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

The extreme dry conditions that have persisted for more than two decades across the western United States and the resulting megadrought are likely being fueled by human activity, according to a new study from the University of Colorado Boulder.

Researchers found that the prolonged megadrought in the West is driven by a complex connection with ocean patterns in the Pacific, which are influenced by human-amplified climate change.

"Our results show that the drought and ocean patterns we're seeing today are not just natural fluctuations -- they're largely driven by human activity," said Jeremy Klavans, a postdoctoral researcher in CU Boulder's Department of Atmospheric and Oceanic Sciences and the lead author of the study.

The study found that a natural climate pattern in the north Pacific Ocean, known as the Pacific Decadal Oscillation, or PDO, is being impacted by human-created emissions.

The PDO is a natural variation of warmer and cooler sea surface temperatures across the mid-latitudes of the Pacific Ocean, with conditions along the U.S. West Coast typically opposite to those near Japan.

Natural fluctuations of the PDO, classified as either positive or negative phases, drive large-scale weather patterns over the Pacific and eventually North America. But the PDO has been stuck in its negative phase since the 1990s, with cooler waters in the eastern North Pacific near the U.S. West Coast and warmer waters in the western North Pacific near Japan. Klavans noted that this is quite unusual for the natural cycle of the ocean.

The researchers examined a new collection of over 500 climate model simulations developed by climate scientists around the world. They found that existing models tend to overestimate the role of natural variability and underestimate the impact of greenhouse gas and aerosol emissions on the PDO, concluding that the majority of variations since the mid-20th century were driven by human activity.

"People have been trying for a long time to find out why this part of the country is so dry, and we have an answer for that finally," Klavans said.

A previous study found that this megadrought across the western United States, as well as northwestern Mexico, has become the worst drought across the region in at least 1,200 years.

Klavans noted that if greenhouse gas emissions continue to rise, the PDO will likely remain locked in its negative phase and prolong the megadrought for at least the next three decades. This has far-reaching and long-term impacts, influencing weather patterns and keeping much of the West drier than usual, as cooler air and water hold less moisture.

"This study can allow us to better quantify the costs of continued greenhouse gas emissions for Americans," Klavans said. "That can only help our region plan for a better future."

-ABC News meteorologists Kyle David Reiman and Dan Peck

A new study from the University at Albany found that the data gathered during the National Oceanic and Atmospheric Administration's (NOAA) Hurricane Hunter flights during recent Atlantic hurricane seasons boosted the accuracy of forecasts as much as 24% compared to those without the data.

"Our study shows the positive benefits of adding [Gulfstream IV] and other aircraft observational data into weather models and suggests that future forecasting strategies should prioritize these missions," said Melissa Piper, a graduate student research assistant at the University at Albany and the study's lead author.

The study explored data from all tropical systems in the Atlantic basin from 2018 to 2022. It compared forecasts with new Hurricane Hunter data, specifically its Gulfstream IV flights, to those that didn't have access to the information.

The researchers noted the most significant improvement in track forecast accuracy from Hurricane Hunter mission data with weaker storms, such as tropical depressions or tropical storms.

"Previous studies have shown that weaker storms tend to have larger forecast errors," said Ryan Torn, chair and professor at the University at Albany's Department of Atmospheric and Environmental Sciences and co-author of the study. "Therefore, the addition of more observations like G-IV data has greater potential to improve the track forecast of these storms," Torn added.

Hurricane Hunter mission data is also crucial for any areas that the National Hurricane Center is "investigating" because it's harder to determine the center of a developed or developing tropical system. Data from the flights helps forecast models more accurately predict the future track and intensity of storms.

NOAA announced last year that a new advanced plane, NOAA's G550, is expected to be in service with the rest of the Hurricane Hunter fleet later this year.

“Much of the gains in hurricane intensity forecasting over the last 10 to 15 years have come about thanks to the observations taken by Hurricane Hunters. With more observations in the model, you are more likely to obtain accurate forecasts of the hurricane. As shown in our study, these flights are essential for preparation and post-storm recovery,” Torn said.

