The summer of 2003 was a landmark in risk assessment and climate change consequences. In July and August of that year, many European cities suffered the most severe heat wave in the continent since 1540. Paris was the most affected metropolis and, across France, about 15 thousand people died; Italy, Portugal, the Netherlands, Germany and the United Kingdom also recorded thousands of deaths from extreme temperatures.
Heat waves are climate phenomena that have been around forever. The problem is that global warming is making them more frequent and more intense. On top of that, urbanization intensifies their impacts: big cities are usually hotter and have lower ability to drain huge volumes of water when it rains heavily within a short time.
Impermeable surfaces (abundant asphalt and concrete), anthropogenic factors (large influx of cars and people), water deficit (low presence of water sources and plants) and urban geometry with buildings too close of each other (the so-called “skyline factor”: the less I see the skies, the warmer it is) are the main agents forming heat islands in urban agglomerations.
Therefore, to manage or even reverse climate change impacts, big cities should rethink their organization. Today, investments target two strategies: mitigation of global warming’s harmful consequences and infrastructure adaptation to such changes.
Mitigation: Reducing emissions no longer enough
Already in 2012, Brian Stone Jr., urban planning professor at Georgia Institute of Technology, predicted in his book “The City and the Coming Climate: Climate Change in the Places We Live”, that reducing greenhouse gases would not prove sufficient to measurably slow the rapid pace of warming in urban environments.
The common presumption at the time was that climate changes could be successfully mitigated before their effects became irreversible. However, the special report Global Warming of 1.5 ºC, a research by the Intergovernmental Panel on Climate Change (IPCC), indicates a point of no return. The planet is already 1.1 degrees Celsius warmer and, according to the Paris Agreement, we should limit such warming to 1.5 ºC and in no way let it reach 2 ºC. “We’re far from the ideal and we’re heading to go over 3 ºC by the end of the century,” said Andrea Santos, executive secretary of the Brazilian Panel on Climate Change (PBMC).
What is the IPCC?
IPCC is an acronym for the Intergovernmental Panel on Climate Change. This is a political-scientific organization founded in 1988 by the UN. Its aim is to synthesize and disclosure information on climate change and propose actions and solutions. It is the most relevant world authority on global warming and an inspiration for the foundation of PBMC, which works in the same way, but within the Brazilian scope.
Andrea explains that the climate changes we see today are the outcome of preceding emissions. The historical increase in emissions since the Industrial Revolution (early XVIII century) started to release harmful gases into the atmosphere, where they have been lingering for over 100 years. “This means that [the consequences] of gases today will be [felt] by the end of the century. And our emission curve keeps increasing, even when transitioning to a low-carbon economy,” she explained “That’s not enough in the short term.”
“Mitigation aims at reducing the cause, which is greenhouse gases. Politically, some actions can be seen in urban laws: valuation of public transport, investment in clean fuels, change of motor-driven mobility by active mobility (bicycles, for example),” says Denise Duarte, professor in the Architecture and Urbanism College at the University of São Paulo (Fau/USP), and expert in climate changes. “Even so, we should invest in adaptation and make cities more resilient to face problems we already have in our hands,” she says.
“This topic on adaptation took a while to be included in the agenda because the scientific community didn’t want to accept that we wouldn’t accomplish this goal,” Andrea Santos said. “It was the same as admitting the planet’s defeat.”
Adaptation: Actions to solve the problems now
Today, the countries in the European Union are among the most committed ones to react efficiently to global warming. Even so, most of them fail to provide solutions from an urban adaptation standpoint: 66% of EU cities have a mitigation plan, but only 26% have adaptation plans – even less, 17%, have joint actions.
“It’s clear that mitigation alone won’t cut it and that we need adaptation actions. The Fifth IPCC [Fifth Assessment Report of the United Nations’ Intergovernmental Panel on Climate Change] shows that even 0.5 °C makes a huge difference in big cities,” Denise says. The most common crises metropolises face now, in addition to the intensification of heat waves, are heavy rains with flooding or landslide and water stress due to water shortage.
The incidence of tragedies related to climate phenomena is already high – during summer, Rio de Janeiro suffers with landslides and São Paulo with flooding, for example. And the outlook is that such disasters will occur more often. Not only because global warming is increasing significantly, but also because these urban infrastructure systems are obsolete.
Urban planners point out to the risk that even adaptations might be insufficient – a type of “project for the past.” This means that new constructions, such as a faster draining system or a more efficient warming and cooling system, are designed from climate data from the past, whereas today’s reality is different. Climate instability in the coming years may turn the most modern constructions of today into outdated technologies, such as clouds huddling in the sky.
