| Dry river bed. Image credit: iStock photo / © Jyeshern Cheng
A recent report from the United Nations Intergovernmental Panel on Climate Change (IPCC) states that “warming of the climate system is unequivocal.” According to the IPCC, average global temperatures are increasing at an alarming rate. In just the past 50 years, northern hemisphere temperatures were higher than during any other 50-year period in the last 500 years, perhaps even the past 1,300 years. The IPCC projects that the Earth’s surface temperature could rise by as much as 4°C within the next century.
The primary cause of climate change is increasing concentration of greenhouse gases (GHGs), especially carbon dioxide (CO2) in the atmosphere. The 2007 Assessment Report by the IPCC indicates that GHG emissions increased by 70 percent between 1970 and 2004. These gases are primarily emitted as a result of human behavior, such as the burning of fossil fuels to produce energy. Building consturction and energy use account for more than 30 percent of worldwide emissions, while the transportation sector is responsible for another 30 percent.
Experts predict that the increase in the Earth’s temperature, if left unchecked, will have devastating effects. According to the IPCC, the projected sea level rise could reach 19-23 inches by the year 2100. Additional impacts could include increased spread of diseases; extensive species extinction; drought and wildfires; mass human, animal and plant migrations; and resource wars over shrinking amounts of potable water.
There are a range of landscape architecture-based mitigation strategies that, if employed at mass scale, can help reduce GHG emissions by 50-85 percent by 2050 and limit temperature rise to 2 degrees celsius, targets that the U.N. recommends. Given the effects of climate change are already being felt in many communities, landscape architecture-based adaptation measures are also now being planned and implemented across cities and countries.
Climate Change, U.S. Environmental Protection Agency
Climate Change Resource Center, U.S.D.A.
National Climate Change and Wildlife Science Center, U.S. Geological Survey
U.S. Global Change Research Program
U.S. Geological Survey National Climate Change and Wildlife Center
Climate Change, United Nations Environment Programme
European Commission Directorate for the Environment
Global Environmental Facility
Intergovernmental Panel on Climate Change
United Nations Framework Convention on Climate Change
Pew Center on Global Climate Change
Ultimate Climate Change FAQ, The Guardian
U.S. Greenhouse Gas Inventory Report , U.S. Environmental Protection Agency
California Climate Change Research Center , California State Government
"Climate Smart World Within Reach," World Development Report 2010, World Bank Group
Climate Change Research, World Bank Group
Global Change Reports and Assessments, U.S. Global Change Research Program
Carbon Registries and Markets
American Carbon Registry
Chicago Climate Exchange
Climate Leaders Program, U.S. Environmental Protection Agency
European Union Emissions Trading System
Climate Change Mitigation and Landscape Architecture
| ASLA 2009 General Design Professional Award. Urban Corridor
Planning — City of Houston, Houston, Texas. The Planning
Climate change mitigation can be defined as human interventions designed to reduce the sources of greenhouse gas emissions (GHGs) or enhance the capability of sinks to store these gases. Landscape architects work with regional and local elected leaders and planning departments to design and implement the land-use components of mitigation strategies and programs. Low-carbon, "smart growth" communities are designed by urban planners and landscape architects to be mixed-use neighborhoods that increase density, provide access to "complete streets," enable multiple forms of transportation, and offer ample green space. Green open spaces like parks are absolutely central to making low-carbon urban living amenable.
In addition, landscape architects work with architects to increase the energy efficiency of buildings by strategically placing trees and incorporating green roofs and walls that provide insulation.
Lastly, landscape architects also work with parks departments and environmental and conservation organizations to manage sustainable and healthy forests within cities, national parks, and rural areas, thereby enhancing the long-term capability of forests to serve as carbon sinks.
Climate Change Mitigation, ICLEI-Local Governments for Sustainability USA
Landscape Architecture and the Challenge of Climate Change, The Landscape Institute
Sustainable Sites Initiative (SITES)
Urban Mitigation Plans
Climate Action Plan, San Francisco
Chicago Climate Action Plan
Climate Change, PlaNYC
The London Plan
Climate of Opportunity, Washington, D.C.
