The Amazon region stands out as a key area rich in biodiversity, significantly contributing to the climate system by sequestering vast amounts of carbon and influencing the global water cycle. Unfortunately, climate change and intensified deforestation are putting this rainforest at risk. A collaborative international research team has investigated how alterations in Atlantic circulation could affect the Amazon Rainforest.
The climate system of our planet is intricate, consisting of interconnected elements such as the ocean, atmosphere, and vegetation. Changes in one element can lead to widespread repercussions throughout the entire system. While individual components can exhibit resilience and adapt to certain changes, climate and Earth system research suggests that there are specific tipping points. If these tipping points are crossed, the climate system might rapidly shift to a different state. It’s also believed that these tipping points are interrelated and could trigger cascading effects within the system.
Significant global tipping points include the Amazon rainforest and the extensive Atlantic Meridional Overturning Circulation (AMOC). Continued global warming could substantially weaken the AMOC, slowing the transport of warm water to northern regions and altering temperature patterns across the Atlantic. This transformation would impact the Amazon region by disrupting the atmospheric water cycle and consequently changing precipitation patterns and amounts.
Examining Pollen and Carbon Remnants
The intricate relationship between AMOC and the Amazon, particularly how marine circulation influences this region, has not been thoroughly studied. A research team led by Dr. Thomas Akabane and Prof. Dr. Christiano Chiessi from the University of São Paulo has closely examined shifts in Amazonian vegetation. Collaborating internationally, they analyzed ancient pollen and carbon samples from a marine sediment core collected at the mouth of the Amazon River, covering the last 25,000 years.
This research offers a detailed view into the historical changes within one of the planet’s biodiversity-rich ecosystems. The findings demonstrate how vegetation has evolved during different wet and dry periods throughout significant climate events in the last ice age, particularly during the Heinrich Events when the AMOC weakened considerably. A notable regression of rainforest vegetation was observed in the northern parts of the Amazon region.
Strong Link Between Atlantic Currents and the Amazon Ecosystem
“This study stems from a long-term collaborative project between Germany and Brazil, initiated in 2012 with a joint expedition aboard the research vessel MARIA S. MERIAN in the Amazon estuary. Our data indicate that the Amazon ecosystem historically adapted to variations in precipitation patterns caused by reduced Atlantic circulation. However, a future decline in the AMOC, coupled with increased deforestation, could jeopardize this critical global ecosystem’s stability,” explains Dr. Stefan Mulitza from MARUM.
Additional research using climate and vegetation models suggests that a decrease in the AMOC under today’s conditions could impact Amazon vegetation in a manner reminiscent of the past ice age. “Our models reveal that the AMOC does not have to completely fail for the rainforest to be affected. Even slight changes in the AMOC can drastically influence the northern regions of the Amazon,” states Dr. Matthias Prange from MARUM.
The findings underscore the complexity of the global ecosystem. “Processes occurring at high latitudes, such as the melting of Greenland’s ice, can significantly affect tropical regions. These long-range impacts often lead to severe regional consequences, particularly for communities that have played a minimal role in driving climate change,” adds Prof. Dr. Gerrit Lohmann from AWI.
