TORONTO -- that the global economic cost of invasive species has been at least $1.62 trillion over the last 50 years.
Researchers based in France, the Czech Republic and Australia looked at numerous datasets around the world, covering 1970 to 2017, looking at the economic impacts of biological invasions, which refer to the deliberate or accidental introduction of non-native plants and animals. Within this 47-year period, the average costs annual costs are around $33.7 billion per year.
The costliest invasive species were mosquitoes, followed by rats and cats.
In Canada alone, invasive species are estimated to have cost at least $22.8 billion over this period, according to data collected by the authors. The emerald ash borer, the brown rat, the gypsy moth and the Asian long-horned beetle are just some of the invasive species that have impacted this country. In the Great Lakes along the Canada-U.S. border, another $408.6 million in costs have been accrued from zebra and quagga mussels.
When it comes to costs associated with invasive species, the study highlights two types of costs: "damage" costs and "management" costs. Damage costs include the loss of agricultural output, damage to infrastructure and injuries to human health, while management costs refer to the taxpayer resources spent on abating these species.
Damage costs were found to total $1.12 trillion while management costs were only $83.4 billion. Damage costs were also found to increase sixfold every ten years, a much faster rate than management costs, which only increase less than twofold every ten years.
In total, the study found that the costs double every six year, which corresponds to the increase in the population of invasive species.
"This trillion-dollar bill doesn't show any sign of slowing down, with a consistent threefold increase per decade," said lead study author Christophe Diagne.
The authors attribute the explosion in invasive species over the last five decades to the intensification of global trade as well as the loss of natural land from the expansion of agriculture and infrastructure.
The authors also note that these costs are only a conservative estimate, given the differences in reporting consistency and inconsistent availability of data around the world.
"The global costs of invasive alien species are so massive that we spent months verifying our models and this overall estimate, to insure we were not exaggerating" said Diagne. "As it turns out, our very conservative approach is in fact a massive underestimation of the actual economic costs."
