Latest news with #PacificDecadalOscillation
San Francisco Chronicle
5 days ago
- Climate
- San Francisco Chronicle
California summers are getting hotter. This map shows the most dramatic increases
California is heating up. Across the state, average temperatures have risen by 2.5 degrees Fahrenheit since 1895, according to the state's Indicators of Climate Change in California Report. But some places have warmed more than others. While greenhouse gas emissions have made temperatures rise around the planet, other drivers have influenced climate conditions too, on a more local scale. The Chronicle examined gridded temperature data trends to find where summers warmed the fastest in California from 1950 to 2024. The map above is based on gridded temperature data from the National Oceanic and Atmospheric Administration. This data incorporates observations from climate stations — which can move over time — and computes temperatures across the contiguous United States. The Chronicle used the Climate Engine tool to calculate the trends shown. Scientists are still working out how much urbanization, elevation and the ocean collectively impact warming. Other drivers have effects too, including long-term climate patterns like the Pacific Decadal Oscillation, which alters weather patterns in California. Aerosol pollution also dramatically decreased over the U.S. in recent decades. While the cleanup is a boon for air quality, the drop in sunlight-blocking particles in the atmosphere results in more warming on the ground. The variable nature of weather further complicates analyses, leading to ups and downs in average summer temperatures from year to year. July 2024 brought record-breaking heat across California; this month, the Bay Area generally faced cooler-than-average conditions. But over the course of decades, a rising trend emerges, especially in places like Fresno. Summer heat can have deadly consequences. From 2013 to 2022, seven extreme heat events killed nearly 460 Californians, according to a Department of Insurance report. These events led to over 5,000 hospitalizations and more than 300 cases of adverse birth outcomes, including preterm births and stillbirths. Some cities are taking steps to mitigate public health impacts of extreme heat. Fresno aims to cover 20% of the city with tree canopies over the next 40 years. This target requires planting around 4,600 trees per year. Fresno has planted about 7,600 trees since 2022, said Sontaya Rose, director of communications for the city, by email. Even historically cool locations, like San Francisco, are preparing for hot summers. In 2023 and 2024, the city provided 62 air conditioning units to 23 community-based organizations through the Extreme Weather Resilience Program, according to the Department of Emergency Management. The equipment helps the organizations, including Self-Help for the Elderly and Boys & Girls Club of San Francisco, maintain services for vulnerable populations. Scientists expect California temperatures to continue rising in the future, underscoring the importance of preparing communities for the impacts of extreme heat — especially where temperatures are rising the fastest. The Chronicle's most popular stories and best reads of the moment. Sign up This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service By subscribing, you agree to our Terms of Use and acknowledge that your information will be used as described in our Privacy Notice. Credits Reporting, design and development by Jack Lee. Editing by Hannah Hagemann, Dan Kopf and Aseem Shukla. Powered by the Hearst Newspapers DevHub. Advertisement
Newsweek
16-07-2025
- Science
- Newsweek
Southwest US's Alarming 'Megadrought' Could Last Until 2100
Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources. Newsweek AI is in beta. Translations may contain inaccuracies—please refer to the original content. Parts of the United States may be in a drought that will last until the end of the century, according to a concerning new study. Analysis by researchers from the University of Texas at Austin indicates that the Southwest is facing a "megadrought" worse than any in the past 1,200 years—and it could continue until the end of the 21st century if not even longer. The team suggest that ongoing warming could be disrupting the natural rhythm of a climate cycle known as the Pacific Decadal Oscillation (PDO), which brings drought and rains to the Southwest U.S. every 20 or 30 years. However, under certain conditions of warming, this phase can persist for far longer. Researchers noted that in the last period of hemispheric warming, around 6,000 years ago, the PDO was forced out of rhythm, leading to a drought that lasted for millennia—and it now appears to be happening again. A dead fish lies near a lake September 6, 2000 just outside the city of Dallas, Texas, when much of Northern Texas had dried out. A dead fish lies near a lake September 6, 2000 just outside the city of Dallas, Texas, when much of Northern Texas had dried their study, PhD student Victoria Todd and professor Timothy Shanahan analyzed sediment cores from the Rocky Mountains, and found evidence of a major drought 6,000–9,000 years ago far worse than scientists had previously assumed. The drought was primarily caused by a drop in winter rain needed to feed major rivers, coinciding with a swell of plant growth across continents which caused the Earth to warm as it absorbed more of the sun's rays. This triggered a shift in ocean and atmospheric patterns over