Identifying, assessing and minimising the risks

Hazard identification and assessment

Future climate change predictions for a given area are considered initially in terms of what the specific hazards will be. Consideration should be given to the likelihood of hazards given different future CO2 emissions scenarios. The UKCP09 projections indicate changes in daily temperatures in winter and summer, and changes associated with precipitation. For example, in London the annual number of days when temperature is over 28°C is expected to increase from a baseline of 1 in 1990 to 28 in the 2050s and the number of days when precipitation is over 25mm will increase from 3 in 1990 to 18 in the 2050s. As a result, hazards such as those below can be derived:

• increased frequency of flooding, storms and heavy/prolonged precipitation events;
• increased seasonal precipitation;
• increased summer temperatures, drought and frequency/severity of heatwaves; and
• extreme cold weather, snow and ice.

Risk estimation

Consideration is given to the location of the development in terms of urban/rural setting as well as susceptibility to flood risk. Next, the make-up of the actual development is analysed, taking account of issues such as basement areas, foundations, building massing and areas of external landscaping. As a result, potential risks are identified that may include:

• urban heat island effect;
• increased flood risk;
• water shortage and drought;
• subsidence; and
• extreme weather events.

Risk evaluation

Taking account of the above climate hazards, each risk is assessed in terms of its severity/magnitude/consequence, probability and level of influence over the risk/opportunity. This allows the most significant risks to be understood and mitigated against. For a typical major development in a main city location the primary risks may include:

• safety issues for residents or building users from flooding;
• damage to plant or cars parked in basement areas;
• loss of trading through access being lost to site;
• overheating and associated health issues;
• increased energy requirements for cooling;
• failure of planting; and
• water shortages.