Overview of Climate Change Impacts on Wildlife
Climate change is significantly altering ecosystems worldwide, leading to profound effects on wildlife. As temperatures rise, many species are forced to shift their habitats, often moving towards higher elevations or latitudes. This migration is not always beneficial; some species encounter less hospitable environments, increased competition, or even extinction.
In aquatic ecosystems, warmer waters are affecting species distributions. Cold-water fish, such as salmon and trout, are losing their habitats due to rising temperatures, with projections indicating up to 47% habitat loss by 2080.
Additionally, climate change is influencing the timing of life cycle events in wildlife. For instance, warmer spring temperatures have led to earlier plant blooming, creating a mismatch with the timing of animals that depend on these plants for food.
Urgency of Addressing Biodiversity Loss
The rapid pace of climate change presents a significant challenge to biodiversity. Species may not be able to adapt quickly enough or migrate to suitable habitats, leading to increased extinction risks. The Intergovernmental Panel on Climate Change (IPCC) estimates that with a 3°C rise in global temperatures, up to 29% of species assessed could face a very high risk of extinction.
Biodiversity is crucial for ecosystem stability and human well-being. It supports ecosystem services like pollination, water purification, and disease regulation. The loss of biodiversity can disrupt these services, leading to negative consequences for both wildlife and humans. Efforts to mitigate climate change and protect biodiversity are interconnected. Strategies such as habitat conservation, restoration, and sustainable land use can help preserve ecosystems and the species that depend on them.
Marine Species in Peril
Climate change is rapidly transforming the world’s oceans, with far-reaching consequences for marine life. Rising ocean temperatures, melting polar ice, acidification, and disrupted food chains are placing immense stress on marine ecosystems. Many marine species, from microscopic plankton to top predators like whales and seals, are being forced to adapt, migrate, or face extinction.
Warming waters are shifting the distribution of fish stocks, coral bleaching is reducing biodiversity in reef ecosystems, and the loss of sea ice is devastating for animals that rely on it for breeding, hunting, or resting. Ocean acidification, driven by increased CO₂ absorption, is weakening the shells of mollusks and disrupting the sensory systems of fish. Among the most visibly affected marine animals are emperor penguins, which depend on Antarctic sea ice for both reproduction and access to food. Their struggle is emblematic of the broader crisis facing marine species worldwide.
1. Emperor Penguins
Dependency on Sea Ice for Breeding
Emperor penguins (Aptenodytes forsteri) are uniquely adapted to breed during the harsh Antarctic winter. Unlike most birds, they rely exclusively on stable sea ice as a platform for breeding and chick rearing. This sea ice must be land-fast—firmly attached to the shoreline—to provide a safe environment for their eggs and developing chicks. The ice offers protection from predators and extreme weather, while its proximity to open water enables adult penguins to hunt for food efficiently.
However, climate change is causing sea ice to break up earlier in the breeding season. This instability forces penguins to abandon their colonies or results in chick mortality when the ice collapses prematurely. Without stable sea ice during critical breeding periods, reproductive success declines drastically, threatening long-term population viability.
Decline Due to Melting Ice and Reduced Krill Populations
The reduction of sea ice affects more than just penguin nesting—it also impacts their food supply. Krill, which form the base of the emperor penguin diet, rely on algae that grow on the underside of sea ice. As ice coverage diminishes, krill populations decline, leading to food scarcity for emperor penguins and other marine predators.
In 2023, record low sea ice levels led to breeding failures in about 20% of emperor penguin colonies. Chicks were forced into the ocean before developing waterproof feathers, leading to widespread mortality. This event underscored how closely tied emperor penguins are to their icy environment. Projections suggest that if current trends continue, emperor penguin populations could decline by up to 99% by the end of the century.
2. Loggerhead Sea Turtles
Vulnerability of Nesting Beaches to Rising Sea Levels
Loggerhead sea turtles (Caretta caretta) are facing significant challenges due to rising sea levels, a direct consequence of climate change. These turtles rely on sandy beaches for nesting, where females lay their eggs in shallow pits. However, increasing sea levels are eroding these vital nesting habitats, reducing the available space for turtles to nest and increasing the risk of nest inundation during high tides or storms.
