Làm thử Đề thi thử tốt nghiệp THPT · Tiếng Anh · Đề 086

Question 15. a. As a result, many households now rely on virtual assistants for simple daily tasks.
b. Artificial intelligence has changed the way people manage their homes.
c. For example, a smart speaker can turn off the lights or set a reminder with a single voice command.
d. However, some people still worry about how much personal data these devices collect.
e. This concern has led several companies to publish clearer privacy policies.

Question 17. a. Despite that doubt, she went on to represent her country at an international competition years later, thanks to years of consistent practice.
b. When she was a child, Lan practised swimming every morning before school, even in the coldest months.
c. Her coach often says that her success came from consistency rather than natural talent.
d. Few people back then believed that a small-town girl could ever become a professional athlete.

Ask a teenager how many hours a day they spend online, and the number is often startling. Yet a growing body of research suggests that reading habits have not disappeared; they have simply changed shape. A 2023 survey of secondary school students found that most of them still read for pleasure at least once a week, although the format has shifted from paper books toward e-readers, apps, and audiobooks. Publishers who once worried that screens would kill reading now describe a quieter, more flexible kind of reader.

Researchers who study reading point out that fiction, in particular, does something that a scrolling feed cannot. When a reader follows a character through difficult choices for two hundred pages, they practise imagining another person's mind in a way few other activities require. This sustained attention also appears to strengthen concentration more generally; several studies have linked regular novel-reading with better performance on tasks that require sitting still and following a long line of thought, from exam essays to complex instructions at work.

None of this means reading is easy to protect. Short videos and instant messages compete for the same minutes that used to go to a novel, and many students admit they now finish fewer books than they did at ten years old. In response, some school libraries have started twenty-minute daily reading periods with no phones allowed, and local book clubs have begun choosing shorter titles so that busy members can finish one together. These small changes, organisers say, matter more than any single grand campaign to save reading.

Ask a teenager how many hours a day they spend online, and the number is often startling. Yet a growing body of research suggests that reading habits have not disappeared; they have simply changed shape. A 2023 survey of secondary school students found that most of them still read for pleasure at least once a week, although the format has shifted from paper books toward e-readers, apps, and audiobooks. Publishers who once worried that screens would kill reading now describe a quieter, more flexible kind of reader.

Researchers who study reading point out that fiction, in particular, does something that a scrolling feed cannot. When a reader follows a character through difficult choices for two hundred pages, they practise imagining another person's mind in a way few other activities require. This sustained attention also appears to strengthen concentration more generally; several studies have linked regular novel-reading with better performance on tasks that require sitting still and following a long line of thought, from exam essays to complex instructions at work.

None of this means reading is easy to protect. Short videos and instant messages compete for the same minutes that used to go to a novel, and many students admit they now finish fewer books than they did at ten years old. In response, some school libraries have started twenty-minute daily reading periods with no phones allowed, and local book clubs have begun choosing shorter titles so that busy members can finish one together. These small changes, organisers say, matter more than any single grand campaign to save reading.

Ask a teenager how many hours a day they spend online, and the number is often startling. Yet a growing body of research suggests that reading habits have not disappeared; they have simply changed shape. A 2023 survey of secondary school students found that most of them still read for pleasure at least once a week, although the format has shifted from paper books toward e-readers, apps, and audiobooks. Publishers who once worried that screens would kill reading now describe a quieter, more flexible kind of reader.

Researchers who study reading point out that fiction, in particular, does something that a scrolling feed cannot. When a reader follows a character through difficult choices for two hundred pages, they practise imagining another person's mind in a way few other activities require. This sustained attention also appears to strengthen concentration more generally; several studies have linked regular novel-reading with better performance on tasks that require sitting still and following a long line of thought, from exam essays to complex instructions at work.

None of this means reading is easy to protect. Short videos and instant messages compete for the same minutes that used to go to a novel, and many students admit they now finish fewer books than they did at ten years old. In response, some school libraries have started twenty-minute daily reading periods with no phones allowed, and local book clubs have begun choosing shorter titles so that busy members can finish one together. These small changes, organisers say, matter more than any single grand campaign to save reading.

Ask a teenager how many hours a day they spend online, and the number is often startling. Yet a growing body of research suggests that reading habits have not disappeared; they have simply changed shape. A 2023 survey of secondary school students found that most of them still read for pleasure at least once a week, although the format has shifted from paper books toward e-readers, apps, and audiobooks. Publishers who once worried that screens would kill reading now describe a quieter, more flexible kind of reader.

Researchers who study reading point out that fiction, in particular, does something that a scrolling feed cannot. When a reader follows a character through difficult choices for two hundred pages, they practise imagining another person's mind in a way few other activities require. This sustained attention also appears to strengthen concentration more generally; several studies have linked regular novel-reading with better performance on tasks that require sitting still and following a long line of thought, from exam essays to complex instructions at work.

None of this means reading is easy to protect. Short videos and instant messages compete for the same minutes that used to go to a novel, and many students admit they now finish fewer books than they did at ten years old. In response, some school libraries have started twenty-minute daily reading periods with no phones allowed, and local book clubs have begun choosing shorter titles so that busy members can finish one together. These small changes, organisers say, matter more than any single grand campaign to save reading.

Ask a teenager how many hours a day they spend online, and the number is often startling. Yet a growing body of research suggests that reading habits have not disappeared; they have simply changed shape. A 2023 survey of secondary school students found that most of them still read for pleasure at least once a week, although the format has shifted from paper books toward e-readers, apps, and audiobooks. Publishers who once worried that screens would kill reading now describe a quieter, more flexible kind of reader.

