Another Strait Is Closing

AMOC moves water from the Southern Atlantic to the north, where it cools and sinks. The climate in Europe is milder than in parts of Canada at the same latitude, because of this circulation. A study from the University of Miami concludes—on the basis of direct observation—that the current has been weakening over the past 20 years, which could lead to more extreme storms, changes in rainfall patterns, and colder winters in some regions. It could also cause sea levels to rise along coastlines. Previous computer modeling had predicted the changes, but this study shows actual measurements of them.

Human-caused climate change is the explanation for the changes. The scientists used monitors on the seafloor along the western part of the North Atlantic that showed a long-term trend of consistent decline in the strength of the overturning circulation. They add this may serve as an early warning, like a canary in a coal mine. If the AMOC weakens further, it could reach a tipping point, then switch off, and might not turn on again for thousands of years. 

A separate study led by the University of Cambridge shows that warm water in the deep ocean is moving under Antarctica’s ice shelves and could cause them to melt from the bottom up. Like the AMOC study, this one is also based on observations, not just modeling. The result of this movement could be that massive ice shelves surrounding Antarctica could melt, leading to ice on the land flowing into the ocean faster. While this occurrence is not imminent, it is still worrisome, because Antarctica’s land ice is enough to raise global sea levels by 58 meters, according to Earth.com.

Speaking of tipping points, researchers led by Tim Lenton of the University of Exeter, have identified positive ones that could spark nature’s rapid recovery, instead of collapse. For example, if meat consumption declined, it could lead to a reduction in agricultural expansion and loss of natural regions, and according to the scientists there have been significant reductions of eating meat in several rich nations, which had overconsumed. The keys to this change, they say, are social norms, and the availability of meat-free options.

Another example was shown after wolves were reintroduced to Yellowstone National Park about 30 years ago. The ecosystem was positively tipped into a regenerated state for vegetation recovery, boosting the numbers of birds, beavers, and bison.

The positive tipping point study was published in Nature Sustainability.

Zachary Handloss, of the Georgia Institute of Technology, wrote in The Conversation that parts of the Southeast have been in drought since last July. In March and April this year, the areas received less than 25 percent of normal precipitation. Temperatures have been warmer than usual, which has dropped relative humidity, and a high-pressure system has prevented the formation of clouds and precipitation. This system was brought on, Handloss writes, by a northward bend in the jet stream, the fast-moving current of air several miles above Earth, which brought southeasterly winds.

All these conditions add up to what is needed for wildfire—dried out vegetation, high winds, and low humidity. The spread of fire in the region has been fueled by leftover debris from hurricanes that have struck the region—like Helene in 2024 that rapidly intensified over the ocean where temperatures were warmer probably because of climate change. Georgia governor Brian Kemp declared a 30-day state of emergency for 91 counties because of the wildfires.

Inside Climate News reports that as climate change accelerates, it’s expected that Southeastern droughts will be more common. A climate scientist told NBC that these wildfires are yet another sign that climate change is wreaking havoc on natural ecosystems and increasing fire activity across the country even in historically humid landscapes.

A new study from the University of Toledo and the University of Missouri found goldfish, which can grow to nearly two feet long when not confined to a tank, can trigger dramatic ecological collapse in freshwater lakes, threatening native wildlife at every level of the food web. The researchers introduced goldfish, which are related to carp, into two experimental lake types—one nutrient-poor (oligotrophic) and the other nutrient-rich (eutrophic). They then monitored the consequences over time. 

The results were stark. Water quality degraded rapidly as the fish churned up bottom sediments. Native species like snails and small invertebrates, which form the foundation for healthy aquatic ecosystems, declined as they fell prey to the goldfish, had their habitat destroyed, or suffered as they competed for food. 

A “regime shift”—the scientific term for when an ecosystem rapidly reorganizes into something fundamentally different, and often worse—was documented in their study. Once triggered, the team says these shifts are notoriously difficult and expensive to reverse.

So, if you have a goldfish that you’ve outgrown, the researchers say to return it to the pet store or find a friend who is willing to adopt it.

The study was published in the Journal of Animal Ecology.

The Strait of Gibraltar sits between Europe, in southern Spain, and Africa in Morocco, connecting the Atlantic Ocean to the Mediterranean Sea. At its narrowest it’s only around 13 kilometers or nine miles wide. A computer-model by the University of Lisbon says things are shifting—tectonically speaking—and that the plate beneath the Strait of Gibraltar may be slowly sliding toward the Earth’s interior, in a process called subduction.

According to the Geological Society of America, subduction zones have more seismic and volcanic activity. Currently, the Atlantic Ocean has fewer subduction zones than the Pacific, which has the active and famous Ring of Fire, so any geologic activity around the strait gets the attention of researchers—and, they say, should warrant the attention of countries in the region.

Although subduction in the strait is probably creeping along at around 2” per year, it still raises the risk for earthquakes, landslides, and tsunamis. Scientists advise that now’s the time for stricter building codes, emergency planning, and public awareness campaigns.