Effects of Climate Change On Animals

Climate change is devastating wildlife. Elevated temperatures upset animal and plant life cycle rhythms (phenology). Heatwaves deplete water holes and water supplies, resulting in stressful competition between species. Drought and high temperatures trigger wildfires leading to mass fatalities among animals. Marine heatwaves and ocean warming can lead to loss of corals and shellfish. Excess CO2 emissions lead to ocean acidification and deoxygenation with deadly impacts on marine life. Loss of sea ice means fewer and weaker polar bears. The list of climate impacts is endless.
Pride of lions, Tanzania
A pride of lions in the Selous Game Reserve, Tanzania. Photo: © SueBrady5. CC0 via Pixabay

As global temperatures rise, threatening habitats and biodiversity in every corner of the globe, we look at the effects of climate change on 20 animals from a variety of different ecosystems on land and sea. Many are on the IUCN’s list of endangered species, and all are vulnerable to extinction.

Of course, species do not become vulnerable for just one reason: size of habitat, breeding success and human activities are usually critical factors. But global warming is degrading habitats and upsetting food chains, and adds significant stress to a species already under pressure.

10 Endangered Animals
10 Endangered Birds of Prey
10 Iconic Birds Threatened By Climate Change

The Importance of Biodiversity

Earth’s unique biosphere consists of a huge cluster of different biomes – from Arctic tundra, temperate grasslands, deserts and tropical rainforest, to deep sea as well as coastal mangrove environments. And each biome contains a host of different ecosystems, each with its own complex interlocking system of foliage, soil, air, and water, of bacteria, viruses, fungi, plants, trees, birds and mammals. Marine ecosystems have their own amazing assortment of sea vegetation, corals, plankton, krill, fish, penguins and predators.

Each of these ecosystems is built around the biodiversity (variety) of its plants and animals. It’s a system in which each creature and plant has a role to play. For example, each ecosystem has a food chain in which energy is first created (from sunlight) by plants (the so-called “primary producers”), then passed up the chain to apex predators, who themselves maintain the health of the system by ensuring that no lower species gets too numerous or too sick to upset the balance. In addition to their role in the food chain, plants and other creatures have numerous other functions, including: oxygen production (plants, phytoplankton), waste disposal (fungi, vultures), water circulation (trees), seed distribution (birds, apes), fertilization and nutrient cycling (hippos, whales), and so on.

The point is, when an ecosystem suffers a loss of biodiversity – for instance, when it loses a particular species, or experiences a change in climate – its balance may be upset, and it may become less healthy. Up until the arrival of humans, this type of change happened only very gradually. But since the start of the Anthropocene epoch, humans have exploited and abused natural environments throughout the world, causing the mass extinction of thousands of species.

See our article: How To Reduce Your Carbon Footprint.

10 Effects of Climate Change On Animals

Here are 10 ways in which climate change impacts on animals, birds and fish throughout the world. Note that the list is far from complete.

