Living organisms and the atmosphere are locked in a continuous, two-way exchange of gases, particles, moisture, and energy that shapes weather, climate, and air quality on every scale from a single leaf to the entire planet. Plants pull carbon dioxide out of the air and release oxygen; microbes in soil and wetlands push carbon dioxide and methane back; ocean phytoplankton emit sulfur compounds that seed clouds; forests pump water vapor that fuels rainstorms hundreds of kilometers away. These are not background processes. They are among the primary forces regulating Earth’s atmosphere, and in many cases the atmosphere returns the favor by influencing how organisms grow, reproduce, and spread.
Carbon Dioxide and Oxygen
The most familiar exchange between the biosphere and the atmosphere is the carbon cycle driven by photosynthesis and respiration. Green plants, algae, and cyanobacteria absorb carbon dioxide and, using sunlight, convert it into organic carbon while releasing oxygen. Animals, fungi, and most microorganisms reverse the equation, consuming organic carbon and breathing out carbon dioxide. On a global scale these flows are enormous, moving well over a hundred billion tons of carbon per year between living systems and the air.
Soil adds a less visible but equally important chapter to this exchange. Soil microbes break down dead plant material and exhale carbon dioxide as they do so, and their activity is sensitive to temperature. Short-term experiments have long shown that microbial respiration rises sharply as soils warm. A study in Nature found that after about 90 days of warming, the microbial community’s own response amplified that temperature sensitivity rather than dampening it, increasing the heat-driven release of carbon dioxide by a factor of roughly 1.4 in high-latitude soils compared to the immediate response alone.1PubMed. Temperature sensitivity of soil respiration rates enhanced by microbial community response Because Arctic and boreal regions hold vast stores of soil carbon, this amplification could turn cold soils into an unexpectedly large source of atmospheric carbon dioxide as the climate warms.2Ecological Research. Drivers of temperature sensitivity of decomposition of soil organic matter along a mountain altitudinal gradient in the Western Carpathians
Transpiration and the Water Cycle
Plants do not just exchange carbon with the atmosphere; they move staggering volumes of water. Roots pull moisture from the soil and leaves release it as water vapor through tiny pores called stomata, a process called transpiration. This vapor rises, cools, and condenses into clouds and rain, effectively recycling moisture back into the atmosphere for redistribution. A moisture-tracking study across North America found that much of the northern and northeastern part of the continent receives up to 80 percent of its summertime precipitation from water that evaporated or transpired from the land surface, and more than half of that moisture comes from transpiration alone.3Journal of Geophysical Research: Atmospheres. The Contribution of Local and Remote Transpiration, Ground Evaporation, and Canopy Evaporation to Precipitation Across North America
In southern and western regions, local moisture recycling proved especially important, meaning the rain falling on a given area depends heavily on whether nearby vegetation is healthy and the soil is moist. Remove the vegetation and you do not just lose shade or habitat; you cut a major supply line for regional rainfall. This is one reason large-scale deforestation in the tropics is feared not only for its carbon consequences but for its potential to suppress precipitation across entire river basins.
Biogenic Volatile Organic Compounds and Aerosol Formation
Trees and shrubs release far more than water vapor. They emit a suite of reactive carbon-based gases, collectively known as biogenic volatile organic compounds, or BVOCs. Anyone who has smelled a pine forest on a hot day has inhaled some of these molecules. The major categories include isoprene, monoterpenes, and sesquiterpenes.4Chemosphere. Biogenic secondary organic aerosols: A review on formation mechanism, analytical challenges and environmental impacts Once airborne, these compounds react with sunlight-driven oxidants in the atmosphere to form tiny particles known as secondary organic aerosols.5PubMed. Kinetics, products, and mechanisms of secondary organic aerosol formation
Those aerosol particles matter for climate and air quality in several ways. They scatter and absorb sunlight, they serve as seeds around which cloud droplets form, and they contribute to the haze you can sometimes see over forested mountain ranges. At global scale, biogenic aerosols are a major natural component of the particle load in the lower atmosphere, and they can either cool or warm the surface depending on their optical properties and whether they brighten or thicken clouds.
