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Modern Animals' Responses to Global Warming

Updated: Dec 4, 2023

The planet’s warming oceans, increasingly dangerous weather, and environmental deterioration due to pollution is not the only thing changing - so are the animals that call Earth home. Caused by the hand of the human race, climate change and global warming are putting millions of species at risk of extinction, including 40% of amphibians, a third of sea animals, 10% of insects, and almost all of the animals that live off of coral reefs. (Nature Is Deteriorating Faster Than Ever, n.d.) Current studies are showing that these animals are actively “shapeshifting” to adapt to rising temperatures, as their physical features race to keep up with the warming planet. Tails, legs, and ears are such features that are changing to provide maximum heat loss efficiency to cope with such warm environments.

A 19th-century zoologist named Joel Asaph Allen devised an idea to explain how animals in warmer habitats bore larger limbs, ears, beaks, and tails than their counterparts in colder conditions. This idea is now referenced as Allen’s rule, and many modern scientists are using it to research if climate change-induced adaptations will continue to follow this rule. One study involving Australian parrots saw a 10% increase in the surface area of their bills since the late 1800s, and another study involving bats saw an increase in wing size in response to climate change. The same went for mice, pigs, and shrews, with all animals seemingly shapeshifting into longer-tailed versions of themselves. (Ashworth, 2021)

In South Africa, ecologist Miya Warrington and her team are observing in real-time the shape-shifting of Cape ground squirrels. She notes the various ways the species tries to keep itself cool, such as laying flat on the ground to shed heat, curling their tails above their heads for shade, and retiring to their cool underground burrows. Despite all of these alternatives that don’t require physical changes, Warrington has still observed shape-shifting changes in their bodies. Their already large hind feet that are used to spread heat have grown even bigger, and their spines have become shorter. (Carstens & Lynch, 2023) These real-life translations of Allen’s rule confirm that little bodies and big limbs are such thermal adaptations animals take to try to eliminate heat.

Casey Youngflesh, a Michigan ecologist studying whether shrinking bird sizes is due to climate change, can explain this observation perfectly: “When you’re a smaller individual, you have a larger surface area to volume ratio, which allows you to basically dissipate heat more readily.” (Carstens & Lynch, 2023)

A cape ground squirrel covers itself with its tail in order to stay cool.

It is worth noting that these climate change-induced adaptations are not observed in every animal species across the globe. For some animals, they cannot make such drastic bodily changes as it will impact their very way of life, leading to population decline and extinction. For other animals, it is too difficult to spot if they are “shape-shifting” due to already high amounts of variation in their population. But for those adapting to climate change, it is important to know that they cannot continue to adapt for the long term. Take birds with larger beaks as an example. Although the larger surface area is better for heat loss, it is unsuitable for the long-term to continue growing larger beaks, as it can have negative implications on feeding, flight, and overall quality of life.

Due to this fact, it is extremely concerning that many of the Earth’s animals, who rely on a steady environment and a habitat in equilibrium, will begin to struggle for survival as the planet only continues to get warmer and the loss of biodiversity harms both global species and the human race. (Ashworth, 2021)

Birds are shrinking in size in response to climate change.


Ashworth, J. (2021, September 16). Animals 'shapeshifting' to adapt to rising temperatures. Natural History Museum. Retrieved July 26, 2023, from

Carstens, A., & Lynch, C. (2023, January 3). Animals Are Shape-Shifting in Response to a Warming World. The Scientist. Retrieved July 26, 2023, from

Nature is deteriorating faster than ever. (n.d.). Active Sustainability. Retrieved July 26, 2023, from


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