Regional and national differences
Las ciudades de distintas partes del mundo se enfrentan a retos y oportunidades diferentes y únicos ante el cambio climático. Sin embargo, un factor que las vincula es su inevitable adhesión a los "patrones globales dominantes de urbanización e industrialización", que a menudo catalizan "la modificación a gran escala de los impulsores de los procesos hidrológicos y biogeoquímicos".[32] Los patrones de urbanización e industrialización son especialmente evidentes en regiones como Asia, África y América del Sur, regiones que actualmente se entiende que experimentan rápidos cambios relacionados con la población y el poder económico.[32].
Africa
Africa is urbanizing faster than any other continent[33] and it is estimated that by 2030 more than one billion Africans will live in cities.[34] This rapid urbanization, coupled with the many complex interrelated challenges of climate change, pose a major obstacle to Africa's sustainable development.[35] Much of this urban development is informal, with urban residents settling in informal settlements and slums often on the outskirts of Africa. cities.[36] This phenomenon suggests that lower-income countries should be the target of initiatives to increase the sustainability of infrastructure. A recent study has concluded that in "countries with a per capita income of less than $15,000 per year (in 2011 PPP dollars) carbon pricing has, on average, progressive distributional effects" and that "carbon pricing tends to be regressive in countries with relatively higher income," indicating that imposing and changing carbon prices could incentivize governments to shift to green energy as a means of reference energy consumption for developing peri-urban areas.[37] Although urbanization is seen positively, its effects can be negative for urbanized people. African cities are exposed to multiple climate threats, such as floods, drought, water stress, sea level rise, heat waves, storms and cyclones, as well as the effects related to food insecurity and disease outbreaks such as cholera and malaria caused by floods and droughts.[38].
Climate impacts in rural areas, such as desertification, biodiversity loss, soil erosion and declining agricultural productivity, are also driving the migration of poor rural communities to cities.[39] To achieve sustainable development and climate resilience in cities in Africa, and elsewhere, it is important to take into account these urban-rural interrelationships.[33] There is increasing attention to the important role that peri-urban areas play in the climate resilience of cities, especially with regard to the ecosystem services provided by these areas, which are rapidly deteriorating in sub-Saharan Africa.[40] Peri-urban ecosystems can perform functions such as flood control, reducing the urban heat island effect, air and water purification, supporting food and water security, and waste management.[41].
Asia
China currently has one of the fastest growing industrial economies in the world, and the effects of this rapid urbanization have not been without consequences for climate change. The country is one of the largest by area, and therefore the most prominent region in terms of urbanization is the Yangtze River Delta, or YRD, since it is considered "the most developed, dynamic, densely populated and concentrated industrial area in China" and supposedly "is becoming an influential world-class metropolitan area and plays an important role in the economic and social development of China."[42] In this way, urbanization in China could be understood as closely related not only to the functionality of its economic system, but with the society that integrates it; something that turns climate change mitigation into an intersectional issue that affects more than just infrastructure.[43].
Historically, data have shown that "climate change has been shaping the Delta and its socioeconomic development" and that such socioeconomic development in the region "has shaped its geography and built environment, which, however, are not adaptable to future climate change."[42] Thus, it has been stated that "it is imperative to adopt policies and programs to mitigate and adapt to climate change" in the DRY, specifically, policies aimed at reducing the impact of certain climate threats based on the geography of the DRY. This includes the region's current infrastructure in mitigating flood disasters and promoting efficient energy use at the local level.[42].
