Frozen Skies: How Ice and Snow Shape Our Planet's Atmosphere
Exploring the critical connections between Earth's cryosphere and atmospheric chemistry through CATCH research
The Icy Breath of Our Planet
Imagine a world where snow-covered landscapes actively shape the very air we breathe, where ice crystals influence global climate patterns, and where the fate of our warming planet is written in frozen scripts.
This isn't science fiction—it's the fascinating realm where atmospheric chemistry meets Earth's cryosphere, the frozen parts of our planet. As climate change accelerates, understanding these connections has never been more urgent.
Did You Know?
The cryosphere contains about 75% of the world's freshwater, stored in glaciers, ice caps, and snow cover. As it melts, it not only raises sea levels but also transforms atmospheric chemistry.
Enter CATCH (The Cryosphere and ATmospheric CHemistry), an international scientific initiative that brings together researchers across disciplines to unravel the complex interactions between ice, snow, air, and clouds in cold regions 1 . From the polar ice caps to the highest mountain glaciers, CATCH scientists are decoding how these frozen frontiers influence everything from air quality to global climate patterns. Their work reveals that the cryosphere is far from inert—it breathes, reacts, and transforms our atmosphere in ways we're only beginning to understand.
What Exactly is CATCH?
CATCH represents a collaborative effort to understand the intricate relationships between environmental ice and atmospheric chemistry. This interdisciplinary community spans 14 countries and brings together atmospheric chemists, glaciologists, biologists, physicists, and climate modelers 5 . The initiative is officially sponsored by major international scientific organizations including the International Global Atmospheric Chemistry (IGAC) project and the Surface Ocean-Lower Atmosphere Study (SOLAS) 7 .
Global Collaboration
14 countries working together to understand cryosphere-atmosphere interactions
CATCH Research Mission
Key Research Questions
- How are aerosols formed and processed in cold regions?
- How do these aerosols influence cloud properties?
- What feedbacks exist between climate change and atmospheric chemistry?
- How can ice core records help us understand global environmental change?
- How do changes in sea ice and snow impact atmospheric chemistry?
Core Focus
CATCH operates on a simple but profound recognition: cold temperatures introduce unique interfaces and chemical environments that impact reaction mechanisms, atmospheric composition, and physicochemical properties in ways dramatically different from what occurs in warmer atmospheres 3 . From the molecular level to global scales, CATCH seeks to connect fundamental science with real-world impacts.
The Crucial Unknowns: Mysteries of Cold Chemistry
Why does atmospheric chemistry in cold regions behave so differently? The answer lies in the unique properties of ice and snow at low temperatures.
How does cold impact emissions?
Winter brings different emission patterns from both human activities (like heating) and natural sources. In polar oceans, biological activity beneath sea ice produces gases that enter the atmosphere when the ice fractures, but the full range and impact of these emissions remain poorly understood 3 .
How is chemistry in snow impacting the air?
A quarter-century after the discovery that sunlit snowpack releases nitrogen oxides to the atmosphere, scientists still lack a predictive understanding of the underlying snow chemistry. The locations where these reactions occur within snow and ice—and how they proceed differently than in liquid water—remain active research areas 3 .
What will happen in a warming climate?
As seasonal snowmelt occurs earlier and sea ice extent diminishes, these changes profoundly impact atmospheric chemistry. For example, reduced sea ice has been linked to increased sea salt aerosol production, while melting snow can create new reactive environments and alter the preservation of environmental records in ice cores 3 .
How is the cold relevant to multiphase chemistry?
Cold temperatures dramatically alter fundamental chemical parameters like trace gas solubility and reaction rates. Recent research has revealed unexpected phenomena, such as apparently accelerated reactions in microscopic droplets and at ice interfaces, though the mechanisms remain hotly debated 3 .
"These questions highlight a critical insight: the cryosphere is not a passive player but an active chemical reactor that significantly influences regional atmospheric composition and global climate forcers."
A Closer Look: Tracing Sea Ice Leads' Atmospheric Impact
How fractures in Arctic sea ice influence atmospheric chemistry
The Methodology: Connecting Ice, Satellites, and Models
In this 2025 study, researchers combined satellite observations with atmospheric modeling to quantify how "leads" (fractures in sea ice) affect sea salt aerosols and atmospheric chemistry across the Arctic 9 .
Research Approach
Satellite Detection
Used NASA's AMSR-E instrument to identify lead locations and sizes across the Arctic during cold seasons (2002-2008) 9 .
Emission Parameterization
Developed a method to calculate sea salt aerosol emissions from leads based on area and sea spray production mechanisms.
Atmospheric Modeling
Incorporated lead emissions into the GEOS-Chem chemical transport model to simulate aerosol dispersion and reactions.
Model Validation
Compared simulations against ground-based observations of aerosol concentrations at Arctic monitoring stations 9 .
