The Amazon River Basin is one of the most critical pieces of the Earth's climate system, generating rainfall, lowering land surface temperatures, and influencing global weather patterns. It is known for its unique and irreplaceable biodiversity in plant and animal life. But the rainforests that formed over millions of years have experienced dramatic changes in the last few decades.

The loss of this valuable resource prompted a historic scientific consortium in late 2021 at the 26th United Nations Climate Change Conference, or COP26, in Glasgow, United Kingdom. The Science Panel for the Amazon, or SPA, was a group of over 200 prominent scientists including Dr. Sandra B. Correa, assistant professor in the Department of Wildlife, Fisheries and Aquaculture and FWRC scientist.

Their objective was to create a comprehensive report assessing the state and future of the region's ecosystems in response to climate change and human activity.

In 2019, representatives from the eight countries in the Amazonian region convened to discuss the need for creating a path for sustainable development.

Jeffrey Sachs, an economist at Columbia University, Director of the Center for Sustainable Development, and senior UN advisor, led the initiative for producing the report. Correa, who is from Colombia and spent two decades conducting research in the Amazon, contributed to two chapters of the report: one describing how the Amazon's ecosystems function and the other focusing on present and future effects of climate change on these ecosystems.

The report presents a comprehensive view of the current literature on Amazonian ecosystems and highlights patterns and trends. The two main trends Correa and her team discussed were an overall reduction in precipitation and increasing temperatures.

"From my own experience and research, one of the patterns that strikes me most is how erratic the changes in river flow patterns have become in recent years," she said. "In the last 20 years, we have seen seasonal flooding and drought patterns become more extreme. And what were once called 'century floods' have happened multiple times within a decade."

Extreme drought, Correa explained, causes temporal fragmentation when river tributaries stay dry, and sediments cannot reach floodplains to fertilize plants. On the other end, massive floods threaten both terrestrial and aquatic animals.

Large-scale famine and drowning of wildlife, as was seen in the Mississippi flood of 2019, has become more frequent. Moreover, these severe fluctuations have affected human livelihood, from hunting, fishing, and farming to transportation, as many locations in the Amazon are accessible only by boat.

"We need to achieve a plan for sustainable development that doesn't leave behind the rich indigenous and rural communities. The number of groups and ethnicities in the region is incredibly diverse," Correa said.

Although the impacts of climate change on the Amazon alone are important, the report stresses the interdependence of the rest of the world on the Amazon's climate.

What happens there affects every ecosystem and every person on the planet, Correa pointed out.

"The Amazon's forests are the lungs of the planet — the rainforest acts as a water-pumping system to perpetuate the rainfall cycle and growth of trees, which capture carbon from the air in their stems and leaves," Correa said. "Clearing forestland for timber, farming, and mining and damming rivers for energy creates a drier environment and slows down the growth of existing trees, weakening the forest's carbon sink.

These activities have placed so much stress on the system that it is no longer doing what it is supposed to do."

Correa explained that there is a tipping point at which the Amazon will transform from a rainforest to a savanna environment. Recent studies estimate that the pumping system will be effectively shut off when deforestation of the region reaches about 20-25 percent.

The report proposed a number of strategies to slow down and prevent reaching this point, including government commitment to stopping large-scale deforestation, holding off construction of large dams, and reducing CO₂ emissions on a global scale.

"Studying the changes in this ecosystem and how plants and animals respond is critical to its survival," Correa said. "Once we have that knowledge, we can conserve, restore, and adapt."

Correa's work in the Amazon, though 3,000 miles away, provides application in Mississippi, where she studies rivers and aquatic life dependent on these ecosystems.

"How can we apply the lessons learned in the Amazon to the Pascagoula River, which are similar with extended periods of flooding?" Correa said. "Flooded forests provide important habitats for wildlife and fish, and understanding their function provides an opportunity to save these diminishing landscapes."