分类： environment

Perched high on the sunbaked hills surrounding Las Vegas, French tourist Choune Osterero stares out at a stark, unavoidable marker of human-caused climate change: a thick, pale band of mineral-encrusted rock that circles the entire basin of Lake Mead, the United States’ largest man-made reservoir. Known locally as the “bathtub ring,” this chalky line sits 186 feet (57 meters) above the reservoir’s current water surface, a 25-year record of relentless drought that has drained the lake to historic lows. For Osterero, the unmissable geologic clue makes abstract climate talk tangible. “You can see the effects of climate change with the naked eye,” she told Agence France-Presse during her visit. “It’s truly striking; it really makes you wonder.”

The retreating waters of Lake Mead have exposed hidden relics long swallowed by the lake: sunken boat wrecks, and even scattered human remains, including the body of a man believed to be a victim of 20th-century Las Vegas organized crime. But far beyond these macabre discoveries, the shrinking reservoir threatens the foundational infrastructure that powers and sustains the entire American West.

The modern development of iconic desert metropolises — from Las Vegas to Los Angeles and Phoenix — was only made possible by an extensive water distribution system tapping the Colorado River. The river, which originates from snowmelt in the Rocky Mountains and flows south through the U.S. Southwest into Mexico, provides drinking and irrigation water to more than 40 million people across seven U.S. states. Two massive hydroelectric dams, built 300 miles apart along the river’s course, created the country’s two largest reservoirs: Lake Mead and Lake Powell. These basins store snowmelt to ensure year-round water access, while the dams’ turbines generate carbon-free electricity for hundreds of thousands of households across the region.

Today, that entire system is teetering on the edge of crisis. The roots of the vulnerability stretch back a century: the 1922 interstate agreement governing Colorado River water allocations assigned more annual water to the seven basin states than the river actually carries on average. But human-caused climate change has drastically worsened this systemic flaw, altering regional precipitation patterns, extending extreme heat and drought events, and amplifying precipitation volatility across the continent.

Against a backdrop of global record-breaking temperatures in 2026, the Colorado River system is facing dual pressures that have pushed reservoirs to unprecedented lows, explains David Kreamer, a hydrology professor at the University of Las Vegas. An unusually dry winter left the Rocky Mountains with far less snowpack than average — the primary source of the river’s annual flow. At the same time, the record-hot July the U.S. experienced this year has accelerated evaporation from the open surfaces of Lake Mead and Lake Powell, draining stored water even faster.

“As climate change is affecting things, and it gets more intense, the challenges become greater,” Kreamer noted. Currently, Lake Mead holds only 25% of its total capacity, while Lake Powell dropped to an all-time historic low in August. Both reservoirs are now perilously close to the critical threshold where dam operations for electricity generation become impossible. A further decline could push the system into “deadpool” — a state where water levels drop too low to flow through the dam’s intake structures, cutting off water access for millions across the Southwest. The catastrophic consequences would reach far beyond the region’s big cities.

“The majority of the winter vegetables in the United States are grown in California, and so if the irrigation systems in Southern California are impacted, it would impact people beyond just the Colorado River Basin, but throughout the United States,” Kreamer explained.

In response to the deepening crisis, the Trump administration — which has repeatedly questioned the scientific consensus around human-caused climate change — released a 10-year management plan this month that imposes deep water use cuts on three lower basin states: California, Arizona, and Nevada. The three states are required to reduce their collective annual water withdrawals by 3.7 billion cubic meters — a volume equal to 1.5 million Olympic-sized swimming pools — while upper basin states including Colorado, Utah, Wyoming, and New Mexico face no mandatory cuts. The unequal burden of the plan prompted Nevada to file a lawsuit against the federal government on Monday challenging the policy.

The divisive cuts have laid bare long-simmering tensions between water users across the basin, with many pointing the finger at other regions and industries for overconsumption. Bruce Nelson, whose family has owned a marina on Lake Mead for nearly 70 years, argues that Las Vegas has already done more than its share to cut use: over the past two decades, the city has reduced its total water consumption by a third through aggressive wastewater recycling programs, restrictions on lawn watering, and limits on new residential swimming pool sizes. He argues that the burden falls disproportionately on southern Nevada, while other states continue to waste water.

“Las Vegas has done a phenomenal job in preserving and reclaiming water,” Nelson said. In contrast, he noted, neighboring Utah recycles very little of its wastewater and continues to approve large, water-intensive recreational projects inland, including artificial surf parks in fast-growing cities like St. George. “Maybe they need to think about how they’re conserving water,” he added.