Ocean Life, Sulfur, and Cloud Seeds
The biosphere’s influence on the atmosphere extends across the ocean surface. Marine phytoplankton produce a sulfur compound called dimethyl sulfide, or DMS, as a metabolic byproduct. When DMS escapes into the air, it oxidizes into sulfate particles that act as cloud condensation nuclei, the tiny seeds needed for water vapor to coalesce into cloud droplets. More nuclei generally mean more, smaller droplets, which makes clouds brighter and more reflective. Modeling work has shown that when DMS emissions increase globally due to greater phytoplankton activity, the resulting increase in cloud brightness produces large-scale cooling, particularly in polar regions.6Atmosphere. Polar Cooling Effect Due to Increase of Phytoplankton and Dimethyl-Sulfide Emission
Phytoplankton also influence the atmosphere more directly through sea spray. When waves break, they loft tiny droplets into the air, and those droplets carry biological material from the ocean surface. Research tracing chlorophyll signals in sea spray aerosol found that the biological material transferred from seawater to airborne particles is dominated by cyanobacteria and cell fragments from microbially degraded phytoplankton.7PubMed Central. Factors controlling the transfer of biogenic organic species from seawater to sea spray aerosol These biologically enriched particles affect how sea spray interacts with sunlight and how easily it nucleates cloud droplets, adding another biological fingerprint to the marine atmosphere.
Biological Ice Nucleation
Clouds are not just about liquid droplets. In colder parts of the atmosphere, ice crystal formation is crucial for precipitation, and organisms play a surprisingly active role. Certain bacteria, fungal spores, pollen grains, and even fragments of plant and animal tissue can trigger ice formation at much warmer temperatures than pure water would freeze on its own. These biological particles are collectively called primary biological aerosol particles. Field measurements in the European sub-Arctic showed that locally emitted fungal spores serve as high-temperature ice nucleating particles, capable of seeding ice in clouds well above the temperatures at which mineral dust would do the same job.8Atmospheric Chemistry and Physics. Locally emitted fungal spores serve as high-temperature ice nucleating particles in the European sub-Arctic
Modeling studies have explored how five distinct groups of biological particles, including fungal spores, bacteria, pollen, plant and animal detritus, and algae, collectively contribute to ice nucleation in mixed-phase clouds.9Atmospheric Chemistry and Physics. The influence of multiple groups of biological ice nucleating particles on microphysical properties of mixed-phase clouds observed during MC3E In clean, rural environments where industrial aerosol concentrations are low, biological ice nucleators can dominate the process, giving the biosphere a direct handle on when and where rain or snow forms.
Methane From Wetlands
Wetlands are the single largest natural source of methane, a greenhouse gas roughly 80 times more potent than carbon dioxide over a 20-year window. The methane comes from microbes called methanogens that thrive in waterlogged, oxygen-free soils, breaking down organic matter and exhaling methane as a waste product. Wetland plants play a dual role in this process. Their roots and fallen leaves supply the organic carbon that methanogens feed on, and their stems contain internal gas channels that act as chimneys, conducting methane from the soil directly into the atmosphere, bypassing the water layer where it might otherwise be consumed by methane-eating bacteria.10PubMed Central. Methane emission from natural wetlands: interplay between emergent macrophytes and soil microbial processes. A mini-review
At the same time, some of the oxygen that plant roots leak into the surrounding soil feeds a different group of microbes that oxidize methane before it escapes. So the same plant can simultaneously fuel methane production, pipe it to the surface, and partially neutralize it. The balance between these opposing effects depends on plant species, water level, and temperature, which is why predicting future wetland methane emissions as climate shifts is so challenging.
