So, no real understanding of how biology works? Let's discuss.
Creatures adapt to an ecological niche, often a very particular one. Water depth, current temperature, sand composition, mineral concentrations. Tide strength, water salinity. Many other things.
There's some give, some range where the creature can continue to thrive or even do better. But go too far over on any of those bell-curves, the creature is under stress. Particularly where reproduction is concerned.
The result of changes occurring for decades can be, sudden die-off when their operating parameters are finally exceeded. When their eggs don't stick to the surface they're supposed to stick to, or their embryo won't get past a certain point in development without another degree of water temperature.
Or just, something else got wiped out, something microscopic perhaps that we don't see and don't measure and now they have nothing to eat.
Never mind snow crabs. Coral reefs are particularly sensitive to light levels, water depth, current temperature, salinity. You raise the water level by inches, coral grows on continental shelves that slant, now the coral could survive if it was 100 feet closer to shore (or further away, whatever). But it's not there, it doesn't have legs, it dies.
Sure a new one will grow in the new optimal space 100 feet over (if the water doesn't keep rising anyway). But that take about like a century. In the meantime, all those creatures that depended utterly on that reef for survival for whatever reason, be it reproduction or camouflage or food or shelter, they die off catastropically.
Ultimately the human beings that depend on the ocean for their livelihood or food source, well if you are a rich westerner you just move or get a different job. But if you're a poor peasant scratching out a living on a shoreline, you just starve.
Does that matter? How many people are we talking about? 100's of millions.
So dismiss climate change, easy from an armchair in Idaho or wherever. But don't insult the intelligence of the rest of us with naive ideas about how silly and unwarranted the concerns are. Better to keep quiet. Or learn something, anything about how biology and the environment all works together and try to make legitimate informed contributions to the conversation.
That's my rant, my advice. I know most folks will just put up their ego shields, ignore anything that doesn't jibe with their guesses and wishes and continue to slander folks who do have some idea. That's another tragedy of all this: like a 12-step program, denial is an early stage. Eventually everybody will get through that, get through all the stages and come to understand the predicament our world is in. But we don't have time to do that nicely, let folks come around in their own time. Things are falling apart too fast, and maybe gaining momentum. There is some urgency to this.
So my best advice is, be still and let the grownups talk, if you don't have any real education in all this.