While humanity, like ants, is engagedeveryday life, the climate on our planet is changing rapidly, having a devastating impact on ecosystems. So, 2020 became the hottest year in the entire history of observations, and we witnessed unprecedented fires, hurricanes and landslides. But if we see what is happening to wildlife today, how will global warming affect cities? The laws of thermodynamics dictate that cities lose on at least one front: they tend to get unbearably hotter than the surrounding rural areas. This is due to an effect known as a heat island, in which buildings and roads easily absorb solar energy and release it at night. In contrast, rural greenery provides shade and cools the air by releasing water. Recently, using new modeling techniques, researchers have demonstrated that climate change amplifies the heat island effect, making future urban environments virtually unlivable.
What is a heat island?
Structures such as buildings, roads and othersinfrastructure facilities absorb and re-emit more solar heat than natural landscapes, such as forests and water bodies. Urban areas, where these structures are highly concentrated and the amount of greenery is limited, become “islands” of higher temperatures compared to remote areas. These hot spots are called and are called heat islands. They can form in a wide variety of environments, including day or night, in cities or towns, in suburban areas, in northern or southern climates, and at any time of the year.
Review of a large number of scientific studiesshowed that this effect will increase in the future as the structure, spatial extent and population density of urban areas change and grow.
Interestingly, heat islands are formed as a result of several factors:
- Trees, vegetation and water bodies havethe tendency to cool the air by providing shade, evaporating water from plant leaves and evaporating surface water, respectively. In contrast, hard, dry surfaces in urban areas - such as roofs, sidewalks, roads, buildings and parking lots - provide less shade and moisture than natural landscapes, which contribute to higher temperatures.
- Dimensions and distance between buildings withincities affect the flow of wind and the ability of urban materials to absorb and release solar energy. In highly developed areas, surfaces and structures obstructed by neighboring buildings become large thermal masses that cannot easily release their heat. Cities with many narrow streets and tall buildings become urban canyons that can block the natural flow of wind, which brings cooling effects.
- Vehicles, air conditioning, buildings andindustrial facilities generate heat into the urban environment. These sources of human-generated (anthropogenic heat) can contribute to the heat island effect.
- Calm and clear weather conditions result inharsher heat islands, maximizing the amount of solar energy reaching urban surfaces and minimizing the amount of heat that can be carried away by the wind. Conversely, strong winds and cloud cover inhibit heat island formation. Geographic features can also influence the heat island effect. For example, nearby mountains can block the wind from reaching the city or create wind patterns that pass through the city.
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What does the future hold for the city?
Since cities account for only 3% of the totalthe surface of the land, researchers are more interested in the dynamics of oceans, ice and air currents. Now climate scientists at the University of Illinois, the authors of a new study published in the journal Nature Climate Change, are providing a detailed description of how climate change will affect cities.
The model obtained during the studysuggests that higher temperatures in cities could prove disastrous for urban public health, which is already suffering from the effects of increased heat waves. According to the World Health Organization (WHO), between 2000 and 2016, the number of people exposed to extreme heat increased by 125 million; The heat wave claimed more than 166,000 lives between 1998 and 2017.
As the authors of the new study note, despiteWhile half of the world's population now lives in cities, this proportion is expected to rise to 70% by 2050. It turns out that people, in search of economic opportunities, unconsciously rush towards danger.
To calculate how much it can risetemperature in cities, the researchers modeled a statistical model of the climate of urban areas, focusing on changes in temperature and humidity. When the human body detects that it is overheating, it redirects blood from organs to the skin, thus dissipating more heat into the air around you (which is why the skin turns red when you are hot).
In extreme heat conditions, this process canget out of control, which can lead to ischemia or critically low blood flow to organs. This, in turn, can damage important organs such as the brain or heart. Humidity also exacerbates the risk of overheating and organ failure. Extreme heat can cause serious harm to human healthespecially if you have cardiovascular or respiratory conditions such as asthma.
See also: Which countries will be hit hardest by climate change?
Overall, this is bad news for anyone wholives in large metropolitan areas. The researchers note that we still have a chance to avoid disaster by preparing urban areas for extreme heat from climate change by making them greener. Greening public spaces both decorates cities and gives people shade. Moreover, one short walk in the park can make you happier. How scientists figured it out, read our material.