Researchers who study reading point out that fiction, in particular, does something that a scrolling feed cannot. When a reader follows a character through difficult choices for two hundred pages, they practise imagining another person's mind in a way few other activities require. This sustained attention also appears to strengthen concentration more generally; several studies have linked regular novel-reading with better performance on tasks that require sitting still and following a long line of thought, from exam essays to complex instructions at work.

None of this means reading is easy to protect. Short videos and instant messages compete for the same minutes that used to go to a novel, and many students admit they now finish fewer books than they did at ten years old. In response, some school libraries have started twenty-minute daily reading periods with no phones allowed, and local book clubs have begun choosing shorter titles so that busy members can finish one together. These small changes, organisers say, matter more than any single grand campaign to save reading.

Ask a teenager how many hours a day they spend online, and the number is often startling. Yet a growing body of research suggests that reading habits have not disappeared; they have simply changed shape. A 2023 survey of secondary school students found that most of them still read for pleasure at least once a week, although the format has shifted from paper books toward e-readers, apps, and audiobooks. Publishers who once worried that screens would kill reading now describe a quieter, more flexible kind of reader.

Researchers who study reading point out that fiction, in particular, does something that a scrolling feed cannot. When a reader follows a character through difficult choices for two hundred pages, they practise imagining another person's mind in a way few other activities require. This sustained attention also appears to strengthen concentration more generally; several studies have linked regular novel-reading with better performance on tasks that require sitting still and following a long line of thought, from exam essays to complex instructions at work.

None of this means reading is easy to protect. Short videos and instant messages compete for the same minutes that used to go to a novel, and many students admit they now finish fewer books than they did at ten years old. In response, some school libraries have started twenty-minute daily reading periods with no phones allowed, and local book clubs have begun choosing shorter titles so that busy members can finish one together. These small changes, organisers say, matter more than any single grand campaign to save reading.

Ask a teenager how many hours a day they spend online, and the number is often startling. Yet a growing body of research suggests that reading habits have not disappeared; they have simply changed shape. A 2023 survey of secondary school students found that most of them still read for pleasure at least once a week, although the format has shifted from paper books toward e-readers, apps, and audiobooks. Publishers who once worried that screens would kill reading now describe a quieter, more flexible kind of reader.

Researchers who study reading point out that fiction, in particular, does something that a scrolling feed cannot. When a reader follows a character through difficult choices for two hundred pages, they practise imagining another person's mind in a way few other activities require. This sustained attention also appears to strengthen concentration more generally; several studies have linked regular novel-reading with better performance on tasks that require sitting still and following a long line of thought, from exam essays to complex instructions at work.

None of this means reading is easy to protect. Short videos and instant messages compete for the same minutes that used to go to a novel, and many students admit they now finish fewer books than they did at ten years old. In response, some school libraries have started twenty-minute daily reading periods with no phones allowed, and local book clubs have begun choosing shorter titles so that busy members can finish one together. These small changes, organisers say, matter more than any single grand campaign to save reading.

Ask a teenager how many hours a day they spend online, and the number is often startling. Yet a growing body of research suggests that reading habits have not disappeared; they have simply changed shape. A 2023 survey of secondary school students found that most of them still read for pleasure at least once a week, although the format has shifted from paper books toward e-readers, apps, and audiobooks. Publishers who once worried that screens would kill reading now describe a quieter, more flexible kind of reader.

Researchers who study reading point out that fiction, in particular, does something that a scrolling feed cannot. When a reader follows a character through difficult choices for two hundred pages, they practise imagining another person's mind in a way few other activities require. This sustained attention also appears to strengthen concentration more generally; several studies have linked regular novel-reading with better performance on tasks that require sitting still and following a long line of thought, from exam essays to complex instructions at work.

None of this means reading is easy to protect. Short videos and instant messages compete for the same minutes that used to go to a novel, and many students admit they now finish fewer books than they did at ten years old. In response, some school libraries have started twenty-minute daily reading periods with no phones allowed, and local book clubs have begun choosing shorter titles so that busy members can finish one together. These small changes, organisers say, matter more than any single grand campaign to save reading.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.

On a summer afternoon, a thermometer in the middle of a large city can read several degrees higher than one in the surrounding countryside, even under the same open sky. Scientists call this gap the urban heat island effect, and it is becoming one of the clearest signs that how a city is built, not just the regional climate, shapes the heat its residents actually feel. As heat waves grow more frequent worldwide, researchers are paying closer attention to why some neighbourhoods bake while others, only a few kilometres away, stay comparatively cool.

The causes are mostly physical. Asphalt, concrete, and dark rooftops absorb sunlight during the day and slowly release that heat after sunset, so a paved district can stay warm long into the night. Streets lined with dense buildings also trap heat between walls the way a narrow canyon traps warm air, further slowing the escape of heat once the sun goes down. Tall buildings block the wind that would otherwise carry warm air away, and the loss of trees removes one of the cheapest natural coolants a city ever had: shade.

[I] The effect is rarely spread evenly across a city. [II] Older, low-income neighbourhoods often have fewer parks and more paved surfaces than wealthier districts nearby, so residents there can face daytime temperatures several degrees higher. [III] Public health officials worry that this gap turns heat waves into a matter of inequality as well as weather, since the households with the least shade are frequently the ones least able to afford air conditioning. [IV] Closing this gap, they argue, will require planting trees and adding shade specifically in the hottest, most exposed streets.

Cities that have taken the problem seriously are experimenting with a range of fixes. Some have painted rooftops white or silver to reflect sunlight rather than absorb it, a cheap change that can lower a building's indoor temperature noticeably. Others are replacing asphalt in playgrounds with lighter-coloured, more permeable surfaces, and requiring new developments to set aside a fixed percentage of land for trees. None of these measures alone will reverse the trend, but planners increasingly treat them as essential rather than optional, alongside larger efforts to cut the emissions that are warming the planet as a whole.