Cities around the world are not adapting quickly enough to climate change


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(THE CONVERSATION) Climate change is amplifying threats such as floods, forest fires, tropical storms and drought. In 2020, the United States experienced a record 22 weather and climate disasters that each caused at least $ 1 billion in damage. So far in 2021, the number rises to 18.

I study urban issues and I have analyzed the relationship of cities to nature for many years. In my opinion, cities are quickly becoming more vulnerable to extreme weather events and permanent changes in their climatic zones.

I am concerned that the pace of climate change is accelerating much faster than urban areas are taking action to adapt to it. In 1950, only 30% of the world’s population lived in urban areas; today that figure is 56% and is expected to reach 68% by 2050. Failure to adapt urban areas to climate change will put millions of people at risk.

Extreme weather conditions and long-term climate zone changes

As the Intergovernmental Panel on Climate Change shows in its latest report, published in August 2021, global climate change is widespread, rapid and accelerating. For cities in temperate latitudes, this means more heat waves and shorter cold seasons. In subtropical and tropical latitudes, this means wetter rainy seasons and hotter dry seasons. Most coastal towns will be threatened by rising sea levels.

Cities around the world will face a much higher probability of extreme weather events. Depending on their location, these will include heavier snowfall, more severe drought, water shortages, punitive heat waves, larger floods, more forest fires, larger storms, and severe storms. longer storm seasons. The heaviest costs will be borne by their most vulnerable residents: the elderly, the poor and others who lack the wealth and political connections to protect themselves.

Extreme weather conditions aren’t the only concern. A 2019 study of 520 cities around the world predicted that even if countries limit warming to 2 degrees Celsius (about 3.6 degrees Fahrenheit) above pre-industrial conditions, climate zones will shift hundreds of kilometers. north by 2050 in the world. This would cause 77% of the cities in the study to experience a major change in their weather patterns throughout the year.

For example, the study’s authors predicted that by mid-century, London’s climate will resemble today’s Barcelona, ​​and Seattle’s will resemble San Francisco’s current conditions. In short, in less than 30 years, three out of four major cities in the world will have a completely different climate from that for which its urban form and infrastructure were designed.

A similar study of the impacts of climate change on more than 570 European cities predicted that they will face a whole new climate regime within 30 years, characterized by more heat waves and drought, and an increased risk of floods.

Mitigate climate change

Cities’ responses to climate change fall into two broad categories: mitigating (reducing) the emissions that cause climate change and adapting to effects that cannot be avoided.

Cities produce more than 70% of global greenhouse gas emissions, mainly from heating and cooling buildings and powering cars, trucks and other vehicles. Urbanization also makes people more vulnerable to the impacts of climate change.

For example, as cities expand, people clear vegetation, which can increase the risk of flooding and sea level rise. They also create impermeable surfaces that do not absorb water. water, such as roads and buildings.

This contributes to the risk of flooding and produces urban heat islands – areas where temperatures are warmer than on the outskirts. A recent study found that the urban heat island of Jakarta, Indonesia has grown in recent years as more land is developed for housing, businesses, industry and warehouses.

But cities are also important sources of innovation. For example, the first Oberlander prize for landscape architecture was awarded on October 14, 2021 to the American landscape architect Julie Bargemen for reimagining polluted and neglected urban sites. And the prestigious Pritzker Architectural Prize was awarded this year to French architects Anne Lacaton and Jean-Philippe Vassal for creating resilient buildings by transforming existing structures instead of tearing them down to make way for new construction.

Only 25 cities in the world are responsible for 52% of total urban greenhouse gas emissions. This means that focusing on these cities can make a huge difference in the long-term warming arc.

Cities around the world are implementing a wide variety of mitigation measures, such as electrifying public transport, cooling with green buildings, and introducing low-carbon building codes. I see these steps as a source of hope in the medium and long term.

Adapt too slowly

In contrast, shorter-term adaptation evolves much more slowly. This does not mean that nothing is happening. For example, Chicago is developing policies that anticipate a warmer, more humid climate. They include repaving streets with permeable materials that allow water to seep into the underlying soil, planting trees to absorb air pollutants and stormwater runoff, and tax incentives to install green roofs as cooling elements on office buildings. Similar plans are underway in cities around the world.

But timely remodeling of cities can be extremely costly. In response to the dike failures that flooded New Orleans during Hurricane Katrina in 2005, the U.S. government spent more than $ 14 billion to build an improved flood control system for the city, which was completed in 2018. But many other cities around the world face similar threats. , and few of them – especially in developing countries – can afford such an ambitious agenda.

Time is also a critical resource as the pace of climate change accelerates. In the European Union, around 75% of buildings are not energy efficient. A 2020 report from the European Commission predicted that it would take 50 years to make these buildings more sustainable and resilient to changing climatic conditions.

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At best, urban infrastructure that was built for past weather patterns and less extreme weather events can only be changed at a rate of around 3% per year. At this rate, which would be difficult to sustain even for the richest cities in the world, it will take decades to make cities more sustainable and resilient. And the most vulnerable city dwellers live in fast growing cities in the developing world, like Dhaka, Bangladesh, Lagos, Nigeria and Manila, Philippines, where local governments rarely have enough resources to make the costly changes that are needed.

Remaking cities around the world quickly enough to cope with more extreme weather events and new weather patterns requires massive investments in new ideas, practices and skills. I see this challenge as an ecological crisis, but also as an economic opportunity – and a chance to make cities fairer for the 21st century and beyond.

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