Climate and environment updates: Wind and solar generated record amount of US electricity in 2025

Last month was the third-warmest September on record globally, behind 2024 and 2023, according to new data analyzed by the Copernicus Climate Change Service (C3S). The planet’s average surface air temperature was around 61 degrees Fahrenheit.

While global air and sea surface temperatures are currently falling short of new record highs, climate scientists warn the pause in record-breaking warmth is unlikely to persist as human-caused greenhouse gas emissions continue to drive the long-term warming trend.

Scientists anticipated a short-term drop in global temperatures because of the La Niña event in the equatorial eastern Pacific Ocean, which ended in April. This climate pattern typically causes a temporary dip in average global temperatures. According to the National Oceanic and Atmospheric Administration (NOAA), La Niña conditions are likely to reemerge by the end of the year.

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 69.29 degrees Fahrenheit, the third-highest value on record for September, according to Copernicus.

This includes much of the Atlantic Basin, where tropical activity increased during the second half of the month following a quiet start, as atmospheric conditions became more favorable for storm development. According to NOAA, these unusually warm sea surface temperatures are expected to continue playing a key role in tropical cyclone development for the remainder of the Atlantic hurricane season, which runs through Nov. 30.

Sea surface temperatures are also frequently above average in the polar regions, negatively impacting sea ice. Antarctic sea ice coverage was about 5% below average in September, ranking as the fourth-lowest value on record for the month. In the Arctic, it registered 12% below average, Copernicus said.

-ABC News meteorologist Dan Peck

Scientists from around the world are warning that more than 75% of the planet's health and life support systems, known as Planetary Boundaries, are in danger.

The 2025 Planetary Health Check report from the Planetary Boundaries Science Lab found that seven of the nine critical Earth system boundaries have been breached due to human activities.

These Planetary Boundaries were established by the lab as a way of measuring the planet's current health.

According to the report, ocean acidification – where the water's pH, a measure of its acidity or alkalinity, is lowered due to excess carbon dioxide - is the newest boundary broken and for the first time has reached dangerous levels.

"The ocean is becoming more acidic, oxygen levels are dropping and marine heatwaves are increasing," said Levke Caesar, co-lead of Planetary Boundaries Science Lab and one of the authors of the report.

The report found evidence of recent shell damage to marine life, attributed to increased ocean acidity, particularly in polar and coastal waters. The authors warn that this is due to increased levels of human-introduced carbon dioxide, which raises the risks for other marine life.

Caesar also stated that the ocean's acidification, combined with warming and loss of oxygen, will have "rippling" consequences that negatively impact food insecurity, global climate stability and human well-being.

"The Ocean is our planet's life-support system," commented Dr. Sylvia Earle, an oceanographer and member of the Planetary Guardians.

The report also warns that increasing ocean acidification can disrupt ocean currents that are important for regulating marine climate and global weather patterns, leading to more intense climate extremes and undermining agricultural stability.

"Today, acidification is a flashing red warning light on the dashboard of Earth's stability. Ignore it, and we risk collapsing the very foundation of our living world," added Dr. Earle.

The other six planetary health boundaries that have been crossed are climate change, biodiversity loss, freshwater use, biogeochemical flows, land system change and novel entities, which is the safe limit for the production and release of chemicals, plastics and other synthetic substances.

The authors found that these six metrics of the planet's health are facing increasing pressures, suggesting that further deterioration and destabilization of the Earth's health could come soon.

"We are witnessing widespread decline in the health of our planet," said Johan Rockström, director of the Potsdam Institute for Climate Impact Research. "But this is not an inevitable outcome… Even if the diagnosis is dire, the window of cure is still open. Failure is not inevitable; failure is a choice. A choice that must and can be avoided," Rockström added.

Only Ozone Depletion and Aerosol Loading, which measure the global air quality and the planet's ability to protect from harmful sunlight, remain within safe limits and show some signs of improvement.

-ABC News meteorologist Kyle David Reiman