July 6, 2024
SummaryThe Amazon faces worsening climate impacts, with increased droughts and floods due to global warming. Water, not just carbon, is crucial for climate stability, affecting weather patterns globally. We urgently need climate solutions that manage water resources and curb carbon emissions to protect Amazonian ecosystems and communities worldwide.
About the author:
Marcia Nunes Macedo
Dr. Macedo is a Senior Scientist and Water Program Director at the Woodwell Climate Research Center, a Research Associate at the Instituto de Pesquisa Ambiental da AmazĂ´nia, and a member of the Science Panel for the Amazon. Her research investigates the impacts of tropical deforestation and forest degradation on climate and ecosystems. Macedo combines field observations, satellite data, and scientific modeling to understand these processes and develop science-based solutions.
As I look out over the river from a floating cabin at the Mamirauá Sustainable Development Reserve in central Amazonia, it’s hard to imagine that water could become an issue here. It’s the end of the rainy season and river levels, as usual, have peaked at 9-12 meters above their dry season mean. To my delight, we take canoes for a “hike” on the forest trails and spot large fish like tambaqui and pirarucu, temporarily released from the confines of the riverbanks. The riverside communities we visit are practiced in dealing with these large seasonal fluctuations, having built their houses on stilts high on the riverbank and using boats to negotiate the ebbs and flows of the river, which they rely on for their livelihoods and transportation.
Water is omnipresent here. Moist air from the Atlantic brings rain westward over South America. As it falls over the Amazon's forests, farms, and cities, it percolates through the soil, replenishing underground aquifers, interacting with vegetation and infrastructure and flowing out through river networks back to the ocean. Water is also energy. It takes a massive amount of solar energy to evaporate it, which cools the land surface and produces water vapor. As Amazon forests pump water back into the atmosphere, they feed flying rivers that transport energy and water over long distances, releasing them as rainfall elsewhere. This water cycle acts like a giant conveyor belt that moves energy around the world, supplying clean water for people, crops, and ecosystems.
If all goes as planned, COP30 will take place in Belém do Pará next year, not far from where the Amazon River sends 7000 cubic kilometers of water annually into the Atlantic Ocean – one-fifth of the world’s freshwater discharge, rushing by at speeds up to 250,000 cubic meters per second.
As world leaders and climate negotiators prepare to convene in an Amazonian city for the first time, they should remember that water, not carbon, holds the key to our climate future.
As world leaders and climate negotiators prepare to convene in an Amazonian city for the first time, they should remember that water, not carbon, holds the key to our climate future. While climate warming is driven by greenhouse gasses like carbon dioxide, methane, and nitrous oxide accumulating in the atmosphere, the climate crisis is fundamentally a water crisis.
No doubt carbon emissions alter global climate, but the water cycle is the engine that drives it, connecting the land surface, oceans, and atmosphere. Climate warming is now supercharging this engine and intensifying extreme droughts, floods, and water insecurity. Local impacts of climate change highlight the imperative for climate solutions that prioritize water alongside efforts to mitigate carbon emissions.
The last two years show we have strained the water cycle to the breaking point. In 2023, the El Niño brought below-normal rainfall to northern South America and above-normal rainfall to southern Brazil. Record-high air temperatures attributed to climate change made the drought even drier in central Brazil. In contrast, unusually high sea surface temperatures in the Atlantic intensified rainfall in the south, causing unprecedented droughts, fires, and floods that have dominated headlines over the last year.
The recent floods in the state of Rio Grande do Sul, Brazil highlight the staggering social costs. For the over 640,000 people who were displaced and the 163 who lost their lives during that devastating event, climate change is undeniable.
From 2017-2022, nearly 29 million Brazilians were affected by rain, floods, or landslides. The economic costs are estimated at up to R$18.9 billion (US$3.5 billion) in a single year. The human costs are incalculable. At the other extreme, the ongoing drought has devastated natural and manmade systems across Amazonia. As air temperatures rose to record highs, river levels dropped precipitously last year – much earlier and lower than normal. In Brazil’s central Amazon, this led to massive fish kills, wildfires, and agricultural losses that disproportionately impacted family farmers, including Indigenous people and riverside communities. Low water levels disrupted river navigation, cutting off hundreds of communities from the rivers they depend on to access markets, health care, education, and other essential services.
To make matters worse, the number of fires detected in old-growth Amazonian forests rose by over 150% in 2023 compared to the previous year, despite progress in reducing deforestation. A single mega-fire near the city of Santarém, Pará, burned over 2,500 km2, adding to the suffocating smoke that spread across much of the Amazon last year. In October and November, air quality in the city of Manaus, Amazonas, was among the worst in the world, with particulate matter reaching almost 315 micrograms per cubic meter of air (µg/m3), exposing millions of people to pollution levels far beyond the 15 µg/m3 limit recommended by the World Health Organization.
In the headwaters of the Xingu River in southeast Amazonia, the pace of change has been astonishing. When I began working there nearly 20 years ago, the forests were too humid to sustain large wildfires.
In the headwaters of the Xingu River in southeast Amazonia, the pace of change has been astonishing. When I began working there nearly 20 years ago, the forests were too humid to sustain large wildfires. Inhabitants of the Xingu Indigenous Territory regularly used fire, knowing they could not escape into nearby forests. Today, large-scale deforestation and global warming have resulted in hotter nights, a longer dry season, and more frequent droughts – a recipe for uncontrolled forest fires that have damaged at least 25% of the reserve’s forests and reduced air quality for everyone.
Hard times are ahead. These extreme events will get worse and more frequent unless the world swiftly stops burning fossil fuels and ends deforestation. There is no way around it: in a 2°C warmer world droughts will be 3-4 times more likely than today. To slow and eventually reverse these changes, we must stop emissions and find ways to remove carbon from the atmosphere. This includes protecting old growth forests and actively managing landscapes to enhance carbon uptake and prevent forest degradation by fires and other disturbances.
Our intense focus on carbon has led to a paradoxical logic in our approach to climate solutions. Government programs incentivize low-carbon agriculture while also promoting expansion into arid regions already suffering from extreme water stress. Efforts to reforest and afforest aim to offset carbon emissions by growing forests, yet many use thirsty, non-native trees like eucalyptus, exacerbating water scarcity and fire risk. Some misguided programs have attempted to replace native grasslands and savannas with nonnative forests or croplands in regions that won’t be able to sustain them within a decade. Moreover, deforestation rates far outpace reforestation efforts. It takes decades or centuries to grow a forest and just days to cut one down and burn it, releasing all its stored carbon and disrupting its water-cycling potential.
Addressing and reversing climate change hinges on effective carbon management to prevent emissions and reduce greenhouse gas concentrations. Adapting to ongoing changes depends on robust water management to bolster food security, mitigate fire risk, and fortify social and ecological resilience. These efforts can and should overlap. As extreme climate events become more likely, urgent action is needed to overhaul our disaster preparedness approach.
Recent events underscore the imperative to reform policies, including proactive support for forecasting and early warning systems, drought contingency plans, sustainable water management practices, and fire management to cope with climate instability. Governments at all levels must invest in coordinated strategies for prevention, forecasting, and emergency response to help communities and ecosystems “weather the storm” and navigate the many challenges posed by the climate crisis.