Environment

A glacial outburst has sent floodwaters rushing through the town of Juneau, Alaska, forcing residents to evacuate parts of the state capital. The unusual event, called a glacial lake outburst flood, or GLOF, happened as water spilled out of an ice-dammed lake and gushed downstream through melted tunnels in the underside of a large glacier.

The people of Juneau have experienced at least one such flood every summer for the last 15 years.

“It’s a story about glacier change,” says Jason Amundson, a glaciologist at the University of Alaska Southeast in Juneau, who is monitoring the event. The warming climate has caused glaciers here to shrink and separate from one another. That’s left an empty valley along the edge of Mendenhall Glacier, which now fills with rain and meltwater each summer. At some point, the water collects deep enough that its pressure forces an opening under the edge of the glacier — allowing it to escape. More

The sky abounds with aerosols, tiny particles with large sway over Earth’s temperature. A new NASA visualization reveals how these airborne particles swirl through the atmosphere.

The agency’s Goddard Earth Observing System tracks major aerosol types — sulfates, black carbon, dust and sea salt. It combines satellite and ground-based observations with advanced computer simulations to show how aerosols can affect air quality and visibility far from their sources. See where they loft in this visualization spanning August 1 to September 14, 2024. More

Sprinklings of life appear key to the recipe for rain.

Lofted flecks of organic material like bacteria, pollen and fungal spores play a profound role in regulating rainfall patterns, a new study suggests. These bioparticles can make up a major portion of all the particles that can seed rain in the sky, and their levels fluctuate in a daily cycle, researchers report May 5 in npj Climate and Atmospheric Science.

The study is the first to clearly show that the movements of bioparticles drive daily fluctuations of rainmaking particles more broadly. “This really has not been included in any [weather] models before,” says atmospheric scientist Athanasios Nenes of EPFL, the Swiss Federal Institute of Technology in Lausanne. “It’s something we need to start thinking about.” More

Soot from forest fires in the Amazon might play a role in the melting of faraway ice in Antarctica.

For decades, scientists have known that black carbon from burning fossil fuels or forests accelerates ice melt in different parts of the world. According to remote sensing researcher Sudip Chakraborty, the slash-and-burn practices encouraged by Brazil’s former president Jair Bolsonaro, who held office from 2019 to 2023, inspired his team to investigate whether black carbon from the Amazon affected ice melt in Antarctica. More

United by FireDenver Museum of Nature & ScienceAvailable wherever you get your podcasts

For hundreds of millions of years, wildfires were directed solely by the weather, vegetation and terrain. But in the last century in the United States, people have sought to suppress even those beneficial fires that would otherwise clear out dead vegetation, which can fuel wildfires, and stimulate new growth. Now, catastrophic megafires erupt each year, and in some places, climate change has extended the fire season. Clearly something has to give — our society must change its relationship with fire. More

People are flocking to nature’s doorstep, and into wildfire territory.

Homes constructed where human development meets undeveloped wildland are particularly vulnerable to wildfires and other natural hazards (SN: 11/9/23). Nonetheless, people are moving into the wildland-urban interface, or WUI, and rapidly expanding it. From 2000 to 2020, the global footprint of the WUI grew by about 35 percent, reaching a total area that’s roughly the size of Mexico, researchers report November 8 in Science Advances. More

An experiment to grow new forests in central Mexico offers hope that the crucial winter habitat for millions of migrating monarch butterflies could survive into the next century.

When scientists decided to plant hundreds of baby oyamel fir trees (Abies religiosa) about 100 kilometers from their native habitat, they weren’t sure how many trees would survive. Today, most of the saplings are flourishing, researchers report September 17 in Frontiers in Forests and Global Change. Even at an altitude of 3,800 meters, high above where the trees usually grow, almost 70 percent of the saplings survived at least three years. More

One of the world’s richest biodiversity hot spots is Peru’s Madre de Dios, a region of the Amazon nestled at the base of the Andes mountains. When biogeochemist Jacqueline Gerson first traveled there in 2017, she found herself on a boat headed downstream through the forest. As the riverbanks passed by, she observed a scenic shift.

At first, “it was beautiful, primary old-growth forest, lots of birds, lots of different wildlife,” says Gerson, a Ph.D. student at Duke University at the time. “Then, as I continued downstream … first you see these rocks,” she adds. “As you keep going, you see pile after pile after pile, and then you started to see some deforestation.”

She was witnessing the signs of artisanal and small-scale gold mining. Unlike large-scale industrial operations with fleets of dump trucks and excavators, workers here use basic tools or their own hands to extract ore. These informal gold-mining efforts are so prolific in Madre de Dios that they support at least half of the region’s economy.

In Madre de Dios, artisanal and small-scale gold miners tear down lush tracts of Amazonian rainforest to make way for mining operations, leaving behind mounds of sediment and pits that fill with water.Melissa Marchese

But there is a price to that gain. The small-scale miners mix mercury into riverbank sediments that contain flecks of gold. This produces a gold-mercury amalgam that can easily be separated from the muck and then burned to isolate the gold. But that burning also releases fumes of mercury into the open air.

For Gerson, now at Cornell University, illuminating how toxic contaminants flow through the environment is a calling. She studies how human activities contribute to these contaminants and alter their paths. More