Have temperature regimes

changed over time?

Mossel Bay (1920-2014) annual regime shifts:

1. 1935-1936 = increase 2. 1952-1953 = decrease 3. 1996-1997 = increase 4. 2007-2008 = decrease*

*But station change could influence results Riversdale (1973-2013) annual regime shifts:

1. 1996-1997 = increase 2. 2004-2005 = decrease*

*But station change could influence results

 Mossel Bay and Riversdale annual time series were consistent with each other in 1997 to 1998 with a shift of increasing temperature.

 Mossel Bay seasonal time series are in agreement with annual time series of shift to warmer period in late 1990s.  Riversdale spring time series in agreement with annual

and coastal seasonal time series of shift to warmer period after mid-1990s.

 Both stations adjusted downwards in annual and seasonal time series to a cooler temperature regime period from mid 2000s; however this is possibly due to station change for both sites over this period and results should be treated with caution.

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Temperature displayed significantly cooler and warmer periods over time, with a long cooler period experienced from the 1950s to mid-1990s and again after the mid-2000s. On the coast, a warm period occurred between 1940 and 1950 and both inland and coastal temperature data sets indicated a clear warm period from the late 1990s to mid/late 2000s. At both observation stations, spring was the season most sensitive to regime shifts for temperature. These shifts in temperature in the 1990s correspond findings in regime shifts in the southern Benguela marine ecosystem by Blamey et al. (2012). While temperature shifts in the late 2000s are also possibly in agreement with marine findings (Blamey et al., 2015; Jarre et al., 2015), these should be treated with caution due to station gauge changes in both coastal and inland locations during this time period.

4.4.4. Summary

Data from both rainfall and temperature time series in the research area showed complexity and high variation, only displaying subtle changes over time rather than clear- cut trends. Experiences of farmers were largely in agreement with rainfall variation within different areas and catchments, particularly when seasonality was considered with the later onset of seasonal autumn rainfall since the mid-2000s. Across the catchment areas, the western and central extent of the research area experienced an increase of dry spells over time. While the eastern extent of the area experienced the highest frequency of dry spells before 1981, there is an increase in dry spells after the early 1980s to present. Increased dry spells and commonly occurring extreme outliers of temperature that tend to fall above average could have significant impacts on farming livelihoods in the research area. The eastern extent of the research area also experienced an increase in extremely high rainfall months since the 1980s, again showing complexity at a local scale and that change is not necessarily a uniform experience for farmers located in the area.

Change in temperature patterns were more difficult to discern from a farming perspective and analyses did not clearly link changes in temperature regimes to subtle changes in rainfall patterns. It should be noted that temperature analyses were limited to only one coastal and one inland point, whereas rainfall data sets were more abundant and

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could therefore examine fine-scale changes at a local level in more detail. Findings from terrestrial temperature stations indicating warming in the late 1990s could signal a shift in the larger system and this is in agreement with work carried out by Blamey et al. (2012) on the marine component of the ecosystem. To better understand terrestrial changes in climate patterns in the research area and contextualize subtle changes within a broader scale in this coastal region, it will be useful to overlay terrestrial climate variability with changes in the local marine system.

4.5. Conclusion

In conclusion, points highlighted from this chapter include:

Rainfall:

 Corroboration of farmers’ observations on rainfall changes and analyses of rainfall patterns over time;

 No clear, significant trends of change over time in rainfall and temperature time series but decadal-scale variability present;

 Increasingly more dry spells experienced since 1980s across all three catchment categories and vlakte area;

 The eastern extent of research area experienced an increase in extreme monthly rainfall events since the 1980s;

 Across the research area, the onset of seasonal autumn rainfall has shifted to a month later after the mid-2000s.

Temperature:

 Analyses showed clear seasonal differentiation in temperature that were in agreement between the coastal and inland stations;

 Coastal temperatures displayed more variability in comparison to inland temperatures;

 Outliers were more prevalent for warmer temperatures, particularly in winter months;

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 Inland and coastal temperature annual time series were consistent with each other for shift to warmer regime in late 1990s until mid/late 2000s, which correspond to regime shifts in the southern Benguela marine ecosystem.

Scale:

 It is important to consider fine geographical scale as weather patterns differ within and across research area, as evident in results;

 Changes in rainfall patterns differed across catchments and areas could potentially give greater insight in challenges faced by local farmers;

 The warmer temperature regime of the late 1990s into the 2000s could indicate a larger shift in the system, thus it will be useful to overlay terrestrial climate variability with changes in the local marine system;

 Fine-scale complexity is important to understand within the broader context of climate variability and how this influences local livelihood strategies under change.

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CHAPTER 5