Understanding causes of extreme weather

Extreme weather events are becoming more frequent and severe because human activities continue to warm the climate.

The disastrous impact of the recent record-breaking rains of tropical storms Henri and Ida, and the six tornadoes that touched down on Long Island last month remind us that understanding how and why they occur is more critical than ever. The more we learn about weather and climate systems, the better we can forecast, prioritize our response, and save lives.

Earth’s atmosphere is complex. Researchers at Brookhaven National Laboratory, Stony Brook University and institutions nationwide are collaborating to create unprecedented depictions of what is occurring in the air over land and sea.

Small changes in the atmosphere can significantly influence the strength and track of individual storms. Shifts that affect humidity and temperature patterns concentrate the energy required to form clouds and storms over days and weeks.

Microscopic particles in the sky, called aerosols, serve as seeds for clouds as moisture condenses around them. Some aerosols occur naturally from ocean spray. Others are created from human activities such as burning fossil fuels. Some aerosols help cool Earth’s climate, reflecting the sun’s rays back out to space, while others absorb the sunlight, warming the atmosphere. They also interact with cloud droplets which grow, shrink, freeze, and melt within minutes and seconds, changing the characteristics of clouds and rain that are the building blocks of all storm systems.

To improve weather and climate forecasts we need to better understand the life cycle of clouds and aerosols, including how the chemical and physical properties of aerosols change over time, what factors determine when a cloud starts to rain or snow, and whether aerosols strengthen storms.

At Brookhaven Lab, we are creating and deploying new instruments that measure dynamic properties in Earth’s atmosphere, including aerosols. Artificial intelligence analyzes those measurements. High-resolution computer models simulate the life cycles of aerosols, clouds, and storms.

Brookhaven Lab and Stony Brook University are taking a leading role in exploring interactions between the atmosphere and urban landscapes. State-of-the-art mobile measurement stations mounted on two trucks collect data on wind, precipitation, aerosols, and other atmospheric conditions while being driven around complex urban landscapes in New York City, neighborhoods on Long Island, and North and South Shore beaches.

These trucks are providing new insights into how weather occurs in urban canyons, the nooks and crannies of the city, and different neighborhoods. This will help us understand how urban planning affects environmental equity. We’ve seen evidence that residents in low-income neighborhoods, which tend to have fewer trees, often require more medical care for heat-related illness compared with those from more affluent neighborhoods, which tend to have more greenery and remain cooler during heat waves. Data from our mobile stations will further quantify those observations, help explain how those differences come about, and point us to ways they can be fixed.

Predictions always include some level of uncertainty and, as we saw with Henri, conditions change. Science has a major role in assessing the changes, forecasting consequences, and identifying solutions — some of which include developing more environmentally friendly infrastructure, long-term energy policies, and better practices for managing water and other resources.

We’ve seen it during the pandemic and in past hurricane seasons, and we’ll see it again. We need science more than ever. People’s lives depend on it.

This guest essay reflects the views of Michael Jensen, a meteorologist at Brookhaven National Laboratory.