This is the globe.

And we've been on the move ever since, taking other species with us, which can play havoc with local ecosystems.

Today, the problem is worse than ever. Invasive species are on the rise.

Here in the UK where the number of grey squirrels has increased rapidly,

scientists have come up with a novel way of controlling the population,

hazelnut paste laced with contraceptives. trolling the the UN's Biodiversity Conference in Montreal, Canada.

It's not going to be an easy one to solve.

Preventing, tracking and managing the spread of these species is a serious challenge. So today we're getting an update from COP15 and

taking a closer look at the billion dollar problem of invasive species. I'm the Guardian Science Editor Ian Sample and this is Science Weekly.

Patrick Greenfield as a Guardian Biodiversity reporter you've been covering the long lead up to COP 15

but now you're finally there in Montreal what's it been like so far? It is fantastic to finally be

here after two and a half years of delays in multiple possible venues and

negotiators are finally getting down to what should be in the text for

this decades global biodiversity framework. In terms of what it's actually like in

the city, well look it's the start of winter in Canada.

So I was in Egypt by the beautiful coral reefs for COP27, only three weeks ago now,

and it's very different. It cold not a lot of sunlight but

Montreal for those who've not been is a kind of beautiful elegant place lots of big

skyscrapers nice restaurants very comfortable the Canadians

done a brilliant job organizing this at the last minute so there's a really nice

vibe I think around the talks that might not have been there in Egypt for those who suffered I think with the food and water

and the rest of it.

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