I think you've both got it backwards. The ecosphere in general is gravely threatened. Humans specifically though? We have engineering on our side. We can air-condition our buildings; coral reefs cannot. We can rapidly adapt to changing circumstances using technology and ingenuity, while most other life cannot adapt except through evolution (which will prove too slow to keep up.)
I usually count the "Earth" as separate from the ecosystem.
And certainly there is going to be a massive reduction in biodiversity, with a lot of the species we value a lot going extinct, but overall the ecosystem will not go kaput.
Humans will have to drastically restructure their land use, for example a lot of Midwestern farmers are going to go broke as they adjust to a new climate. Some cities and states like Florida will be in dire straights with 10 feet of sea level rise, which will be a nearly unimaginable expense to relocate. And then all throughout the world we will have absolutely massive migrations of people, along with draught, crop failures, etc. This will result in wars and massive social disruption. Europe can barely deal with a very small number of refugees as it is. Once a country like India becomes unlivable in large areas, there's little telling how countries will react.
Quality of human life will decrease. Many humans will die earlier than they otherwise would have. Many non-human species will go extinct.
Life won't end. It'll suck, probably about as badly as it has ever sucked.
The Earth is a 4,550,000,000-year-old, 5,973,600,000,000,000,000,000-tonne ball of iron and silica. Earth is fine. But Earth doesn't matter, because essentially nothing is going to do anything substantial to Earth. When people refer to "Earth", they're usually referring to the ecosphere of Earth. But I suspect a few people in this thread are referring to the ball of rock & iron.
Are you Earth? Or are you a monkey that developed into salience during the ice age, and expects a certain amount of temperature variation and CO2 levels to survive?
