Six Degrees: Our Future on a Hotter Planet

They also found that the 2003 thaw penetrated up to half a metre deeper into the rock than any thaw during the previous two decades.

Surprisingly, however, the worst rockfalls didn't take place on sunny slopes where the direct heat was strongest, but on shaded northern faces, where the high air temperature penetrated the mountain. Ominously, the study concludes that with one degree of further global warming, more permafrost degradation in the Alps is unavoidable. ‘Widespread rockfall and geotechnical problems with human infrastructure are likely to be recurrent consequences of warming permafrost in rock walls due to predicted climatic changes,’ Haeberli and his colleagues warn. ‘The extreme summer of 2003 and its impact on mountain permafrost may be seen as a first manifestation of these projections.’

As mountain slopes thaw out and fail, whole towns and villages will be at risk of destruction in the Alps and other mountain regions. Some towns, like Pontresina in eastern Switzerland, have already begun building earthen bulwarks to guard against deadly landslides from the melting slopes above. But many more will remain unprotected and unprepared-until the worst happens, bringing death crashing down from above, suddenly and with no warning. Moreover, this won't be the only danger associated with mountains in the warming world: as later chapters show, just as dangerous will be the likelihood of running out of life's most precious resource-water.

Queensland's frogs boil

No one could accuse the Australian authorities of not taking their responsibility to protect the Queensland Wet Tropics rainforest seriously. Visitors must stay on walking tracks at all times. Fuel for stoves must be brought in, as campfires might disturb the delicate nutrient cycle of the forest. Every tuft of moss, leaf and twig is protected: removing living materials is a criminal offence. Dogs and cats are banned, as are soap, toothpaste and sunscreen, in case these chemicals leach into streams and harm aquatic animals. And you're most certainly not allowed to swing from vines in the trees.

There is good reason for this intense conservation focus. Recognised since 1988 as a UNESCO World Heritage Site, seven hundred species of plants are found nowhere else on Earth. The Wet Tropics ecosystem contains many species that are unique relicts from ancient rainforests which once grew on the Gondwanan supercontinent 120 million years ago. Many of the same fern species which are still found there today were once grazed by dinosaurs. Amazing carnivorous plants-like pitcher plants and sundews-poke out from the forest floor. Pythons wind around branches, whilst skinks and geckos scurry across rocks and up tree trunks. Thirteen mammal species-including tree kangaroos and ringtail possums-are also unique to the Wet Tropics region. Overall the area is home to a quarter of Australia's frogs, a third of its freshwater fish, and nearly half of its birds-all on a fraction of 1 per cent of the continent.

Yet there is one threat which the Australian authorities are powerless to prevent-and indeed have actively conspired to ignore. It comes not from feral pigs or cane toads, nor even from a thousand swinging, littering, tooth-brushing humans. This threat comes as the climate which sustains the forests-in some areas with a staggering 8 metres of annual rainfall-gradually begins to warm up. It turns out that the Queensland Wet Tropics rainforest is one of the most sensitive areas on the planet to climate change. Just one degree of warming will have devastating impacts on species diversity and habitats.

The reason lies in the unusual topography of the Wet Tropics area. Unlike the Amazon forest, which covers a huge, flat basin until it rises into the eastern slopes of the Andes, the Queensland rainforest comprises hilly terrain-starting from the white sands fringing the ocean to heights of 1,500 metres or more in places. Many of the species which are unique to the area are found only above certain heights: there's a ring-tailed possum which is only found above 800 metres in altitude, and many birds, reptiles and frogs only live at the tops of mountains. As the climate warms, temperature zones rise up the mountainsides, squeezing these species into diminishing islands of habitat-and eventually leaving them with nowhere to live at all. They, like the polar species in the Arctic, will have been literally pushed off the planet.

Dr Steve Williams, of James Cook University's School of Tropical Biology, has been warning for years about the dangers that even small degrees of climate change pose to the Wet Tropics rainforest. Williams-who leads teams of Earthwatch volunteer helpers on his survey trips-has conducted 652 bird surveys, 546 reptile surveys, 342 frog surveys, and at various times set around 50,000 night traps to catch small mammals. Armed with this voluminous wildlife data, he ran a computer model representation of the area under a changing climate and studied the results to see what happened. Even with just a one-degree rise, the results were dramatic. In particular, 63 of the 65 modelled species lost around a third of their core environment. One species of microhylid frog, which instead of having tadpoles in ponds lays its eggs in moist soil, is predicted to go extinct altogether. With higher degrees of warming, rates of biodiversity loss become increasingly dramatic, adding up, in Williams's words, to ‘an environmental catastrophe of global significance’.

