Shifting frontiers: mapping Africa’s agricultural land under a future climate
Data visualisation is as old as the sun dial. For thousands of years, humans have communicated complex information by rendering it visually. That’s why, CSIRO’s Dr Uday Nidumolu favours maps to illustrate how climate change is changing the borders of viable farming land.
Dr Nidumolu is a principal research scientist with CSIRO, working on climate smart agriculture and agricultural systems modelling to help advance our understanding of where climate change threatens food security.
“People understand maps,” Dr Nidumolu says. “When you put a line on a map and say what it means, you can communicate climate change in a slightly different way, and it’s easier to have a discussion. It’s simply saying, if we get these changes in rainfall and temperature, this is the impact on agricultural margins.”
Dr Nidumolu, along with CSIRO colleague David Gobbett, is lead author of a new research paper that demonstrates the projected impacts of climate change on farming land and the implications for food security and livelihoods.
Using historical climate data and global climate change models, the research assesses how current agropastoral-pastoral zones (areas that comprise crops and pastures for grazing livestock and pasture-only zones, respectively) in Africa, are likely to shift by 2050.
The projections showed that the margins will retreat across the African continent, resulting in substantial conversion of the agropastoral mixed crop and livestock farming system to pastoral land for livestock grazing alone.
Climate change could reduce 4.43 million square kilometres of current agropastoral land down to between 1.2 to 3.6 million square kilometres. That shift of the agropastoral-pastoral system boundary is a clear threat to food security and livelihoods in those areas.
The estimated 100 million people living in these regions who rely on agriculture are at the frontier of the effects of climate change and will need solutions to adapt into the future.
CSIRO works with an extensive network of partners in agriculture to understand the global context of climate change and increasing land and water scarcity and the challenges this poses to agriculture.
The power of mapping science
“It would be useful for this research to trigger discussion that can lead the global community to think about solutions in these hotspots where the biggest changes are happening,” Dr Nidumolu says.
Dr Nidumolu brought together a diverse team to tackle this research challenge.
“It’s a good showcase of Australian research applied in Africa which builds on a vast amount of work on climate impacts and adaptation done in Africa by many global and local institutions,” he says.
Led by CSIRO, four other institutions contributed to the paper including the South Australian Research and Development Institute, Institute for Climate, Energy & Disaster Solutions, Australian National University (ANU), Queensland Alliance for Agriculture and Food Innovation, The University of Queensland (UQ), and the University of Twente in the Netherlands.
Dr Nidumolu applied similar methodologies in earlier research in South Australia. The team conducted workshops with farmers in the region and used maps to illustrate the projected speed of change in climate and its impact on the margins of the state’s grain belt.
A key map centred around a line drawn in 1865 on the map of South Australia by George Goyder, the young colony’s Surveyor General. ‘Goyder’s Line’ marked a boundary for land deemed reliable to grow cereal crops.
There were only limited rainfall records as Goyder travelled on horseback to hear from pioneer graziers in the wake of failed crops attempted too far inland. “He was a great visionary,” Dr Nidumolu says.
In workshops with farmers, Dr Nidumolu showed the 1865 line and the potential changes to the cropping boundary based on climate projections.
“It acted as great opening to the discussion on climate risk/change because they understand Goyder’s Line,” he says. “It’s more compelling than graphs and numbers to start a discussion.”
An Australian approach to a global problem
Dr Nidumolu and his colleagues saw an opportunity to apply the same approach to cropping margins in Africa.
“Africa has a much more complex climate than Australia,” he says. “It spans almost from the Mediterranean across the equator to the subtropics.”
“Farming systems’ maps exist for all developing regions of the world,” Dr Dixon, a visiting fellow at the ANU and Adjunct Professor at UQ, says.
But there was a gap in this critical knowledge for Africa and implications for global food security.
Filling this gap has led to new methods that the team is now applying to map Australian cropping margins under future drought scenarios.
Frontier shifting viable cropping land to pasture
“We looked at 12 climate models that worked well for Africa, and picked three representing a range of future scenarios,” Dr Nidumolu says.
Agropastoral farming systems span 20 African countries. The models showed that the climate frontier line is pushing into the agropastoral region, turning it into pastoral land and changing the viable land use from a mixture of cropping and livestock to only the latter.
At the drier edge of the margins, “sustainable cultivation of rainfed crops is generally not possible”, the paper states. Not dissimilar to the desert expanding, Dr Nidumolu explains.
“Now we can discuss what’s projected for these regions, and that can lead to thinking about potential solutions,” he says.
Supporting African farmers to adapt
Dr Dixon has spent much of his career working on flexible and sustainable adaptations of farming systems.
“Africa has had forever changing land-use patterns, partly in response to changing climate,” he says.
“However, we’ve never witnessed the rate of change that we expect to see in the next 100 years. These changes are massive, fast and will disrupt the old ways of life.”
Nevertheless, he says there are adaptations that can build resilience for agropastoral systems.
“Conservation agriculture is a way of establishing crops without ploughing the land,” Dr Dixon says.
“This conservation agriculture and farmer-managed natural regeneration have been demonstrated across large areas of West African countries, and also some southern African countries,” Dr Dixon says.
“Opportunities include water harvesting, conservation agriculture, agroforestry, drought-tolerant varieties with improved markets, and farmer training, including targeted low levels of fertiliser.
“These could all dramatically boost the resilience of the farming landscapes of the agropastoral system.”
It doesn’t happen overnight, but the team is pleased the research is sparking global discussion around farming adaptations.
“If action is taken now there is enough time for substantial proofing of these systems before the worst of climate change impacts these agropastoral systems.
“African and Australian scientists have the knowledge; we’ve demonstrated how to improve these African agropastoral systems.
“Now we need to support these farmers to adopt and make effective use of these improved adaptive farming methods.”
CSIRO is also working on climate resilient adaptations for global agriculture. This includes information rich farming systems, improved and reliable climate forecasting and new resilient crop varieties.
Dr Nidumolu admires how Goyder deployed scientific thinking to draw his cropping line back in 1865 at a time when blind optimism was driving farmers to plant crops in zones that would never yield reliably.
He and his colleagues would never compare themselves to Goyder, but hope their work will be a valuable contribution for the livelihoods of global farmers.