Wednesday 23 October 2013

The Year of Unprecendent Climate in African Cities

There is increasing evidence that greenhouse gases emissions are influencing our climate. To date, many of these changes could be described as 'precedented' or 'having occurred before in recent history'. The ‘precedented’ nature of these climate change events may be one of the reasons why global warming has not been addressed urgently, as these events are seen as part of the natural course of events. 

However a recent paper in the journal Nature draws on earth systems models  to show that in the near future the earth will begin experiencing unprecedented climate caused by global warming. Unprecedented climate refers to a situation where climate moves outside the range of historical precedent defined as a ‘shift continuously outside the most extreme records experienced in the past 150 yearsThis condition is shown in the graph below in red, with the blue and green areas indicating the first 3, and 11, years outside precedent. 

The paper goes on to plot specific dates for world cities when this condition will be experienced. In Africa this will occur in Nairobi in 2026, in Pretoria in 2043 and in Lagos in in 2029. This is shown in the figure below.

The dates listed in the paper are in the near future and have significant implications for the built environment that need to be considered and addressed. These include:
  • Local effects: Impacts of climate change will differ depending on location. Climate impacts such as flooding, extreme winds, drought need to be understood at a local level and local resilience and mitigation plans developed. Resilience and mitigation plans should consider sustainability (using for instance a framework such as the Built Environment Sustainability Tool (BEST))  and ensure that measures not only improve levels of local resilience but also sustainability. Gauge is also working on a resilience tool and integrating aspects of resilience into BEST.
  • Urban design and planning: Consideration of local impacts of climate change should be integrated into local development plans such as Integrated Development Plans (IDPs) and Spatial Development Frameworks (SDFs) to ensure that new development is appropriately located and resilient as well as strengthening existing area.
  • Buildings: Local impacts of climate change such as increased wind speeds and flooding should be reflected in more stringent building codes. This can be addressed through revising building regulations and national technical standards as well as through municipal bylaws. 

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