The future infrastructure needs to be designed; therefore, with future outlook – and the IPCC recommends to take into consideration the most pessimistic estimates. “Before anything, we need to carefully elaborate impact assessment,” advises Andrea.
“Only then we can think of other important questions, such as sustainable constructions. In Brazil, for example, we vastly use concrete and steel, carbon-intensive technologies, and we don’t take advantage of our climate opportunities, such as the application of biomaterials in home-building,” she proposes.
Examples of climate change actions
Denise states that effective actions against climate change impacts should have as focus prioritizing highly capable and clean energy-driven public transport, more efficient constructions for provision of thermal comfort, restoring and expanding green areas, high quality blue infrastructure, a public health database network for prevention against the effects of excessive heat (especially for the elder and children), and installation of cooling places (easy access areas with powerful air conditioning).
“In São Paulo, for example, the city should invest more in urban vegetation, in draining systems with focus on micro drainage [for buildings] and macro drainage [for general urban systems], with change in building codes, stricter environmental compensation mechanisms and proposals to improve urban densification – people should live close to work and buildings should be more efficient in thermal terms,” she analyzed.
Most cities under risk with climate changes are located in coastal areas. In Brazil alone, Florianópolis, Rio de Janeiro, Salvador, João Pessoa and Natal should have temperatures 4.5 °C higher by the end of the century and more severe peaks of heat than those of today. They should also suffer with high tides, undertows and intense precipitations. The outlook is even worse for Recife: it’s the 16th most vulnerable city in the world to climate changes, especially considering the rise in the sea level.
This is why acting now is urgent. In Brazil, Santos is the model city in combating the consequences of global warming. Other global metropolises, especially in developed countries, are getting ready.
See how some cities are getting ready
Check out an overview of what Santos, New York, Miami, Melbourne, Paris and Barcelona are doing to face climate change.
Santos is the best Brazilian example of climate change adaptation – and also one of the cities expected to be affected the most. By the year 2100, an increase of 4.5 °C in average temperature and occurrence of 80% warmer nights per year is estimated. Also, at least 20 beaches may disappear. The rise in the sea level in the city’s southeast and northwest regions (that altogether shelter 117 thousand residents) may reach 45 cm by 2100, according to the PBMC’s document Mudanças Climáticas e Cidades: Relatório Especial [Climate Changes and Cities: Special Report].
The city has structured a line of tax deductions and investments in alternative energy sources, energetically efficient appliances and climate impact-proof infrastructure. Hence, active urban interventions are being encouraged (such as nebulizer systems and operable awnings) and passive systems (vegetation covers, green walls and roofs, trees on the streets and water body structures).
From the point of view of infrastructure, the following actions have been proposed: preservation and restoration of mangroves; rise in the sand strip of some beaches; building and implementation of control gates for tides in rivers, drainage channels, pumping stations and a protection wall along the seashore (breakwater).
New York (United States)
In 2018, the mayor of New York, Bill de Blasio, announced an investment of US$ 10 billion to put in motion, by 2100, The Big U, a coastal resilience project to guard the lower portion of Manhattan from floods. The protection system will be about 16-kilometer long and, in addition to guarding the coast against rises in sea level and strong storms and tornadoes, it will provide a range of social, cultural and sports equipment.
The city in Florida is in the way of tornadoes and tropical storms, which have already left a trail of destruction in the Caribbean region and the expectation is that they become more frequente and more intense. Therefore, Miami devised a plan of US$ 500 million to improve its infrastructure. Some actions include building offshore roads and the installation of a new water pumping system.
The first climate-oriented project developed by the Australian city dates back to 2009 – a pioneer in the subject. Today, Melbourne, like other big Australian cities, has updated its planning based on new climate estimates. Urban design and building adaption measures, creation of cooling places (well-refrigerated shelters during heat waves), home-building strategies based on natural products (like bamboo) and risk management for flooding, storms and water shortage.
Following 2003’s heat wave, the French capital sets off an emergency warning between June and August. During that period, parks and cooling places are 24 hours open a day and equipped with temporary installations with a rife of shade and water. Among perennial measures are mandatory vegetation in business ventures and urban arrangement so that no Parisian lives 7 minutes away, on foot, from at least one vegetation area.
The Catalan city also invests in efforts in the building and installation of parks and cooling places. Additionally, the local healthcare system collects data of all elder and children, the main victims during heat waves, with income and living condition ratings, and gives priority to those in a situation of higher vulnerability. When summer comes in, public agents lead actions to minimize the impact of the heat and avoid health problems and even deaths.
Content published in July 15, 2019