Nor are animal species the only ones affected. A similar modelling study by David Hilbert of the CSIRO Tropical Forest Research Centre concluded that one degree of warming would reduce the area of highland rainforest by half, wiping out the habitat of many of the rare animal species mentioned above. Rainforests as a whole won't disappear from Queensland as long as the region receives high rainfall, but without these precious throwbacks to an ancient supercontinent, today's world will be immeasurably poorer. Moreover, Australia's national government, which refused for over a decade to take global warming seriously, will have failed in its international duty to protect a UNESCO World Heritage Site.

Just a few miles offshore from the sparkling white sands of the Queensland coast lies another threatened World Heritage Site: the Great Barrier Reef. This is the biggest and most pristine of all the world's coral reefs, a massive subsea wall of coral which is the largest natural feature on Earth, stretching more than 2,300 km along the north-east coast of Australia. One of the most spectacular and diverse ecosystems on the planet, the reef is home to 1,500 species of fish, 359 types of hard coral, 175 bird species and more than 30 types of mammal. It is one of the last refuges of the dugongs (sea cows) and hosts six of the world's seven species of threatened marine turtle.

But the oceans around the Great Barrier Reef are warming-as they are all over the planet-threatening to tip this unique ecosystem into irreversible decline. Coral reefs are actually the external skeletons produced by billions of tiny coral polyps, which secrete calcium carbonate into branches, fans and globes. These constituents in turn combine over thousands of years to form a reef. Each polyp contains algae, tiny plants which live in symbiosis with their animal hosts. Both parties benefit-the coral gets the sugars which the algae produce by photosynthesising light (turning it into energy), whilst the algae derive fertility from the polyp's waste products. But this cosy relationship can only continue in the right aquatic conditions: once the corals' thermal tolerance threshold of 30°C is crossed, the algae are expelled, and the ‘bleached’ corals will die unless cooler waters return quickly.

Bleaching is undoubtedly a recent phenomenon, observed around the world's oceans only since about 1980. Scientists have drilled deep into reefs and found no evidence that such episodes have happened during past millennia. But as the oceans have warmed due to the human-enhanced greenhouse effect, bleaching episodes have hit the world's coral reefs with increasing-and devastating-regularity. The first mass bleaching event occurred on the Great Barrier Reef in 1998. Since then things have got steadily worse. In 2002 another mass bleaching event occurred-this time 60-95 per cent of all the reefs surveyed across the marine park were bleached to some extent. A small number of reefs, particularly those close to shore where the waters were hottest, suffered almost total wipeout.

As luck would have it, I was on the Great Barrier Reef in the summer of 2002, visiting the University of Queensland's research station on Heron Island. The place was frighteningly efficient-within minutes of disembarking from the Grahamstown catamaran I had learned to tell the difference between a white-capped noddy tern and a muttonbird, and discovered that Heron Island was actually misnamed: the white birds in question are in fact eastern reef egrets. The place was stunning-‘an aviary surrounded by an aquarium’, as one of the scientists accurately put it. Buff-banded land rails scampered about like domestic chickens, in and out of the research huts. (Two female students had adopted one and named it Sheryl.) Very soon I spotted the man I had really come to see, striding purposefully around the station with his wetsuit peeled off down to the waist. Ove Hoegh-Guldberg was clearly a man happy in or out of the water. One of his favourite stories was about the time he managed to get his finger clamped in the jaws of a giant clam, and had to rip the animal off the seabed in order not to be drowned by the rising tide-only to be scolded on returning to the beach by a marine park official for damaging a protected species.

Hoegh-Guldberg was the author of a landmark 1999 paper which first drew the world's attention to the threat posed to coral reef survival by bleaching. Having determined the thermal tolerance threshold for corals in different parts of the world, he then applied these to a model of rising sea temperatures during the twenty-first century. The results shocked even him. By the 2020s, he discovered, with less than a degree of global warming, the seas will have heated up so much that the 1998 Barrier Reef mass bleaching event would be a ‘normal’ year. Given that it takes 30 years or so for a seriously bleached reef to recover, annual bleaching events will devastate the ecosystem-transforming, as Hoegh-Guldberg wrote in the paper, ‘Great Barrier Reef communities into ones dominated by other organisms (e.g. seaweeds) rather than reef-building corals’. Other coral reef ecosystems-from the Caribbean to Thailand-would be similarly transformed. With the end of the coral reefs, one of the world's great treasure troves of biodiversity will be destroyed for ever.