the North Pacific that resembled the drought phase of the PDO, which is causing the current drought in the Southwest—except that this drought phase dominated for thousands of years. Todd told Newsweek: "By combining new paleoclimate reconstructions and climate model simulations, we showed that moderate Northern Hemisphere warming—in the past and projected into the future—can lock North Pacific sea surface temperatures into a temperature pattern that dramatically reduces winter precipitation and drives long-term drought in the Southwest US. "The fact that this is wintertime drought is particularly important because of the impact on snowpack in the Rockies and its role in Colorado River flow and western U.S. water resources." The researchers examined whether this could happen again by teaming up with the University of Colorado to build climate model projections. When these results were averaged, they noted a similar response—including steady declines in winter precipitation. Shanahan said in a statement: "If global temperatures keep rising, our models suggest the Southwest could remain in a drought-dominated regime through at least 2100. Referencing the Colorado River, where flows have declined by 20 percent over the last century, Shanahan added: "Many people still expect the Colorado River to bounce back. But our findings suggest it may not. "Water managers need to start planning for the possibility that this drought isn't just a rough patch—it could be the new reality." Todd told Newsweek: "Our work […] also suggests that, while the simulations with warming produce a North Pacific response and lead to winter precipitation declines, they still underestimate the magnitude of this response. "This suggests that it is likely we are underestimating the magnitude of future drought as well. We need to better understand why the magnitude of the precipitation response is being underestimated by models and what it means for future precipitation in the Southwest U.S." Do you have a tip on a science story that Newsweek should be covering? Do you have a question about drought? Let us know via science@ Reference Todd, V. L., Shanahan, T. M., DiNezio, P. N., Klavans, J. M., Fawcett, P. J., Anderson, R. S., Jiménez-Moreno, G., LeGrande, A. N., Pausata, F. S. R., Thompson, A. J., & Zhu, J. (2025). North Pacific ocean–atmosphere responses to Holocene and future warming drive Southwest US drought. Nature Geoscience, 18(7), 646–652.
Yahoo
09-06-2025
- Climate
- Yahoo
Hurricane Barbara becomes first storm of the 2025 Eastern Pacific season
Two tropical storms formed off the coast of Mexico this weekend, with Barbara strengthening and becoming the season's first hurricane on Monday. Forecasters are tracking both Hurricane Barbara and Tropical Storm Cosme as they swirl west of Mexico. Periods of heavy rain could lead to flooding and mudslides around some major tourist destinations. DON'T MISS: Hurricane season is in full swing across the eastern Pacific, and a favourable environment off the western coast of Mexico allowed two tropical storms to form this weekend. Hurricane Barbara strengthened southwest of Mexico on Monday morning, marking the first hurricane of the 2025 season. #Barbara is now a #hurricane - the first hurricane-strength tropical cyclone of the 2025 Northern Hemisphere season. Barbara is the latest 1st Northern Hemisphere hurricane since 1993. — Philip Klotzbach (@philklotzbach) June 9, 2025 According to the U.S. National Hurricane Center (NHC), Barbara's maximum sustained winds reached 120 km/h, meeting the threshold for hurricane classification. There are no coastal watches or warnings in effect, but swells generated by Barbara will affect portions of the coast of southwestern Mexico during the next few days. "These swells are likely to cause life-threatening surf and rip current conditions," the NHC warns. "Please consult products from your local weather office." The NHC calls for widespread rainfall totals of 25-50 mm throughout the region, with totals of 50-100 mm possible toward Acapulco. Locally higher totals are possible, bringing along the risk for flash flooding and mudslides. While the system is close enough to spread rain over land, the centre of the storm should remain safely out to sea. The NHC expects Barbara to strengthen slightly on Monday before gradually weakening through the middle of the week. Cosme formed to Barbara's west on Sunday afternoon. Forecasters predict that the small system could reach hurricane strength on Monday before encountering cooler waters and drier air by the middle of the week, forcing the system to quickly weaken and fall apart. Hurricane season in the eastern Pacific basin runs through the end of November. NOAA's seasonal outlook called for 12-18 named storms, with 5-10 of those systems growing into hurricanes, and 2-5 of those hurricanes achieving Category 3 status or stronger. This is close to the eastern Pacific's seasonal average of 15 named storms, 8 hurricanes, and 4 major hurricanes. MUST SEE: This season's activity is influenced by the lack of El Niño and La Niña, as well as a negative phase of the Pacific Decadal Oscillation (PDO), a pattern that can lead to cooler-than-normal ocean temperatures. Cooler waters can suppress tropical cyclone development. Most storms in the eastern Pacific head out to sea and don't affect land. Those that do affect land frequently hit the mountainous communities of western Mexico, often triggering widespread flooding and mudslides. Click here to view the video
