Biomes matter because they are the planet’s life-support infrastructure. Each major biome, from tropical rainforests to deep-ocean floors, performs specific functions that regulate climate, cycle nutrients, store carbon, generate rainfall, buffer coastlines, and maintain the genetic diversity that underpins agriculture and medicine. These functions do not operate in isolation. Biomes feed into and depend on each other across vast distances, and the loss or degradation of one biome can destabilize ecosystems thousands of kilometers away.
Carbon Storage on a Planetary Scale
One of the most consequential things biomes do is move carbon between the atmosphere, land, and ocean. Different biomes handle different parts of this job. Northern peatlands, for instance, have cooled the global climate over millennia by locking up enormous quantities of soil carbon. Keeping those carbon stores intact is considered critical for reaching net-zero carbon dioxide emissions targets by mid-century.1Frontiers in Ecology and the Environment. The essential carbon service provided by northern peatlands Grasslands, which cover huge swaths of every continent except Antarctica, store roughly a third of all terrestrial carbon stocks, mostly underground in their soils rather than in visible vegetation. Research shows that plant diversity in grasslands directly increases how much carbon ends up locked in the soil, because diverse root systems feed more organic material into deeper layers where microbes convert it into stable forms.2PubMed. Grassland soil carbon sequestration: Current understanding, challenges, and solutions
The ocean runs a parallel operation. Through what scientists call the biological carbon pump, marine organisms at the surface capture carbon and transport it to the deep ocean by several routes: particles sinking under gravity, currents carrying suspended organic matter downward, and animals physically migrating between surface and deep waters each day. Carbon that reaches the deep ocean stays sequestered there for years to centuries, effectively removing it from the atmosphere on human-relevant timescales.3Global Biogeochemical Cycles. Quantifying the Carbon Export and Sequestration Pathways of the Ocean’s Biological Carbon Pump Coastal upwelling zones are particularly productive at this, with multiple biological pathways working simultaneously to push carbon into deep storage.4Nature Communications. Carbon sequestration by multiple biological pump pathways in a coastal upwelling biome
The combined effect is staggering. Peatlands, grasslands, forests, and oceans each operate on different timescales and through different mechanisms, but together they regulate how much carbon dioxide stays in the atmosphere. Damage any one of these biomes and you remove a piece of the system that keeps atmospheric carbon in check.
The Concentration of Life in Tropical Forests
Tropical rainforests cover about 7% of Earth’s land surface but harbor close to half of the world’s plant species. That ratio alone makes them disproportionately important as reservoirs of biological diversity.5PubMed. Plant phylogeny as a window on the evolution of hyperdiversity in the tropical rainforest biome Why tropical forests are so species-rich is a question researchers have chased for decades, and there is no single answer. A review of theories organized them into four broad categories: genetic differentiation within populations, environmental change over geological time, diversification of habitats and niches, and interactions between species that drive specialization.6Progress in Physical Geography: Earth and Environment. Why are tropical rain forests so species rich? Classifying, reviewing and evaluating theories
Phylogenetic studies point to the tropical rainforest biome being both old and relatively stable. It has persisted long enough for species to accumulate, with low extinction rates and steady speciation rates building up diversity over millions of years.5PubMed. Plant phylogeny as a window on the evolution of hyperdiversity in the tropical rainforest biome Think of it less as an engine of rapid evolution and more as a vault that has been collecting biological wealth for an extraordinarily long time. When tropical forest is cleared, you are not just removing trees. You are liquidating an inventory that took tens of millions of years to build.