Ozone and Vegetation
Ground-level ozone, the main ingredient of smog, is produced when sunlight drives reactions between nitrogen oxides and volatile organic compounds. Because plants are a major source of those volatile compounds, they indirectly contribute to ozone formation. But the relationship runs in both directions: ozone damages the very plants that helped create it. Ozone enters leaves through open stomata and injures cells inside, reducing growth and crop yields.11Geoscientific Model Development. Development of an ecophysiology module in the GEOS-Chem chemical transport model version 12.2.0 to represent biosphere–atmosphere fluxes relevant for ozone air quality
The timing of ozone exposure matters more than you might expect. Experiments on lettuce species showed that when an equivalent dose of ozone was delivered at night rather than during the day, the resulting loss of plant biomass was about 8 to 10 percent greater.12PubMed Central. Ozone uptake at night is more damaging to plants than equivalent day-time flux This is partly because plants close their stomata at night under normal conditions, so any ozone that does enter encounters tissues that are less prepared to detoxify it. As ozone levels and nighttime temperatures rise in many regions, this interaction could quietly erode agricultural productivity.
Wildfire Smoke and Weather Feedbacks
Wildfires are a dramatic example of the biosphere altering the atmosphere. Burning biomass injects enormous plumes of black carbon (soot) and organic carbon particles into the air, and those particles then reshape the very weather conditions that influence fire behavior. During Australia’s catastrophic 2019–2020 fire season, modeling revealed that carbonaceous aerosols from the fires caused surface radiative cooling exceeding 100 watts per square meter in southeastern Australia, lowering the planetary boundary layer and trapping smoke near the ground, which increased fine particulate concentrations by roughly 28 percent.13PubMed. Contrasting Responses of Smoke Dispersion and Fire Emissions to Aerosol-Radiation Interaction during the Largest Australian Wildfires in 2019-2020 At the same time, the cooling and altered circulation brought more moisture toward the fire zone and suppressed some fire activity, partially offsetting the air-quality hit.
A separate analysis of the same fire season found that the effects of smoke depend on the landscape. Black carbon and organic carbon reduced the most extreme fire weather indices in arid central Australia while increasing extreme fire danger in the vegetated, fire-prone southeast through warming and drying effects.14Fire Ecology. The role of wildfire emissions on extreme fire weather during Australia’s Black Summer through smoke-weather feedbacks The biosphere burns, and the smoke it produces changes where and how intensely the biosphere burns next.
Biological Soil Crusts and Dust
In arid and semi-arid landscapes, thin communities of cyanobacteria, mosses, and lichens form biological soil crusts, or biocrusts, that glue loose soil particles together and protect the surface from wind erosion. When intact, biocrusts can dramatically reduce the amount of dust lofted into the atmosphere. Laboratory experiments showed a strong, nonlinear relationship between cyanobacterial inoculum and erosion control: at the highest dose tested, biocrusts eliminated virtually all soil loss compared to bare ground.15Land Degradation & Development. Dose‐Dependent Cyanobacterial Soil Stabilization: Linking Inoculum Density to Biocrust Development and Erosion Control on Dried Lakebeds
This matters because mineral dust is one of the most abundant aerosol types in the atmosphere. It scatters sunlight, fertilizes remote ocean ecosystems with iron, and affects cloud formation. The bacteria that compose biocrusts have dispersal strategies of their own that influence surface stability across drylands.16Journal of Geophysical Research: Biogeosciences. Surface Stability in Drylands Is Influenced by Dispersal Strategy of Soil Bacteria Modeling of a major Central and East Asian dust storm in 2018 found that including biocrust inhibition in the dust emission scheme changed the simulated dust load, demonstrating that these tiny organisms meaningfully regulate a large-scale atmospheric phenomenon.17Advances in Climate Change Research. Adding the impacts of biological crusts on sand and dust storm emission in Asia
Forests, Surface Properties, and Local Climate
Beyond exchanging gases and particles, forests alter the physical surface that the atmosphere “sees.” A forest canopy is rougher, darker, and more textured than bare soil or grassland, and these properties change how energy and momentum move between the ground and the air. Deforestation changes surface roughness, which in turn shifts the surface energy balance and local temperatures.18Journal of Geophysical Research: Atmospheres. Importance of Surface Roughness for the Local Biogeophysical Effects of Deforestation A rougher canopy generates more turbulence, mixing heat and moisture more efficiently into the lower atmosphere and moderating surface extremes. When you remove the forest, the surface becomes smoother and often more reflective, but it also loses the cooling services of transpiration and turbulent mixing, frequently leading to warming on a local scale even if more sunlight bounces away.
