[RESUMO] Large Brazilian cities, historically unequal and exclusionary, react to the extreme heat wave with individual actions that worsen (increased use of cars and air conditioning) or do nothing to mitigate (clubs and private swimming pools) the climate crisis, in a vicious circle which harms the whole of society, but especially punishes the most vulnerable. Breaking this cycle requires moving from individualism to the systemic and collective thinking of life in large cities.
Brazil faces the fourth wave of extreme heat in just a few months. The climate crisis and El Niño combo should make 2023 the hottest year in 125,000 years — a record that, unfortunately, may not take long to be surpassed.
We are experiencing a preview of what is to come in the coming decades. Along with high temperatures, health impacts arise, deaths of people and animals, ecosystem destruction, fires, atmospheric pollution, water heating, and production losses.
The appetizer highlights a phenomenon that tends to deepen: feedback loops) that worsen crisis situations. Similar to what we call a vicious circle, it is a type of process in which the response to a certain change intensifies that change. This is a central problem of the planetary climate crisis and also of cities.
The understanding of the Earth as a system gained momentum in the 1970s, when scientists began seeking to describe the complex interactions occurring on the planet. Biologists James Lovelock and Lynn Margulis were important in this approach, who put the Gaia hypothesis on the table: the idea that the Earth should be understood “as a system subject to positive and negative feedbacks that combine to generate global self-regulation”, as summed up the philosopher Tatiana Roque in “The Day We Returned from Mars”.
The scientists’ work supported research on the composition of the atmosphere, contributed to highlighting the role of human action in altering the planet’s balance, and resulted in studies on holes in the Ozone layer and the ban on chlorofluorocarbons in many countries in the 1990s. 1980.
At the basis of the approach is the understanding that complex systems are marked by interactions between elements that alter characteristics of the system itself, in feedback loops.
Responses to changes can be considered positive or negative — the terms do not indicate a valuation of the result, but the role that the responses have in relation to the initial phenomenon. Feedback is considered positive when it intensifies the ongoing process; and negative when it reduces that process.
A well-known example of positive feedback in the climate crisis is the melting of glaciers in the Arctic. The dissolution of ice causes sea water to become more exposed. As it is darker than glaciers, it absorbs more heat from the sun. Thus, the temperature in the Arctic has risen above the global average, which intensifies the melting of ice. This, in turn, causes the release of methane, a gas that, in the atmosphere, contributes to the warming of the planet.
This type of phenomenon adds gravity and uncertainty to the climate crisis. A study launched at the beginning of the year by scientists from the United States, England, the Netherlands and Germany identified 41 feedback loops generated by the climate crisis, 27 of which intensify the problem.
In addition to being separately serious, the phenomena are connected — for example, the melting of glaciers leads to the growth of fires, which increases emissions. All of this makes it “challenging to accurately predict the impacts of climate change”, summarizes William Ripple, professor of Ecology at the University of Oregon, and one of the study’s authors.
This, however, is not a process restricted to the natural environment. The social response to crisis situations can also generate feedback loops of the problem, with significant effects. Journalist Jane Jacobs described, back in the 1960s, how the adaptation of cities to car traffic tended to degrade conditions for walking and public transport, which led to the use of more cars.
Today we know that rising temperatures also have an effect on increasing the use of private vehicles. Analyzing travel data and weather records in the United States, researchers Nick Obradovich and Iyad Rahwan concluded that “rising temperatures substantially amplify the use of motorized transport in the country.”
For the individual who stops walking on a hot day, an air-conditioned car seems like a good solution. The vehicle’s engine, however, burns oil and emits carbon dioxide into the atmosphere, in addition to heating the urban microenvironment. In other words, the individual solution worsens the collective problem — and encourages others to adopt that individual solution, which further worsens the collective situation.