-ABC News meteorologist Kyle David Reiman

Last month was the third-warmest July on record globally, trailing only July 2024 and 2023, according to new data analyzed by the Copernicus Climate Change Service (C3S). The planet’s average surface air temperature was 16.68 degrees Celsius, or 62.02 degrees Fahrenheit.

July was just the fourth month in the last 25 that did not surpass the 1.5-degree Celsius warming threshold established in the 2015 Paris Climate Agreement. Instead, it registered 1.25 degrees above the pre-industrial reference period (1850-1900).

Climate scientists anticipated a short-term drop in global temperatures due to the previous La Niña event in the equatorial eastern Pacific Ocean. This climate pattern typically brings a temporary dip in global average temperatures. However, scientists caution that this pause is unlikely to last, as human-caused greenhouse gas emissions continue to fuel the long-term warming trend.

“The recent streak of global temperature records is over -- for now. But this doesn’t mean climate change has stopped. We continued to witness the effects of a warming world in events such as extreme heat and catastrophic floods in July. Unless we rapidly stabilize greenhouse gas concentrations in the atmosphere, we should expect not only new temperature records but also a worsening of these impacts – and we must prepare for that,” Carlo Buontempo, the director of C3S, said in a statement.

Global daily sea surface temperatures remained above average across much of the world’s oceans last month. Between the latitudes of 60 degrees south and 60 degrees north, the average global sea surface temperature was 69.39 degrees Fahrenheit, the third-highest value on record for July, according to the report.

Unusually warm sea surface temperatures could play a key role in tropical cyclone development in the coming weeks as the Atlantic hurricane season nears its Sept. 10 peak. NOAA is expected to release an updated seasonal outlook on Thursday.

-ABC News meteorologist Dan Peck

Forests play a crucial role in stabilizing the planet’s carbon balance, the equilibrium between carbon emissions and carbon absorption. They are also essential in limiting the worst impacts of human amplified climate change.

As essential carbon sinks, forests usually absorb more carbon dioxide than they emit. They also remove excess carbon dioxide from the atmosphere, providing a net reduction of the heat-trapping greenhouse gas. However, new research suggests that their vital role is now under threat due to increasing global wildfire activity.

In a typical year, forests and other vegetation absorb about 30% of the carbon dioxide released from burning fossil fuels, according to the World Resources Institute (WRI). However, new data from WRI’s Global Forest Watch (GFW) and Land & Carbon Lab shows that in 2023 and 2024, extreme wildfires significantly reduced the ability of forests to absorb carbon dioxide, taking in only a quarter of their average annual carbon intake.

Globally, forests still remain a net carbon sink, but their influence is dwindling and this recent decline reflects a troubling longer-term trend. While some forest regions, including parts of the eastern U.S., continue to act as strong carbon sinks, others are shifting from net sinks to net sources of CO2.

For example, Canada’s boreal forests became a net carbon source in 2023 due to an extreme wildfire season, which accounted for 79% of global forest fire emissions, according to the analysis. That same year marked the lowest “forest carbon sink” in over two decades when factoring in both wildfire-related losses and ongoing deforestation.

According to the National Oceanic and Atmospheric Administration (NOAA), these effects extend beyond Canada, impacting the Arctic tundra. Rapidly warming conditions and increasing wildfire activity are now transforming the vast region, from a critical carbon sink that existed for thousands of years into a growing source of carbon dioxide emissions.

While reducing fossil fuel emissions is the most effective way to curb the impacts of human-induced global warming, protecting and sustainably managing forests is essential to preserving this vital carbon budget resource for future generations.

The Appalachian region in the eastern U.S. offers a promising example of how conservation efforts and natural regeneration can reverse the impacts of past land use. By the mid-20th century, much of the region’s forests had been cleared for agriculture and logging. However, many of these lands were later abandoned and allowed to regrow naturally. Today, according to WRI, these recovering forests now account for a quarter of the country’s net forest carbon sink despite only making up about 14% of U.S. forested area.

- ABC News meteorologist Dan Peck