10 Hawaiian honeycreepers
Small island species, confined to limited terrain, are always vulnerable, particularly to invasive species, burgeoning human populations, and new diseases. On Hawaii, climate change intersects with these three factors to imperil its unique birds, including six species of honeycreeper.
The small, often brightly coloured honeycreepers tend to survive at higher altitudes where their forest habitat is less likely to be destroyed by humans. Higher elevations are also cooler, and less attractive to mosquitoes, which were first carried to Hawaii in the 19th century, long after the birds had evolved there. Outbreaks of mosquito-borne diseases such as avian malaria and avian pox began soon afterwards.
As the world warms, so mosquitoes move into higher elevations – and there is nowhere for the honeycreepers to escape to. The birds are particularly susceptible to avian malaria. Last year, a scientific study noted that the prevalence of avian malaria has more than doubled since the 1990s in the upper regions of the Hawaiian island of Kauai. Naturalists working in the Kauai mountains never encountered mosquitoes despite searching for them until the last six years or so, during which time they have become commonplace. As well as mosquitos, climate change is also assisting non-native competitors and invasive weeds, which may hasten the native birds’ demise.
Eben Paxton, of the US Geological Survey’s Pacific Island Ecosystems research centre, fears that two honeycreepers, the ‘akikiki and the ‘akeke’e, will fall extinct in the next decade “without major intervention”. This means action unfamiliar to many conservationists: removing standing water to reduce mosquito populations, and even releasing genetically modified mosquitoes to reduce populations over time, as undertaken in Brazil to combat the Zika virus.
9 Baird’s sandpiper
The Baird’s sandpiper (Calidris bairdii) is not likely to become extinct any time soon. It is still listed as a species of “least concern” on the International Union for Conservation of Nature’s (IUCN) Red List. But the challenge posed by climate change for this elegant little wading bird is one experienced by many other species: it’s a problem of phenology and synchronicity. Phenology, the study of the timing of natural events in relation to weather and climate, is increasingly complex and important in an era of rapid climate change. Changes in phenology may be a positive sign, demonstrating that species are adapting to climatic conditions and migrating earlier, or flowering sooner, or having offspring earlier in the spring to coincide with food supplies that are changing with the season.
But many species are struggling to adapt quickly enough. Increasing temperates in the high Arctic are encouraging shore birds such as the Baird’s sandpiper to breed earlier in the season. This means that more chicks are emerging before the peak abundance of the insects that they feed own. Studies show that chicks raised outside the period of peak abundance grow much more slowly, which means they are less likely to survive into adulthood. A similar mismatch between chick emergence and peak food has also been shown to occur with the European pied flycatcher in the Netherlands.
8 Giant mountain lobelia
Increasing temperatures are posing a challenge for all kinds of montane species. They may retreat to higher altitudes but, eventually, they will run out of mountain. Mountainous regions are also likely to experience particularly extreme temperature changes: while the Intergovernmental Panel on Climate Change estimates that 21st-century climate warming is likely to exceed 2C in many scenarios, the rate of temperature increase in mountainous areas is predicted to be much higher – possibly three times the increase recorded over the 20th century.
The giant mountain lobelia (Lobelia rhynchopetalum) is a native of Ethiopia, a spectacular-looking tropical alpine plant that resembles a spiky tropical palm but then shoots up a huge woolly protuberance, sometimes more than 10 metres tall. Implausibly large in arid mountainous terrain, the family of lobelia plants remarkably predate the formation of tall mountains in eastern Africa, to which they’ve adapted.
They are not finding it so easy to adapt to rapid anthropogenic climate change. A scientific study of the plant’s prospects last year concluded it “will suffer massive reduction in range” under warmer climes, with just 3.4% of its habitat still suitable by 2080. By then, it is predicted to be confined to just four suitable mountain-top habitats “which may be too small to sustain viable populations”. There’s a further problem. As alpine species such as the giant mountain lobelia are confined to isolated mountaintops, their genetic diversity will narrow dramatically – by 82% – further increasing the likelihood of extinction.
The travails of this mountain giant are matched by mountain plant species around the world, including high-altitude species in Britain. Botanist Trevor Dines, of the charity Plantlife, says: “It’s already clear that some of our rarest Arctic-alpine plants, such as Highland saxifrage, are at risk. As the climate warms, they’re already moving to higher altitudes to find cooler, damper conditions. At some point, they’ll run out of mountain to climb and we’ll be facing the extinction of some of our most enigmatic and wonderful flora.”
