Warning over 'heat island' effect in cities as tree coverage declines

Australian cities are increasingly becoming concrete jungles as trees and canopy coverage disappear, according to experts who warn this is contributing to an urban "heat island" effect.

Rooftop gardens could be key to cooler cities.

Australia just sweated through its hottest and driest year on record, but researchers and urban planners say the way to make our cities more liveable is as simple as increasing the amount of greenery.

"We know a tried and tested strategy is the introduction of more trees and green roofs in urban spaces, reducing surface temperatures by up to 40 per cent," Griffith University urban and environmental planner Tony Matthews said.

Read the ABC News story by Patrick Wood - “Warning over 'heat island' effect in cities as tree coverage declines.”

Concrete products reabsorb nearly half CO2 released in cement manufacture

More than 76 billion tons of cement was
 produced around the world between
 1930 and 2013.

The production of cement is a major source of carbon dioxide, but new research suggests the material that makes up our concrete jungles also plays an important role in reabsorbing carbon emissions.

During the manufacture of cement, carbon dioxide is emitted when limestone is converted to lime under heat in a process called calcination.

But as cement ages and weathers over time, it also absorbs carbon dioxide in a process called carbonation.

In a paper published today in Nature Geoscience, a team of researchers calculated that the carbonation process has offset as much as 43 per cent of the emissions associated with cement production, not including the emissions associated with fossil fuel use during cement production, over the past 70 years.

Read the ABC story by Bianca Nogrady - “Concrete products reabsorb nearly half CO2 released in cement manufacture.”