Ancient Rome knew in regards to the urban heat island effect – how lessons from history may be applied to today’s cities

So intense Heat breaks records Around the world, a little-reported fact offers hope for urban cooling: Even in periods of maximum heat, some city blocks never experience heatwave temperatures.

How is that this possible?

Civilizations have recognized the flexibility of cities to heat and funky themselves for hundreds of years. Urban architects in ancient Rome called for Narrowing of streets to mitigate late afternoon temperatures. Narrow streets have been found to chill the air by limiting the realm exposed to direct sunlight.

The whitewashed architecture of the Greek islands is one other long-standing strategy. Bright partitions and roofs might help cool cities by reflecting incoming sunlight.

In hot and humid regions within the southern United States Thomas Jefferson proposed a unique approach for cooling: All latest settlements must have a checkerboard pattern of heavily vegetated city blocks interspersed with dense buildings. This could promote cooling through convective air movement between cool and warm zones.

As I explain in my latest book, “Radical Adaptation: Transforming Cities for a Climate Changed World”, Modern cities unintentionally increase their very own temperatures and create the so-called “urban heat island effect”.

How cities heat up

Cities increase their temperature in Four essential paths:

In combination, these 4 aspects of the urban heat island effect can increase temperatures in cities by 10 to twenty degrees Fahrenheit (5.6 to 11 degrees Celsius) on a hot summer afternoon – a big man-made change within the weather that may pose a serious health risk to people without air con.

In conjunction with the design of the built environment, a city's natural topography can amplify temperature differences between neighborhoods. San Francisco's hills and fog patterns, for instance, consistently divide neighborhoods into different climate zones. And the extensive Use of garden irrigation systems In hot and dry climates, temperatures in cities may be lower than in the encompassing desert. Hence the so-called “cool city islands”.

Simple steps to chill down cities

By understanding the extent to which cities can heat up, we will find effective tools to chill them down when human-caused global warming causes baseline temperatures to rise.

First, it is crucial that cities drastically reduce their greenhouse gas emissions to stop climate change from accelerating. Urban areas world wide, with their industries, vehicles and buildings, greater than 70% of greenhouse gas emissions from energy consumption and Their population is growing rapidlyEven a globally coordinated reduction in greenhouse gas emissions requires many many years to measurably decelerate the warming trendsdue to this fact, cities will still need to adapt.

Cities may slow urban heat island warming by taking sometimes easy measures. Research shows that Health advantages of reducing urban heat islands may very well be significant.

On Georgia Tech Urban Climate Labmy colleagues and I are working with cities to estimate the cooling potential of urban heat management—strategies designed to reverse the urban heat island effect. We do that by measuring the direct health advantages of actions comparable to expanding tree cover and other green infrastructure and using cool materials for streets and roofs.

Our work shows that planting trees on just half the realm available for tree cover growth—comparable to along roads, in parking lots, and in residential gardens—can reduce summer afternoon temperatures by 5-10 F (2.8-5.6 C) and reduce heat-related deaths by 40%-50% in some districts.

Recognizing these significant advantages, New York City set a goal of 1 million trees in its five districts.

Cool roofing material and light-colored finishes may help lower the temperature. Wearing a black shirt within the sun on a hot day will heat you up greater than wearing a white shirt. Likewise, light-colored constructing materials, roof coatings and shingles reflect more incoming solar heat than darkand absorb less heat. This is particularly effective in the warmth of the day when the sun's rays are at their strongest.

To benefit from this cooling effect, Los Angeles was the primary major city to require cool roofs for all latest buildings.

What cities can do now

Aggressive strategies to extend green tree cover in cities, a rapid transition to cooling roofing materials and even Replacing some parking lanes on the road and other unused sealed areas with biofilter troughs crammed with vegetation can significantly reduce temperatures in cities. In this manner, the resilience of a city to rising temperatures may be increased.

We have conducted heat risk assessments in quite a few U.S. cities, including Atlanta; Dallas; Louisville, Kentucky; And San Franciscoshow that a mixture of urban heat management strategies could reduce neighborhood temperatures by greater than 10 °F (5.6 °C) on hot days and reduce heat-related premature deaths by 20 to 60%.

A cooler city is a safer city. And it’s clearly as much as the communities to realize this.