ABSTRACT
The age of planet Earth is now estimated at 4.54 billion years (https:// pubs.usgs.gov/gip/geotime/age.html), but modern humans, Homo sapiens, evolved in Africa 250,000 to 400,000 years ago having migrated from the continent only 50,000 to 100,000 years ago (en. wikipedia.org/wiki/Human_evolution). A review of atmospheric carbon dioxide and oceanic pH concentrations over geologic time scales from the present to 545 million years ago is briefl y presented below. Over the past 200 years, the increase in the burning of forest fuels and changes in land use has increased atmospheric CO2 concentrations from about 280 ppm to 385 ppm (Turley 2008). These are the highest rates of atmospheric CO2 increase for at least 800,000 years, and possibly for the past 30 million years. Increasing anthropogenic CO2 may result in increased acidity of the world’s surface oceans, with rapid decreases in ocean pH predicted for this century, concomitantly with warming seas, creating multiple threats to the marine environment. The future addition of massive amounts of CO2 to surface waters could have a profound impact on ocean chemistry and could have an equally profound impact on biogeochemical cycles and marine ecosystems (Turley 2008). Throughout Earth=s history, the oceans have played a dominant role in the climate system through the storage and transport of heat and the exchange of water and climate-relevant gases with the atmosphere (Riebesell et al. 2009). The ocean=s heat capacity is about 1,000 times larger than that of the atmosphere and its content of reactive carbon more than 60 times larger. Through a variety of interlinked and nonlinear processes, the ocean acts as a driver of
interglacial; however, the sign and magnitude of the ocean’s carbon cycle to climate change is as yet unknown (Riebesell et al. 2009).