It was with this grim scenario in mind that we both went for a snorkel on the afternoon I arrived on Heron Island. Splashing through the shallows, we disturbed a huge shoal of pilchards, which turned en masse and darted off further up the shore. Halfa dozen large stingrays flapped lazily further out, where a stronger wind raised enough of a chop to make snorkelling a hazardous experience. Every so often a wave would break over the top of my snorkel, giving me a sudden gulp of salty water. Ove was unfazed, and we trod water for a while as he pointed out affected corals.

‘See that bright blue and red? That's actually bleached. It's ironic you get the best colours when it's bleached.’ Some of the worst-hit was the branching coral, where whole areas were blanched bone-white. In some places just the tips of the underwater antlers were bleached, whilst in others the entire structure had been hit. But only a minority were the healthy brownish colour indicating the symbiotic algae still at work.

‘How likely is it to come back?’ I spluttered, swallowing another wave.

‘So long as it stays cool from now on, most of it will probably come back,’ he replied. ‘But some of it won't, and if temperatures rise again soon much of this will probably die.’

Hoegh-Guldberg's work has been complemented by a more recent study which gives a slightly more optimistic forecast. Work in the Caribbean and Indian Ocean by Andrew Baker and colleagues (later published in Nature) suggests that corals may be more adaptable-and therefore less vulnerable to outright extinction-than previously thought. The scientists studied coral communities that had been bleached in the 1998 event to see how far they had managed to recover, and were surprised to find that the type of symbiotic algae within the coral had changed to a more heat-tolerant version in all the places they surveyed. With a higher thermal stress threshold than before, damaged reefs may be able to survive future warmer seas without dying out completely, the scientists suggested.

But Ove Hoegh-Guldberg doesn't agree. Even with an increase in heat tolerance with different algae, he points out, ocean temperatures are still set to get too hot for most corals to survive. He and his co-authors used the latest models and reef analysis to again project bleaching frequencies in the decades to come-and their results confirmed the earlier pessimistic analysis. Severe bleaching will occur on most of the world's reefs every 3-5 years by the 2030s, and by the 2050s will strike every two years.

A more recent bleaching event, which struck the Caribbean in 2005, also seems to bear this out. That summer saw sea temperatures in the region reach highs never before measured during the entire 20-year satellite record. These were the same high temperatures, in fact, which made 2005's hurricane season so deadly: Hurricane Katrina hit New Orleans in 2005 after travelling over these same unusually warm areas of ocean. And they were temperatures which would be vanishingly unlikely in an atmosphere without today's loading of greenhouse gases. The effect on Caribbean corals was disastrous. According to surveys carried out by scuba divers, 90 per cent of coral bleached in the British Virgin Islands, 80 per cent in the US Virgin Islands, 85 per cent in the Netherlands Antilles, 66 per cent in Trinidad and Tobago and 52 per cent in the French West Indies. Some reefs may recover in years to come, but model predictions suggest that in this region too bleaching events of this magnitude will hit every other year by the middle of the century.

In any case, very few of the world's reefs are in any state to take on the challenges of climate change. Direct human interference-from sewage, overfishing and agricultural run-off-has already reduced coral reefs across the globe to shadows of their former pristine selves. In total 70 per cent of the world's reefs are now either dead or dying. This is a disaster of an almost unimaginable scale for global biodiversity: second only to rainforests in terms of the vibrancy and diversity of life they nurture, coral reefs worldwide shelter and feed a third of all life in the oceans, including 4,000 types of fish.

Heron Island's reef may be under good management, but the same cannot be said for reefs elsewhere in the Pacific. In the same trip as I visited Ove Hoegh-Guldberg, I also snorkelled along Fiji's so-called Coral Coast, at one of the few gaps I could find between the 5-star hotels and luxury resorts which now blight the entire area. Instead of vibrant-coloured reefs, teeming with parrotfish and groupers, I found piles of rubble-the shattered remains of coral-looming bleakly through a murky ocean. None of the sun-bathers crowding onto the beach seemed to mind, but for me the experience was a depressing reality check. Fiji's Coral Coast is no longer vulnerable to climate change, I was forced to conclude, because it is already dead.

