Architects have unveiled designs for skyscrapers that can remove carbon from the atmosphere. The 'Urban Sequoia' is the brainchild of the Chicago-based architectural firm Skidmore, Owings & Merrill. The idea behind the concept is to make buildings act like a tree by capturing carbon and purifying the air. According to SOM, the tower could capture 1,000 tons of carbon dioxide a year, equivalent to 48,500 trees. Each high-rise would employ multiple approaches to sequester carbon including construction with carbon-absorbing materials, growth of plants and algae (for fuel, energy and food), and direct air capture technology. The latter would be aided by the tower design's 'stack effect' which would help draw in air to the centre of the building for processing a carbon extraction while contributing to the building's net zero energy system. SOM notes that 40% of global carbon emissions are generated by the building sector and 230 billion square metres of new building stock will be needed by 2060 to meet population increases. By constructing buildings from materials like bio-brick, biocrete, hempcrete and timber It is possible to reduce the carbon impact of construction by 50 per cent as compared to using concrete and steel.