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Invasive pests are wreaking havoc across the planet, destroying crops, spreading pathogens, decimating the fish stocks that people rely on for food and driving native plants and animals to extinction, a major United Nations report says supported report.
The landmark assessment found that more than 3,500 harmful invasive species cost society more than $423 billion annually. This number is expected to rise as the modern era of global trade and travel accelerates the spread of plants and animals across continents like never before.
By taking cargo ships and passenger planes, exotic species span oceans, mountain ranges and other geographical boundaries that would otherwise be insurmountable without human help. The result is a major mess in the planet’s flora and fauna, with devastating consequences for humans and the ecosystems on which they depend.
“One of the things we’re really emphasizing is the enormous threat this poses not only to human civilization – and I know this is going to sound grandiose – but to human civilization,” said Peter Stoett, a professor at the Ontario Tech University, who helped lead a group About seven dozen experts helped produce the report.
The spread of plants and animals between continents is a major cause of Earth’s ongoing biodiversity crisis, an extinction comparable to the asteroid that killed the dinosaurs. Invasive species play a role in 60 percent of extinctions, according to the report.
As more harmful invasive species take hold and proliferate, humanity also faces great risks as pests threaten to chew through farmland and spread mosquito-borne diseases and other illnesses.
“It’s normal for species to migrate,” said Aníbal Pauchard, a professor at the University of Concepción in Chile, who co-chaired the group behind the report with Stoett. But what is unprecedented, he added, is the current era in which plants and animals overcome the “great barriers” between continents.
“It’s not normal for a species to cross the Atlantic,” he said. “It’s not normal to go from Australia to Chile.”
The report was authored by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), a panel of more than 140 countries that provides policymakers with scientific assessments to help protect the Earth’s biodiversity and prevent… contribute to extinction. A summary of the results was approved over the weekend and released on Monday. Full chapters are scheduled to be released later this year.
The panel concluded that the threat of invasive species is “underestimated, underestimated and often unrecognized,” with only about a sixth of the world’s nations having laws or regulations protecting invasive plants and animals. With new species being introduced at an “unprecedented” rate of 200 per year, the problem is expected to get worse before it gets better.
The most widespread invasive animal, according to the report, is the black rat, which spread by hiding on ships and making its way not only into dense cities but also to far-flung islands, where it decimated bottom-nesting seabirds and other animals. The impact of terrestrial rats on islands is so profound that even nearby reef fish can feel it after the rodents alter the flow of nutrients into the ocean.
Remote islands are particularly vulnerable to invasion because they are often home to plants and animals found nowhere else.
On Guam, for example, the voracious brown tree snake has already driven several native birds to extinction. On Maui, the destructive power of invasive vegetation was on full display last month after introduced grasses fueled wildfires that killed more than 100 people.
Many invasive species have also become established in aquatic ecosystems. In the Caribbean, poisonous lionfish are reducing the number of native fish. In the Great Lakes, zebra mussels clog the intake pipes of drinking water systems and power plants.
But one of the most devastating water invaders is a delicate-looking flower.
Originally from South America, water hyacinth is a free-floating plant that grows so quickly that it can cover entire ponds and lakes, leaving a matted mass that impedes boat traffic and fishing. In some cases, the plants soak up so much water that they dry up lakes and leave communities without drinking water. The report called water hyacinth, which appears everywhere from Africa to Australia, the most widespread invasive plant on Earth.
Antarctica is not spared either. The introduction of invasive grasses combined with rising temperatures risks converting parts of the southern continent to grasslands.
In addition to invasive species, climate change, habitat destruction, pollution and direct exploitation of species are other four major causes of extinction, with one million plants and animals at risk of extinction.
Climate change is likely to worsen the problem of invasive pests by allowing animals like tropical fire ants to move north to higher latitudes.
“With climate warming, there will be some species that would not have been able to establish and thrive in some regions of the world, but in the future they will be able to establish and thrive,” said Helen Roy, a British ecologist and a third co-chair of the assessment.
Invaders, in turn, can increase climate change. Tree-killing insects like the emerald ash borer, which is spreading across North America, make it harder for forests to sequester carbon from the atmosphere.
“The overlap of this report with the United Nations climate goals is profound,” said Leigh Greenwood, who works on forest pests and pathogens for the Nature Conservancy, a global environmental nonprofit.
In December, under an international agreement negotiated in Montreal, nations agreed to reduce the spread of harmful invasive species by at least half by 2030. According to the report, the best way to deal with them is to prevent them from entering in the first place through border surveillance and import controls.
“We keep coming back to: prevention, prevention, prevention,” Stoett said.
Even if an invasive species has taken hold, eradication is possible, especially on islands. Conservationists have eradicated the rodents plaguing the South Atlantic island of South Georgia, while others in the Galapagos have rid some islands of destructive goats.
And new technologies also offer hope, even as they generate controversy. In Hawaii, officials are preparing to release a special strain of bacteria to suppress mosquitoes that transmit avian malaria and kill songbirds. Others try to manipulate the genes of mosquitoes and other pests to control their numbers.
“Every challenge nature faces amplifies all the others,” said Monica Medina, a former U.S. State Department biodiversity official who now leads the Wildlife Conservation Society. “Invasive alien species increase stress on fragile ecosystems that are already facing a variety of other threats.”
Climate change and global warming
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