In regions like Florida, USA, and the Mediterranean coast, rising sea levels have led to the loss of critical nesting areas. For instance, in Florida’s Gulf Coast, loggerhead turtle nests increased in 2023, but many were washed away by hurricanes, highlighting the vulnerability of nesting sites to extreme weather events exacerbated by climate change.
Additionally, in the Mediterranean, loggerhead turtles have been increasingly nesting on beaches in France’s Pyrénées-Orientales region. While this indicates a potential range expansion, it also underscores the pressures on existing nesting sites and the need for effective conservation measures to protect these areas from rising sea levels and other climate-related threats.
Impact of Temperature Changes on Hatchling Sex Ratios
Unlike mammals, the sex of sea turtle hatchlings is determined by the temperature during incubation, a phenomenon known as temperature-dependent sex determination (TSD). For loggerhead turtles, temperatures above approximately 29°C during incubation favor the development of female hatchlings, while cooler temperatures produce more males.
Studies have shown that in certain regions, such as Malaysia’s Redang Island, warmer temperatures have resulted in a significant decline in male hatchlings. To mitigate this, conservationists have implemented strategies like relocating nests to cooler, shaded areas and using irrigation techniques to lower sand temperatures, aiming to produce a more balanced sex ratio and ensure the sustainability of loggerhead turtle populations.
3. Atlantic Salmon
Threats from Warming Water Temperatures and Altered Streamflows
Atlantic salmon (Salmo salar) are facing significant challenges due to climate change, particularly concerning rising water temperatures and altered streamflows. These fish are highly sensitive to temperature changes, thriving in cool, oxygen-rich waters. However, as global temperatures increase, many rivers and streams are experiencing elevated water temperatures, which can be detrimental to salmon populations.
In regions like the Pacific Northwest, the combination of reduced snowpacks and earlier snowmelt has led to decreased summer streamflows. This reduction in water volume not only raises water temperatures but also diminishes the availability of suitable habitats for juvenile salmon. As a result, salmon are increasingly exposed to stressful conditions that can impede their growth and survival.
Moreover, altered streamflows can disrupt the timing and magnitude of freshwater inputs, affecting the availability of spawning and rearing habitats. These changes can lead to mismatches between the salmon’s life cycle events and the environmental conditions necessary for their success.
Terrestrial Species Facing Challenges
Climate change is reshaping terrestrial ecosystems across the globe, forcing many land-based animals to adapt to rapidly changing conditions—or perish. Rising temperatures, prolonged droughts, shifting weather patterns, and more frequent and intense wildfires are disrupting the delicate balance that many species rely on for survival. These changes are causing habitat fragmentation, altering food availability, and increasing competition for limited resources.
1. Koalas (Habitat Loss from Droughts and Bushfires)
Koalas (Phascolarctos cinereus) are particularly susceptible to climate change due to their dependence on eucalyptus forests. Prolonged droughts dry out these ecosystems, weakening trees and making forests more flammable. Bushfires, increasingly intense and widespread due to rising global temperatures, have devastated koala habitats. The 2019–2020 Australian bushfire season destroyed over 5.5 million hectares of land, with tens of thousands of koalas either killed or displaced. In places like Kangaroo Island, nearly half the local koala population was lost.
Nutritional Deficiencies Due to Eucalyptus Leaf Changes
Koalas feed almost exclusively on eucalyptus leaves, which provide both their food and water. However, climate change is altering the nutritional composition of these leaves. Elevated levels of atmospheric CO₂ reduce the nitrogen content in eucalyptus, making the leaves less nutritious. At the same time, concentrations of toxic compounds like tannins may increase, making digestion more difficult.
Additionally, drought conditions reduce the water content of leaves, leading to dehydration in koalas—an animal that typically does not drink water and depends on leaf moisture. These nutritional and hydration stresses can weaken their immune systems, making them more vulnerable to disease and reducing reproduction rates.
