I’ve spent most of my “academic” time the past two summers studying and writing on the economics of climate change. It has become quite clear to me that were we to line up the honest economic and environmental experts and received their honest assessments about what the worst case scenarios look like, and where the most serious consequences are likely to occur, that we would hear a lot of talk about the oceans. It seems to me that the decreased pH levels of oceans due to the dissolving of carbon dioxide in the water, that the rising sea-levels due to thermal expansion, groundwater depletion (wait, that’s not from global warming), and melting glaciers (which have been melting for long before the emissions of CO2 picked up steam, though you may conclude that the rate of melting is sharper), and threats to ocean biodiversity are the things that most worry people.
What do these threats have in common? They are all ocean related. Now, this just may happen to be a coincidence, but my money is not on that horse. It should not be surprising that the biggest perceived threats are happening to the parts of the planet we know the least about, and have had the least experience tweaking and such. Contrast these threats to something we know a lot about – pests and disease. If you look back to earlier IPCC reports (3rd one and earlier) you will see ample space given in the reports that one of the hugest threats to humanity was that mosquito and other disease vector ranges were going to expand, and cause massive amounts of death. That has not only not happened as the planet has warmed, but the malaria threat is already 1/3 as serious as it was two-decades ago, and we may even be on the cusp of eradicating it.
This is not to imply that we will solve all of our ocean problems, but it is to suggest that we lack both experience and knowledge of ocean systems, and perhaps even an imagination. I recently read (and forgive me for not having a link, but it was an old article and I was on an elliptical machine reading it) that the EPA once estimated that it would cost on the order of $1,000 per mile to protect sea coasts from sea-level rise. And given the expected rise of seas over the next century of something like a foot-and-a-half, something like a fifth of one-percent of the planet’s land area is at risk. I do not expect these numbers to move north, per the points made above.