Likewise, the air conditioning that cools a home or office throws heat into the external environment, making the city hotter. The phenomenon is not marginal. The heat wave in September drove energy consumption to a record level in Brazil, along with the sale of air conditioning units. In November, this record was broken again. Electrical energy in Brazil comes from low-emission sources — but it is not infinite, and hydroelectric plants also generate significant environmental impacts. In many other countries, polluting sources play a relevant role in energy production.
The engines of cars and air conditioning units, together with the asphalt of the streets and the concrete of buildings, produce what are called heat islands in cities. Urban centers measure a few degrees above the rural areas in their surroundings.
When the heat wave caused the temperature in the center of São Paulo to reach 37ºC in September, in a rural region surrounding the city the thermometers registered 30ºC. Even in medium-sized cities, the phenomenon has been consistent, with a 5ºC to 10ºC temperature difference between neighborhoods.
In Brazil, when we deal with environmental issues, we have the correct priority of seeking to reduce and eliminate deforestation in the Amazon. But, the day this happens, we will be on the same page as other countries, where the bulk of emissions are in transport, construction, energy and waste. And we are making very little progress in decarbonization in these sectors.
Cities are the nerve center of the climate crisis. These territories, which occupy 2% of the world’s land surface, are responsible for 78% of energy expenditure and 60% of the emissions that cause global warming, according to UN Habitat, a specialized UN agency dedicated to promoting more socially and environmentally sustainable cities. .
Articulating this node is mobility. Today the transport sector accounts for 25% of emissions and 57% of the planet’s oil demand; and automobiles are the largest emitters within the sector. In 45% of countries, transport is the largest source of emissions; in the others, it is the second largest source.
Between 2000 and 2019, transport emissions grew in all regions, except in Europe, where they remained stable (in other sectors, emissions fell significantly on the European continent).
In this context, climate crisis feedback loops in cities have the potential to further delay our already slow transition to a low-emission, low-energy world.
The solution involves finding solutions that work collectively. It’s about producing a type of response that reduces the problem for everyone, not just a small group. The key shift is from individualism to systemic and collective thinking.
Here is a challenge: overcoming the individualist ideology that has been consolidated over the last four decades, based on the false assumption that individual advancement necessarily produces collective improvements.
An air conditioning unit that does not produce emissions, captures carbon and does not heat the surrounding area is called a tree. Tree-lined streets can reduce the temperature of cities by up to 12ºC, according to a recent study.
Installing green roofs or painting roofs white can have a significant effect on reducing the heat island and internal temperature of buildings. Experiments carried out around the world show good results in this regard.
Recovering the watercourses that cross cities, renaturalizing their beds and leaving them clean and open reduces temperatures and improves air quality. In Brazilian cities, many streams and rivers were covered by asphalt tracks — a policy that peaked during the dictatorship, but is still present.
In Seoul, the capital of South Korea, the Cheonggyecheon River was covered in the 1950s to make way for a double-decker expressway. At the beginning of this century, the river was restored, creating a park in the stretch that runs through the center.
The temperature on the banks of the river was 3.3ºC to 5.9ºC lower than in surrounding streets. This is the result of the removal of asphalt, the surface evaporation of water, the increase in vegetation, the reduction of vehicles and the induction of air circulation produced by the river.
Cities that seek to democratize access to milder temperatures on hot days have created climate refuges, as is happening in Barcelona. These are wooded, shaded and ventilated spaces, with public access to the population. Other cities, such as Medellín, have invested in green corridors for walking, which have been able to reduce the temperature in their surroundings by up to 3ºC.
In Brazil, one of the most unequal countries in the world, the possibility of escaping extreme heat is marked by inequality. The richest access their villas, clubs and private pools. Few cities, however, offer public swimming pools, parks with open and clean rivers, tree-lined streets on the outskirts, safe and shaded cycle paths, accessible and air-conditioned public transport.
The difficulty with collective and sustainable solutions is that they are not short-term and cannot deliver the air conditioning temperature to 23ºC. It turns out that “every man for himself” is unsustainable, as well as unfair to the most vulnerable. Breaking the vicious circle of the climate crisis in cities is not simple, but the worst option is to do nothing about it.