2. Mountain Pygmy Possums
Food Scarcity from Declining Bogong Moth Populations
Mountain Pygmy Possums are heavily dependent on the annual migration of Bogong Moths (Agrotis infusa) as a primary food source. These moths migrate from lowland areas to the Australian Alps during spring, providing essential nutrients for the possums after their hibernation period. However, climate change has led to significant declines in Bogong Moth populations, with numbers plummeting by up to 99.5% since 2019 . This drastic reduction is attributed to factors such as drought, land clearing, and altered migration patterns due to climate-induced changes.
Impact of Shorter Winters on Survival Rates
Mountain Pygmy Possums rely on hibernation during winter, using snow-covered rock piles as insulation to maintain a stable and cold environment. However, rising temperatures and altered snowfall patterns due to climate change have led to earlier snowmelt and warmer conditions. This change causes the possums to emerge from hibernation prematurely, often before sufficient food sources are available.
Avian Species in Decline
Climate change is significantly impacting avian species, particularly seabirds like the Atlantic Puffin (Fratercula arctica). These birds are facing challenges due to shifting prey availability and extreme weather events, both of which are influenced by changing climatic conditions.
1. Atlantic Puffins
Food Shortages from Fish Migration Due to Ocean Warming
Atlantic Puffins primarily feed on small fish such as sand lance, herring, and capelin. However, rising sea temperatures are causing these fish species to migrate to cooler waters, often farther from puffin colonies. This shift forces puffins to undertake longer and more energetically costly foraging trips, sometimes exceeding 100 km round trips . The increased distance and energy expenditure result in reduced feeding frequency for chicks, leading to higher chick mortality rates due to starvation.
Breeding Failures Linked to Extreme Weather Events
Extreme weather events, such as heatwaves and unseasonably warm sea-surface temperatures, have been linked to breeding failures in Atlantic Puffins. For instance, during the summer of 2016, nearly 90% of puffin chicks on Machias Seal Island in the eastern Gulf of Maine died due to a combination of dry weather and unusually warm sea temperatures.
2. Bicknell’s Thrush
Habitat Loss from Climate-Induced Forest Changes
Bicknell’s Thrush relies on dense coniferous forests, particularly balsam fir (Abies balsamea) and red spruce (Picea rubens), for breeding. However, climate change is altering these forests. Rising temperatures are causing a shift from coniferous to deciduous forests, which are unsuitable for the thrush. Models predict that by 2100, under worst-case climate scenarios, suitable breeding habitat could be reduced by over 50% due to the replacement of balsam fir forests by hardwood species.
Additionally, forest management practices, such as clear-cut logging and lack of fir regeneration, have further degraded suitable habitats. In Quebec, for example, widespread thinning has rendered habitats unsuitable for the thrush.
Ecosystem Engineers and Their Role
Ecosystem engineers are species that significantly modify, maintain, or create habitats, thereby influencing the availability of resources for other organisms. Their activities can lead to increased biodiversity and the restoration of ecological balance. In the UK, reintroducing species like the elk is being considered as part of rewilding initiatives to restore ecosystem functions and enhance biodiversity.
Elk in the UK
Elk (Alces alces), also known as moose in North America, were once native to Britain but were driven to extinction around 4,000 years ago due to overhunting and habitat loss. Recent rewilding projects aim to reintroduce elk to the UK to restore ecological processes and enhance biodiversity. One such initiative is led by the Derbyshire and Nottinghamshire Wildlife Trusts, which plan to introduce elk into fenced enclosures in the Willington Wetlands and Idle Valley to study their impact on floodplain ecosystems.
These projects are supported by Rewilding Britain, which is funding various rewilding efforts, including the reintroduction of species like elk, bison, and beavers, to restore natural processes and biodiversity.
Potential Benefits to Biodiversity and Habitat Restoration
Elk are considered keystone species and powerful ecosystem engineers due to their significant impact on their habitats. Their activities, such as bark stripping, fraying, wallowing, and seed dispersal, help shape the landscape and promote natural regeneration of vegetation. By grazing and trampling, elk maintain open clearings and prevent the overgrowth of certain plant species, thereby promoting a diverse plant community.
