Climate change: colonial diaries in South Africa are helping scientists reconstruct weather patterns of the past to protect against future events

A copy of the VOC's registers for April 1789. These daily registers contained rich detail - including about the weather. Tracing History Trust

The current climate crisis raises many questions. Some are forward-looking: how can this be fixed? Some look to the recent past: how did we get here? And some reach further back into history: are today’s extreme heat waves, catastrophic droughts and floods all due to climate change? Was climate and weather this bad 100 or a few hundred years ago?

For scientists to answer those last two questions, they need to consult reliable instrumental weather records. But these only go back a few decades for many regions of Africa. The continent’s longest continuous single station weather record is that of the South African Astronomical Observatory in Cape Town, starting in 1841. This record shows that rainfall has gradually declined since about 1900.