• Ocean acidification by elevated CO₂
• Principal concern: Loss of coral reefs (solubility equilibria at high CO₂ prevent corals from forming skeletons)

• In prior high-CO₂ episodes prior to human evolution, corals survived as plankton
• Similar changes at this date would still deplete fisheries and destroy a rich environmental heritage
• Threshhold is at CO₂ concentrations that we are highly likely to exceed, and substantially so, in the near future without actions that many deem as radical
• However, other environmental shifts become serious at similar CO₂ levels and, in combination, should push us to such radical actions:
• Loss of Arctic sea ice (despite its advantage for shipping)
• Loss of permafrost (with subsequent oxidation of soil organic carbon and thawing of methane clathrates - also in oceans), which could release vast quantities of greenhouse gases (CO₂, methane).  The resultant spike in GHG would make control of climate extremely difficult, if not impossible
• Niche for us, in view of considerable work already done and in progress by various research and policy groups: Perhaps generating presentations to apprise the public, community leaders, and policymakers of the issues - and to generate more comprehensive educational packages that effectively tie in many other issues