Global Hotspots of Biodiversity Loss
The Gran Chaco, spanning Argentina, Paraguay, Bolivia, and Brazil, is one of the most biodiverse regions in South America. However, it is also experiencing rapid deforestation, making it a critical hotspot for biodiversity loss.
Deforestation and Its Impact on Species Like Jaguars and Howler Monkeys
The Gran Chaco is undergoing severe deforestation driven by agricultural expansion, primarily for beef and soy production. Between 1998 and 2023, Argentina lost 7 million hectares of native forest, with 80% of this loss occurring in the Gran Chaco. This destruction has accelerated in recent years, with illegal logging and weak enforcement of environmental laws exacerbating the situation.
Jaguars (Panthera onca), once widespread in the Gran Chaco, have experienced significant habitat loss. Since the mid-1980s, one-third of critical jaguar habitat has been lost due to deforestation and hunting. The conversion of forests into croplands and pastures has facilitated easier access for hunters, further threatening jaguar populations.
Howler monkeys, such as the black howler (Alouatta caraya), are also affected by habitat degradation. These primates play a crucial role in forest dynamics by dispersing seeds and aiding in forest regeneration. However, deforestation and fragmentation of their habitats have led to population declines.
Conservation Strategies and Solutions
With climate change accelerating the decline of global biodiversity, it is essential to implement coordinated and science-based conservation strategies. These efforts not only aim to preserve species and ecosystems but also to build resilience against ongoing environmental stressors.
Habitat Protection and Restoration Efforts
One of the most effective conservation strategies is the protection and restoration of critical habitats. Establishing protected areas—such as national parks, wildlife sanctuaries, and marine reserves—provides safe havens for threatened species and helps maintain ecosystem functions. Equally important is the creation of wildlife corridors, which connect fragmented habitats and enable species to migrate, find food, and reproduce.
Climate Change Mitigation and Adaptation Plans
Conservation efforts must now also incorporate climate adaptation and mitigation strategies to address rapidly changing conditions. Mitigation focuses on reducing greenhouse gas emissions—through clean energy, sustainable agriculture, and rewilding initiatives that increase natural carbon sinks like forests and wetlands.
Adaptation strategies include ecosystem-based approaches (EbA), which use biodiversity and natural processes to buffer communities and wildlife against climate-related events. For example, mangrove restoration helps protect coastlines from storm surges while also providing critical fish habitat. Similarly, shifting conservation priorities to include climate-resilient species and habitats ensures that ecosystems can adapt to future conditions.
Community Engagement and Indigenous Knowledge Integration
Sustainable conservation depends heavily on the involvement of local communities and Indigenous peoples. These groups often possess deep-rooted ecological knowledge and manage large areas of high biodiversity. Engaging them as partners not only supports conservation goals but also ensures ethical and equitable outcomes.
Indigenous knowledge systems—passed down through generations—can inform land management, species monitoring, and fire control strategies. In regions like the Amazon and Australian outback, integrating traditional practices has improved conservation results while strengthening community resilience.
Community-led conservation, co-management of protected areas, and participatory decision-making foster long-term stewardship and build public support for biodiversity initiatives.
Conclusion
The accelerating impacts of climate change have intensified the threats to global biodiversity, pushing numerous species toward the brink of extinction. According to the IPCC Sixth Assessment Report, even a 1.5°C rise in global temperatures could place 9–14% of species at a very high risk of extinction, with these figures escalating significantly under higher warming scenarios.
Species are already exhibiting range shifts, altered migration patterns, and disrupted breeding cycles as they respond to changing climates. For instance, polar bears face habitat loss due to melting sea ice, while coral reefs suffer from bleaching events linked to rising ocean temperatures. Global initiatives, such as the “30 by 30” target to protect 30% of Earth’s land and ocean areas by 2030, represent significant steps toward halting biodiversity loss. Collective action, informed by science and driven by a shared commitment to preserving life on Earth, is essential to ensure a sustainable future for all species.