7 Bramble Cay melomys
For many creatures, climate change is the most vicious component of a perfect storm driving them towards extinction. For some, extinction is quite literally caused by storms and rising seas. Anthropogenic climate change has almost certainly driven our first mammal species to extinction. The Bramble Cay melomys (Melomys rubicola), or mosaic-tailed rat, lived the unobtrusive life of a small rodent in the eastern Torres Strait. It was first discovered – and killed – on the tiny vegetated coral island of Bramble Cay by Europeans in 1845. Several hundred lived there as recently as 1978. But the highest point of Bramble Cay is three metres above sea level and around the Torres Strait the sea level rose at almost twice the global average rate between 1993 and 2014. Since 1998, the area of Bramble Cay above high tide has shrunk from from 4 hectares to 2.5 hectares. The melomys has lost 97% of its habitat and was last seen by a fisherman in 2009. Scientists laid traps in 2011 and twice in 2014 to catch the little rodent and start a captive breeding programme to save it from extinction. But they were too late: they couldn’t find any trace of the animal. There’s a small chance an as-yet-undiscovered population may survive in Papua New Guinea but the scientists have judged it is almost certainly extinct.
6 Sierra Nevada blue
The Sierra Nevada blue (Polyommatus golgus) is a small butterfly that is both brilliant blue (the male) and dark black-brown (the female) and is one of four endangered species unique to Spain. It is only found in the peaks of the Sierra Nevada and in another small mountainous area further north.
It has already lost habitat to overgrazing by animals, a ski resort, and the trampling of vegetation by people on roads and footpaths. But its biggest threat is climate change, according to a species recovery plan drawn up by the researcher Miguel Munguira for Butterfly Conservation Europe. Drought, increased temperatures and reduced snow coverage are set to displace the species to higher areas where the habitat might not be suitable. “For the populations living on the highest areas of the mountains these changes would mean their extinction,” says Munguira.
Of the 482 species of butterfly in Europe, 149 are restricted to such small areas that it is difficult for scientists to assess how the changing climate will affect them. Isolated in such small pockets of land makes these rare insects hugely vulnerable – wild habitat is too fragmented for even winged creatures to easily find a suitable alternative. And those that can only live in northern Europe, or on the tops of mountain ranges, will be the first to go.
“The scale of threat to the species of Europe is massive,” says Nigel Bourn, conservation director of Butterfly Conservation in Britain. “I don’t really think policymakers have even begun to come to terms with that.”
The disappearance of a few butterflies may not move the hardest of human hearts but these are the most closely monitored insects: the impact of climate change on hundreds of butterflies will be replicated in other less-known pollinators and insect populations – from bees to hoverflies – and the very fabric of life on earth will start to fray.
5 Sea turtles
Rising seas and stormy weather will affect turtle species in the most direct of ways, eroding or destroying many of the beaches where they lay their eggs. But scientists have discovered that hotter sands also cause greater numbers of sea turtles to be born female. In the short term, over the next 20 or 30 years, this will increase turtle numbers. But a study published in Nature Climate Change examining the loggerhead turtles of Cape Verde in the Atlantic, warns that significantly warmer sands in the next 150 years could cause such a preponderance of females that species become extinct. Hotter sand can also cause complete nest failure.
Turtles are facing more problems than most animals: warming ocean temperatures will alter currents and shift the distribution and abundance of prey species. Species such as the hawksbill turtle are dependant on coral reefs which are bleaching and dying with climate change.
4 Adélie penguin
The Adélie penguin is one of just two true Antarctic penguins, surviving on the ice-bound continent for 45,000 years. Now its survival is being questioned by scientists puzzling over the precise cause for sharp declines that correlate with a rapidly changing climate. Colonies of this little penguin on the West Antarctic Peninsula have declined by at least 80% since the 1970s, and this is an area with more years of warmer-than-average sea surface temperatures than other regions.
Changes in sea temperature and sea ice affects the availability of food, and where fish populations have fallen the penguins eat more krill, which is less nutritious. Nest sites may not be ideal if warming is creating premature melt and puddles on the ground as eggs cannot survive if they are lying in a pool of water. Most importantly, the Adéie penguin cannot survive without sea ice.
In a paper published last year, researchers predicted that 60% of the present habitat would be unsuitable for the penguins by 2099. But Adélie populations in the southern most parts of Antarctica, where there has been fewer climatic and environmental changes, are much more stable. The Adélie has refugia but for how long?