Results and Significance: Small Features, Widespread Effects
The study revealed that while leads contributed modestly to Arctic-wide sea salt emissions (increasing them by 1.1%-1.8% overall), their impact was concentrated in regions where leads occur and where background aerosol concentrations are typically very low 9 . The additional aerosols led to a 2.8%-8.8% increase in surface bromine atom concentrations, enhancing atmospheric reactivity 9 .
| Parameter | Change Due to Lead Emissions | Scientific Significance |
|---|---|---|
| Sea Salt Aerosols (Regional) | Notable increases near leads | Affects cloud formation & radiation scattering |
| Bromine Atoms | 2.8%-8.8% increase | Enhances atmospheric reactivity, influences ozone depletion |
| Ozone Concentrations | Negligible direct change | Suggests complex chemical interactions |
This research matters because it identifies a specific mechanism through which changing sea ice conditions—specifically, more fractures as ice thins—can modify Arctic atmospheric chemistry. As climate change continues, thinner sea ice more prone to fracturing may increase lead formations, potentially creating a feedback loop that further influences Arctic atmospheric composition and climate 9 .
Climate Feedback
Thinner sea ice → More leads → Increased aerosol emissions → Altered atmospheric chemistry → Further climate impacts
The Scientist's Toolkit: Probing Frozen Atmospheres
CATCH researchers employ a diverse array of methods and technologies to unravel the complexities of cryosphere-atmosphere interactions.
Satellite Remote Sensing
Primary Function: Large-scale monitoring of cryospheric and atmospheric changes
Applications: Tracking sea ice lead dynamics 9 , measuring snow cover extent, observing cloud properties
Chemical Transport Models
Primary Function: Simulating atmospheric composition and processes
Applications: Testing hypotheses about aerosol sources 9 , predicting pollutant transport, estimating climate impacts
Ice Core Analysis
Primary Function: Extracting historical climate and atmospheric records
Applications: Reconstructing past atmospheric composition 3 , identifying anthropogenic influence timelines
Major International Field Campaigns
Major international field campaigns have been particularly important for advancing this science. The MOSAiC expedition (2019-2020) involved freezing a research icebreaker into Arctic sea ice for a year to collect comprehensive atmospheric and cryospheric data 4 . The ALPACA campaign studied air pollution in Arctic cities during winter, revealing unique chemical processes under cold, dark conditions 4 . These efforts demonstrate the multidisciplinary collaboration essential to the CATCH mission, bringing together scientists from atmospheric chemistry, biology, physics, and computational modeling.
Why This Matters: From Science to Society
Climate Feedbacks and Projections
The cryosphere plays a crucial role in Earth's climate system through multiple feedback mechanisms. Snow and ice reflect solar radiation back to space (the albedo effect), but as they melt, darker surfaces are exposed that absorb more heat—a positive feedback that accelerates warming 8 .
CATCH research aims to quantify these feedbacks and reduce uncertainties in climate models, helping improve predictions of future climate change 1 . The 2023 IPCC report dedicated significant attention to cryospheric processes, recognizing their importance in climate projections .
Environmental and Human Health
In wintertime cities worldwide, cold temperatures and snow cover create unique air pollution challenges. Studies of "wintertime haze" in locations from Beijing to Fairbanks have revealed special chemical processes that occur under cold, dark conditions 3 .
Understanding these processes is essential for developing effective air quality management strategies that protect human health. Similarly, research on how pollutants accumulate in snow and are released during melting helps assess risks to ecosystems and water resources 3 .
Informing Policy and International Cooperation
CATCH science provides critical evidence for international environmental assessments and agreements. The United Nations has declared 2025-2034 the "Decade of Action for Cryospheric Sciences" to boost research and drive urgent action to protect Earth's frozen areas 6 .
This global initiative recognizes that when the cryosphere changes, everything does—affecting water resources for billions, sea level rise, and climate stability worldwide 6 .
The Future of Frozen Skies
The work of CATCH represents science at its most collaborative and urgent. By bridging disciplines and crossing national boundaries, researchers are gradually decoding the complex interactions between our planet's frozen surfaces and its atmosphere.
"The speciality of atmospheric chemistry in cold environments lies in the recent progress in better understanding the evolution of multiphase chemistry at low temperatures, where many relevant properties such as solubility and volatility change dramatically" 4 .
What they've discovered reveals a system of astonishing complexity—one where snow breathes chemicals into the air, where microscopic ice crystals host sophisticated chemistry, and where the polar regions act as chemical engines with global reach.
As climate change rapidly transforms cold regions worldwide, understanding these processes becomes increasingly critical. The CATCH community continues to push forward, planning new field campaigns, developing more sophisticated models, and training the next generation of scientists. Their work reminds us that protecting Earth's cryosphere means more than preserving beautiful landscapes—it means safeguarding the stable climate and clean air that have enabled human civilization to flourish.
The frozen skies above ice and snow hold many secrets yet to be discovered. In unlocking these secrets, we gain not only knowledge but the wisdom to become better stewards of our changing planet.