  • Higher temperatures driven by heatwaves dry out forests, creating ideal conditions for wildfires, leading to huge loss of wildlife and their habitat. The Australian bushfires 2019-2020 that devastated parts of NSW and Victoria caused the deaths of an estimated 1 billion animals.
    Excessive heat can also lead to loss of vegetation as well as high numbers of insects and insect-driven disease. For example, a 2018 report found that warming in the Arctic region led to a reduction in plant growth, causing caribou numbers to plummet by half (from 5 million to around 2.1 million) – due to the animals being unable to find their normal sources of lichen. On top of this, caribou are now plagued by a huge increase in insects 1 caused by the warmer climate.
  • Higher temperatures also lead to marine heatwaves which cause mangrove die-back, loss of corals and major changes to phytoplankton and fish behaviors. 2
  • Ocean warming also leads to acidification and loss of oxygen, as well as a slowdown in thermohaline circulation around the globe, with significant consequences for marine nutrition. 3
  • Hotter temperatures also lead to adverse living conditions across the grasslands of eastern and southern Africa, as water holes dry up forcing animals (hippos, crocodiles, elephants and giraffes) to compete for dwindling resources. 4
  • As rising temperatures migrate away from the equator, a host of pathogens, parasites and ticks follow in their wake, causing distress, illness and death among animal and human populations unused to their attentions. For example, higher temperatures in the Pacific Northwest have led to the presence of a harmful salmon parasite entering the Yukon River. Canadian moose are also affected by parasites because of the warmer weather. In their case it’s a massive increase in winter ticks. Tens of thousands of these organisms can gather on a single moose to suck its blood, causing illness even death, especially among calves. 5
  • Ocean warming leads to rising sea levels that damage coastal habitats, including bird nesting sites, as well as crops and plants. According to a report from the U.S. Center for Biological Diversity, 233 endangered species in 23 coastal states are at risk from rising seas. Among them are the Delmarva peninsula fox squirrel, the Hawaiian monk seal, the loggerhead sea turtle, and the western snowy plover. 6
  • As heat levels rise, animals migrate away from the tropics, leading to increased competition for resources with native species at their destination. 7
  • Heat also affects the breeding habits of species in several ways. The African cheetah, for example, is losing its ability to reproduce due to rising temperatures. Sea turtles are also affected: a recent study shows that in warmer temperatures predicted by IPCC scenarios, 76-93 percent of green turtle hatchlings will be female. 8
  • Rising temperatures also results in the melting of sea ice, as well as ice shelves and ice-sheets, causing a drastic loss of habitat for polar bears and seals in the Arctic, as well as krill habitats in the Antarctic. 9
  • Extreme weather events triggered by climate change cause enormous harm to animal, bird and marine life throughout the world. The Australian wildfires of Dec 2019/Jan 2020, led to a catastrophic loss of wildlife across the country, including the deaths of over 20,000 koala bears (Phascolarctos cinereus) in a single reservation. The fires were caused by the Indian Ocean Dipole (IOD) weather system – a cousin of the El Niño and La Niña phenomena in the Pacific. All these regional weather systems are considerably amplified by global warming, with disastrous effects for marine and terrestrial wildlife. 10

All in all, climate change is having a massive effect on biological diversity across the planet. This, combined with the impact of deforestation, illegal poaching and mining, is leading to the extinction of species on every continent. 11 12 13

The Damaging Effects of Climate Change On 20 Animals

Here are profiles of twenty species from all around the world whose survival is threatened by global warming and human activities of varying kinds.

1. Blue Whale

Blue Whale off California Coast
Blue Whale (Balaenoptera musculus). Conservation status: endangered species. Seen here a blue whale off Californian coast. Photo: D Ramey Logan/CC BY-SA 3.0

Capable of exceeding 29.5 meters (96 feet) in length and 190 tons in weight, the blue whale is the largest animal on Planet Earth. Found in virtually every ocean on the planet until around 1900, they were hunted almost to extinction. The current population is estimated by the IUCN Red List of Threatened Species at around 10,000-25,000 whales, about 3-11 percent of its 1911 population. The blue whale’s stomach can hold about one ton of krill – the tiny crustaceans upon which it feeds, and of which it needs to eat about four tons every day. Unfortunately, sea ice in the Southern Ocean around Antarctica is decreasing, which threatens the population of krill, and with it the blue and humpback whale. A recent study 14 indicates that blue whale habitats are projected to shrink significantly as global warming takes hold.

2. Orangutan

Orangutan close up
The Orangutan (Pongo abelii, Pongo pygmaeus). Conservation status: critically endangered species. Seen here in Borneo. Photo: Julielangford/CC BY-SA 3.0

The Orangutan, southeast Asia’s sole surviving great ape, is native to only two islands – Sumatra and Borneo. Orangutans are threatened by deforestation and climate change – see: Deforestation in Southeast Asia. In Borneo, their numbers have dropped by 60 percent since 1950.

Two of the main factors that support Western Indonesia’s orangutan habitat are the two gigantic climate drivers, the Indian and Pacific Oceans. Historically, these two oceans deliver very predictable patterns of rainfall and temperature. However, three oceanic climatic events can occur that can produce major shifts in Indonesia’s weather: these are “El Niño”; its opposite sister “La Niña”; and the “Indian Ocean Dipole”.

