Paleontologist Peter D Ward is scared and not afraid to admit it. He doesn’t mince matters in his latest book The Flooded Earth: Our Future in a World Without Ice Caps. His own study of Earth’s geological past makes him well aware of what changes to the ice caps can mean for sea level and also of how closely past temperature rises and falls have been tied to levels of atmospheric carbon dioxide. He is alarmed by the prospect for this century and also for the centuries ahead if we keep loading the atmosphere with carbon dioxide from fossil fuels. Over coming centuries we can expect metres of sea level rise at a minimum, and much more if there is rapid disintegration of one or more ice sheets. His example of how rapid change can be is a rise which occurred during the most recent ice melt 14,000 to 16,000 years ago when the sea appears to have risen by nearly 50 feet over 300 years.
Scientific reticence is not for him. He discusses it at one point in the book. In relation to sea level rise he considers the fear of being wrong is inhibiting the sounding of the alarm that new discoveries call for. He refers to James Hansen on the question of caveats and caution. Hansen regards caveats as essential to science, but warns that there is a question of degree and “gradualism” as new evidence comes to light may not be appropriate when an issue is pressing. Ward welcomes the robustness of Hansen who says he expects more than 3 feet sea level rise by century’s end. Ward also notes climatologist Stephen Rahmstorf’s recent estimate, based on a new kind of model, of a minimum of 2 feet and a maximum of almost 5 feet this century. Ward doesn’t himself settle on a particular figure for this century, but has no doubt that the rise will continue so long as carbon dioxide levels are permitted to continue to rise, and that it will be very difficult for human society to cope with.
The book has many warnings to give about what rising sea levels will mean. They are pitched to the understanding of non-specialist readers and they bring into focus the work of a wide range of researchers in a variety of fields. One area of major concern is how even a modest increase in sea level will dramatically affect world agricultural yields. Some land will be drowned, but Ward draws particular attention to salt intrusion from the sea in agricultural areas near to oceans. A detailed examination of the Sacramento Delta region in California illustrates just one highly susceptible area. Ward considers the world overpopulated, and the prospect of feeding 9 billion or more people is certainly not enhanced by encroaching sea water.
It is estimated that even an 8-inch rise in the Bay of Bengal will displace 10 million Bangladeshis in an already heavily populated country.
The flooding of threatened countries and cities as sea level rise gathers pace is the focus of another chapter of serious warning. Bangladesh and Holland are two countries he discusses. It is estimated that even an 8-inch rise in the Bay of Bengal will displace 10 million Bangladeshis in an already heavily populated country. A 3-foot rise in sea level will put Holland on the ropes; a 16-foot rise will knock it out, flooding huge areas and displacing millions. Venice and New Orleans feature in his discussion of cities, but he points to myriad coastal cities which will face neighbourhood triage – deciding which areas to fight for and which to give up. If sea level rises much beyond 5 feet expensive infrastructure will be threatened and some enormous economic blows suffered. Airport runways in San Francisco, Honolulu, and Sydney will be the first to go. In many cases it will be more cost-effective to abandon coastal cities rather than try to protect them.
Ward frequently offers imaginary scenarios at various stages of the future, ranging from twenty years through to several hundred or even thousand years. They are not comforting, but they are all too possible if we refuse to take seriously the effects our fossil fuel habits are having on the global environment. His picture of what effect the Canadian operations to extract oil from tar sands will have had by 2030 if they continue is shocking – the desolate, devastated landscape, the health and environmental hazards visited on the First Peoples, the vast increase in carbon dioxide emissions. Another imaginary picture in 2045, with carbon dioxide levels at 450 ppm, portrays the last visit of tourist divers to Osprey Reef in the Coral Sea. The reef has changed tenants. Its once-numerous corals have been replaced by microbes that thrive in hot, acidic water. No longer a coral reef in the Coral Sea, it has become a bacterial reef in the Bacteria Sea. A more distant scenario is in 2400 on the Bangladesh-India border. Carbon dioxide levels are at 1200 ppm. More than half of Bangladesh is under water. He pictures a mass border breakthrough of a tide of humanity met by tactical nuclear weapons killing fifty thousand Bangladeshis instantly and many more in weeks to come.
One can hear the scoffing of denialists and delayers. But I found nothing alarmist in the scenarios. What else do we think is going to happen as the seas continue an inexorable rise brought on by the gradual or more than gradual disintegration of the ice sheets? Ward knows what the ice sheets mean for sea level. He also knows what elevated carbon dioxide means for global temperature. Earth has been through this before. The difference this time is that it is our own doing and that it is happening to a planet heavily populated with human beings.
The book includes a chapter titled “Extinction?”. The question mark was a small relief. Here he discusses his concern at the eventual possibility of a slow changeover of the oceans through global warming from their current “mixed” states to a stratified state which in the past has always been a prelude to biotic catastrophe. The chapter recapitulates briefly the argument of his previous book Under a Green Sky, reviewed here, and emphasises the contributory role of sea level rise to the process of slowing oceanic currents and interrupting the mixing of oxygenated top waters with those below. In his view this is a point where we need to see a vital connection between ancient climates and impending climate change. He observes that the media have not allowed scientists to make this case, not because they disbelieved it but because the past scenarios were too horrifying for us to contemplate their happening again, and soon.
There’s an element of understandable desperation in Ward’s final chapter. It considers carbon sequestration possibilities through afforestation, charcoal burial, acceleration of natural weathering processes and other measures. Also, albeit with not much conviction and some trepidation, it canvasses major geo-engineering proposals to which we may be driven in extremity.
I found Ward’s book hard to put down. He draws out the implications of what we already know with clarity and force. That is a most valuable service. The more scientists will overcome their inclination to reticence and share their fears with the general population the better. Any risks in doing so pale beside the consequences of not doing so. We must be faced with the full reality of what we are doing to the climate while we can still escape the more extreme consequences.