The net climate effect of planting or preserving forests is not straightforward, because it depends on how much carbon dioxide the trees absorb, how much they change surface reflectivity, and how their transpiration affects regional cloud cover. Model estimates suggest that under low-emission scenarios, the biophysical cooling benefit of full-scale forestation is modest, around −0.06 °C on the global land surface. Under higher CO₂ concentrations, that benefit shrinks further, to roughly −0.02 °C, primarily because the non-local cooling effects of forestation weaken as the atmosphere accumulates more carbon dioxide.19PubMed Central. Diminished biophysical cooling benefits of global forestation under rising atmospheric CO2 This does not mean planting trees is pointless for climate, but it does mean the biophysical side of the ledger is more complicated than “more trees equals cooler planet.”
Urban Trees and Ozone
City planners around the world are expanding urban tree cover to cool streets and improve livability, but the choice of tree species matters more than many realize. A study combining direct emissions measurements in Beijing with atmospheric modeling found that urban vegetation contributed more than half of the organic chemical reactivity needed for ozone production in the city, and was the main driver of ozone exceedances during hot weather.20PubMed Central. Tree selection in urban greening shapes air quality for global cities The culprit was an abundance of tree species with high BVOC emission rates planted throughout the city. Model extrapolations showed that cities across Asia and Oceania face similar or worse challenges because their greening programs also favor high-emitting trees. The takeaway is that the biosphere-atmosphere interaction works both ways in cities: trees clean some pollutants from the air while chemically feeding the production of others, and which effect wins depends on what you plant.
How Life Built the Atmosphere in the First Place
Every interaction described so far plays out against a backdrop that the biosphere itself created over billions of years. Earth’s atmosphere was essentially oxygen-free for its first two billion years. The shift began with cyanobacteria, photosynthetic microbes that originated in the mid-Archean and eventually drove what geologists call the Great Oxidation Event. Molecular clock analyses suggest cyanobacteria evolved multicellularity before this event, and that transition may have allowed them to increase in abundance enough to tip the atmospheric balance toward free oxygen.21PubMed Central. Cyanobacteria and the Great Oxidation Event: evidence from genes and fossils
Hundreds of millions of years later, the colonization of land by plants around 470 million years ago triggered another wave of oxygenation. Modeling combined with carbon isotope records suggests that these early land plants raised atmospheric oxygen to roughly modern levels by about 420 to 400 million years ago, largely by burying organic carbon that would otherwise have been oxidized.22PubMed Central. Earliest land plants created modern levels of atmospheric oxygen Land plants also accelerated the chemical weathering of rocks, drawing down carbon dioxide and cooling the planet, while producing decay-resistant compounds like lignin that locked carbon away in soils and sediments.23Chemical Geology. The impacts of land plant evolution on Earth’s climate and oxygenation state – An interdisciplinary review The atmosphere we have today, its oxygen content, its carbon dioxide concentration, its capacity to support an ozone layer, is fundamentally a product of biological activity accumulated over deep time.
When Thunderstorms Make Trees Glow
One of the more surprising recent discoveries in biosphere-atmosphere research involves electricity. Scientists have long hypothesized that the pointed tips of tree leaves might produce corona discharges, tiny electrical glows, under the strong electric fields of a thunderstorm. But no one had directly observed and measured the phenomenon until a team deployed ultraviolet-sensitive instruments in forests from North Carolina to Pennsylvania. They recorded coronae flickering sporadically among leaves on every branch in their field of view as storms passed overhead, with each discharge emitting roughly 100 billion photons at 260 nanometers and producing electrical currents on the order of one microampere.24Geophysical Research Letters. Corona Discharges Glow on Trees Under Thunderstorms Consistent results across multiple storm intercepts paint a picture of entire forest canopies scintillating with faint ultraviolet light during thunderstorms. These discharges could influence the local chemistry of the air, potentially generating small amounts of ozone and nitrogen oxides right at the canopy surface, though the atmospheric significance of that chemistry is still being worked out. It is a vivid reminder that the boundary between the biosphere and the atmosphere is not passive; even the physical shapes of leaves can change the electrical and chemical state of the air around them.