Climate Sense

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specifications. Such modelling should inform more long-range urban

management applications, such as definition of lands that will be at

risk of flooding and are to be covered by a hazard setback ordinance.

For other sorts of climatological phenomena, while climate change

projections generally agree, taking action seems to be a low priority for

local decision-makers. This is the case with addressing projected heat or

cold waves, as well as mean temperature rise. While responses such as

modernized building codes are possible, to date suchmeasures have not

attracted priority attention in the CCCI countries. This is because other

issues such as flooding are seen as more urgent – despite the real havoc

that heat or cold waves can cause (the heat wave that struck western

Europe was blamed for killing more than 35,000 people). At present

none of the pilot cities are planning to undertake more sophisticated

localized modelling of temperature change, such as taking into account

radiation from asphalt and paved surfaces.

Implications for the World Meteorological Organization

and partners

Research leading to a higher level of convergence among projections

is a priority. This is particularly the case where localized projections

disagree as to the direction of change, as the CCCI team

in Esmeraldas found with projections for mean precipi-

tation. However, different models will always yield

somewhat different results, so increased capacity-build-

ing for officials and urban managers as to how best to

pick and choose between conflicting projections when

this issue materializes would be of great assistance.

Establishing and operating meteorological stations that

collect data of adequate quality and quantity is impor-

tant. Several decades of trends of changes in temperature,

rainfall, mean sea level and similar phenomena help

local decision-makers to convince a sceptical public

about the risks. They also serve as an important refer-

ence point when taking up regional climate projections.

Furthermore, local weather stations need to be able to

support urban or river basin-level hydrological modelling

with adequate data. Efforts at local modelling and subse-

quent risk and vulnerability mapping run into difficulties

if only one local station is actively collecting data, and

where daily but not hourly rainfall data are available.

Some actions, fromthe perspective ofmid-sized cities in the

developingworld, appear to be of lower priority. Researchers

suggest that much work remains to be done to generate site-

specific urbanized data, by developing advanced models

based on computational fluid dynamics.

However, to the

CCCI cities such sophisticatedmodelling (particularlywhere

the outputs would focus primarily on improved projections

ofmean temperature andheat waves)would be a lower prior-

ity than an improved hydrological model of the city. This is

because a family will be more concerned as to whether their

house will be swept away due to flooding than about a more

precise projection of future temperature rise.

Future scenarios

In an uncertain world, local officials and planners crave

certainty upon which to base decisions. Where such

certainty is not possible – as it rarely if ever is – officials at

least desire clear future scenarios that they can understand

and explain to constituents. When making decisions plan-

ners have often sought out vulnerability assessments based

on a clear future scenario (a 100 year flood event), rather

than full-blown probabilistic analyses of various risks.

Full-scale risk analyses have not been used extensively for

planning purposes, possibly because planners and local

officials are less familiar with these concepts and methods,

and because of the relative paucity of land use manage-

ment tools based on risk rather than vulnerability.

This preference for certainty is as deeply, if not more

profoundly, felt in the new and relatively unfamiliar

terrain of climate change. UN-HABITAT welcomes

the recent surge of interest in the urban dimension of

change, for example the upcoming IPCC Expert Group

Meeting that will take up the topic, and a special report

on human settlements being prepared for the IPCC’s

fifth annual meeting. UN-HABITAT’s hope is that such

research will lead to projections that are more useful to

practitioners at the city level, and that will allow plan-

ners to embrace a fuller range of tools to address climate

change in all of its various manifestations.

Detailed mapping of road interruptions and damages along

Avenue Julius Nyerere, Maputo

Source: UN-HABITAT, Climate change assessment for Maputo, Mozambique, 2009

A: New trajectory of Avenue Julius Nyerere and alternative way to Avenue

Marginal Maputo. B: The point where the bridge fell down and evident source of

soil erosion during the rainy season. C: Second point of the avenue interrupted.

Pavement damaged and source of soil erosion during the rainy season. D:

Confluence zone of material, soil erosion and water during the rainy season and

infrastructures of Costa do Sol Stadium use to be affected