Under the influence of global warming the swings produced by these three events have become much more intense, causing much more severe floods or droughts than usual. This is playing havoc with the ecology of the region bringing stresses and dangers to the Orangutan as well as thousands of animals, and their habitats.

3. Snow Leopard

Loss of snow cover is the main effect of climate change on the snow leopard.
Snow Leopard (Panthera uncia). Conservation status: critically endangered species. Photographed in Kashmir. Photo: © Snow Leopard Conservancy/Jammu & Kashmir Wildlife Protection Department.

Snow leopards are native to around twelve countries – including India, Pakistan, Afghanistan, China, Bhutan, Nepal, Russia, and Mongolia – but their numbers are falling fast. Today, there are fewer than 4,000 snow leopards in the wild.

The biggest threats include: (a) Revenge killings by farmers. Wild Argali sheep are an important food source for snow leopards and also for human inhabitants. As humans kill more, so the leopards target farmers’ livestock, triggering reprisals. (b) Poaching by fur hunters. (c) Loss of habitat. (d) Climate change. According to the World Wildlife Fund, impacts from climate change could lead to a reduction of up to 30 percent of the snow leopard habitat in the Himalayas alone.

4. Bengal Tiger

Loss of habitat from rising seas are among the effects of climate change on animals like Bengal tigers in Bangladesh.
Bengal tiger (Panthera tigris). Conservation status: endangered species. An apex predator of the terrestrial food web, it is seen here catching a sambar deer (Rusa unicolor) in the Ranthambore tiger reserve. Photo: © Harsh.kabra.98 (CC BY 4.0)

Once upon a time, tigers ranged from Indonesia and south-east Asia, north to China and Siberia and west to India and beyond, reportedly as far as eastern Turkey. Today, the tiger’s range is fragmented, stretching from temperate Siberian forests to tropical forests on the Indian subcontinent and Sumatra. Tigers typically rely on concealment for stalking and ambushing their prey, and so prefer areas with moderately dense cover, such as thickets or long grass along river banks. When attacking, they can cover 15 feet (4.5 meters) in a single leap. Tigers try to overpower their prey using their size and strength to knock them off balance. Once the prey is caught, the tiger bites the back of its neck, pulling it to the ground, and either breaking the spine, piercing the windpipe or severing an artery in the process. The tiger holds onto the neck until its prey dies. When attacking large prey, tigers tend to bite the throat rather than the neck.

Rising sea levels caused by climate change are reducing the coastal habitats of hundreds of endangered Bengal tigers in parts of India and Bangladesh.

5. Red Belly Toad

The genus Melanophryniscus Gallardo includes 26 species native to South America. Most species are considered to be threatened. The Red Belly Toad (Melanophryniscus admirabilis) is a unique species known only from its type site, located exclusively along 700 meters of the Forqueta River, in a steeply forested area of the southern Brazilian Atlantic Forest, in the Municipality of Arvorezinha, State of Rio Grande do Sul, Brazil. Up until recently the toad was threatened by the forest clearance needed for the nearby construction of a hydro-electric power plant. Fortunately, collaborative efforts between scientists, government, and non-governmental organizations have succeeded in halting the deforestation and construction. 15


Deforestation in the Amazon Rainforest
The Amazon Rainforest – A Unique Biome
Effects of Deforestation

6. Giant Panda

Giant Pandas – now found in only the Minshan, Qionglai, Liangshan, Daxiangling, Xiaoxiangling and Qinling mountains in China – rely on bamboo for 99 percent of their diet. A new study 16, shows that the Qinling Mountains could experience widespread bamboo flowering and synchronous die-off leading to a high risk of widespread food shortages for the Giant Pandas by 2020. In addition to being the Panda’s staple diet, bamboo also provides them with shelter from the elements. The Minshan Mountains are likely to experience a similar bamboo wipe-out between 2020 and 2030. Climate change magnifies the problem by drying out and degrading the animal’s habit.

