James Voogt is taking London’s temperature.
The tiny heat sensors his research depends upon hang unobtrusively on building walls and sit on rooftops. Some, attached to a research truck, roam the streets. On occasion, they are mounted to tall towers or on aircraft.
It’s a novel approach intended to help understand the degree of temperature swings in London over time. Voogt hopes to learn how the city is affected by climate change and offer clues for devising more effective strategies to deal with it.
“You can tell what the atmosphere is doing by looking at the surface,” the Geography professor explained. “Conditions in the lowest parts of the atmosphere are strongly influenced by characteristics of the surface. Because surface characteristics are so different in cities, this means they are able to create their own urban climate.”
Temperature readings of surfaces within the city are far more precise than those emanating from weather at the airport, for example, or from satellites spinning 35,000 kilometres above London. The data generated by these sensors will also help understand how urban areas influence the atmosphere above them.
Satellite sensors have limitations – they cannot capture the temperature variations of buildings, pavements and roads, each of which absorb and reflect sunlight in different ways, depending on their colour and material.
Voogt’s sensors provide a more complete picture of the temperatures of the complex, three-dimensional surfaces characteristic of cities. That information will help build more powerful computer models for accurate weather forecasting and climate-change predictions for cities.
Global warming will affect cities disproportionately, compared with rural areas. The concrete, asphalt and other construction materials used to pave roads and construct buildings readily absorb sunlight and raise local temperatures to a higher degree in cities. That warming effect in rural areas is often mitigated by vegetation and other natural features.
The dearth of data about climate change in urban areas has even been highlighted in the latest report from the Intergovernmental Panel on Climate Change (IPCC), an organization that shared the 2007 Nobel Peace Prize with Al Gore and Western Geography professor Gordon McBean for its work on climate change. That report noted, “urbanization is missing from climate model projections.”
Voogt recently participated in the first CitiesIPCC meeting in Edmonton in March.
In the coming years, cities will get bigger and more crowded, contributing to more extreme weather patterns, including intense precipitation and extreme heat waves and increased surface temperatures, he said.
In August 2003, for example, Europe had its hottest summer since 1540. For 10 days, heat waves swept through most major cities. Dehydration, hyperthermia, heat strokes and respiratory problems were blamed for the deaths of more than 70,000 people.
Climate change models predict that by 2050 such intense, week-long heat waves will become almost commonplace – striking Eastern Europe once a decade, and Western Europe once every 15 years. Across the globe, the number, duration and frequency of heat waves is projected to increase.
At the same time, cities are important sites of activity that drive more than 70 per cent of greenhouse gas emissions. This means that cities are important sites both for climate change mitigation efforts, intended to reduce our greenhouse-gas emissions, and climate-change adaptation, which can help cities cope.
In the specific case of London, Voogt’s research can identify ‘hot spots’ city planners and politicians can focus on in designing strategies to reduce temperature – planting trees or increasing the surface reflectivity, for example.