, but are often incalculable,” the study states.
Bradshaw, Diagne and their colleagues are part of a growing number of scientists asking for world governments to work together to address the globe’s worsening biodiversity crisis.
Last fall, a group of ecologists and data scientists identified cost-effective ways of converting land now used for agriculture and commerce back to natural areas, to help slow species extinctions and sequester carbon emissions from the atmosphere.
In their paper, the authors of Wednesday’s study emphasize the necessity of new research and cost estimates across the globe, noting that most estimates are conducted in the U.S., Australia and Western Europe and that more studies are needed especially in low-income regions where the damage wrought by invasive species may hit hardest.