Climate problem targeted

Climate change is a serious and cross-cutting issue, and the European Union has recognized it through the adoption of an EU Strategy on Adaptation to Climate Change (COM (2013)2016). Urban areas are particularly sensitive to climate impacts, especially to heatwaves, floodings and droughts.

Typically, urban phenomena (such as the ‘urban heat island effect’ – where the urban area is significantly warmer than the surrounding rural areas) and the impacts of extreme weather events demonstrate the high vulnerability of cities.

Specific urban adaptation strategies are therefore needed to make cities more resilient. In this context, green areas and infrastructures are seen among the most widely applicable, economically viable and effective tools to combat the impacts of climate change and help people adapt to or mitigate adverse effects of this change.

Green areas for climate change adaptation (and mitigation)

Urban heat island effect

Typically, urban areas have higher average temperatures compared to the surrounding rural areas. Materials commonly used in urban areas, such as asphalt and concrete, store a lot of solar energy and can remain hot long after sunset, creating a phenomenon known as the urban heat island effect. Increased urban temperature can cause heat wave periods leading to heat stroke and respiratory problems among the elderly and increasing the energy usage for air conditioning and refrigeration in work places and homes.

water balance

Green areas in cities have an important role in the water balance. Trees regulate the hydrological cycle and help to reduce the impacts of heavy rains by intercepting, infiltrating, and evaporating significant amounts of rainwater. Strategic tree planting and maintenance of existing street trees can decrease storm water runoff, reducing the impacts of urban floods.

Cooling and increased air quality

Trees and vegetation have a natural cooling effect, providing shade to the surrounding places and constructions. In addition, vegetation absorbs a significant proportion of the available heat energy in the atmosphere and use this energy to convert water stored in the leaves into water vapour, which is then transpired through the trees (evapotranspiration). Urban greening is also an effective way to reduce concentrations of CO2 and pollutants in the atmosphere.

The importance of green areas efficient management

Urban green areas are spaces where natural processes, such as evapotranspiration and rainwater interception and infiltration, can occur, ensuring the provision of safe, healthy and pleasant urban spaces. On the contrary, common practices, such as tree felling to reduce hazards near roads, development of infill in gardens and redevelopment of biodiverse “urban wastelands”, degrade the ability of the city to regulate temperature and provide other valuable services to inhabitants.

Ecosystem services commonly provided by urban greenery are often overlooked and undervalued!

The management of urban green areas is a challenging task, which can even bring to unsustainable results, possibly bringing to paradoxical statement such that “Urban ‘green’ spaces may contribute to global warming”: greenhouse gas emissions from fertilizer production, mowing, leaf blowing and other lawn management practices can be up to four times greater than the amount of carbon stored by ornamental grass in parks.

It is clear then, that guidance and innovative tools are needed for local authorities and other practitioners on how to manage public urban green spaces to respond to a warmer future. This is the challenge that LIFE URBANGREEN aims to target.