Beautiful, Multifunctional, Impactful, and Cost-Effective: Why Greening Cities Should Be a Pillar of Climate Action
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This summer’s extreme weather conditions battered most of Europe. In the North of the continent heavy precipitations devastated large part of Belgium and Germany. This had a dramatic human impact. In the South, wildfires ravaged large areas in Spain, Italy and Greece. In Sicily, Italy, the mercury column reached 48.8 °C (nearly 120 °F), the highest temperature ever recorded in Europe. Sadly, these events were not limited to Europe: extreme weather was a phenomenon witnessed by communities across the globe, showing that even some of the world’s richest countries remain unprepared for the intensifying consequences of climate change.
Unless significant reductions in CO2 and other greenhouse gas emissions occur in the coming decades, the global temperature will increase above 1.5 °C and the consequences for the health of planet Earth and for humanity will be dire.
On August 9, 2021 in the Sixth Assessment Report of the United Nations Intergovernmental Panel on Climate Change, 234 scientists, from 66 countries reminded us that unless significant reductions in CO2 and other greenhouse gas emissions occur in the coming decades, the global temperature will increase above 1.5 °C and the consequences for the health of planet Earth and for humanity will be dire. The report findings, grounded in an evaluation and agreement of underlying evidence resulting from a major review of over 14.000 scientific papers, highlight that human influence has warmed the climate at a rate that is unprecedented in at least the last 2,000 years. And human-induced climate change is the cause of many weather and climate extremes in every region across the globe.
Regrettably, many changes due to past and future greenhouse gas emissions are irreversible, especially changes to the ocean, ice sheets and the global sea levels. Others can be addressed with effective mitigation and adaptation actions. The scientists are hopeful that if we can cut global emissions in half by 2030 and reach net zero by the middle of this century, we can halt and possibly reverse the rise in temperatures.
Hear from Luigi Petito at the International Market and Project Showcase during CitiesAlive Virtual on November 11, 2021
In cities for example, we can reverse the trends if we renature urban areas. By interweaving green infrastructure with the built environment, we can tackle some of the effects of human-induced warming locally. At the same time, we can limit further urbanization, which, according to the IPCC report, will increase the severity of heatwaves as well as mean and heavy precipitation and resulting runoff intensity.
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The findings of a recent scientific report published on Nature in June 2021 are inspiring. The authors carried out a European Union (EU)-wide assessment and quantification of the benefits of urban greening in terms of availability of green water, reduction of cooling costs and CO2 sequestration from the atmosphere, for different climatic scenarios. Results show that greening 35 per cent of the EU’s urban surface (i.e., 26,000 sq km/16,000 sq mi) would avoid up to 55.8 Mtons/year CO2 equivalent of greenhouse gas emissions, reducing energy demand for the cooling of buildings in summer by up to 92 TWh per year, with a net present value (NPV) of more than 364 billion Euro.
Greening approximately 1/3 of EU urban areas would also transpire about 10 cubic km/year of rain water, turning about 17.5% of the “blue” water that is now urban runoff into “green” water, thus helping to reduce pollution of the receiving water bodies and urban flooding. In addition, greener urban surfaces would decrease cities’ summer temperature by 2.5–6 °C, with a mitigation of the urban heat island effect estimated to have a NPV of 221 billion Euro over a period of 40 years. The monetized benefits would cover less than half of the estimated costs of greening, having a NPV of 1.323 billion Euro on the same period. Yet, net of the monetized benefits – which do not include the additional benefits of urban greening related to biodiversity, water quality, health, wellbeing - the cost of greening would be just around 60 Euro/year per European urban resident.
Every policy and decision maker should be guided by the report’s findings when devising urban planning strategies, building renovation programmes and more generally climate mitigation and adaptation actions.
Green roofs can provide open and recreational space that is essential for supporting mental and physical health and well-being in dense urban areas.
Something that deserves attention is the positive social and health impact of greening the urban environment. The Covid-19 pandemic, at its peaks and during the lockdowns, changed the way many people viewed and interacted with the natural environment. Everyone has been forced to reflect on why green and blue infrastructure that can be installed on billion of square meters of roofs and impervious surfaces which would be otherwise unused, are essential infrastructure supporting mental and physical health and well-being. The beneficial socio-economic and health effects of green infrastructure are tremendous and have been widely researched since many decades. Very interestingly, a literature review carried out by the World Health Organization, highlights that urban green space has health benefits particularly for economically deprived communities, children, pregnant women and senior citizens. It therefore suggests ensuring proximity and adequate access to green space, with priority placed on provision for disadvantaged communities.
At the forthcoming COP26 Global Climate Change conference, that will take place in Glasgow, Scotland next November 26, leaders will seek to achieve further cooperation and commitment to address the climate crisis. They need to act fast and scale up sustainable solutions that are already available. Green infrastructure is one of those solutions: beautiful, multifunctional, impactful and cost-effective. There will be no regrets. What are we waiting for?
Luigi Petito, 45, father of two, is an expert in European public affairs. He is based in Brussels, a cross-roads for international affairs and the European Institutions. In 2019 he was invited to establish and lead the EU Chapter of the World Green Infrastructure Network. Since then he has followed policy and regulatory developments related to green infrastructure and advocates for a more systematic integration of green infrastructure in urban areas.
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Email Luigi at luigi.petito@wgin.org or follow the World Green Infrastructure Network on Twitter at @WGINetwork
Learn more about international green roof and wall markets at the International Market and Project Showcase during CitiesAlive Virtual on November 11, 2021
