The Amazon Cooperation Treaty Organization (OTCA) has named El Nino the climate factor most worth watching in 2026. The latest bulletin from the U.S. NOAA puts the odds of formation in May-July at 61%. Across the drier northeastern Amazon, northern Brazil, Colombia and Venezuela, the concern is spreading wildfire and sharply falling river levels.
What 61% Means
El Nino is a warming of sea-surface temperatures in the tropical Pacific that brings broad drought to South America. OTCA reads it as a transitional scenario — most likely a weak-to-moderate event lasting through year-end. The odds of a high-intensity event were put at about 20% in CIIFEN's April bulletin. The framing some have used, a record El Nino not seen in 155 years, traces back to sources that may be overstated. The numbers deserve a calm reading.
That said, weak does not mean no impact. Temperature anomalies in the tropical Atlantic can shift Amazon rainfall and apply drying pressure that exceeds the Pacific-side effect. The state of the soil and vegetation amplifies it further.
First, the Rivers Fall
When rain declines, river levels drop first. Much of life along the basin depends on river transport, and falling water feeds straight into daily life. In the great drought of 2023, record low levels persisted on Amazon tributaries; settlements were cut off, and food and medicine grew hard to deliver. The warning is that the same could come in the second half of 2026.
Wildfire risk stacks on top. When dry vegetation meets fires set to clear land for farming, flames spread easily. The Lula government has championed Amazon protection heading into COP30 (held in Belem in 2025), yet, as a $75 million investment in the BR-319 highway shows, the tug-of-war between development and protection continues.
Even Drought-Tolerant Trees Begin to Fail
What makes El Nino difficult is that it does not act alone; it combines with long-term climate change. A study published in Nature in May 2026 showed that deforestation-induced drying lowers the Amazon's climate threshold. Even tree species that should resist drought are beginning to fail when rising heat and falling rainfall coincide. OTCA is calling on its eight member states to build early-warning systems and strengthen cross-border firefighting. It starts with reading the monitored numbers accurately.
Even a weak El Nino, on land that has dried out completely, can turn a small spark into a large fire.
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References
- El Nino in the Amazon and its climate impacts 2026 – OTCA — otca.org
- Fire Frontiers: Regional cooperation to protect the Amazon, El Nino 2026 – OTCA — otca.org
- Deforestation-induced drying lowers Amazon climate threshold – Nature (2026) — nature.com
- Cropped 3 June 2026: Highway through the Amazon | El Nino impact – Carbon Brief — carbonbrief.org
※ This article is the author’s commentary based on public information. Please confirm the latest figures, dates and procedures with governments and primary sources. Quotations are kept minimal and sources are cited.