Every year, the Red List reminds us how much of the natural world now lives on the edge. This time, it shows how quickly climate breakdown is changing many species' habitats.

From seals losing the ice beneath them to birds collapsing in heatwaves, the planet's species are being forced into unfamiliar conditions. Yet at least one resilient reptile is showing recovery is possible – even in a warming world. 

You're reading the Imagine newsletter – a weekly synthesis of academic insight on solutions to climate change, brought to you by The Conversation. I'm Will de Freitas, energy and environment editor. This week, we're looking at the latest classifications of conservation status, and how it relates to climate change.

The Red List is published by the International Union for Conservation of Nature (IUCN) and is an inventory of the world's species and their conservation status. Plants and animals are put into one of nine categories, ranging from "least concern" or "near threatened", through to "critically endangered", "extinct in the wild" and ultimately "extinct". Its latest list, published last weekend, includes 172,620 species of which 48,646 are threatened with extinction.

Climate change isn't a huge factor for many of those species, of course. Some might be threatened more by deforestation, hunting or invasive species. Check out our pieces on wild honeybees (now endangered in the EU) or the now-endangered Dracula orchids, rare flowers that look like "tiny monkeys peering out from the mist". 

But we'll start with some bad news regarding animals whose fates really are directly tied to the climate. 

Three seal species – hooded, harp and bearded seals – were downgraded in the latest Red List. With their native Arctic warming even faster than the rest of the world, there's less of the sea ice which these seals rely on to mate, feed and rest.

Earlier this year, Kirsten Freja Young and Brendan Godley of the University of Exeter noted that two of these species – harp and bearded seals – have been spotted in UK waters. 

Young and Godley were calling for the Arctic Ocean to be transformed into a marine reserve. The case is pretty simple: "Establishing a new North Pole marine reserve where industrial activities such as shipping, oil and gas exploration and fishing are banned could provide an ocean sanctuary for wildlife."

"Projected climate change", they say "poses great peril for wildlife such as polar bears and narwhals which are highly adapted to Arctic waters, relying on multi-year ice for foraging and breeding habitat." (Seals are polar bears' favourite food). 

Birds in decline

The IUCN also highlighted birds. Some 61% of bird species have declining populations, it points out – up from 44% as recently as 2016. Habitat loss, mostly deforestation, is the biggest cause, but climate change plays a role too. 

For instance, scientists in Australia recently gathered 70 years of data to show extreme heat is already wiping out tropical bird populations. 

Birds in the tropics are experiencing dangerously hot days "about ten times more often than they did in the past", writes conservation scientist James Watson, of the University of Queensland, and his colleagues. They say this has a greater effect than longer-term changes in average temperature or rainfall, especially in the tropics where birds often exist in fairly small areas and are "highly specialised in terms of the habitats and climates they persist in". 

In fact, many tropical birds "exist within a small range of heat tolerance". This means they can't cope if the weather is much hotter or colder than they're used to (which makes sense, as they evolved in the tropics where the temperature generally doesn't change much from day to day or month to month).

Here's what Watson and colleagues say happens next:

"At temperatures beyond a bird’s limit of endurance, they go into hyperthermia, where their body temperature rises uncontrollably. In this state, birds may adopt a drooped-wing posture to expose more skin for heat loss, hold their beaks open and pant rapidly, spread their feathers, and become lethargic or disoriented. In severe cases, they lose coordination, fall from perches, or even collapse unconscious."

Finally, the authors say their research helps explain "why bird numbers are falling even in wild places relatively untouched by humans, such as some very remote protected tropical forests."

Heroes in a half shell

We'll end with some good news: the green sea turtle has rebounded from "endangered" to "least concern". Though many individual groups of green turtles are still threatened, the global population has grown 28% since the 1970s, reports the IUCN. This, it says, is down to "decades of sustained conservation action". 

Earlier this year, Mollie Rickwood and her colleagues, all marine conservationists at the University of Exeter, reported on one such action. 

"Rising global temperatures are a particularly acute threat for the world’s sea turtles", they write. "That’s because the temperature of a turtle’s nest controls the sex of their offspring."

They work in Turkish-occupied northern Cyprus, where green and loggerhead turtles are "arriving [to nest] earlier in the year to offset some of the impacts of rising incubation temperatures". In their research, they found green turtles are nesting "6.47 days earlier for every degree celsius increase in sea temperature".

Things are improving, though:

"As a result of conservation measures such as protecting the nests from predation and relocating nests laid too close to the high water line we have seen a big population increase in the green turtles at our study site in North Cyprus. Since 1992, numbers have grown from 55 nests per year to over 400."

While the overall outlook remains grim, green turtles demonstrate that climate-related species losses aren't inevitable. Even if we keep emitting and the world keeps warming, some small wins are still possible. 
 

- Will de Freitas, Energy & Environment Editor

Why we need to transform the Arctic Ocean into a North Pole marine reserve

Explorer Pen Hadow is campaigning for a North Pole marine reserve to protect the Arctic’s peoples, its species and its natural landscape.