February 2022

Mohammad Anas Wahaj | 27 feb 2022

Climate change and environmental issues are prompting landscape architects to consider carbon as an important aspect in their planning and designing. Landscape practitioners and experts came together at ASLA (American Society of Landscape Architects) 2021 to discuss various approaches and tools that can help in creating a positive impact on environment and reduce carbon footprint of building and construction projects. Pamela Conrad, founder of Climate Positive Design and principal at CMG Landscape Architecture, says, 'Approximately 75% of all emissions are from the urban built environment, with 40% from buildings and 35% from transportation and landscapes. We need to keep warming to 1.5°C. We can only add 300 gigatons of additional carbon to the atmosphere and need to work within this remaining carbon budget. We need to reduce emissions by 65% by 2030 and hit zero by 2040.' Climate Positive Design, ASLA, IFLA (International Federation of Landscape Architects) and Architecture 2030 are collectively committed to attain these targets through the development of Climate Action Commitment and Architecture 2030's 1.5°C COP26 Communiqué. Climate Positive Design's Pathfinder App helps landscape architects find ways to reduce space for carbon-intensive hardscapes and increase carbon-sequestering trees, shrubs, and grasses. Chris Ng-Hardy of Sasaki says, 'We realized we need to consider carbon from the beginning, before the project even starts. Measuring embodied carbon is about 10-15 years behind the curve in terms of measuring operational carbon.' Team at Sasaki developed Carbon Conscience App to help with the preliminary planning decisions that determine a project's long-range carbon footprint. The research at Sasaki led to following conclusions for landscape architects - don't destroy ecosystems; add wetlands, prairies, and forests; minimize hardscapes and concrete; and reduce the use of plastics and metals. Deanna Lynn, landscape designer with Wild Land Workshop, says, 'Soil carbon sequestration is hard to study. But generally, the more life there is in ecosystems, the more carbon is stored in soils.' Underground there is a complex web, made up of tree roots, organic matter, microbes, earthworms, mycorrhizal fungi, and insects. In the book, 'The Hidden Life of Trees: What They Feel, How They Communicate? Discoveries from A Secret World, the author Peter Wohlleben, describes one aspect of this underground world - mycorrhizal fungi - which form a subterranean 'world wood web' that enables trees to share carbon, nutrients, and information across their roots. Soils are complex adaptive systems, and while designing for carbon sequestrian the goal should be to support the self-organizing systems of soil life. Ms. Lynn says that more carbon can be stored naturally in ecosystems and soils if species diversity is increased and suggests that andscape architects can introduce more woody plants; warm season grasses; deciduous trees, which are denser; and nitrogen-fixing plants, which enable the productivity of the entire plant communities. She also advocates the use of native plants, which have deeper roots, are more productive and resilient and therefore will store more carbon over time. She suggests that while designing new forested landscapes it is important to mimick the arrangement of treas and plants that exists in surrounding ecosystem and also planting an understory of plants that tolerate leaf litter, as it helps build carbon in soil. Read on...

The Dirt: Designing with Carbon
Author: Jared Green