7. Orinoco Crocodile

Saltwater Crocodile
Orinoco Crocodile (Crocodylus intermedius). Conservation status: critically endangered species. Photo: fvanrenterghem/CC BY-SA 2.0

The Orinoco crocodile is among the largest living reptiles and is the largest predator in the Americas. A large male today may reach 4.1 to 5 m (13 to 17 ft) in length and a weight of 380 to 635 kg (838 to 1,400 lb), while females are substantially smaller with the largest likely to grow to 3.25 m (10.7 ft) and weigh about 225 kg (496 lb). An apex predator, it preys opportunistically on a variety of large fish, reptiles, birds, and mammals, including monkeys, deer, domestic animals, and even caimans.

Its population is now very small, and the species is only found in freshwater environments in Venezuela and Colombia, such as the Orinoco river and its tributaries. The Orinoco crocodile was widely hunted for its skin during the 19th and 20th centuries. In fact, during the 1940s, 1950s and 1960s, thousands were killed in the Llanos wetlands and the Orinoco River, and the crocodile nearly became extinct.

It was given protected status in the 1970s but has not yet recovered from its ordeal. It is still listed as a critically endangered species. It’s not known exactly how many individuals remain in the wild but estimates range between 250 and 1500. Current threats to its survival include illegal poachers and loss of habitat from climate change as well as commercial development.

8. African Elephant

African Elephant (Loxodonta africana). Conservation status: critically endangered species. Seen here is a baby African elephant, 6 weeks old. Photo: Axel Tschentscher/CC BY-SA 4.0

Elephants are vulnerable to global warming for several reasons, including sensitivity to high temperatures and susceptibility to disease. The biggest concern, however, is their need for large amounts of fresh water, and the impact that water shortage has on their daily activity, reproduction and migration. Other non-climate threats include ivory poachers and habitat loss. Conservation priorities therefore revolve around securing fresh water, provision of protected areas or reserves; monitoring for disease; replacement of poaching with ecotourism.

9. Common Bottlenose Dolphin

Bottlenose dolphins are renowned for their intelligence (including emotional intelligence), which has been repeatedly confirmed by investigations into their use of tools (such as, marine sponges), their mimicry, use of artificial language, categorization of objects, and self-recognition. Sadly, millions of dolphins become entangled in fishing nets (mostly tuna nets) and drown. Bottlenose dolphins off the coast of Britain have also been found to contain high levels of heavy metals (like mercury and cadmium), PCBs and other toxic chemicals in their organs. Fortunately, this species is not endangered as a whole. However, specific sub-populations are threatened due to numerous environmental hazards and changes.

10. Lion

As one of the apex predators of the savannas of eastern and southern Africa, the lion is crucially dependent upon the grassland biome for its food and health. But as climate change intensifies and grasslands become more arid and inhospitable, lion habitats become less secure. A significant loss of those habitats, due to extreme temperatures, water shortage or absence of prey, would drive them to extinction. African lions are listed as vulnerable on the IUCN Red List and the present population is estimated at around 20,000 animals. The African Wildlife Foundation states that lion numbers have dropped by 43 percent in 21 years. Meantime, the Asiatic lion has been listed as Endangered. Its final refuge is the 1,412 sq km (545 sq mi) Gir National Park and surrounding areas in the Kathiawar Peninsula in Gujarat State, India.

Lions improve the health of their ecosystem by limiting the spread of disease among herds of herbivores such as zebras. In fact, most studies indicate that the loss of predators such as lions, would reduce the number of healthy herd individuals and increase the number of diseased animals. This is because lions typically prey on those herd members who are sick or lame. Without such predatory intervention a pathogen is more likely to spread through a population and significantly reduce its size, thus impacting on the biodiversity of the entire ecosystem.

