Every year a few hundred species step off a ship, a plane or a pallet and start a new life somewhere they have never been. Most are harmless. A small fraction rewrite an ecosystem — and send humanity an invoice that has quadrupled every decade for half a century.
US$423 BILLION
The minimum global cost of invasive alien species in 2019 alone — damage plus control. IPBES calls it an underestimate: most countries simply do not count. (IPBES, 2023)
That figure has at least quadrupled every decade since 1970. Not because nature changed, but because we move more cargo, faster, to more places — and each shipment is a lottery ticket.
37,000Alien species humans have moved and established worldwide
3,500Of those that turn seriously harmful — roughly one in eleven
~200New alien species recorded in a new region every year
01 — Arrivals
The curve that will not bend
Biologists have logged 45,813 "first records" — the first time a species was confirmed living outside its native range. Plot them by decade and there is no plateau anywhere in two centuries of data.
First records of established alien species · global mean per year, by decade
Seebens et al., Nature Communications 2017
Decade means computed from the Seebens et al. global first-record database. Post-2000 decades are omitted: recent years are distorted by reporting lag, not by fewer arrivals.
More than a third of every alien species first record in history — 37% of all 45,813 — was logged in the 45 years after 1970. The single worst year on record was 1996: 585 new alien species, more than one and a half a day.
02 — Escalation
From passenger to problem
Arriving somewhere new is common. Causing harm is rare. Driving something extinct is rarer still. The whole story is a funnel — and almost all the damage is concentrated at the dark end.
Established37,000Alien species now living outside their native range because we moved them
Harmful3,500Documented as seriously damaging nature, food security or health
Killers218Invasive species tied to recorded local extinctions
Losses1,200+Local extinctions those 218 species are responsible for
Pace~200/yrNew alien species still arriving somewhere new, every year
Source: IPBES Thematic Assessment on Invasive Alien Species and their Control, 2023 — 86 experts, 49 countries, 13,000+ references.
03 — The ledger
Where the money goes
Researchers have standardised more than 2,400 cost estimates from 850 studies into a single database, InvaCost. Totals are cumulative, and each figure comes from its own study with its own window — so they overlap. Every one is a floor, not a ceiling.
Cumulative documented cost, US$ billions
InvaCost-derived syntheses, 2021–2024
Mammal invasions $462.5 bn
1960–2021 · 90% of it damage, only 7% management
Invertebrates, mostly insects $416.0 bn
1970–2017 · insects are ~90% of the invertebrate total
Aquatic species, all taxa $345.0 bn
to 2020 · invertebrates 62%, vertebrates 28%, plants 6%
Five costliest mammals alone $183.2 bn
European rabbit, domestic cat, black rat, wild boar, coypu
Aedes mosquitoes & the diseases they carry $94.7 bn
1975–2020 · 166 countries · dengue, Zika, chikungunya
Categories overlap by design — mammals appear inside several rows. Bars are not additive.
The geography of these numbers says as much about accounting as about ecology. North America accounts for 48% of all reported aquatic invasion costs and 61% of reported mammal costs — largely because North America counts. The map of invasion costs is, for now, a map of who keeps receipts.
04 — The biological bill
Sixty percent
Money is the easy part to measure. The harder ledger is the one that does not reopen: of every plant and animal extinction humanity has documented, invasive species were involved in most of them.
Recorded global plant & animal extinctions, by role of invasive alien species
IPBES, 2023
16%
44%
40%
Invasive species the only driverA contributing driverNo invasive involvement recorded
Shares of documented extinctions, not of all species lost — many extinctions were never recorded at all.
60%Of recorded extinctionshad an invasive alien species among their causes
16%Nothing else to blameinvasive species were the sole documented driver
218Named culpritsinvasive species tied to 1,200+ local extinctions
05 — Timing
Paying late
Invasion economics has one blunt rule: a dollar spent before arrival is worth many spent after. The world does almost the exact opposite.
Damage vs. management, global, since 1960
Damage from invasions $1,130.6 bn
Spent managing them $95.3 bn
12× less than the damage it was meant to prevent
Of that management money, when it was spent
After arrival $72.7 bn
Before arrival — prevention $2.8 bn
26× less than clean-up · scaled to the bar above
12×The response gapdamage costs versus all money spent on management since 1960
26×The prevention gapclean-up spending versus spending to stop arrivals in the first place
$1.2 tnThe cost of waitingextra global cost attributed to delayed action versus acting immediately — modelled estimate
Source: Cuthbert et al., Science of the Total Environment, 2022. All figures in 2017 US dollars. The $1.2 trillion delay figure is modelled, not observed.
06 — Ahead
The next 24 years
Trade volumes are the engine, and trade is forecast to grow. But this is one of the few environmental problems where a hard, physical fix demonstrably works — islands prove it.
Projected growth in alien species numbers by 2050 vs. 2005
Seabird populations growing after predator removal 151 of 181
median growth rate 1.119; 23 populations still declining
The policy gap is the loudest number in the whole assessment: 80% of countries have invasive-species targets in their national biodiversity plans. Only 17% have national laws or regulations that specifically address them.
Why it matters
A problem with a door
Most global environmental problems are diffuse — everyone contributes a little, nobody can stop it alone. Invasions are different. They have a chokepoint: the moment of arrival. Ballast tanks, timber pallets, nursery soil, aquarium dumps, a boat trailer that was not rinsed. Stop a species at the door and it costs almost nothing. Miss it and you may be paying, and losing species, for centuries.
Clean, drain, dry
Boats, waders and fishing gear move zebra mussels, algae and pathogens between watersheds. Rinsing and fully drying gear between water bodies is the single highest-leverage thing a private individual does.
Never release, never dump
Aquarium fish, plants and water, unused live bait, and unwanted pets are a documented introduction pathway. Rehome them; do not release them, and do not tip tank water into a drain or pond.
Declare it at the border
Biosecurity declarations on seeds, soil, fruit, wood and honey exist because 200 new arrivals a year mostly travel as freight. Declaring costs you a minute. The alternative is on this page.
Report early
Eradication only works while a population is small. National invasive-species reporting lines and apps exist in most countries precisely to catch the first dozen individuals, not the first thousand.