How Ice and Air Shape Earth's Climate
The bright, white surface of snow and ice reflects large amounts of sunlight back into space, contributing to stabilizing Earth's temperature—a critical role now being disrupted by climate change.
Imagine a world where falling snow cleanses the air, where ice crystals release chemicals that transform the atmosphere, and where frozen landscapes influence weather patterns thousands of miles away. This isn't science fiction—it's the fascinating reality of how Earth's cryosphere interacts with our atmosphere. The cryosphere, comprising all the frozen parts of our planet from polar ice caps to mountain glaciers, acts as both a thermometer and a thermostat for the global climate system. Yet until recently, scientists had only fragmented understanding of the complex chemical conversations occurring between ice and air.
Now, an international scientific initiative called Cryosphere and ATmospheric CHemistry (CATCH) is piecing together this puzzle. This collaborative effort brings researchers from across the globe together to study how snow, ice, oceans, aerosols, and clouds interact in cold regions 1 . As climate change rapidly transforms these frozen environments, understanding these processes has never been more critical—not just for predicting future climate, but for protecting the delicate balance that supports life on Earth.
The cryosphere covers about 10% of Earth's surface, but its influence on global climate is disproportionately large.
CATCH represents a growing recognition that understanding our changing planet requires breaking down traditional scientific boundaries. Established as an official activity of the International Global Atmospheric Chemistry (IGAC) project and endorsed by SOLAS (Surface Ocean-Lower Atmosphere Study), CATCH facilitates exactly the kind of interdisciplinary research that complex environmental challenges demand 1 5 .
The mission of CATCH is as ambitious as it is crucial: to facilitate atmospheric chemistry research focused on natural processes specific to Earth's cold regions 5 . These areas include not just the obvious polar ice sheets, but any regions seasonally or permanently covered by snow and ice—from high mountain glaciers to the microscopic ice crystals that form high-altitude clouds.
Through international collaboration, CATCH scientists aim to understand how aerosols form and evolve in cold environments, how ice cores preserve historical climate information, and how physical, chemical, and biological changes in sea ice and snow impact atmospheric composition 5 .
Perhaps most importantly, CATCH seeks to link molecular-level processes with larger-scale phenomena observed through field measurements and satellites 1 . This multi-scale approach helps bridge the gap between fundamental chemistry and global climate models, ultimately leading to more accurate predictions of how our world will continue to change.
Despite significant advances, fundamental questions about atmospheric chemistry in cold environments remain unanswered. Recently, the CATCH community identified ten crucial unknowns that represent the frontier of research in this field 3 . These questions highlight both the complexity and importance of understanding our frozen atmosphere:
Winter brings dramatically different emission patterns from both human activities and natural sources. Heating homes through combustion becomes a significant local emission source, while natural emissions from soil and plants show distinct temperature-dependent changes that are challenging to quantify 3 .
New pollutants constantly emerge through consumer product innovation and shifting transportation routes. Organophosphate esters from flame retardants, for instance, have recently been identified in the Arctic, posing new threats to aquatic ecosystems 3 .
Ice cores preserve invaluable records of past atmospheric composition, but interpreting these archives is complicated by chemical changes that occur in snow before it fully transforms into ice 3 .
A quarter century after the discovery that sunlit snowpack releases nitrogen oxides to the atmosphere, scientists still lack a predictive understanding of the underlying chemistry 3 .
| Research Question | Significance | Knowledge Gaps |
|---|---|---|
| Cold Impact on Emissions | Understanding seasonal pollution patterns and natural emissions | Temperature-dependent emission rates from soils and plants |
| Snow Chemistry Effects | Influences regional air quality and geochemical cycles | Location and mechanisms of reactions within snow and ice |
| Warming Climate Effects | Predicting future atmospheric composition | How declining snow/ice cover will alter chemical processes |
| Multiphase Chemistry in Cold | Accurate modeling of pollution events | Reaction rates and thermodynamic properties at low temperatures |
Among the many fascinating processes occurring in cold regions, one recent study offers a perfect example of the intricate connections between ice and atmosphere. Research published in 2025 investigated how sea ice leads—fractures that create open water channels within sea ice—affect atmospheric chemistry in the Arctic 6 .
