Africa’s Climate Challenges

Africa is arguably the most diverse continent on Earth. This incredible land stretches across the equator from the northern extratropics to the southern; deserts keep company with rainforests and snow-capped mountains overlook savannas. Ancient tribal religions mix with Christianity and Islam, and people from a multitude of cultures converse in one of the thousands of languages spoken. And now, Africa must be prepared for a diverse range of climatic changes, from increased rainfall in eastern Africa to drying in the far north and south but with more intense events when it does rain.

Organisers and Chairs at the Africa Climate Conference 2013

At the end of last year I attended the Africa Climate Conference 2013 in Arusha, Tanzania. For me the most interesting aspect of this conference was the effort to combine scientific, social and political frameworks, with much for all scientists to learn on how to make our research applicable and useful to those who need it most.

Scientific Challenges

From a scientific viewpoint the meeting highlighted the difficulties of predicting Africa’s future climate. Rainfall over much of the continent is controlled by the tropical rain belt, or inter-tropical convergence zone (ITCZ). This is a zone of intense rainfall largely forced by solar heating of surface air which then rises, resulting in convection. The ITCZ therefore has a seasonal cycle in line with that of the solar equator; it moves northwards during northern hemisphere summer and southwards during winter. However, the exact location of this rain belt can be influenced by other atmospheric conditions, for example local temperature gradients. A small shift in the average location leads to very large changes in rainfall for regions at the edge of the belt, with regions experiencing rainfall increases neighbouring those seeing decreases. Accurately projecting future shifts is difficult and there remains a lot of uncertainty. Another scientific challenge lies in the prediction of future drought frequency, of paramount importance to millions of Africans. Future changes in extremes are much harder to predict with confidence than changes to annual average temperature or rainfall. This is in part due to both computational restraints and the relatively limited amount of observational data available with which to validate modelling results.

But with these challenges come opportunities for novel and exciting research. This is true particularly in the coupling of climate and forecasting models with the different components that make up the environment we live in. One example, which should help save many lives, is an operational dynamical malaria forecasting system for Africa. A dynamical malaria model predicts the likely abundance of malaria-transmitting mosquitoes based on rainfall amounts, surface temperatures and environmental factors such as land use type. The model even takes into account local population density in order to calculate its primary output: a prediction of the malaria transmission rate for a particular localised region. Combined with ECMWF forecasting capabilities this model will be able to provide seasonal forecasts of malaria transmission rates. These predictions will inform intervention schemes and regional medical requirements.

Social Challenges

Advances in our understanding of the atmosphere, combined with increasing computational resources, have resulted in great improvements in African forecasts and future projections. But even if we knew everything we could about the interactions that produce African weather and had a perfect forecasting model, social challenges would remain, preventing the optimum use of this hypothetically amazing forecast data. Bear in mind that, thanks to chaos, an element of uncertainty will still exist in our ‘perfect’ forecast.

Getting a seasonal forecast to the millions of farmers who have no internet connection is hard enough, but how do you rapidly disseminate warnings of imminent extreme events to those who need it most? Mobile phones have their uses here, but some rural Africans are still dependent on local radio announcements for news. The building of an efficient infrastructure to link the forecast providers with the forecast users was identified as a key area requiring immediate development.

So let’s imagine that we can successfully distribute accurate forecast information to the people who could make use of it; we’re done now, right? Sadly, communicating science is never that easy! One fascinating concept raised during this conference concerned trust and the ‘ownership’ of forecast data. Recent research shows that people are more likely to act on forecast data if they feel some sense of ownership of the data: if they have been a part of the production process or at least have an active role in providing feedback that is used to improve future forecasts. If a forecast has been given to you, with no explanation of where the information came from and how it was produced, would you trust it a second time if it was wrong once? What if the people who made it didn’t even know it was wrong for you? A basic understanding of how a forecast is produced and the ability to feedback into this process are fundamental to making the best use of the data.

Similarly, scientists will be able to provide information of greater practical use if they have better understanding of the decision-making processes of the various forecast users. At this point it seems we can turn to games to help us; at the African Climate Conference the CAULDRON game was played by a mixture of scientists and decision-makers. The game is designed to develop understanding of the roles, requirements and priorities of the various stakeholders involved in using forecast information. Who says learning can’t still be fun?

Another social aspect concerned the indigenous forecasting knowledge hidden in African communities. Indigenous forecasting methods are based on observations of the local environment over many generations. But many of these techniques are being lost in a new generation less interested in keeping old traditions alive. Documenting and scientifically assessing this knowledge is an incredibly sensitive task, but must be done if we are to gain understanding of how such methods work, which are the most accurate, and how such knowledge can complement scientific modelling results.

Policy Challenges
Africa also presents some interesting policy-related issues. One rather curious feature of future climate projections is the prediction of an increase in rainfall over East Africa, in stark contrast to the drying trend seen over the past 10 years. The task of policy development to deal with the opposite problem to that which currently exists is pretty tough. One answer is to design policies that provide future flexibility and multiple pathways. This way the final solution will be a result of many choices, each made at some point in the future time as we learn more about likely climate impacts. A good example of such planning in the UK is the Thames Estuary 2100 Plan, which incorporates thresholds and defined decision points to give flexible, progressive, adaptation. Another policy-related challenge is how exactly to measure the impacts of climate-related disasters. Sometimes the knock-on effects can be greater than the direct impact on human life. For example, a flood event may occur with no immediate deaths and few injuries; however there can be serious subsequent impacts on water availability, electricity supply, access to health care facilities, and access to trade routes resulting in food shortages. These indirect effects can often have more impact on human life than the direct effects that are often the only official measure.

Scientific + Social + Policy Challenges….

Many of these challenges are not unique to Africa; however Africa is perhaps unique in combining so many together. It is a complex task that lies ahead for physical and social scientists, politicians and decision-makers, forecast-makers and forecast-users, to work together to meet these challenges. Together we can help Africa adapt as best as possible to the changes that will come.

Kilimanjaro, Africa's highest mountain

Kilimanjaro, Africa’s highest mountain

And as for personal African challenges, if you ever have the opportunity to climb Kilimanjaro I can wholeheartedly recommend the experience!

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Rachel White

I'm a Post-doc in atmospheric and ocean physics at Imperial College London. I'm interested in many aspects of climate physics, with current work on the influence of rivers on ocean temperatures, and cyclones in the south-west Indian Ocean. My previous research has improved the modelling of runoff and investigated ways to improve biases in the general circulation model forcing of regional climate models.'

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