Waterskiing enthusiast Brian Essex, who was visiting the lake, echoed that frustration. “It’s not our problem, really,” he said. He pointed to two major drivers of unsustainable water use: unregulated rapid real estate development in Phoenix, which is constantly expanding into the desert, and the massive water consumption of California’s alfalfa industry. Alfalfa, a lucrative forage crop for livestock, is one of the most water-intensive crops grown in the Southwest.

“What do you want to do?” Essex asked. “Do you want to build houses or do you want to sell alfalfa? You can’t do both.”

Australia is facing an unprecedented challenge from the H5N1 bird flu outbreak, which has already claimed the lives of native mammals for the first time in the nation’s recorded history. To address this escalating public and environmental health crisis, the Albanese government has unveiled a new $145 million funding boost to strengthen the country’s bird flu response, but conservation leaders have slammed the allocation for wildlife resilience as woefully insufficient.

Of the total funding package, $125 million will be split equally between the Commonwealth government and state and territory administrations. This portion of the budget is earmarked for immediate national emergency biosecurity operations, including expanded surveillance and early detection systems, enhanced on-the-ground response capacity, and targeted interventions for high-priority threatened species. Conservation groups acknowledge that since the outbreak intensified in June 2024, officials have confirmed the virus cannot be fully eradicated, making these core response activities critical.

An additional $20 million has been dedicated to expanding and extending on-the-ground work to boost the resilience of vulnerable native species, with a focus on ecologically sensitive locations including federally managed national parks. The federal government is requiring state and territory partners to provide matched funding for this specific resilience allocation.

Despite the government’s framing of the package as a robust response, leading conservation leaders have harshly criticized the $20 million wildlife resilience allocation as unfit for the scale of the crisis. Invasive Species Council Chief Executive Jack Gough pointed out that the sum amounts to less than 1% of the bailout the government provided to the Tomago aluminium smelter, calling the commitment “deeply unserious.”

Earlier this month, Gough joined BirdLife Australia Chief Executive Kate Millar in lobbying federal officials in Canberra for a $200 million resilience package – a figure that Gough emphasizes was the absolute minimum baseline investment required to give native wildlife a fighting chance against both the current outbreak and future waves. The requested package would fund long-term protective measures such as invasive pest control, which reduce additional stress on vulnerable populations already impacted by bird flu.

“Surveillance, testing and carcass removal are essential, but they won’t stop vulnerable wildlife populations being pushed towards extinction,” Gough explained. “There’s a deep understanding across government departments of the scale of this crisis and the devastation it will cause, but the funding committed does not match that understanding. We will need far greater, sustained long-term investment to help wildlife populations recover.”

Millar echoed these criticisms, arguing that the insufficient funding shows the government is “asleep at the wheel when it comes to nature.” She noted that many practical, effective conservation programs the government had previously invested in – including pest control initiatives – have already been forced to shut down after their funding expired. She warned that the Albanese government is underestimating the anger and political mobilization of Australia’s large birdwatching community, which spans every electorate and all walks of life, if the government continues to ignore scientific recommendations and its conservation obligations.

Federal officials have pushed back against the criticism, defending the government’s total investment in bird flu preparedness and conservation. Agriculture Minister Julie Collins told ABC News Breakfast that the government, working with state and territory partners, has already invested more than $40 million in preparedness activities for threatened species habitat protection, including biosecurity measures for captive populations of at-risk species held in zoos and wildlife parks across the country.

Collins added that the government has also invested more than $300 million in the federal Saving Native Species Program overseen by Environment Minister Murray Watt, bringing total national spending on bird flu preparedness to more than $270 million. “The amount of funding is certainly there … we’ll continue to work with all of the experts to make sure that as a government, we’re doing everything we can do,” Collins said, noting the government takes the bird flu crisis seriously.

Announcing the new funding package, Watt said the additional investment would put Australia’s most at-risk species “in a better position to withstand and recover from the impacts of this virus.” He noted that close to 70 on-the-ground resilience projects are already underway across the country, and the new funding will extend protection to an additional 31 threatened species – ranging from Kangaroo Island’s Australian sea lions to the Christmas Island frigatebird – through enhanced biosecurity for captive breeding populations.

“This additional funding will support the expansion and extension of bird flu preparedness and response measures for H5 bird flu in wildlife across Australia, including commonwealth-managed national parks,” Watt said. “We will continue to work with all jurisdictions to ensure we’re taking sensible actions to protect our at-risk bird and mammal species, informed by best available evidence.”