How Forests Generate Their Own Rain
One of the more striking ways biomes maintain themselves and influence neighboring regions involves rainfall. A hypothesis that has gained traction suggests that forests play a much larger role in determining rainfall patterns than older climate models recognized. The mechanism works through evaporation and condensation: forested regions cycle water vapor into the atmosphere, which creates pressure differences that pull moist air inland from the coast. Under this framework, the high rainfall deep in the interiors of the Amazon and Congo basins exists only because near-continuous forest cover stretches from the coast to the interior, maintaining the atmospheric moisture flow.7Oxford Academic. How Forests Attract Rain: An Examination of a New Hypothesis
This idea carries an uncomfortable implication. If large-scale deforestation breaks the chain of forest cover, the remaining forest may not receive enough rainfall to sustain itself. The interior dries out, more forest dies, rainfall drops further, and the biome spirals toward collapse. The relationship between the biome and its climate is not one-directional; the forest and the rain co-create each other.
Biomes Feeding Each Other Across Continents
Biomes are not sealed compartments. One of the most vivid examples of cross-biome dependence involves the Sahara Desert and the Amazon rainforest, separated by an ocean. Dust eroded from the Bodélé Depression in Chad blows westward across the Atlantic, carrying micronutrients like iron and phosphorus that act as fertilizer when they settle over the Amazon basin and the equatorial Atlantic Ocean.8Geophysical Research Letters. Fertilizing the Amazon and equatorial Atlantic with West African dust
This is not a minor contribution. Amazon soils are naturally low in phosphorus, and the rainforest’s productivity is constrained by that scarcity. Satellite-based estimates suggest that African dust delivers enough phosphorus each year to roughly offset the amount lost through the basin’s rivers. Without that resupply, the Amazon would gradually deplete its phosphorus over decades to centuries, threatening the forest’s ability to sustain itself.9Geophysical Research Letters. The fertilizing role of African dust in the Amazon rainforest: A first multiyear assessment based on data from Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations A desert that most people think of as barren is quietly keeping the world’s largest tropical forest alive.
Rivers form another kind of connective tissue. Streams, rivers, and lakes couple the biogeochemical cycles of continents, atmosphere, and oceans, transporting carbon, nitrogen, and other elements across biome boundaries.10Frontiers in Ecology and the Environment. Riverine coupling of biogeochemical cycles between land, oceans, and atmosphere Inland waters are not just passive channels; they actively transform the materials passing through them, releasing gases to the atmosphere and delivering nutrients to coastal zones. Every river delta, every estuary, every floodplain is a point where one biome’s outputs become another’s inputs.
Coastal Biomes as Storm Defenses
Tidal marshes and mangrove forests provide some of the most tangible ecosystem services to human communities: coastal storm protection. These wetlands are effective at dampening short-period storm waves, reducing the energy that reaches shorelines and human infrastructure.11PubMed. Marshes and Mangroves as Nature-Based Coastal Storm Buffers Measurements of the largest wave heights ever recorded passing through forested wetlands show that mangroves can reduce storm wave heights by about 35% over a relatively short distance, except in rare cases where water levels nearly submerge the canopy entirely.12PubMed Central. Predicting nature-based coastal protection by mangroves under extreme waves
The picture is not entirely rosy, though. Long-period storm surges, which can elevate sea levels by several meters for more than a day, are attenuated less effectively or sometimes not at all, depending on the storm’s characteristics and the geometry of the coast.11PubMed. Marshes and Mangroves as Nature-Based Coastal Storm Buffers Storms also damage the wetlands themselves; mangrove trees can take years to recover from a major hurricane. So while these biomes are genuinely useful as natural buffers, they are not invulnerable walls. Treating them as infrastructure means also planning for their maintenance and recovery.