The research team employed an innovative approach that combined satellite observations with sophisticated atmospheric modeling:
The study revealed that while leads contribute modestly to Arctic-wide sea salt emissions (increasing them by just 1.1%-1.8% at latitudes ≥60°N), their impact is concentrated in regions where background aerosol concentrations are exceptionally low 6 . This means that despite their small overall contribution, leads can cause significant local changes in atmospheric composition.
Perhaps more importantly, the additional sea salt aerosols led to increases in bromine atom concentrations—a key player in Arctic atmospheric chemistry. Bromine atoms drive catalytic ozone destruction cycles that can completely remove ground-level ozone during springtime "depletion events" 6 . The model showed that sea salt from leads increased multi-year monthly mean surface bromine atom concentrations by 2.8%-8.8% during the cold seasons studied 6 .
| Impact Metric | Low Latitude Arctic (≥60°N) | High Latitude Arctic (≥75°N) |
|---|---|---|
| Increase in Sea Salt Aerosol Emissions | 1.1% - 1.8% | 5.6% - 7.5% |
| Increase in Bromine Atom Concentrations | 2.8% - 8.8% | 2.8% - 8.8% |
| Impact on Ozone Concentrations | Negligible | Negligible |
This research highlights how seemingly minor features in the cryosphere can have chemically significant atmospheric effects. As climate change causes sea ice to thin and fracture more easily, leading to more leads, these processes may become increasingly important to include in climate models 6 .
Understanding the complex interactions between the cryosphere and atmosphere requires specialized approaches and technologies. Researchers in this field employ an diverse arsenal of tools to probe the frozen frontiers of our planet:
Historical climate archives that provide past atmospheric composition from trapped bubbles 3 .
Simulating atmospheric processes and predicting how emissions affect composition across regions 6 .
In-situ data collection for validating models/satellites and measuring LAP effects on snow .
| Research Tool | Primary Function | Key Insights Provided |
|---|---|---|
| Ice Cores | Historical climate archives | Past atmospheric composition from trapped bubbles 3 |
| Satellite Remote Sensing | Large-scale cryospheric monitoring | Sea ice lead detection, snow cover extent, albedo measurements 6 9 |
| Chemical Transport Models | Simulating atmospheric processes | Predicting how emissions affect composition across regions 6 |
| Field Measurements | In-situ data collection | Validating models/satellites, measuring LAP effects on snow |
Each of these tools provides a different piece of the puzzle. For instance, while satellite data might detect the presence of leads in sea ice, only ground-based measurements can confirm the precise chemical composition of aerosols emitted from those leads 6 . Similarly, ice cores provide crucial long-term context that helps scientists distinguish between natural variability and human-caused changes in atmospheric composition 3 .
This multi-tool approach reflects the inherently interdisciplinary nature of cryospheric research. As highlighted in a recent editorial on atmosphere-cryosphere interactions, "additional in-situ measurements and experiments are needed to better constrain the effects of light absorbing particles on snow albedo, melt rate, and other associated processes, as well to provide data to validate and improve existing models" .
The research coordinated through CATCH reveals a critical truth: Earth's cryosphere functions not as a passive victim of climate change, but as an active participant in climate regulation 1 3 . The intricate chemical exchanges between ice and atmosphere—from snowpack releasing nitrogen compounds to sea ice leads emitting sea salt aerosols—demonstrate that frozen surfaces breathe chemical life into our skies, with consequences that ripple across the globe.
The rapid changes now occurring in cold regions make this research urgently relevant. As the Second Inter-Polar Conference in 2025 will emphasize, building resilience requires "taking actions towards preserving the Earth's cryosphere" 2 . The decline of frozen surfaces creates a dangerous feedback loop: as bright, reflective snow and ice disappear, less sunlight is bounced back to space, causing further warming and more ice loss 2 .
The work of CATCH represents more than abstract scientific curiosity—it provides the fundamental understanding needed to predict and potentially mitigate some of the most severe consequences of climate change.
By unraveling the complex relationships between ice, air, and climate, scientists are not just documenting the transformation of our planet's frozen regions; they're illuminating the processes that affect us all, regardless of where we call home. As this research continues to evolve, it reminds us that preserving Earth's icy realms means protecting the delicate atmospheric balance that sustains life everywhere.