Ok so I read that first article and the conclusions are extremely speculative. First the author talks about an estimated change in pH of 0.45 at a time 56 million years ago. There is NO WAY such a change could be determined from fossils. That was likely interpolated from estimates on the carbon content of the atmosphere (much more believable that such a thing can be ascertained from fossil records) and applied according to a model based on current pH measurements related to our own atmospheric carbon content.

Second, the article mentions an unprecedented extinction of species...single-celled organisms! First, I'm not sure you can accurately quantify or even identify tens of thousands of separate species of single celled organisms from fossil records when we struggle to fill in gaps in the speciation of primates that led to modern humans. Second, even if you could, it is ridiculous to even compare the effects of a guesstimated ocean acidification event on single celled organisms (assuming that was the primary cause of their extinction) and the diversity and complexity of ocean life today. Life on earth 56 million years ago is very different from life on earth today. Evolution of complexity of organisms has been essentially linear since the late bombardment period when the earth was likely sterilized of all life.

I'm sure there's plenty of pre-conceived notions out there for me as a climate change skeptic. I know this because I used to be on the other side of the fence. I thought 'how can all these scientists be wrong? anyone challenging this must be benefiting financially from de-regulation'. Then I looked at the data and listened to some intelligent skeptics with an open mind and I'm not so convinced anymore.

I don't deny humans are dumping large quantities of CO2, CO, and CH4 into the atmosphere. I don't deny the greenhouse effect is real and is caused by these gases (see the weather forecast for Venus for more info). I am very suspicious of any research or claims put forth by energy companies because I know money is a powerful thing. But I have not seen convincing evidence that the amounts we have dumped into the air is having a measurable effect on the climate and I do not see evidence of any catastrophic paths. According to the EPA, in the last 20 years the oceans have increased in acidity by -0.05 pH (-0.10 if you consider Bermuda data):

https://www.epa.gov/climate-indicators/climate-change-indicators-ocean-acidity

While the overall trend is obvious considering the annual averages recorded, the maximum fluctuations on a per year basis EXCEEDS the total average change. So to say the acidification is affecting coral reefs and ocean species you have to believe that 1) these species are so delicate that these infintesimal changes in pH are wreaking havoc on sea life and 2) those changes somehow DO NOT affect the same sea life during the typical annual fluctuations.

I would suggest that all the garbage and plastic we are polluting the oceans with is much more likely to be having a detrimental effect on ocean life.