A nationwide policy analysis conducted in the arid lands of northern China presents the notion of "sustainable urban landscape planning (SULP)" which specifically aims to "prevent the occupation of important habitats and natural corridors, prime cropland and floodplains".[44] The research indicates that the adoption of SULP in the future can "effectively manage the impacts of climate change on water resource capacity and reduce water stress" not only within of the experimental model of northern China, but for "dry lands around the world".[44]
South Asia's urban population grew by 130 million people between 2001 and 2011 - more than the entire population of Japan - and is projected to increase by almost 250 million by 2030.[45] However, urbanization in South Asia is characterized by increased poverty, slums, pollution, crowding and congestion.[46] At least 130 million South Asians - more than the entire population of Japan. population of Mexico - live in informal urban settlements characterized by poor construction, insecurity of tenure and unserviced plots.[45] Despite being a water-rich area, climate projection models suggest that, by 2050, between 52 and 146 million people living in South Asia could face increased water scarcity due to climate change, representing 18% of the world's population exposed to water scarcity.[47] Access to water in cities is especially critical in South Asia, where more than 40% of the world's poor (living on less than $1.25 a day) and 35% of the world's undernourished live there.[47] A study conducted in some Himalayan cities in India and Nepal found that none of them have a robust water planning and governance system to address the challenges posed by rapid urbanization and change. climate.[48] Khulna, Bangladesh, also faces many problems related to water insecurity. When sea levels begin to rise, due to climate change, salinity will shift inland, reducing the amount of drinking water available to the residents of Khulna. Plans have been put in place to improve water quality in cities, but this decreases availability for inhabitants of informal urban areas. For now, they depend on using as little water as possible, specifically for their crops.[49].
North and South America
Areas of South America have also been cited in recent studies that highlight the dangers of urbanization on local and transnational climates and for a country like Brazil, one of the most populated nations in the world, as well as the majority owner of the Amazon rainforest. The United Nations Development Program highlights that the Amazon rainforest plays a "key role in global climate systems", due to its great usefulness in capturing CO2 emissions.[50] UN research has indicated that, because Brazil's climate depends so closely on the health of the rainforest, deforestation measures are currently considered to have adverse effects on the "natural adaptive capacities" of the rainforest to extreme climate changes, thus predisposing Brazil to what is expected to be greater volatility in temperature and precipitation patterns.[50] More specifically, it is expected that if global warming continues on its current course without extensive mitigation strategies being put in place, what is currently projected to be a 2 °C average increase in global temperature could lead to a 4 °C increase both in the interior of the country and in the surrounding Amazon region.[50] Rapid urbanization in other countries will also lead to greater resource needs. This includes raw materials that will cause further deforestation of the Amazon rainforest to obtain them. This will inevitably create many more climate problems as we continue to lose more trees in the Amazon rainforest.[51].
The issue of climate change in Brazil does not begin and end with what has already been done with respect to urbanization; It is an issue deeply rooted in socioeconomic contexts. Factor analysis and multilevel regression models sponsored by the US Forest Service revealed that, for all of Brazil, "income inequality significantly predicts higher levels of a key component of vulnerability in Brazilian urban municipalities to flood risks."[52].
The future of Brazil's climate effect is likely to change, as through its NDC Brazil has committed to reduce its greenhouse gas emissions by 37% below 2005 levels by 2025.[53] This will be a challenge for Brazilian cities, as 86% of the country's population lives in urban areas, and this is likely to increase to 92% by 2050.[53] As for to deforestation, since Brazil is home to the Amazon rainforest, it has always had a high rate of deforestation.[54] Brazilian deforestation reached its highest point in 2004, with 27.77 thousand kilometers of forest destroyed, had its lowest point in 2012, with only 4.57 thousand kilometers of forest destroyed, and has since risen again, with 10.85 thousand kilometers of forest destroyed.[55].
The United States, as one of the largest industrialized nations in the world, also has problems of infrastructural insufficiency related to climate change. Take as an indicator a study on the topology of Las Vegas. Research that created three land use and land cover maps, or LULC maps, of Las Vegas in 1900 (although hypothetical), 1992, and 2006 found that "urbanization in Las Vegas produces a classic urban heat island (UHI) at night, but a minor cooling trend during the day."[56] In addition to temperature changes in the city, "increased surface roughness," caused by the addition of skyscrapers/narrow buildings, "has a mechanical effect of slowing down the climatological wind field over the urban area."[56] These non-natural environmental phenomena reinforce the idea that urbanization plays a role in determining the local climate, although researchers acknowledge that more on-the-ground studies are necessary.