The Amazon River stretches more than 4,100 miles (6,600 km) and nourishes the largest diversity of freshwater fish species on Earth. But a new study warns that this vital ecosystem — and rainforests across the tropics — could face devastating drought if one of Earth’s major ocean currents continues to slow.
The Atlantic Meridional Overturning Circulation (AMOC), which includes the Gulf Stream, plays a critical role in regulating global climate. Acting like a planetary conveyor belt, it transports warm tropical waters northward and pushes cooler waters south, balancing temperatures and rainfall patterns worldwide. Yet scientists have found troubling signs that the AMOC is weakening, and some models predict it could collapse within this century.
By analyzing 17,000-year-old climate records, researchers uncovered a clear link between a weaker AMOC and reduced rainfall in tropical regions. The findings, published July 30 in Nature, suggest that even a modest slowdown could nearly halve rainfall over the Amazon, pushing this lush rainforest toward widespread drought.
“This is bad news, because we have these very important ecosystems in the Amazon,” said study lead author Pedro DiNezio, an atmospheric and ocean scientist at the University of Colorado Boulder. “The Amazon contains almost two years of global carbon emissions, making it one of Earth’s greatest carbon sinks. If drought releases that stored carbon, it could fuel a vicious cycle that worsens climate change.”
The Amazon rainforest, often called the “lungs of the planet,” is already nearing critical tipping points due to deforestation and warming. A collapse of the AMOC could accelerate this shift, transforming humid forest into dry savanna and unleashing enormous amounts of carbon into the atmosphere.
This research serves as a stark reminder that the health of global ocean currents and rainforests is deeply intertwined. Protecting both is essential to stabilizing Earth’s climate in the decades to come.
