A team led by McGill University researchers came up with a method they hope could improve climate models over Africa by combining them with 19th century missionary records, refashioning dubious documents in a bid to better inform projections of global warming鈥檚 impact.
Models are an important way for scientists and decision-makers to understand how human influence is changing the climate. To come up with those projections, climate models depend on historical baselines 鈥� temperature and precipitation, for example 鈥� to validate and refine their results.
But a lack of historical region-specific data across parts of Africa, plus a major deficit in weather stations compared to North America and Europe, has contributed to model uncertainty.
鈥淎frica鈥檚 absence from the underlying data makes deploying these projections uncomfortable, as it partly represents the continent鈥檚 marginalization from global scientific discourse during and after colonialism,鈥� says a study published last month in the peer-reviewed journal Climate of the Past.
To fill that data gap, lead author Philip Gooding turned to a perhaps unlikely source 鈥� writings of 19th century Christian missionaries in Tanzania.
Those are problematic records, Gooding said, derived from people who contributed to Africa鈥檚 colonization and had their own reasons to misrepresent climate conditions.
But perhaps by analyzing the climate models and those missionary records together, both could be improved upon, he said.
鈥淭he hope moving forward (is) basically, we鈥檝e made a better baseline on which global warming scenarios for Tanzania can now be projected,鈥� said Gooding, a project administrator at McGill鈥檚 Indian Ocean World Centre.
Climate model uncertainty is one example of how decision-makers in Africa are left to predict and prepare for extreme weather with fewer resources than their counterparts in other parts of the world.
Researchers have been sounding the alarm over how a lack of weather radar stations, which also inform climate models, have left areas of the continent without lifesaving early-warning systems for extreme weather.
Europe and the United States have about 636 radar stations for a population of 1.1 billion people. Africa 鈥� with a comparable population and a greater land mass 鈥� has about 37 stations, says a 2023 article in the scientific journal Nature, outlining the continent鈥檚 undue exposure to climate risks.
East Africa is one of the most vulnerable regions to climate change and yet one of the least understood, said Obed Ogega, a climate scientist and program manager with the African Academy of Sciences based in Nairobi.
To plan climate-resilient communities, whether that鈥檚 around drought-resistant agriculture or flood-resilient roads, 鈥渨e have to be informed by climate information.鈥�
鈥淭he more we understand our weather and climate systems, the better for the region, not just for the sake of building resilience of communities, but also for systems and ensuring that we minimize the vulnerability that is currently being experienced in the region,鈥� said Ogega, who is also an adjunct professor at Halifax鈥檚 Mount Saint Vincent University.
Gooding, a historian, realized his doctoral research on Lake Tanganyika, the world鈥檚 second deepest freshwater lake that straddles Tanzania鈥檚 western border, may be helpful. His research included hundreds of written accounts from missionaries and imperialists who described conditions over a roughly 30-year period in Tanzania ending in the 1890s.
In those accounts, Gooding recognized region-specific data that鈥檚 so often missing from climate modelling of Africa.
Yet, relying on missionary accounts came with some obvious issues and limitations, the study notes.
鈥淣ineteenth century meteorology, like cartography, was part of a wider practice that sought to impose European science, and thus Europeans鈥� ideas of 鈥榗ivilization鈥� on equatorial eastern Africa(ns), erasing indigenous patterns of human鈥揺nvironment interaction and their understandings of climate and weather,鈥� the study says.
In some cases, missionary reports may have also been exaggerated to provoke emotional responses from readers back in Europe who funded the missions. In others, reports may have minimized harsh conditions in a bid to establish the mission鈥檚 feasibility.
鈥淚n short, although highly valuable, the documents are highly subjective, and they both affected and were influenced by imperial knowledge-making,鈥� and contributed to the further colonization of Africa in the 19th century, the study said.
Working with an international team of climate scientists and data analysts, Gooding standardized the documentary data into a seven-point scale so it could be combined with the climate models. Accounts of regular climate conditions were in the middle of the scale, with severe drought and severe rainfall at either end.
While there鈥檚 no simple way to measure whether climate models are more accurate when 19th century missionary accounts are included, 鈥渋t can be safely assumed that by adding data from the region from the deeper past, it gives a more rounded picture of what we can think happened,鈥� Gooding said.
Ogega, the Nairobi-based climate scientist, commended the researchers鈥� efforts, but was skeptical of the missionary records and the limited time series.
鈥淯ntil I鈥檓 certain that the source I鈥檓 using is credible enough, is fit for purpose, I鈥檒l be very hesitant to use it,鈥� he said.
鈥淚f you make a conclusion based on wrong data, you can easily have a very serious policy implication.鈥�
He preferred to focus on nature-based records of Tanzania鈥檚 historical climate, such as studies of lake sediment or tree rings. But he suggested the research was a good start and could inspire further study to bolster confidence in the missionary record.
鈥淢aybe this a resource that we haven鈥檛 thought about enough, but apart from that I wouldn鈥檛 say, as of now, it鈥檚 conclusive enough for me to say, 鈥榥ow, going forward, we look for missionary reports and see how we can put those into climate modelling,鈥欌�� he said.
Gooding said he shared some of Ogega鈥檚 skepticism of the missionary records. The study included sorting through records and comparing them against climate models to determine which accounts appeared more or less confident.
鈥�(They) are both inherently flawed, but I think reading them together enhances both their value,鈥� he said.
The study suggests further challenges could include integrating evidence from local oral traditions into historical climate reconstructions.
