The planet under heat stress: impacts beyond people and assets
Contemporary discussions on climate change and extreme heat remain largely anthropocentric, centring human health, infrastructure, and economic disruption while obscuring broader environmental impacts.
Namely, the profound pressures exerted on non-human systems that also shape planetary resilience, regulate climate, and sustain ecosystems. Viewed through this broader lens, extreme heat is not merely a human-centred hazard, but a force reshaping interconnected Earth systems, with consequences that extend far beyond solely social or economic loss.
The following selections illustrate how extreme heat manifests across these interconnected systems. Together, they highlight how rising temperatures disrupt animal physiology, degrade soils, and alter environments and ecosystems, including the cryosphere. Read collectively, these examples underscore how pressures on non-human systems ultimately reshape the conditions that support life on Earth.
Animals
Extreme heat imposes direct and multifaceted pressures on animals that extend far beyond human-centred concerns. Animals can only maintain homeostasis within their “critical thermal limits”, or a set range of optimal temperatures. Otherwise, they must migrate to cooler temperatures or find a means of adaptation. Both wild and domesticated animals are becoming more vulnerable to rising temperatures, with impacts observed across physiological, behavioural, and ecological dimensions.
In the context of pets and companion animals, researchers applying the “five-domains model” of animal welfare have shown that climate change will degrade conditions related to nutrition, physical health, environment, behaviour, and mental state. The result will be increased heat stress, behavioural disruptions, and health risks across the animal kingdom as heatwaves become more frequent and intense. Learn more about the unique toll that extreme heat will take on animals below.
Insects
Insects, which play foundational roles in many ecosystems, illustrate another dimension of heat vulnerability. Many species have a limited capacity to adjust their internal temperatures, meaning that rapid temperature rise can push them beyond thresholds at which survival and reproduction are possible.
Because insects play foundational roles in pollination, nutrient cycling, and food webs, their decline under heat stress has cascading effects on broader ecosystem functioning. These effects force us to confront the broader implications of insect loss and make the need for solutions even more urgent. Read more on how insects are critical to the functioning of a healthy ecosystem and our planet’s future.
Soil health
Our need for soil extends far beyond crop yields. Soil quietly supports the resilience of all terrestrial ecosystems, yet they are not immune to the pressures of extreme heat. Heatwaves accelerate soil drying, diminish organic matter, and can disrupt the delicate balance of microbiota that sustain nutrient cycling and plant health. Soils also regulate water, sequester carbon, and support countless organisms that form the foundation of terrestrial food webs.
Researchers are seeking to understand how heat reshapes soil systems and invite readers to see soil not just as a catalyst for production, but as a living matrix whose integrity is essential to the broader health of ecosystems. Explore how soil quality mediates the effects of heat stress and consider how its decline reverberates through landscapes in ways that transcend traditional metrics.
Rivers
Rivers are the lifeblood of many landscapes, sustaining biodiversity, regulating freshwater flows, and linking terrestrial and aquatic worlds. Yet they are increasingly vulnerable to extreme heat in ways that go beyond human use. Recent observations show that heatwaves in U.S. rivers are rising four times faster than air heatwaves, pushing water temperatures into ranges that can exceed the thermal limits of sensitive aquatic species. As river waters warm, oxygen levels decline and the balance of freshwater ecosystems shifts.
This can mean dire consequences for fish, invertebrates, and the broader communities that depend on them. Scientific reviews further reveal that climate change is altering water quality, increasing the prevalence of harmful algal blooms, and amplifying stress on rivers already burdened by pollution and altered flow regimes. The following selections invite you to understand rivers not as passive conduits, but as lively dynamic systems whose health is inextricably tied to thermal conditions.
Forests
Forests are among Earth’s most complex and climate-regulating systems, yet they are increasingly tested by rising temperatures that push them toward thresholds of unprecedented stress. In regions like the Amazon Basin, extended heat and drought are manifesting in declines of forest resilience that some researchers warn could approach a tipping point by 2050.
A study found that as heat intensifies, trees experience reduced growth, greater susceptibility to pests and disease, and diminished capacity to recover from drought and fire. These changes amplify outward, affecting species that rely on forest habitats and altering the way forests influence regional and global climate patterns. The following selection prompts consideration of heat’s imprint on forests as signs of a large-scale transformation in which the health of forests becomes a measure of broader ecological change.
Cryosphere
Heatwaves in the Arctic now linger longer and intensify more rapidly than historical norms. The effects include melting sea ice, weakening snowpack, and extending the thaw season into times of the year once defined by deep freeze. These thermal shifts will have cascading effects across the planet including accelerated glacier retreat, permafrost destabilization, and large-scale greenhouse gas emissions.
As frozen ground thaws, bonds between rock and ice are loosening, increasing hazards such as rockfalls and slope instability in mountain and polar regions. What were once seasonal patterns of freeze and thaw have become prolonged periods of warmth. This was the case in the extraordinary Siberian heatwave of 2020, when temperatures far above average reshaped ice conditions and exposed new vulnerabilities in once-frozen landscapes.
The selection below invites you to explore how heat reshapes the cryosphere not as a peripheral consequence of climate change, but as a central and dynamic domain of transformation. From the slow fade of sea ice to the sudden collapse of rock faces once held firm by permafrost, these narratives reveal a world where heat is reaching even the coldest places on earth. Yet these impacts are not confined to a single ecosystem and will have profound implications for global climate feedback loops.
Ocean
Marine heat waves are periods of unusually warm ocean temperatures that persist over days, months, or even longer. Over time, they are becoming more frequent and intense. Oceans are collectively the Earth’s largest carbon sink and absorb excess heat from the atmosphere. Unlike gradual ocean warming, however, marine heat waves represent thermal stress that can rapidly disrupt marine ecosystems and the processes that sustain them.
These events have far-reaching consequences for ocean life. Elevated temperatures can trigger coral bleaching, alter plankton productivity, shift species distributions, and disrupt food chains that have evolved around stable thermal conditions. Fisheries and marine biodiversity are affected not only through direct heat stress but also through cascading changes in habitat quality and oxygen availability. In some regions, repeated marine heat waves are pushing ecosystems toward long-term transformation. Their adverse effects are not limited to land; ocean heatwaves can also increase heat and humidity on land. Read below to learn more about the often overlooked impacts of marine heatwaves.
Seeing heat beyond human impact
What often makes extreme heat impacts difficult to address is not only their scale, but their visibility. Many non-human effects of heat unfold below thresholds that trigger formal alerts or policy responses. Ecological stress, shifts in species composition, and changes in physical stability often register only after they have progressed significantly. By the time impacts are measurable in conventional terms, systems may already be operating under altered conditions.
Viewing extreme heat holistically highlights the need for vigilance beyond immediately visible or human-centred impacts. Sustained heat alters ecological and physical processes in gradual but consequential ways, making non-human systems critical indicators of emerging risk. Paying attention to these responses strengthens the ability to anticipate longer-term transformations before they become irreversible.