3 White lemuroid ringtail possum
The polar bear may be the poster-creature of climate change victims but this equally attractive – and rather more timid – white furry mammal is much closer to the edge of extinction. This arboreal marsupial lives on the wooded slopes of Mount Lewis in the Daintree rainforest in Queensland, Australia, where scientists have judged it already “ecologically extinct”. The white lemuroid ringtail possum (Hemibelideus lemuroides) lives off leaf moisture and are only found in the high-altitude cloud forest and cannot survive temperatures above 30C for more than a few hours. At less than 3,000 metres high, the climate of Mount Lewis is rapidly changing. A severe heatwave in 2005 killed off most of these cool-loving creatures. In July 2014, scientists observed four or five adults during 10 surveys. Even if the population bounces back, soon it will have nowhere left to go. Genetic studies have never been carried out to determine whether the white possums are a separate species or simply colour variations of the brown-furred lemuroid ringtail possums, which appear to be able to survive higher temperatures. But Prof Bill Laurance of James Cook University has argued that the white form is “a unique evolutionary unit and therefore worthy of conservation”. It is also just one furry symbol of the “ecological catastrophe” that scientists warn will soon befall thousands of species who will find that Australia’s tropical rainforests offer them no shelter in an era of warming.
2 Ringed seal
The most commonly pictured victim of climate change is the polar bear clinging to a rapidly diminishing iceberg. But there is another vulnerable Arctic mammal that is just as photogenic and even more dependant upon Arctic sea ice for its survival.
Climate change is driving polar bears from the safety of sea ice and on to hazardous dry land, and into more conflict with humans. But the ringed seal, the smallest Arctic seal species, cannot adapt to dry land so easily.
Ringed seals rest on sea ice, conceive beneath it, and give birth upon it, excavating snow dens on the surface of the sea ice to shelter their newborns. These dens keep the young warm, and depends upon sufficient annual snowfall.
Warmer spring temperatures causes snow dens to collapse and the ice to break up early, separating young – just 60cm long when born – from their mothers, and exposing them to the cold, predators and pathogens.
Ring seal reproductive rates are already showing declines associated with climate change. Hundreds of pups are usually born each year on the fjords along the west coast of Svalbard but pups were “virtually non-existent” in 2006 and 2007, when many fjords did not freeze for the first time in recorded history.
If ringed seal populations slump, there will be another victim, too: they are the prime food source of the polar bear.
1 Staghorn coral and other corals
Coral is not merely a living species; it’s a miraculous ecosystem engineer, building elaborate and beautiful subterranean structures that provide food and shelter for so many other forms of life on Earth. Coral reefs are hailed as the “rainforest of the sea” but such analogies underplay their significance: they house a greater diversity of animal and plant life than rainforests. Coral is being killed by climate change and its extinction is coming sooner than many other creatures imperilled by climate change.
Staghorn coral (Acropora cervicornis) is experiencing disastrous declines in its range in the southern Gulf of Mexico, Florida and the Bahamas, declining by up to 98% in parts of the Caribbean since the 1980s. It is listed as “critically endangered” on the IUCN red list.
Since 2005, the Caribbean region has lost 50% of its corals, largely because of rising sea temperatures and mass bleaching incidents which have killed coral around the world. Species such as the orange-spotted filefish are completely dependent on coral reefs, and highly sensitive to warmer water.
Across the world, coral reefs are bleaching and dying: Japan’s government this year reported that almost three-quarters of its biggest coral reef has died, blaming rising sea temperatures caused by global warming. Australia’s Great Barrier Reef experienced the worst bleaching ever recorded by scientists in 2016. Researchers at the US National Oceanic and Atmospheric Administration have predicted that by 2050 more than 98% of coral reefs around the world will be afflicted by “bleaching-level thermal stress” each year. They conclude that reefs, including the Great Barrier Reef, are unlikely to survive such events.
Homo sapiens is not dependant on the coral reefs but their loss would be a devastating and demoralising indictment of our era, and the destructiveness of our species. “We’ll lose more species of plants and animals between 2000 and 2065 than we’ve lost in the last 65 million years,” environmentalist Paul Watson, the founder of Sea Shepherd, has pointed out. “If we don’t find answers to these problems, we’re gonna be victims of this extinction event that we’re at fault for.”
