Invasive species cost the world $423 billion every year and are causing environmental chaos, UN report finds

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.

‘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.”

Alamy

Growing up to half a meter in width, the Northern Pacific Seastar (also known as the Japanese Starfish) has spread from the North Pacific to the south coast of Australia. A single female can carry up to 20 million eggs. It's just one of the invasive species that are traveling to new environments and harming native ecosystems. Scroll through the gallery to see more of the planet's most problematic invasive species.

Alamy

The humble comb jelly has no brain, stomach or bones. It eats microscopic sea organisms, as well as fish eggs and larvae. Native to the Atlantic coasts of North and South America, warty comb jellies reached the Black Sea, Aegean Sea and Caspian Sea during the 1980s. The jellies traveled across oceans in the ballast water of ships. In these new waters, they flourish thanks to a lack of natural predators. It is associated with crashes in fish numbers. Dolphin populations, dependent on fish supplies, have plummeted in the Black and Azov Seas as a result of the jelly invasion, according to the World Wildlife Fund.

Alamy

Trees where these beetles lay their eggs are doomed to a slow death, as larvae gnaw away at their bark from the inside. Native to Asian countries including China and Japan, this species has reached Europe and North America, mostly through wooden packaging. They have already infested many poplar plantations in China, and have also been found in chestnut trees, willows and elms. The US Department of Agriculture has warned that the insects could devastate American timber industries and forests if left unchecked.

Ian Hitchcock/Getty Images AsiaPac/Getty Images

These creatures are indigenous to South America. They were deliberately introduced to many countries in the 1930s (including the USA and Australia) to help control sugar cane pests, like beetles. But cane toads proved to be disastrously voracious, eating anything from honeybees to dog food. An estimated 1.5 billion cane toads live in Australia alone. When attacked or eaten, they emit venom that can be fatal to wild animals and household pets alike. Studies in Bermuda show they are outcompeting native frogs.

Alamy

Related to weasels, polecats and ferrets, the stoat is a small but ferocious predator. Stoats have no qualms about attacking larger animals, including rabbits and chickens. European settlers took stoats to New Zealand for pest control purposes, where they wreaked havoc on native bird populations. The New Zealand Government spends millions of dollars each year protecting native birds from stoats, which feast on their chicks and eggs.

Menahem Kahana/AFP/Getty Images

Sixty of these birds were set free in New York in 1890, in a bizarre plan to introduce to the USA every bird mentioned in a Shakespeare play. European Starlings were also deliberately introduced to regions of Australasia and South Africa to control native insect populations. Today, between 100 million and 200 million Common Starlings on six continents destroy many crops, and out-compete birds like woodpeckers in the United States and black cockatoos in Australia. However, their numbers appear to have fallen in recent decades, possibly due to intensive farming techniques.

Phil Mislinski/Getty Images

Its native range is coastal East Africa, but this snail has reached all continents except Antarctica. They are sold as food, pets, and for medicinal purposes, which led to their accidental introduction to the wild. In New Zealand, the Giant African land snail eats many types of local snails, as well as native plants.

Jeff J Mitchell/Getty Images

This large deer species was brought from Europe and Western Asia to Australia, New Zealand and South America, for trophy hunting and livestock. It flourishes in a wide range of habitats and can outcompete native mammals searching for food.

Shutterstock

Originally from the Americas, this cactus is an invasive species in South Africa, Kenya and Australia. It grows in bristly thickets up to two meters high, and was often introduced to contain livestock. It is highly drought resistant and frost resistant, and can spread across millions of hectares of land. During an infamous spell dubbed "the green hell" in Australia in the 1920s, the cacti spread so rapidly and thickly across rural plains that people abandoned their homes and farms. The plants were tamed when authorities introduced a foreign cactus gourmet, the cactoblastis moth, in 1925.

Sanjay Kanojia/AFP/Getty Images

Also known as the ship rat, it is native to India but over thousands of years, it spread to every continent except Antarctica by hiding in ships. These furry stowaways can devastate wildlife populations as they guzzle through native insects, bird eggs and chicks, and fruit.

Munir Uz Zaman/AFP/Getty Images

These purple-blossoming plants can spread to cover every inch of a lake, blocking out sunlight and crowding out native plants. The water hyacinth most likely originated in Brazilian rainforests, and became a popular addition to garden ponds worldwide in the 1890s. But this formidable species can double its size in a fortnight. The flowers are now found in most of the United States, and on every continent except Antarctica.

Sarefo / Wikimedia Commons

The big-headed ant first spread from southern Africa via ships during the 18th century. They are now found in both tropical and temperate regions, from Japan to Puerto Rico. They chew through electric wires as well as seeds, aphid honeydew, and other insects. As they graze, the ants can spread viruses among crops. Native spiders and weaver ants also struggle when this species infests new land.

‘Prevention, prevention, prevention’

Along with invasive species, other key drivers of biodiversity loss include destruction of land and sea habitats, exploitation of organisms, climate change and pollution.

The climate crisis will only amplify the threat of invasive species, becoming a major cause of these species spreading and establishing themselves in new regions, the report said.

As well as flammable invasive plants sparking and spreading wildfires, climate change is enabling invasive species to move north – even to remote areas such as high mountains, deserts and frozen tundra.

But there is hope. The scientists are optimistic that humanity can stop the march of invasive species. What’s needed first and foremost is: “prevention, prevention, prevention, especially when it comes to marine systems,” Stoett said.

Preventing the arrival of new species into new regions is the best way to manage threats from invasive species, according to the report. This includes strict import controls and early warning systems to detect and respond to species before they are able to establish.

For invasive species that have already taken hold, eradication has been a useful tool, especially on islands, according to the report.

“One of the most important messages from the report is that ambitious progress in tackling invasive alien species is achievable,” Stoett said.

“What is needed is a context-specific integrated approach, across and within countries and the various sectors involved in providing biosecurity, including trade and transportation; human and plant health; economic development and more. This will have far-reaching benefits for nature and people.”

Last year, governments around the world agreed to the Kunming-Montreal Global Biodiversity Framework to reduce the introduction and establishment of invasive alien species by at least 50% by 2030.

The scientists hope their findings – developed over four years by a team of 86 experts – will contribute to achieving these international targets.

“Governments around the world really need this assessment to get action going to reduce this tremendous threat to biodiversity and people,” Pauchard said.