11. Tiger Shark

Lack of oxygen caused by ocean warming are among the effects of climate change on animals like tiger sharks.
Tiger Shark (Galeocerdo cuvier). Conservation status: near threatened species. Photo: © Albert Kok (CC BY 3.0)

The Tiger Shark is one of the largest sharks in the ocean. Adults commonly reach lengths of 4.3 m (14 ft) and weigh up to 635 kg (1,400 lb), but some can reach 6 m (20 ft) in length and weigh over 800 kg (1750 lb). They are named after the vertical tiger-like stripes which usually fade in adulthood. Sharks rank second to killer whales as the top predator of the ocean and play an important role in the marine food web to help maintain the balance in the ocean’s ecosystem. Unfortunately, sharks are being specially targeted by Asian fishing boats because their fins are prized as the key ingredient in shark fin soup, a symbol of status in Chinese culture. Around 100 million sharks are killed every year for their fins. In addition, ocean warming is reducing the amount of available oxygen to larger fish like sharks, tuna and swordfish.

12. Leatherback Turtle

The Leatherback Turtle is the largest of all living turtles. It is distinguished from other sea turtles by its lack of a shell. Instead, its body is protected by a leathery covering of oily flesh and skin. Despite the lack of a hard shell, adult leatherbacks face comparatively few predators, though they are occasionally eaten by large apex predators like killer whales, great white sharks, and tiger sharks. Found in all tropical and subtropical oceans, their range – the widest of any turtle – extends as far north as Alaska and Norway and as far south as the southern tip of New Zealand. Leatherbacks prey on jellyfish (as well as tunicates and cephalopods) whom they pursue to a depth of 1000 m (3,300 ft). Pollution (chemical and physical) is another dangerous threat. Plastic bags, for instance, bear a strong resemblance to their favourite food, jellyfish.

Climate change is another threat. Turtles are heavily affected by ocean warming because of their wide range of habitats 17 . To begin with, turtles’ egg-laying beaches are commonly very vulnerable to flooding from sea level rise. If this happens, their eggs are washed away or swamped 18

Rising sea surface and air temperatures are another danger. This thermal stress is particularly difficult for reptiles, who rely on outside temperature to regulate their internal temperature. 18

Furthermore, hotter beach sand leads to decreased reproductive output, and also leads to a higher percentage of females being born. It has been estimated that a 2°C increase in temperature leads to a 99.8 percent female hatching rate. 17

13. Cheetah

Cheetahs relaxing on African savanna
African cheetah (Acinonyx jubatus). Conservation status: near threatened species. With a top speed of 70 miles per hour, these black-spotted cats hold the record as the fastest land mammal. Photo: Ray in Manila/CC BY-SA 2.0

The African cheetah, the world’s fastest land animal, is racing against its near-threatened status in the face of global warming. According to Kenyan researchers the big cat has developed abnormalities in its sperm because of warmer temperatures, affecting its ability to reproduce. The warmer temperatures are also affecting its eating habits, they say. Cheetahs like to feed on Thomson’s gazelles – noted for their very high protein content compared to other herbivores – but dwindling numbers of the gazelle, again due partly to poor climate conditions, are forcing them to find other prey.

The cheetah plays a special role in its environment. They are one of the most successful hunters on the savanna, keeping prey species healthy by killing the weak and old. Like most African predators of the African savannas, cheetahs hunt herbivores who might otherwise eat all the grass, threatening the health of the entire ecosystem.

14. Killer Whale

Killer whales can get trapped by sea ice due to ocean warming - another of the effects of climate change on animals.
Killer whale (Orcinus orca). Conservation status: not threatened. Seen here breaching or “porpoising”. Photo: Public Domain

Killer whales are believed to do this in order to get a better look at their surroundings, such as when following prey. Like many marine creatures, orcas are being driven towards the poles by warming ocean temperatures. 19 However, they are not considered threatened or endangered as a species. At present they are found in every ocean and in a variety of marine environments. Unfortunately, like other apex predators in the ocean, killer whales are especially vulnerable to poisoning from bioaccumulation of toxins, including Polychlorinated biphenyls (PCBs) and heavy metals.

In addition, warming ocean temperatures are causing problems for killer whales who are being lured northwards in pursuit of herring and other prey, with uncertain consequences. For example, if temperatures suddenly fall, they can become trapped by sea ice.

