Some of this seems like conflating unrelated issues. For example, the issue of brown tree snakes and other extremely successful "invasive" traveller species. We

Some of this seems like conflating unrelated issues. For example, the issue of brown tree snakes and other extremely successful "invasive" traveller species. Well, obviously that snake is very well-adapted for the environment of Guam. It's natural that a more interconnected world means that any given species which could be well-adapted somewhere else in the world has a better shot of actually reaching that place. Overall what we're really seeing is the collapse of old protective "anti-competitive" barriers. And a new competitive equilibrium will be reached after the dust settles. Superior adaptive strategies will propagate. The only reason I can see to view this is as negative is a) sentimentality about "naturalness," b) aesthetic distaste for hyper-successful species, c) concerns that, in the short-term, rapid homogenisation of ecosystems may degrade their utility to humans (e.g. loss of ecosystem services such as water and air purification, or loss of organisms with useful novel biological properties - frogs with special antibodies and so forth. a) is silly, because what is less natural than a world overrun with hairless apes devouring every resource they can find? b) is again silly - anyone who feels like this really hasn't come to terms with being human, and should be worrying about what they see when they look in the mirror. c) is valid, though of course completely self-centered. So as far as I can see this problem comes down to self-interest and self-disgust. Climate change of course is a rather more serious issue - though it does come down to similar feelings of self-interest and self-disgust