Another hot spot of biodiversity-and yet another World Heritage Site threatened by global warming-is the Cape Floristic Region of South Africa. Covering a huge coastal arc inland from Cape Town, it is home to the greatest concentration of higher plant species in the world outside the tropical rainforests. Its inauspicious rocky soils and arid Mediterranean climate support 9,000 different plants, more than 6,000 of which are found nowhere else on the planet. The most iconic plants in the region are the proteas. The king protea, with its massive sunlike flower head, entirely deserves its designated title as South Africa's national flower. The region is far from pristine, however-lions and rhinoceroses once roamed these hillsides, where now vineyards and rooibos tea plantations encroach on the last wild areas.

According to a team of researchers based at South Africa's National Biodiversity Institute, just small changes in climate could have a devastating impact on the remaining strongholds of the proteas and other endemic species. Using the UK Hadley Centre's model for climate changes in the region by 2020, the scientific team concluded that up to a third of protea species would become threatened or endangered, whilst four would become completely extinct.

In North America too, one degree of climate change could push a threatened species over the brink to extinction-and this one is cute and furry According to WWF, pikas-small, hamsterlike creatures with rounded ears and bushy whiskers-are the first mammal to be endangered by climate change. Pikas live in broken rock on high mountains in the western US and south-western Canada, and are notable not just for being cute and furry, but for their agricultural activities: these small relatives of the common rabbit cut, sun-dry and then store vegetation for winter use in characteristic ‘haypiles’ on top of rocks. (As a charismatic species, pikas have acquired quite a cult following: check out www.pikaworks.com for everything from pika music to pika mouse mats.)

However, as the climate warms, pikas-timid beasts, which never stray more than a kilometre from their nests-are set to become increasingly isolated in ever-smaller geographical islands as temperature zones migrate upwards towards the summits. Already local extinctions have been documented at sites in the United States. As the ecologist and pika enthusiast Dr Erik Beever puts it: ‘We're witnessing some of the first contemporary examples of global warming apparently contributing to the local extinction of an American mammal at sites across an entire eco-region.’

It has become something of a cliché to talk about the ‘canary in the coal mine’ when discussing climate impacts on the natural world-but one group of animals more than any other exemplifies this point: the amphibians. With their moist skins and early lives in water, frogs, salamanders and toads are particularly vulnerable to changes in their environment. Indeed, an amphibian-the Costa Rican golden toad-is often cited as the first known case of a global warming extinction.

Once the ‘jewel in the crown’ of Costa Rica's Monteverde Cloud Forest (to paraphrase the scientist and author Tim Flannery), this Day-Glo orange amphibian was observed in its hundreds back in 1987, gathered around pools in the forest in preparation for mating. But there were already signs of danger: the amphibian expert Marty Crump, who witnessed this last golden toad mating frenzy, also watched the resulting eggs get left behind as the forest pools dried. Only twenty-nine tadpoles lasted out the week, whilst 43,500 eggs were left desiccated and rotting. The following year Crump found only a single, solitary male, and a year later, in 1989, the same male was back once more. That day, 15 May 1989, was the last time anyone saw a golden toad. The species was eventually listed as extinct in 2004. The cause of death seems to have been the general lifting of the mist that nourishes the forest with moist cloud droplets: as the air surrounding the mountains warmed, the cloud base simply rose too high above the forest, allowing the golden toad's spawning pools to dry out.

This memorable animal may be the first, but it is no longer the only amphibian to have gone extinct because of rising temperatures: frog populations have crashed all around the tropics, with more than 100 out of 110 tropical American harlequin frog species having disappeared-even in seemingly pristine forests far away from direct human disturbance. No one knows exactly why: some biologists blame the chytrid fungal pathogen, which is invading new areas and may be causing sudden population crashes. Others blame mystery diseases which are so far undiscovered and unidentified. But experts are largely agreed on one thing: rising temperatures are central to the extinction epidemic, either by helping the new diseases spread, or by stressing amphibian populations and making them more susceptible to die-offs. In this particular murder scene, the weapon may still be in dispute but the overall culprit is clear.

Nowhere, it seems, is safe. One degree of global warming will have severe impacts in some of the world's most unique environments, adding to the biodiversity crisis which is now well under way for reasons unrelated to our changing climate. Pushed out to the margins and isolated in smaller and smaller pockets of natural habitat by ever-expanding zones of human influence, vulnerable wild species will find it impossible to adapt to rapidly changing temperatures by migrating or altering their behaviour.