As of the announcement, more than 200 confirmed cases of bird flu have been recorded across Australia, with the first confirmed mammal fatalities pushing the crisis into uncharted territory for the nation’s environmental management agencies. Requests for further comment from the offices of Watt and Collins are still pending.

On Wednesday morning, a catastrophic disaster of flash floods and landslides struck the Nepal-Tibet border region, leaving at least 160 people dead and hundreds unaccounted for, as experts work to untangle the causes of the event and unpack what it signals about growing hazard risks in the Himalayan highlands.

Footage captured from the Chinese side of the border captures the devastating force of the surge: a towering, churning wall of mud and debris slammed into a multi-story building, swallowing the structure whole and sweeping away buses and private vehicles as if they were lightweight children’s toys. In Nepal’s Nuwakot district, residents have been forced to navigate streets coated in thick, clinging mud in the disaster’s aftermath.

Initial reports suggested a 4.4-magnitude earthquake had triggered a landslide that blocked a mountain river, with the flood unleashed when the natural dam eventually burst. That account was put forward by Nepal’s Foreign Minister Shishir Khanal, but new analysis from the United States Geological Survey (USGS) has revised that narrative. USGS experts found that the seismic activity initially recorded was not caused by an earthquake, but rather by the massive movement of the landslide itself.

Preliminary findings from the International Centre for Integrated Mountain Development (ICIMOD), an intergovernmental organization based in Kathmandu, have ruled out any unusual activity originating on the Chinese side of the border. According to Sarthak Shrestha, a remote sensing and geo-information analyst at ICIMOD, the most likely sequence is that a rock-ice avalanche occurred on Nepal’s side of the border, which blocked the Lhende River and set off the cascading flood that swept through downstream communities.

One of the most alarming details experts have highlighted is that the disaster struck with almost no warning. Hatim Sharif, a hydrologist at the University of Texas San Antonio, noted that there was no heavy rainfall in the region ahead of the flood — a detail that renders most operational global early warning systems useless for this type of event.

By the time a fast-moving mud surge like this is visible to people in its path, it is already too late to escape by running or even by car, Sharif explained. The mixture of water and rock debris moves at high speed and becomes dense enough to act like “liquid concrete,” making escape along flat ground impossible. Sharif’s guidance is that the only chance of survival is to immediately climb to high ground of at least six meters (20 feet) above the river level.

Looking ahead, Sharif said that one viable long-term adaptation is to install real-time river level monitoring gauges across high-risk Himalayan river systems. While this would not prevent the disaster, it could give vulnerable communities 20 to 30 minutes of advance warning to evacuate to safe ground.

Dorothy Heinrich, a climate and hazard researcher at the University of Reading in the United Kingdom, explained the unique geographic factors that make these blockage-induced floods so dangerous in mountain regions. “In these mountain environments, the rivers can be quite narrow in areas,” she noted. When any kind of landslide or avalanche blocks a narrow river channel, water rapidly accumulates behind the natural obstruction, and the eventual breach releases an incredibly fast, powerful surge downstream.

ICIMOD head of climate and environmental risks Qianggong Zhang has warned that the risk is not yet over: an upstream blockage remains in place, raising the possibility of a second destructive flood in the coming days.

While it is too early to draw a direct, definitive link between this disaster and human-caused climate change, scientists say well-documented environmental shifts across the Himalayas — often called the “Roof of the World” — have already increased the likelihood of similar events. Nepal is particularly vulnerable to glacial lake outburst floods (GLOFs), catastrophic events that occur when glacial melt leads to a sudden breach of a natural glacial lake dam, releasing billions of liters of water downstream. A major GLOF event originating in China’s Gyirong County hit Nepal’s Rasuwa District just last July, though investigators have not yet confirmed a GLOF caused the latest disaster.

In the coming weeks, climate scientists around the world will conduct event attribution studies to examine what role climate change may have played, comparing the probability of such an event occurring in today’s fossil fuel-warmed climate versus the climate of the pre-industrial era. Heinrich noted that researchers already have high confidence that climate change is driving major shifts across the Himalayas: rising temperatures, more frequent heatwaves, widespread glacial retreat, and permafrost thaw, all of which increase the frequency and severity of landslides, avalanches, and outburst floods. Still, she emphasized that a definitive connection to this specific disaster can only be confirmed through formal attribution analysis.