Brains
It is no secret that weather patterns are changing, and humans are a major driving force behind them. Our pursuit of innovation—while incredibly beneficial for food production, disease prevention, and technological advancement—is also producing changes in our atmosphere with broad and uncertain consequences. Skiers are feeling the weight of these changes particularly quickly. Winters are becoming more variable, bringing either relentless snowfall or complete drought, and many mountains are now experiencing winter rain that would have been unprecedented just 30 years ago. So how are elevated human emissions of both greenhouse gases and aerosols affecting our climate and beloved winters?
Greenhouse gases and aerosol emissions are atmospheric components that impact the environment in different ways. Greenhouse gases refer specifically to gases that trap heat within Earth’s atmosphere. These gases form a blanket around the planet, and how they interact with photons emitted from the sun determines the extent of warming. Many non–greenhouse-gas aerosols reflect incoming sunlight back into the atmosphere which produces a cooling effect. Greenhouse gases, on the other hand, either allow sunlight to pass through to Earth’s surface or absorb it. Gases such as carbon dioxide absorb this energy and vibrate, increasing their temperature and warming the surrounding atmosphere. While these gases occur naturally, emissions have risen sharply since the Industrial Revolution, and their effects are now felt globally.
The greenhouse effect itself is essential to Earth’s ability to regulate temperature and sustain life. However, excessive concentrations of greenhouse gases lead to global warming and its associated consequences. The most common greenhouse gases include carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and water vapor (H₂O).
Anthropogenic aerosols are particles released into the atmosphere primarily through human activities such as burning fossil fuels, industrial processes, and agriculture. Aerosols also form naturally from sources like volcanic eruptions, desert dust, and wildfire smoke. These particles contribute to smog and reduced air quality which harm humans, but they also influence weather patterns—particularly temperature and precipitation. Common anthropogenic aerosols include sulfates, black and organic carbon, nitrates, and ammonia.
Greenhouse gases and aerosols affect temperature and precipitation in different ways. Increasing greenhouse gas concentrations intensify the global water cycle. As more heat is trapped in the atmosphere, evaporation increases, leading to greater volatility in precipitation—causing heavier rainfall in some regions while worsening droughts in others.
The effects of anthropogenic aerosols are more complex. Over the long term, aerosols tend to cool the atmosphere, resulting in reduced evaporation and lower overall precipitation. However, this effect is not uniform. The impact of aerosols varies depending on their type and the season. Research shows that aerosols can increase precipitation during summer and fall, while winters and springs tend to become relatively drier.
The type of aerosol also matters. Dark aerosols such as black and brown carbon absorb heat and act as warming agents in the atmosphere while shading the surface below. When these particles settle on snow, they reduce reflectivity, causing the snow to absorb more sunlight and melt faster. Lighter aerosols such as sulfates, sea salt, and dust, reflect sunlight and contribute to atmospheric cooling.
Aerosols also influence cloud formation, brightness, and precipitation. By increasing cloud reflectivity, they reduce the amount of sunlight reaching the surface. Aerosols also act as cloud condensation nuclei (seeds for clouds), creating more numerous but smaller cloud droplets. These clouds can hold more water but tend to precipitate less frequently, which can result in heavier rainfall events when precipitation does occur.
As awareness of these pollutants has grown, efforts have been made to reduce emissions and mitigate their effects. However, while aerosol concentrations decrease relatively quickly—lasting from days to a few years—greenhouse gases persist for decades to centuries. As aerosol levels decline, their cooling influence diminishes, while greenhouse gases continue to trap heat without that counterbalance.
Even now, in December 2025, the western United States has experienced a poor start to the ski season due to unusually warm temperatures. A recurring phenomenon known as the “warm blob,” originating from elevated ocean temperatures in the Pacific, has disrupted typical weather patterns by weakening atmospheric rivers and sustaining warmer conditions over land. This event is linked to global warming, with some researchers suggesting that reduced sulfur emissions from cleaner shipping fuels—while beneficial for human health—have removed a cooling influence that previously masked warming in the Pacific. First observed in 2013 and resurfacing in 2019, the warm blob has returned in 2025 at unprecedented intensity, with projections indicating it may become more frequent and severe.
The impacts of greenhouse gases and aerosols are complex and interconnected, but their influence on the climate is undeniable. While long-term projections remain debated, the effects are already evident: stronger and more frequent storms, widespread wildfires, winters defined by either extreme drought or exceptional snowfall, and many other global consequences. Though addressing climate change is no simple task, it is an issue that demands continued care and attention from all.
