The year 2000 has already past.
Because we didn't get it better under control by 2000.
The argument is that these island nations might actually already be lost.
Scientists estimate an around 40 year "climate lag" between cause and effect so if you think this is bad, we're only living out the happy times from the seventies with Pink Floyd and ABBA. And then, once you have it there, CO2 has an atmospheric "half life" counted in centuries. It's why climate change is so damn nasty. :-(
It also really doesn't jive well with our short election periods where after a few years, some new guy with a radically different policy will get in charge if the earlier one wasn't popular because <insert too radical climate policy here>.
The reason this is true is that CO2 emissions can't really be reversed; accounting for all forms of "capture" (biomass, sea exchange, calcification) CO2 disappears in a reverse power law way, such that after 10 000 years 10% of it is still there (https://www.yaleclimatemediaforum.org/pics/1210_ZHfig5.jpg)
The negative is not even true -- no one can guarantee that no countries will ever be covered in water at any point in the future, even if we had presumably gotten the rising temperatures "under control" twenty years ago.
As these crises put more stress on the rest of the world we're just going to accelerate exploitation to support more people with less stuff - we're essentially burning through the world's buffer of habitability to eek out a bit more profits today.
There's never a point where all we can do is throw up our hands and do nothing. There's always something to be done, even if it's not directly related to the cause of the crisis.
That's not worldwide doom. It's just a very clear indicator of the damage that happens elsewhere, where low-lying cities like Amsterdam, New York, and much of Bangladesh have to either go elsewhere or take very expensive damage control measures.
We're at a point where it's still cheaper to prevent that at the climate level. It just grows more expensive by the day. Things can cost a lot of lives and dollars without being apocalyptic, and still worth dealing with sooner rather than later.