For decades, the Congo Basin has remained one of the most significant "data deserts" in global climate science. While the Intergovernmental Panel on Climate Change (IPCC) has been able to track long-term shifts in temperature and precipitation across most of the globe, the heart of Africa's tropical rainforest—the world's second-largest—has lacked the readily available, long-term digital records necessary for high-confidence modeling. That changed on October 12, 2026, with the publication of a landmark study in the journal Earth System Dynamics, which reveals for the first time the precise extent of warming in the region over the last century.
Filling the 'Data Desert' of Central Africa
The lack of data was not due to a lack of history, but rather a lack of digitization. Scientists and meteorologists during the colonial and post-colonial eras in what is now the Democratic Republic of the Congo (DRC) were meticulous record-keepers. However, their observations—daily temperature highs, lows, and rainfall totals—were trapped in thousands of fragile, handwritten ledgers stored in archives in both Kinshasa and Tervuren, Belgium. Without this historical baseline, it was nearly impossible for modern researchers to determine if recent heatwaves were anomalies or part of a consistent long-term warming trend.
The project to bridge this gap involved the digitization of over 9,000 pages of records, spanning the period from 1908 to 2023. A dedicated team of researchers and archivists spent years transcribing more than a million individual observations. This Herculean effort has provided the first continuous climate narrative for the Congo Basin, allowing the region to finally be integrated into the global maps of historical climate change that guide international policy.
The Heroic Rescue of Fragile Archives
The physical condition of these records made the task a race against time. Derrick Muheki, a PhD candidate at Vrije Universiteit Brussel and a lead figure in the data rescue operation, highlighted the precarious state of the source material. The archives in the DRC, housed in buildings without modern climate control, were vulnerable to the very heat and humidity they recorded, as well as more immediate threats like fire and pests.
"Seeing how fragile these paper archives were as I was visiting the archive in the Democratic Republic of the Congo made me realize how urgent this data rescue work is. Just months before my visit, part of the archive had been damaged by fire. We could have lost decades of irreplaceable data."
Muheki's account underscores a broader issue in African science: the loss of historical heritage due to underfunded infrastructure. The fire he mentioned served as a catalyst for the international team to accelerate their work, using high-resolution scanners and specialized software to preserve the ink-on-paper entries before they crumbled or were consumed by the elements. The result is a digital treasure trove that will serve generations of climatologists.
A Century of Observations Deciphered
The findings of the study are both clarifying and concerning. By analyzing the newly digitized data, the research team found that between 1961 and 1990—a crucial baseline period for climate science—the average daily temperature in the Congo Basin rose by approximately 0.9°F (0.5°C). While this might seem like a modest number in isolation, it represents a massive shift in the thermal energy of a tropical rainforest ecosystem, which typically operates within a very narrow temperature range.
The data reveals that the warming trend did not just manifest as a steady rise in the average, but as a significant shift in the frequency of extreme events. The number of "hot days" per year in the basin nearly doubled during the latter half of the 20th century. These are days where the temperature exceeds a specific threshold relative to the historical norm. This doubling of heat extremes has profound implications for the local flora and fauna, many of which are highly specialized to the stable, humid conditions of the deep forest.
Beyond Temperature: The Rainfall Paradox
One of the most complex aspects of the study involves the basin's rainfall patterns. The Congo Basin is a major driver of the global hydrological cycle; it effectively "recycles" its own moisture through transpiration from its vast canopy. The digitized records show that the warming trend has been accompanied by a shift toward more extreme rainfall events. Even as some periods became hotter and drier, the rain that did fall often arrived in heavier, more destructive bursts.
This volatility is particularly concerning for the millions of people who live within the basin and rely on rain-fed agriculture. The historical data shows a clear departure from the more predictable seasonal cycles of the early 20th century. By mapping these changes, scientists can now better predict how future warming will affect the "African Easterly Jet"—a high-altitude wind system that carries moisture from the Congo across the Atlantic, influencing hurricane formation and weather patterns as far away as the Americas.
The Lungs of Africa Under Pressure
The Congo Basin is often referred to as the "second lungs of the Earth," acting as a massive carbon sink that absorbs billions of tons of carbon dioxide. However, the new data suggests that this cooling service to the planet may be under threat. As temperatures rise and extreme heat days double, the forest's ability to sequester carbon could be compromised. Tropical trees, when stressed by excessive heat, can transition from being carbon absorbers to carbon emitters.
The study provides the empirical evidence needed to understand how the basin's peatlands—some of the most carbon-dense ecosystems on the planet—might respond to a warming climate. If the basin continues to warm at its current rate, there is a risk that these peatlands could dry out and release their stored carbon back into the atmosphere, creating a feedback loop that would accelerate global warming. This makes the conservation of the Congo Basin not just a local priority, but a global necessity.
Redefining Global Climate Projections
The successful digitization of these records marks a turning point for African climatology. The trends identified in the Congo Basin mirror those observed in Europe and North America over the same period, confirming that the central African interior is warming in lockstep with the rest of the planet. Until now, the lack of data allowed for a degree of uncertainty that hindered aggressive conservation and adaptation planning in the region.
With this new dataset, the IPCC and other international bodies can refine their models for the next decade. The study, published in Earth System Dynamics, serves as a call to action for other regions with significant "paper gaps" in their climate history. As Derrick Muheki and his colleagues have shown, the keys to understanding our future climate are often hidden in the dusty, handwritten ledgers of the past—provided we can save them before they are lost forever.