Climate change is touching every aspect of our lives – including our daily cups of tea. Kenya and Malawi are the African continent’s largest tea producers and exporters, together accounting for about 27%Global tea trade
Tea producers in both countries have seen the effects of climate shifts. damaging droughts. frost high temperaturesThey are already more common. This threatens tea yields as well as the countries’ economies. It also affects those whose livelihoods depend on tea estates, farms, and the wider value-chain.
Generic climate projections are not often useful for African tea growers. That’s because these projections focus on changes in average conditions. Temperature extremes are the greatest threat to tea crop production. Tea growers need information specific to the tea variety and where it is grown, as well as average temperatures and rainfall across a large area.
Tea growers need to know what the future will look like because the tea plant can live for more than 80 years. It is important to make decisions now that will be sound in the long-term, such as replanting with resilient cultivars, planting shade trees, and crop diversification.
We have developed novel, site-specific climate information for Kenya and Malawi’s tea-growing regions. This, we hope, can better inform tea producers about the range of climate conditions they can expect in the future – specifically, the 2050s and 2080s.
Our researchIt was found that the nine locations studied would experience more heatwave days. This will increase heat stress and decrease yield in tea plants. Tea quality could also be affected by the likely decrease in cold nights by 2050s. The impact on specific locations will vary depending on the location-specific conditions. Some sites will experience small increases while others may see an increase of over 100 heatwave days each year.
It is important to have such tailored climate information because of the significant differences in future conditions. It allows tea managers and tea farmers to choose adaptations that are suitable for the conditions and the desired outcome. These adaptation options can also be determined based on the tea variety grown and the size of the plant.
We partnered up with tea growers in Malawi, Kenya, and other countries to help them understand the climate data that would be most useful in planning and managing their farms to maximize yield and quality.
The tea plant is sensitive heat. It can only withstand heat for a very short time before it becomes damaged. This threshold is specific to different tea varieties and places. For example, in Kenya tea growers want to know about consecutive days with temperatures exceeding 27°C. In Malawi, tea growers asked for 35°C as the threshold beyond which their tea bushes face heat stress.
Then, we combined two sources of data. The first is hidden weather data – observations of temperature and rainfall held in tea estate weather station records. The second is future projections for the 2050s and 2080s from the latest high resolution climate models, including a new convection-permitting model vital for predicting climates in mountainous regions. These models better represent the small-scale atmospheric phenomena that cause extreme weather events in these regions.
To examine uncertainties in future rainfall and temperature changes, we used projections from a collection of 29 global climate model suites. These projections were combined (4.5 km) with a new high resolution climate model. CP4AThe first high-resolution model for Africa. It can capture the small-scale atmospheric processes that create micro-climates.
These micro-climates, which are crucial for tea growth, are not usually discernible in standard global climate model resolution. As a result, the average conditions projected by global climate models over large areas aren’t of much use to tea farmers.
These model projections were combined with historical evidence from past weather conditions to create a map of climate risk for several decades.
We shared the projections and other feasibility criteria with tea growers. These projections, along with other feasibility criteria such as economic viability and social and environmental benefits, helped them to identify emerging risks and potential adaptation strategies.
The tea growers also pointed out that having more detailed information about what might happen to the local climate means they’re better able to garner government support for preferred adaptation options including afforestation and crop diversification.
It is essential to continue such discussions to identify and prioritize adaptation investments to ensure that tea production and quality are not affected and that the sector remains vibrant. Hidden weather data and new climate models will help to sustain our daily cup of tea – and, more importantly, support economic growth and livelihoods in both Kenya and Malawi.