This case study shows the value of examining climate data to supplement, confirm and clarify direct observations. However, it also illustrates the challenges in using climate data, especially when there are gaps in the historical record, a
nd models of future climate change show no clear patterns in the medium and longer term. Looking at the future of Bagamoyo district, there is a great deal of uncertainty about climate hazards. No single, clear message emerges from our
analysis, and the climate data graphs require careful reading and interpretation. We learned that it is important to be cauti
ous in predicting the future, and to compare different sources of data. This is a particularly sensitive issue in dealing with stakeholders’ perceptions of climate risks. While it is important to document and acknowledge those perceptions, they need to be checked against the available data to ensure a more comprehensive view of the issues. People are al
so likelier to remember accurately what has happened over the past few years than over longer periods. At the same
time, we need to remember that any one weather station provides a very limited view of climatic conditions.
The comparison of historical data with local perceptions reinforces the need to use multiple sources of evidence when assessing climatic changes. It also shows that as questions become more specific, more detailed and time-consuming analysis is needed. Another key insight is that climate data only tell us so much. Models can give us a sense of
how patterns may change, for example – but to know whether heavy rains will cause floods, or significant damage, we need to look at the hydrology of the region, and how land use changes, for example, might have increased flood risks. (Similarly, as we noted earlier, saltwater intrusion is a common problem when groundwater is pumped in coastal areas – with or without sea-level rise.) The clearest trends we see are in maximum temperatures and the number of very hot days
(>36 ° C), both of which seem likely to increase in the Bagamoyo area. This raises serious concerns for farming activities (with higher evapo-ranspiration rates and affecting the overall crop production cycles), including seaweed fa
rming, which tends to be sensitive to temperature increases as well. In addition, an increase in the number of hot days
has serious implications for health, potentially affecting the labour availability in the area. Shifts in the rainfall patterns place additional stress on agriculture. This reinforces the need to find alternative agricultural practices (e.g.
conservation agriculture 19 or other “climate-smart” agriculture practices), the introduction of new seed varieties (especially for maize, a staple crop), and drought-tolerant crops such as cassava, which is also an important source of
household food security in the Bagamoyo area. Whether or not climate change is the main cause of Bagamoyo’s saltwater intrusion and soil salinization problems, clearly those issues need to be addressed. Tanzania’s NAPA includes
several measures to protect coastal water resources and reduce local people’s vulnerability to water scarcity.
20 It may also be helpful to look for salt-tolerant crop varieties and trees that can withstand more saline conditions. Likewise, coastal erosion is a well-known problem in Tanzania, and several strategies can be implemented to address it – from curbing illegal sand mining, to increasing coastal forest buffer zones.