The Overlooked Work of Extreme Biomes
Deserts and deep ocean floors seem like ecological afterthoughts, but both support communities that perform outsized roles relative to their visibility. In deserts worldwide, biological soil crusts made of cyanobacteria, algae, fungi, lichens, and mosses blanket the ground surface and carry out primary productivity, nitrogen fixation, nutrient cycling, and soil stabilization.13Reviews in Engineering Geology. Role of biological soil crusts in desert hydrology and geomorphology: Implications for military training operations These crusts are not just incidental growths. In China’s Gurbantunggut Desert, biological soil crusts fix nitrogen across all crust types, supplying the nutrient to surrounding vascular plants in areas too sparsely vegetated to generate it on their own.14Journal of Arid Environments. Comparative study of nitrogenase activity in different types of biological soil crusts in the Gurbantunggut Desert, Northwestern China Research from Oman’s deserts found similar communities rich in nitrogen-fixing cyanobacteria that improve soil stability and productivity.15FEMS Microbiology Ecology. Bacterial diversity, pigments and nitrogen fixation of biological desert crusts from the Sultanate of Oman
At the other extreme, hydrothermal vents on the deep ocean floor host thriving microbial communities that run entirely on chemical energy rather than sunlight. These microorganisms use sulfur, hydrogen, metals, and other chemicals spewing from the vents to power their metabolism, and in doing so they mediate biogeochemical processes that couple carbon, sulfur, nitrogen, and metal cycles in the deep ocean.16PubMed Central. Microorganisms from deep-sea hydrothermal vents These ecosystems demonstrate that life does not require sunlight to build a functioning biome, and they offer a window into how Earth’s earliest ecosystems may have worked.
Why Redundancy Keeps Ecosystems Running
Within any biome, not every species is doing something unique. Many species overlap in their ecological roles: multiple types of pollinators visit the same flowers, several predator species keep the same prey populations in check, different soil microbes break down the same organic compounds. This overlap, called functional redundancy, is often dismissed as waste. It is actually insurance.
A meta-analysis of studies on functional redundancy found that it positively affects community stability and resilience to disturbance.17Ecosphere. Does functional redundancy affect ecological stability and resilience? A review and meta‐analysis The logic is straightforward: if several species perform the same function, the loss of one does not crash the system because others pick up the slack. Field research in Inner Mongolia’s steppe grasslands confirmed this pattern, showing that functional groups containing more redundant species achieved greater niche differentiation during disturbances, providing what researchers described as an insurance effect.18PubMed Central. Functional Redundancy Instead of Species Redundancy Determines Community Stability in a Typical Steppe of Inner Mongolia
This matters for how we think about biodiversity loss within biomes. Losing a species that has no functional equivalent is categorically worse than losing one whose role is shared by others. But as you erode biodiversity within a biome, you steadily strip out redundancy, and each subsequent loss becomes more dangerous. The system works until it suddenly does not.
How Humans Reshaped Earth’s Biomes
Between 1700 and 2000, Earth’s terrestrial biosphere crossed a threshold: it went from being mostly wild to mostly shaped by humans. That 50% mark was passed early in the 20th century. Today, the form and processes of most terrestrial biomes are predominantly anthropogenic, driven by agriculture, urbanization, and other direct human interactions with ecosystems.19Global Ecology and Biogeography. Anthropogenic transformation of the biomes, 1700 to 2000 We live on a planet where human-modified landscapes are the norm, not the exception.
This transformation does not automatically mean those biomes stop functioning, but it changes what functions they perform and how reliably. Cropland still cycles carbon and water, but differently from the grassland or forest it replaced. Managed forests still absorb carbon dioxide, but often with lower biodiversity and less resilience to disturbance than old-growth stands. The transition zones between biomes, known as ecotones, are especially sensitive to these changes. Ecotones control the flow of energy and organisms between adjacent ecosystems, and their positions are set by the physiological limits of the species living in them.20PubMed Central. Ecotones as Windows into Organismal-to-Biome Scale Responses across Neotropical Forests When climate or land use shifts those limits, ecotones move, and biome boundaries redraw themselves in ways that cascade through the surrounding landscape.
