are more completely described in my 2003 book coauthored with Don Brownlee, The Life and Death of Planet Earth. Perhaps most noticeable would be the loss of the Mediterranean Sea, with its space taken up by an enormous mountain range extending from what is now Europe to the Persian Gulf region. Australia will have moved northward, closing the regions that are now composed of Papua New Guinea and Indonesia, while Baja California will have slid northward along the Pacific Coast of North America.
Far more important than these new continental positions will be the formation of new subduction zones, the regions where Earth’s crust dives beneath the continents. Today we know that subduction is initiating in the central Indian Ocean and in the ocean off Puerto Rico. These events suggest that new subduction zones will be in place off both eastern North and South America. As this happens, mountain building will be initiated once again in the Appalachian regions and along the eastern coastline of South America as well. These regions will become home to gigantic active volcanoes and rising mountain chains.
It is not just the positions of the mountains that will change. As Antarctica drifts northwards, its vast ice sheets will melt and the level of the sea will rise. As the sun continues to increase its energy output, it will also cause temperatures to rise, melting other continental ice sheets, with Greenland’s being the most important. When both Greenland and Antarctica have seen all of their ice cover melt, the oceans will rise to a sea level nearly 300 feet higher than it is today. Tectonic forces, including the formation of new mid-ocean spreading centers, will also exacerbate sea-level rise. As these form, they will cause the oceans to spill out of their basins and onto low land surfaces.
Flooding of the continental margins brought about by the rise of the sea will cause our planet to undergo a radical climate change. Will it cause there to be a change in oxygen levels as well? As we saw in previous chapters, the two most radical changes in oxygen spanned the interval from the Carboniferous to the end of the Triassic. From the start of the Carboniferous oxygen levels rose to a maximum of over 30 percent by the early Permian. They then began to drop, reaching minimal values of 10 percent some 210 million years ago.
Why was there this one-two punch, and could it be repeated? We