15. Giraffe

Giraffes are suffering from habitat loss & lack of water - yet more effects of climate change on animals.
Masai giraffe (Giraffa camelopardalis tippelskirchi). Conservation status: vulnerable to extinction. Seen here is an adult female Masai Giraffe in the Masaai Mara national park, Kenya. Photo: © Bjorn Christian Torrissen (CC BY-SA 3.0)

There are an estimated 97,500 giraffes in the wild, down from 155,000 in 1985 – a decline of 37 percent. In the early 20th century, herds of 20 to 30 animals were not uncommon. Now the average herd size is five animals or less. The IUCN categorizes giraffes as vulnerable and lists three main threats to their growth: illegal hunting, habitat loss and lack of water due to climate change.

On top of this, continuing agricultural expansion and road building is reducing the number of acacia trees, which are the giraffes’ main food source. Predators include lions, hyenas and leopards, with giraffes (calves or adults up to 550 kg/1,210 lb) accounting for up to one third of the meat consumed, in some areas.

16. Emperor Penguin

Two Emperor Penguins
Emperor Penguin (Aptenodytes forsteri). Conservation status: near threatened species. Photo: Lin Padgham/CC BY-SA 2.0

The Emperor Penguin is the world’s largest penguin, standing around 115cm (3.8 ft) tall. Their numbers have declined by half in some places, and in 2015 one entire colony near Antarctica – the Halley Bay colony, the second largest emperor penguin colony in the world – disappeared completely. 20 Breeding is very much a shared affair. The female penguin lays a single egg, which is incubated for just over two months by the male (who eats nothing during this period, losing 12 kg in the process) while the female returns to the water to feed. Subsequently, both parents take turns foraging for food and caring for the chick in the colony. Emperor Penguins have an average life expectancy of 20 years. But only 19 out of every 100 chicks survive their first year of life.

In June 2014 a scientific study by the Woods Hole Oceanographic Institution determined that Emperor Penguins are at risk from global warming, due to melting sea ice. The study predicts that all 45 colonies of emperor penguins will decline in numbers, due to loss of habitat, since any shrinkage of sea ice reduces the supply of krill, which are the penguins’ primary food source.

17. Western Lowland Gorilla

Western Lowland Gorilla, male silverback
Western Lowland Gorilla, male silverback (Gorilla gorilla gorilla). Conservation status: critically endangered species. Photo: © Brocken Inaglory/CC BY-SA 3.0

Western lowland gorillas are native to Angola, Cameroon, Central African Republic, Democratic Republic of the Congo, Equatorial Guinea and Gabon. They live mostly in the Congo Rainforest, in forest edges, and riverine forests up to about 1,300 meters in altitude. They are essential to the growth of the rainforest because of their seed distribution. They eat plenty of fruit, discarding seeds as they go. The Western lowland gorilla is the smallest subspecies of gorilla, although an upright male can be up to 1.8 m (5 ft 11 in) tall and weigh around 270 kg (600 lb). On average, male western lowland gorillas weigh about 140 kg (310 lb), while females clock in at around 90 kg (200 lb). As a species they are critically endangered, according to the World Conservation Union. The Ebola virus, poaching and deforestation are all major threats. Climate change will only add to their habitat problems. Exact population numbers are not known but are believed to be around 50,000.

18. Siamese Crocodile

Siamese crocodile, Singapore
Siamese Crocodile (Crocodylus siamensis). Conservation status: critically endangered species. Photo: © BritishArmySgtMonkey

The male Siamese Crocodile – also referred to as the Siamese freshwater crocodile, Singapore small-grain crocodile, or soft-belly crocodile – is a small to medium-sized freshwater crocodile found in Indonesia, Myanmar, Malaysia, Thailand, Vietnam Laos and Cambodia. On average, adult males reach 2.1 m (6.9 ft) in length and weigh up to 70 kg (154 lb). The species is classified as critically endangered and is already extinct from 99 percent of its original range.

