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

More than 60 years have passed since the first satellite was launched into space, sparking an international space race that brought historic missions and a dramatic rise in the number of objects circling our planet. Today, we rely on thousands of satellites for communication, navigation and research. But as their numbers continue to skyrocket, so do concerns about the growing volume of space debris and its potential impacts.

The number of satellites in low Earth orbit, where most are found, is expected to surge in the coming years, growing from thousands to tens of thousands over the next 15 years, according to the Government Accountability Office. While most of these satellites burn up as they plummet back to Earth, some of the particles they leave behind in the atmosphere could have lasting effects as their numbers increase.

Falling pieces of space debris often attract attention, but little is known about the aerosols produced during reentry vaporization and their impacts on Earth’s atmosphere. For example, aluminum, one of the most widely used materials in satellite construction, vaporizes during reentry and forms alumina particles, which can accumulate in the atmosphere.

A recent study in the Journal of Geophysical Research: Atmospheres explored what some of these impacts might be and when they could begin to have a notable effect. Researchers simulated how clouds of alumina vapor could impact Earth’s middle and upper atmosphere, finding that the amount of alumina from plummeting satellites would eventually be significant enough to alter conditions in the stratosphere and mesosphere, which are both part of the middle atmosphere.

According to the study, by 2040, there could be enough alumina in the stratosphere to influence temperatures and wind speeds in the polar regions, potentially affecting both the ozone layer and the polar vortex over the Arctic and Antarctic. Their results show alumina particles could heat the middle atmosphere near Earth’s poles by about 1.5 degrees Celsius, potentially reducing wind speeds in the Southern Hemisphere’s polar vortex by about 10 percent.

Previous research has shown that a weaker polar vortex in the Southern Hemisphere can promote warmer and drier weather conditions across eastern Australia, increasing the threat of dangerous wildfires during the spring and summer months.

Researchers speculate this may also help shrink the ozone hole over the South Pole each year, though the precise relationship between alumina and ozone chemistry remains unclear. Researchers note that some reentry scenarios also showed the opposite effect in the Northern Hemisphere, with possible strengthening of the polar vortex.

While more research is needed to fully understand how increasing space debris may affect Earth’s weather and climate, this study underscores the importance of investigating these potential impacts as our gateway to space becomes increasingly crowded.

-ABC News meteorologist Dan Peck

April 2025 was the second-warmest April on record globally, just behind April 2024, according to new data analyzed by the Copernicus Climate Change Service. Earth's average surface air temperature was 58.93 degrees Fahrenheit.

While the planet may have fallen a little short of breaking another record, global temperatures once again exceeded the 1.5-degree Celsius warming threshold established in the 2015 Paris Climate Agreement, coming in at 1.51 degrees Celsius above the pre-industrial reference period (1850 to 1900).

Last month marked the 21st of the previous 22 months to exceed the warming threshold identified by climate scientists as a critical limit to reduce the worst risks and impacts of human-amplified climate change. While this is a troubling trend, exceeding the threshold temporarily is not seen as a failure to limit global warming, as climate averages are analyzed over several decades.

Antarctic sea ice extent was 10% below average for the month. In the Arctic, the report found sea ice extent was 3% below average, marking the sixth-lowest April extent on record. The Arctic region is warming significantly faster than the global average and, after serving as a carbon sink for thousands of years, has become a source of carbon dioxide emissions due to rapidly rising temperatures and increased wildfire activity, according to the National Oceanic and Atmospheric Administration.

Global daily sea surface temperatures across much of the world's oceans remained well above average in April. Between the latitudes of 60 degrees south and 60 degrees north, the average global sea surface temperature was 69.6 degrees Fahrenheit, the second-highest value on record for the month, according to Copernicus.

Unusually, warm sea surface temperatures could play a key role in tropical cyclone development during the upcoming Atlantic hurricane season, which begins on June 1. NOAA is expected to release its official outlook for the upcoming season on May 22.

-ABC News meteorologist Dan Peck

As carbon dioxide levels in Earth's atmosphere reach record highs and the effects of human-amplified climate change intensify, climate scientists are urgently searching for effective ways to slow global warming. Rapidly reducing atmospheric levels of CO2, a heat-trapping greenhouse gas, is one of the most critical challenges, and in many cases, nature can be part of the solution.

Hidden along the world's coastlines and just beneath the ocean's surface, seagrass meadows are among the most threatened and one of the most overlooked ecosystems on the planet. But they could play an essential role in fighting climate change thanks to their remarkable ability to absorb and store carbon, according to a new study published in Nature Communications.

Although they cover only about 0.2% of the ocean floor, seagrass meadows store a significant portion of the ocean's carbon, accounting for roughly 10% of its total carbon storage capacity. Seagrass absorbs CO2 up to 35 times faster than tropical rainforests, according to the United Nations Environment Programme.

In the largest study of coastal ecosystems to date, researchers analyzed over 3,000 samples of seagrass and soil from 61 countries, revealing significantly greater variation in carbon storage among species and regions than previously understood.

"Seagrass meadows are not just important for marine biodiversity, they are a critical piece of the climate puzzle," said lead author Johannes Krause, a researcher at Conservation International and assistant research professor at Florida International University. "This research underscores their vast potential as carbon sinks and the importance of accurate data to ensure we're protecting them properly."

Researchers say that protecting and restoring seagrass meadows is a promising yet underutilized climate mitigation tool. Greater investment and research on these ecosystems can help preserve biodiversity and strengthen the planet's natural ability to store carbon.

Protecting vegetated coastal ecosystems, like seagrass meadows, could prevent the release of 1.2 billion metric tons of CO2 into the atmosphere, the equivalent of removing the annual carbon footprint of 100 million homes in the United States, according to the nonprofit Conservation International, which funded the study. Researchers also estimate this could avoid more than $200 billion in climate change-related costs through 2050.

-ABC News meteorologist Dan Peck

For the first time, a new study finds climate change is now the primary driver of biodiversity loss in the United States.

Researchers examined the five predominant threats facing 2,766 imperiled species in the U.S. Those are plants and animals that have significantly declined in numbers and are at high risk of extinction.

The team from the Center for Conservation Innovation at Defenders of Wildlife found when they applied climate change assessments to the plants and animals on the U.S. Endangered Species Act list, climate change was the most far-reaching biodiversity threat, impacting 91% of ESA-listed species.

While climate change may be the most common threat, it's not the only one. Changes to land and sea ecosystems, such as land conversion, pollution and resource extraction, was the No. 2 most common at 90%. Other primary drivers of biodiversity loss include overexploitation, invasive species and pollution.

These five threats often overlap. The researchers found that 86% of all U.S. imperiled species faced two or more threats. On average, those on the ESA list faced nearly three of the five threats. And the researchers found a species' habitat largely impacts its risks. Marine species, for example, face the highest number of threats.

"With the biodiversity and climate crises deeply intertwined, not only is addressing climate change necessary for imperiled species, but protecting biodiversity and supporting healthy ecosystems is also essential to shifting our climate trajectory," the authors wrote in the study.

- ABC News Weather and Climate Unit's Matthew Glasser