Climate and environment updates: 7 key measures of Earth's health in danger, report warns

When wildfires fill the air with heat and smoke, the danger isn't just outside. A new study in PLOS Climate finds that when people move indoors en masse, it creates ideal conditions for viruses like flu, RSV and COVID-19 to spread more easily.

Severe weather events, including wildfires, are becoming more frequent as the planet warms. To stay safe during these emergencies, people often seek safety inside -- but that response comes with its own risks, according to the study. Close quarters, poor ventilation and extended time in shared spaces make it easier for viruses to pass from person to person.

During wildfires, smoke can travel far beyond the fire zone, affecting air quality across entire regions. In 2020, counties in Oregon and Washington recorded sustained Air Quality Index levels above 150, the threshold for unhealthy air. The researchers found that in response to the poor air quality, indoor activity in those areas increased between 10.8% and 14.3%, respectively. Urban areas, such as Portland, saw an 11% jump in indoor activity, while Seattle's increase reached 16%.

Even for viruses that spread less easily, and in communities with relatively high immunity, more time spent indoors led to noticeable spikes in viral transmission.

"Places with greater density have worse problems," Giulia Pullano, a Georgetown University researcher and one of the study's authors, explained to ABC News.

While the physical dangers of climate change -- such as extreme heat, wildfire smoke, or poor air quality -- often draw the most attention, Pullano said the indirect effects, like how people behave in response to those threats, also shape public health in meaningful ways.

The PLOS Climate researchers used mobile device data to track indoor versus outdoor activity, comparing wildfire-affected counties with similar counties that had no air quality alerts. They then used computer data to model how this behavior change could affect the spread of respiratory viruses, using different scenarios based on virus characteristics and population immunity.

The study also highlighted one practical way to mitigate the increased disease risk associated with spending more time indoors. Modeling predicted that if 10% of people wore masks indoors during wildfire events, virus spread could be curtailed substantially. If half the population wore masks indoors, infection curve peaks could be flattened.

As climate-amplified disasters become more common, Pullan told ABC News that, "Understanding disruptions of behavior during natural disasters will be critical to protecting public health."

-Board-certified family physician and ABC News medical unit's Dr. Ilan Kokotek

Droughts often unfold quietly, lacking the dramatic visuals of hurricanes or flash floods. Yet their impacts can be equally devastating, and increasingly so, as human-amplified climate change fuels more frequent and intense droughts worldwide.

According to a new report by the Organisation for Economic Co-operation and Development (OECD), the global land area affected by drought has doubled in the last 120 years, with 40% of the planet experiencing more frequent and intense droughts in recent decades.

The OECD’s Global Drought Outlook provides a comprehensive worldwide assessment of drought risks, impacts and policy responses, examining how countries can strengthen drought management to adapt to a changing climate. The report highlights that the growing effects of drought are fueled by multiple compounding factors, including deforestation, urban development, unsustainable farming and human-amplified climate change.

The new analysis reveals a sharp rise in the economic costs of drought, which, on average, have at least doubled since 2000. The report estimates that by 2035, a drought event could cost a national economy at least 35% more than it does today. Globally, agriculture is the most affected sector, with crop yields declining by as much as 22% during the driest years.

In California, for example, the 2021 drought alone resulted in $1.1 billion in agricultural losses, underscoring the vulnerability of even advanced economies. The human toll of drought is equally concerning. While droughts account for only 6% of natural disasters, they are responsible for 34% of all disaster-related deaths, according to the report.

Worsening drought impacts can also influence other weather events, such as heat waves. A recent study published in the Journal of Applied Meteorology and Climatology showed that drought doesn’t just accompany heat; it can also extend the duration of heat waves when the two overlap.

Effectively addressing the escalating drought threat, according to the OECD, requires a coordinated global response and decisive, proactive action from stakeholders. For example, building more efficient irrigation systems could significantly reduce global water use and expanding the number of drought-tolerant crops can help mitigate drought impacts and strengthen long-term climate change resilience.

-ABC News meteorologist Dan Peck

Google has developed a new AI weather model that can help forecast tropical cyclones and is partnering with the National Hurricane Center to make their models available to forecasters for testing.

Google's Weather Lab website allows users to interact with its AI weather models and compare live and historical tropical cyclone tracks to traditional weather forecasting models.

"When read together, these predictions can help weather agencies and emergency service experts better anticipate a cyclone's path and intensity," Google wrote in a recent press release. "This could help experts and decision-makers better prepare for different scenarios, share news of risks involved and support decisions to manage a cyclone's impact," they added.

The new AI model is trained using key historical data from nearly 5,000 observed cyclones over the past 45 years, along with a comprehensive global weather re-analysis dataset comprising millions of weather observations.

Unlike traditional weather models, which rely on atmospheric and physics-based simulations that require significant time and computing power to complete, AI weather models can produce forecasts within seconds. The new AI model is also capable of generating 50 possible scenarios for a tropical cyclone's formation, track, intensity, size and shape up to 15 days in advance.

Google found that their new AI tropical cyclone model performed at a comparable level in most cases to traditional models and outperformed them in a few tests.

In addition to their partnership with the National Hurricane Center, Google's Weather Lab team is working with the Cooperative Institute for Research in the Atmosphere at Colorado State to evaluate the new model's performance. According to Google, CIRA scientists found the new AI model had "comparable or greater skill than the best operational models for tracking and intensity."

-ABC News meteorologist Kyle David

The Earth has hit another climate milestone, and it's a stark reminder that when it comes to climate change, the planet is moving in the wrong direction.

For the first time, the monthly average of carbon dioxide in the atmosphere has surpassed 430 parts per million at the Mauna Loa Observatory in Hawaii. The May 2025 number is higher than it's ever been in human history and marks a significant jump from the previous year.

Scientists from the National Oceanic and Atmospheric Administration and the Scripps Institution of Oceanography at the University of California, San Diego have been taking daily CO2 measurements from the Mauna Loa site since 1974.

"Another year, another record," Ralph Keeling, director of the Scripps CO2 Program, said in a statement. "It's sad."

Carbon dioxide is a key gas in Earth's atmosphere, contributing to the greenhouse effect by trapping heat. Since the Industrial Revolution, its levels have increased due to rising human activities, particularly the emission of fossil fuels.

Researchers at the University of Utah, who participated in a 2023 study with nearly 100 scientists from 16 countries, found that the amount of carbon dioxide in the atmosphere is higher than it has ever been in human history and the highest in at least 14 million years.

The increasing amount of carbon dioxide in our planet's atmosphere has altered the planet's weather patterns and intensified the frequency and severity of extreme events, such as heat waves, droughts, wildfires, heavy rainfall and flooding, according to the Intergovernmental Panel on Climate Change.

-ABC News meteorologist Kyle David