Siamese crocodiles are under threat from loss of habitat due to reclamation of wetlands for agricultural use, or for the development of hydroelectric power plants, notably in connection with dams on the upper Mekong River and its major tributaries. Capture by crocodile farmers is another threat.

In 1992, the crocodile was thought to be extremely close to or actually extinct in the wild until 2000, when scientists from Fauna and Flora International (UK) and Cambodia’s Forestry Administration found Siamese crocodiles in the Cardamom Mountains in Southwest Cambodia. Since then, 30 new sites have been discovered in Cambodia – estimated to contain between 200 and 400 individuals – and a more sizeable population in Laos. Another small but important population is known to exist in East Kalimantan, Indonesia. Its global population in the wild is estimated to be about 1,500 to 2,000 animals, although another 700,000 are held in commercial crocodile farms across Southeast Asia.

19. Atlantic Bluefin Tuna

Effects of climate change on marine animals like Atlantic bluefin tuna include ocean warming which leads to lower survival rates.
The Atlantic Bluefin Tuna (Thunnus Thynnus). Conservation status: endangered species. Seen here is a 2m (7 ft) specimen caught in the North Atlantic. Photo: NOAA Fish Watch

The Atlantic Bluefin Tuna is the cornerstone of the Japanese raw-fish market, for whom all bluefin species are highly prized for sushi and sashimi. As with the whale population, this Japanese appetite for a fish species has led to severe overfishing causing the species to become endangered.

In addition, tuna are also very vulnerable to climate change, due to ocean warming. Studies show that survival rates of juvenile and adult Atlantic bluefin tuna decrease with near-surface warmer temperatures and increase at deeper depths with cooler water.

According to the International Commission for the Conservation of Atlantic Tunas, bluefin tuna stocks have dropped dramatically over the last 40 years – by 72 percent in the Eastern area of the Atlantic, and by 82 percent in the Western area. These tuna fish are capable of reaching depths of 1,000 m (3,300 ft) and can swim at speeds of 65 km/h (40 mph). It feeds on small fish, such as herring, sardines and mackerel, as well as invertebrates like squid and crustaceans.

20. Staghorn Coral

Staghorn coral (Acropora cervicornis) photographed off Saint John, US Virgin Islands
Staghorn Coral (Acropora cervicornis). Conservation status: although on the brink of extinction, the IUCN is unable for technical reasons (species identity) to list it as an endangered species. Photographed here off Saint John in the US Virgin Islands. Photo: © Onislandtimes/CC BY-SA 3.0

Coral reefs represent some of the most diverse ecosystems in the marine world and can take up to 10,000 years to form. Although they cover less than 1 percent of the ocean floor, they play host to around a quarter of all known marine life. A coral is made up of thousands of tiny animals called polyps, protected by a hard skeleton, who feed on zooplankton. There are 160 different types of Staghorn Coral.

Unfortunately, since 1980, Staghorn coral populations have plummeted by as much as 98 percent across their range from disease (notably White band disease), exacerbated by extreme weather events like hurricanes, bleaching, pollution and other forms of human disturbance.

The species is especially affected by Earth’s climate crisis, which interferes with the corals’ mutually beneficial relationship with photosynthetic algae, called zooxanthellae. The algae receive shelter, nutrients and carbon dioxide from the coral, while the coral receives photosynthetic nutrients and oxygen from the algae. Unfortunately, warmer sea temperatures boost algae growth, thus causing oxygen levels to rise too high for the coral, which then expels the algae. This results in “bleaching” as the algae gave the coral its color. Climate change also causes ocean acidification which contributes to bleaching and also undermines the ability of corals to form hard shells.

Effects of Climate Change On Animals: Conclusion

The climate system is rarely the only or even the biggest threat to the survival of a species. Size and security of habitat, population size, and food sources are all very important, as are human threats in the form of commercial development, unregulated hunting and poaching. But the impacts of climate change on animals are intensifying, and exacerbate all the other threats.

Should we humans take into account the needs of animals before making decisions about our climate crisis? For answers to this and other moral dilemmas, see our article on the ethics of climate change.


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