Whilst coral reefs have a vital role in protecting coastlines from storms and nurturing fisheries, no one can reasonably claim that pikas, proteas and harlequin frogs are essential for global economic prosperity. Their value is intrinsic, not financial. But the world will still be a much poorer place once they're gone.

Hurricane warning in the South Atlantic

With all the headlines about hurricanes hitting the United States, there is one storm that stands out above all others in the way that it caught the scientific community off guard. It wasn't Katrina, which devastated New Orleans and killed over a thousand people. It wasn't Rita, another Category 5 monster which reflooded parts of the city only a month after Katrina struck. Nor was it Hurricane Wilma, which bombed in a single day from being a minor tropical storm into the strongest hurricane ever recorded in the Atlantic basin. No, the storm that really made the forecasters scratch their heads occurred a year earlier, in 2004. And it hit in a part of the world that isn't supposed to experience hurricanes. It was called Catarina, and it struck the coast of Brazil.

Received scientific wisdom holds that hurricanes can only form where sea surface temperatures top 26.5°C. As well as warm oceans, tropical storms also need low ‘wind shear’: cross-winds at high altitude which can cut the vortex of a developing storm in half. These conditions, as any weatherman can tell you, only occur in the North Atlantic tropics. Not a single South Atlantic hurricane had ever been documented-that is, before March 2004. Indeed, when a strange swirl of clouds began to form off the Brazilian coast on 20 March 2004, local meteorologists couldn't quite believe their eyes. So unheard of was a South Atlantic hurricane that many of them were still refusing to employ the term ‘hurricane’ when Catarina-complete with 95 mph winds and torrential rain-swept ashore near the town of Torres, damaging 30,000 houses and killing several people. Many of those who suffered, because they also refused to believe that hurricanes were possible in Brazil, had neglected to take shelter as the storm barrelled towards the shore.

In the inevitable meteorological post-mortem, it did indeed look as if the storm was simply a freak, a once-in-a-lifetime experience for those who suffered it. What was strange was that sea temperatures had not been unusually high when it began to gather strength. Instead, what really gave Catarina a boost was a very rare combination of other atmospheric factors which meant that the storm's vortex experienced very little of the deadly wind shear which normally precludes hurricane formation in the South Atlantic. It's a complex picture, but raises an obvious question: will global warming, as well as making the seas warmer and therefore more likely to spark hurricanes, lead more regularly to the conditions which allow tropical cyclones to gather strength in new areas like the South Atlantic?

Two Australia-based meteorologists, Alexandre Bernardes Pezza and Ian Simmonds, addressed this question in their forensic dissection of Catarina which was published in August 2005 by the journal Geophysical Research Letters. Their conclusion was tentative, but contained an alarming prospect: it did indeed seem as if the warming atmosphere would favour the conditions which allowed Catarina to form in such an unusual place. ‘Therefore,’ they wrote, ‘there is evidence to suggest that Catarina could be linked to climate change in the southern hemisphere circulation, and other possible future South Atlantic hurricanes could be more likely to occur under global warming conditions.’

Given that if just 0.8°C of global warming so far has already allowed one hurricane to form, a further degree of global warming could make storms in this vulnerable region much more likely in the future. Not only will Brazilians have to batten down the hatches-and perhaps evacuate large areas of their heavily populated coastline-more often, but hurricane-forecasting services will need to be extended to a whole new oceanic basin.

The hurricane season in the following year, 2005, also contained a surprise, which suggests that Brazil is not the only area which will have to keep an eye out for tropical cyclones in our globally warmed future. On 9 October 2005 a new tropical storm appeared about five hundred miles south-east of the Azores, in the East Atlantic, and rapidly gained strength to hurricane status as it drifted past Portugal's Madeira Islands. Hurricane Vince luckily weakened before it made landfall near Huelva in Spain, but set a new record as the first tropical cyclone ever to affect Europe.

Again, conventional wisdom has it that tropical storms can only form over warmer waters thousands of kilometres to the southwest of Iberia. At the time of writing, tropical meteorologists have yet to dissect the unusual combination of factors responsible for Vince, but again the implication is clear: as global warming accelerates, past experience about areas of hurricane formation is not necessarily a reliable guide to the future. Many more hurricane forecasters may be left scratching their heads before they finally admit that not just Brazil but now Europe is already vulnerable to these terrifying storms.

