We are heading for Pliocene conditions and yes, the tipping point is in the past. Even complete cessation of fossil fuel use and zero net deforestation (growth

We are heading for Pliocene conditions and yes, the tipping point is in the past. Even complete cessation of fossil fuel use and zero net deforestation (growth of timber == harvest of timber) would not stop it at this point, as it would take ~100 years for the system to come to a new equilibrium, and even then, permafrost melt and methane/CO2 outgassing from permafrost would continue (with some offset from tree growth in northern polar regions as the permafrost retreats). Thus continual sea level rise is going to be a fact of life, possibly for several thousand years, until sea levels are 10 to 25 meters higher than today. Average temperatures will be 2-3C higher than the preindustrial Holocene average, (currently ~1.2C higher) with significant regional variation. Many regions that support large human populations will become inhospitable on a decadal timeline (i.e. it takes about ten years for signal to emerge from noise at current warming rate). As far as ocean acidification, this is probably the least of our worries, unlike ocean hypoxia and anoxia, which are steadily expanding due to all the organic matter and fertilizer dumped into the oceans by human civilization. Coral reefs were widespread in the Pliocene, and the acidification is just a surface water phenomenon and is fairly minimal - the buffering capacity of the ocean is vast, and it's just a mixing issue as surface water tends to sit on top of the deeper waters.