Boatmen steer through water hyacinth in the Buriganga River in Dhaka, Bangladesh on June 6.
CNN  — 

Invasive species cost the world at least $423 billion every year as they drive plant and animal extinctions, threaten food security and exacerbate environmental catastrophes across the globe, a major new United Nations-backed report has found.

Human activity – often through travel or global trade – is spreading these animals, plants and other organisms in new regions at an “unprecedented rate,” with 200 new alien species being recorded every year, leading scientists said.

Of 37,000 alien species known to have been introduced around the world, 3,500 are considered harmful and pose a “severe global threat” by destroying crops, wiping out native species, polluting waterways, spreading disease and laying the groundwork for devastating natural disasters.

The global economic cost is tremendous, scientists say, having at least quadrupled every decade since 1970.

That figure is “a huge, huge underestimate… it’s the tip of the iceberg,” said ecologist Helen Roy, co-author of the UN Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) report.

Without intervention to prevent their spread and impact, the total number of invasive species globally will be one-third higher in 2050 than it was in 2005, the scientists say.

“We know that things aren’t remaining unchanged. We know climate change is worsening, we know that land and sea-use change is worsening and therefore we anticipate that the threat posed by invasive alien species will also worsen,” Roy said.

An invasive cane toad sits inside a plastic bag after being removed from a trap at a billabong south of Darwin, Australia on May 11, 2005.

‘Global roots but very local impacts’

Alien species are plants, animals or other organisms that have been moved through human activities to a new region or area.

An alien species becomes invasive when it establishes itself in that new area and creates a negative impact on the local biodiversity and ecosystems, including on people’s way of life.

Numerous examples include water hyacinths clogging up lakes and rivers in Africa, lion fish impacting local fisheries in the Caribbean and the Giant African land snail taking over villages on Christmas Island in the Indian Ocean.

Meanwhile, brown tree snakes have eliminated entire bird populations on the Pacific island of Guam and the rapidly spreading zebra mussel has colonized the Great Lakes of North America.

And elsewhere, mosquitoes are spreading diseases like dengue, Zika, malaria and West Nile Virus to new regions.

“We shouldn’t overlook the magnitude of the impact of some alien invasive species,” said Peter Stoett, co-author of the report and dean of the faculty of social sciences and humanities at Ontario Tech University.

The spread of invasive species across countries and continents is a major driver of biodiversity loss – deteriorating the complex web of ecosystems “upon which humanity depends,” according to the report, which linked invasive species to 60% of recorded global extinctions.

Once an invasive species takes hold, the impacts can be disastrous.

The dried-out non-native grasses and shrubs in Hawaii helped fuel last month’s devastating Maui wildfire, one of the deadliest in modern US history.

“It would be an extremely costly mistake to regard biological invasions only as someone else’s problem,” said Anibal Pauchard, co-author of the report and professor at Chile’s Institute of Ecology and Biodiversity.

“Although the specific species that inflict damages vary from place to place, these are risks and challenges with global roots but very local impacts, facing people in every country, from all backgrounds and in every community – even Antarctica is being affected.”