The Amazon Tipping Point
The Amazon illustrates what happens when multiple pressures converge on a single biome. Modeling work suggests that reducing Amazon forest cover to around 35%, or decreasing atmospheric moisture flow by roughly 10%, could cause the system to flip abruptly from a wet rainforest climate to a drier state dominated by savanna-like vegetation. The transitions are not gradual; small additional changes in either forest cover or moisture can push the system between stable forest, savanna, or shrubland states, and the switches happen fast.21Geophysical Research Letters. Deforestation Could Push Amazonia Close to a Tipping Point Under Future Climate Change
Under current climate projections with continued deforestation, the research suggests this transition to savanna could happen within this century. The consequences would be global: the Amazon currently absorbs billions of tons of carbon dioxide, regulates rainfall for much of South America, and houses a significant fraction of Earth’s terrestrial species. Replacing that forest with savanna would release stored carbon, alter continental rainfall, and trigger extinctions that would ripple through food webs far beyond the tropics.
Biomes as Genetic Vaults for Agriculture
Wild relatives of crop plants live in specific biomes, and they carry genetic diversity that domesticated crops have lost. Crop wild relatives are generally more genetically diverse than their cultivated descendants, carrying adaptations to drought, pests, diseases, and other stresses acquired through evolving in diverse and often harsh environments. For Mesoamerican wild relatives of crops like maize, beans, chili peppers, and pumpkins, the situation is urgent: up to 35% of recently assessed taxa are threatened with extinction according to IUCN Red List criteria.22Nature Communications. Incorporating evolutionary and threat processes into crop wild relatives conservation
These wild plants are not museum curiosities. Plant breeders routinely cross them with commercial varieties to introduce resistance to new diseases or tolerance to changing growing conditions. If the biomes where these wild relatives evolved are destroyed or degraded past the point of supporting them, that genetic toolkit disappears permanently. Every biome loss narrows the options available for adapting agriculture to a warming, less predictable climate.
What Ancient Biome Shifts Reveal
Earth’s biomes have not always been where they are now. During the Last Glacial Maximum, roughly 21,000 years ago, much of the planet’s land surface was covered by open, non-forest biomes: tundra, steppe, and sparse shrubland extended far into latitudes that are forested today. As the climate warmed and ice sheets retreated, a global shift toward forest biomes unfolded, a pattern confirmed both by fossil pollen records and by Earth system model simulations.23Climate of the Past. Global biome changes over the last 21 000 years inferred from model–data comparisons
The details are instructive. A pollen record from southwestern China’s Caohai area shows that the region was covered by evergreen oak forest during the glacial maximum, then transitioned to deciduous broadleaved forest around 15,800 years ago as conditions warmed. Vegetation belts shifted vertically by as much as 1,000 meters in elevation between the glacial period and the Holocene. Both proxy data and models agree that biome transitions occur when temperature and moisture conditions cross specific thresholds.24Quaternary Science Reviews. Vertical biome shifts and climate changes since the last glacial maximum in the southeastern margin of the Tibetan plateau, Southwest China
The lesson from the paleoclimate record is not reassuring in the current context. Biomes do shift in response to climate change, and they have always done so. But the rate of change matters enormously. Post-glacial transitions played out over thousands of years, giving species time to migrate and communities time to reassemble. The climate changes projected for this century are happening orders of magnitude faster, and biomes fragmented by human land use cannot shift as freely as they once did. Species attempting to track suitable climate conditions may find their migration routes blocked by cities, farmland, and highways.
How Climate Defines Biome Boundaries
The very existence of distinct biomes depends on climate patterns, but the relationship is subtler than many textbook maps imply. Biomes are often classified by mean annual temperature and precipitation, yet those averages overlap considerably between biome types. A grassland and a seasonal forest may share similar average rainfall. What actually distinguishes them, according to more recent analysis, is the predictability of temperature and precipitation. When researchers factor in how regular seasonal patterns are, biomes that look indistinguishable on a simple temperature-versus-rainfall chart separate cleanly into distinct climatic spaces.25Global Ecology and Biogeography. Biome‐specific climatic space defined by temperature and precipitation predictability Organisms are adapted not just to how much rain falls, but to when it falls and how reliable that timing is. Disrupt the predictability of a region’s climate and you may push it across a biome boundary even if the annual totals barely change.