The Flooded Earth: Our Future in a World without Ice Caps

Although some people may prefer to ignore the issue, climate change continues to make the headlines: in recent months, record flooding in Pakistan and an unprecedented heatwave in Russia. These impacts, which kill people directly and cause economic misery and severe environmental damage, are entirely consistent with the effects predicted by climate science.

While it is impossible to attribute any extreme event solely to human-caused warming, it has been said that "weather throws the punches but climate trains the boxer". It is disturbing to consider that some of climate change's heavyweight contenders may not yet have even entered the ring. According to Peter D. Ward, rapidly rising sea levels caused by melting polar ice caps could be about to step up and claim the 21st-century title.

Ward, a prolific populariser of natural science and University of Washington earth scientist, puts sea-level rise at the top of the list of dangerous climate-change effects we face. Billions of people live along narrow strips of land abutting the world's coastlines. This includes great cities such as London, Mumbai, New York and Shanghai, as well as highly productive agricultural land and unique environmentally sensitive biomes that provide essential ecosystem services to humanity. Much of this human and natural capital is at clear risk of being swept away under a rising tide.

As Ward points out, when exploring climate change in deep time, sea levels are prone to change rapidly and with great magnitude. At the end of the last Ice Age, for instance, oceans rose 420ft over a few millennia, including one period when the process topped 15ft per century. Back then, 10,000 to 15,000 years ago, our prehistoric hunter-gatherer ancestors kept pace with the encroaching shorelines by simply moving camp and abandoning coastal rock shelters. Still, it must have been quite a sight for ancient people to have beheld, with the beaches and foraging areas of their childhood permanently inundated by the time they were adults.

Yet if such rates of sea-level rise started happening today - and Ward argues that this is nearly inevitable given the inertia in the climate system - modern society will not find it so "easy" to adapt. How do you move New York? Alternatively, how much would it cost to build massive concrete levees to keep Poseidon at bay? How do we replace lost agricultural land as it becomes salt-ridden and degraded by ever more regular storm surges, and eventually unusable as the once-rare inundation becomes a permanent flood? Ward spends considerable space describing such impacts, and his narrative is compelling and deeply worrying.

One of the major reasons that it is so concerning, beyond the obvious massive displacement of populations and livelihoods, is that once large-scale sea-level rise begins, it will be impossible to stop. Climatologist James Hansen famously remarked that "you can't throw a rope around a disintegrating ice sheet", referring to the accelerating melting of Greenland and West Antarctica. At some point melting becomes an irrecoverably "positive feedback", because as bright, white ice and snow cover are lost, the dark rock underneath is exposed, which absorbs rather than reflects incoming solar heat. Ward does a good job of explaining in straightforward terms why such synergies are so critical.

An effective literary device used in the book is to recount future scenarios as if they had already happened. Ward develops hypothetical situations, set in an appropriate time and place, to play-act the resultant human drama and its probable consequences (a flooded Miami in the year 2120 with 10ft of sea-level rise, and Greenland in 2215 when carbon-dioxide levels have hit 1,300 parts per million).

These stories include descriptions of the "future history" preceding these events, allowing readers to understand how the situation evolved. I do not think he intends to offer any particular certainty in these visions; rather, I suspect he wants to convey the gritty "reality" of an otherwise rather nebulous scientific forecast. Indeed, he acknowledges that it is impossible for science to provide a precise prediction of sea-level rise at any given date. But that doesn't mean that the bounds of the possible cannot be explored and their implications dissected. This is his intent and he does it very well.

The Flooded Earth is worth reading and recommending to others, especially those you know who have expressed sentiments such as "global warming might be real, but we can just adapt". There are practical limits to adaptation, or at least the exponentially rising costs involved in coping with significant climate change. Extreme scenarios of sea-level rise frame this climate- adaptation problem in the starkest possible terms.

We would do well to heed Ward's warning and act quickly to eliminate our dependence on fossil fuels soon - before all the ice on the planet is gone and "Water World" becomes a grim reality.