Indeed, there is now evidence for how this might happen: a paper published in July 2007 by Spanish and German climatolo-gists, looking at simulated storms in a computer model, suggests that the whole of the Mediterranean may soon come into the firing line as sea temperatures climb to levels able to spark off genuine tropical cyclones-in a region which has never seen them before. The greatest number of virtual cyclones appeared in the hottest part of the Mediterranean, between Italy and Libya, and once formed, the powerful storms lasted for a week or more.

One computer-generated hurricane formed in the eastern part of the Mediterranean, and then wandered westward all the way to the southern coast of France-much to the amazement of the watching scientists. Another storm formed a tight, symmetrical eye of torrential rain, just as real tropical cyclones do. The idea that once-placid coastlines from Spain to Cyprus could be at risk of landfalling hurricanes in a globally-warmed future has to be one of the most striking projections ever to come from the climate modelling world.

But already real-world evidence is fast emerging that hurricane characteristics are changing as the world's oceans warm up. One of the grandfathers of tropical cyclone physics, Massachusetts Institute of Technology's Kerry Emanuel, recently published a paper in Nature that caused its own academic storm. In contrast to the usual view that global warming is still too small a signal to have a measurable impact on tropical cyclones, Emanuel looked again at the data and concluded that storms were in fact getting more intense and lasting for longer, due in large part to rising sea temperatures driven by global warming. The storm intensity index hadn't simply gone up by a few percentage points over the last 30 years, either, it had actually doubled-a far greater increase than either theory or modelling had predicted.

Emanuel's data and methods have since been challenged in an academic discussion too technical to analyse here, but it is worth noting that his conclusions are supported by a second piece of work, this time published in Science by a team of experts based at the Georgia Institute of Technology in Atlanta. Analysing much of the same storm data-collected by aircraft, satellites and ships over the past three decades-this scientific team identified a large increase in the number and proportion of those hurricanes reaching the strongest categories 4 and 5, despite an overall decrease in the number of cyclones.

Like Emanuel, the team were looking at data from the Pacific as well as the Atlantic Ocean in order to build up a global picture. And like him (though using a different statistical measure), they found a near-doubling in the number of the strongest storms between 1970 and 2004. The Georgia team concluded that the upswing in Category 4 and 5 hurricanes is unlikely to be the result of natural climate cycles, but instead is probably connected to rising temperatures in the tropical oceans.

A year later, after the record-breaking 2005 Atlantic hurricane season-which left 1,000 people dead, 1 million homeless, and caused $200 billion of damage-two leading climatologists tried to settle the argument about whether or not global warming had contributed to the run of disastrous storms. Noting that the warm sea temperatures measured that year-the highest ever-undoubtedly contributed to the ferocity of Katrina, Wilma, Rita and the other 2005 storms, Kevin Trenberth and Dennis Shea used complex maths to figure out how much of the Atlantic warming signal was due to global warming, and how much to natural cycles. Their conclusion should be a wake-up call to us all: at least half of the extra warmth had come from human-caused global warming. As so many people suspected at the time, Katrina was only partly a natural disaster.

Sinking atolls

I hate to put this so bluntly, but in all probability nothing can save the Pacific island of Tuvalu. Like a slowly boiling kettle, the oceanic system has very long response time to changing conditions, and the seas will go on slowly rising for centuries even if all greenhouse gas emissions stopped tomorrow. With Tuvalu already experiencing regular flooding events due to past sea level rise-as I documented in High Tide-this extra rise in the world's oceans will sound the death knell for this fascinating and lively island society.

Tuvalu, with only 9,000 inhabitants, is actually one of the smallest of the five atoll nations which will shortly cease to exist. The others are Tuvalu's sister atoll group Kiribati, with 78,000 population, the Marshall Islands, with 58,000 people, tiny Tokelau (2,000 people; a dependent territory of New Zealand) and the Maldives, the largest and most densely populated of all the island groups, with 269,000 inhabitants. Together with people displaced from coastal areas of other non-atoll islands, this already totals about half a million people who-suddenly divorced from their cultures and their origins-will need to find new homes. New Zealand has hesitantly offered to take a small number of Tuvaluans, but no other nations have yet stepped up to offer themselves as places of refuge, least of all those rich countries who have done most to cause the problem in the first place.