Interview with David Owen, Author of "Green Metropolis: How Living Smaller, Living Closer, and Driving Less Are the Keys to Sustainability," ASLA
Interview with Jan Gehl, ASLA
Interview with Jaime Lerner, Former Mayor of Curitiba, Brazil, ASLA
Interview with Kathryn Gustafson, ASLA
Interview with Peter Calthorpe, Author of "Urbanism in the Age of Climate Change," ASLA
Low-Carbon Community Development through Smart Growth
The U.S. contains five percent of the world’s population but emits one-fifth of global GHG emissions. One-third of U.S. GHG emissions come from the transportation sector. Sparsely populated communities isolated from reliable transportation systems mean increased vehicle usage, resulting in significant car-related emissions. To reduce emissions from the transportation sector, communities can work with urban planners and landscape architects to apply smart growth strategies to create compact, walkable, mixed-use neighborhoods with easy access to multiple transportation options.
A study by the National Resources Defense Council (NRDC) found that if all conditions that accompany densely populated communities were present, such as good transit, proximity to shopping, and recreational activities and a walkable environment, families in that community could reduce vehicle use by 25-30 percent. As a result, comprehensive transportation planning must incorporate community-focused accessibility strategies. Walkable and bikeable communities inspire residents to leave their cars at home.
Go to the Livable Community, Sustainable Transportation, and Sustainable Urban Development Resource Guides to learn more.
McKinsey & Co, a management consulting firm, found that energy use in the U.S. could be cut by 23 percent by 2020 by implementing simple energy efficiency measures. While building owners can take low-cost steps to make the inside of their properties better insulated and therefore more energy efficient, the landscape isn’t often seen as a part of the problem, or the solution. Basic green technologies like smart tree placement and green roofs and walls can be used by landscape architects to dramatically reduce energy usage inside buildings. If placed strategically, trees can reduce summertime cooling energy needs by 7-47 percent and wintertime heating needs by 2-8 percent.
In addition, well-designed residential green roofs, which are growing popular in some parts of the world, can reduce energy usage in both summer and winter. According to one Canadian study, a 32,000-square foot green roof on a one-story commercial building in Toronto reduced energy usage by 6 percent in the summer and 10 percent in the winter. Similarly, the green roof of the American Society of Landscape Architects (ASLA) at just 3,000 square feet reduces energy usage by 3 percent in summer and 10 percent in winter. Weather, roof, and building size and location also have an impact on the amount of energy savings. Lastly, fast-growing green walls can also reduce energy use by providing insulation in the winter and limiting direct sunlight on walls in the summer. In hotter months they also cool air temperatures by up to 10 degrees.
Go to Increasing Energy Efficiency Resource Guide to learn more. Also, see an animation: Energy Efficient Home Landscapes.
Climate Change Adaptation and Landscape Architecture
| Freshskills Park, New York. Image credit: James Corner Field
The Intergovernmental Panel on Climate Change (IPCC) defines adaptation as the "adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities." Regardless of how extensive climate change mitigation efforts are in the near future, environmental policymakers argue that some degree of adaptation to climate change is required in order to handle the worst anticipated effects. Human and natural systems must become more resilient to expected changes. In fact, the smartest communities are using the threat of climate change to invest in long-term environmental, economic, and social sustainability while protecting their infrastructural assets and housing stock.
In preparation of anticipated changes, landscape architects are already working with policymakers and other design professionals to create "climate resilient communities," which have increased capacity to cope with the increased incidence, duration, and magnitude of events like sea level rise and flooding; rising urban temperatures or "urban heat islands;" sprawl, which only increases transportation emissions; and reduced availability of water. Lastly, landscape architects also work with parks departments, conservation biologists, restoration ecologists, arborists, and other scientists to develop ecologically-sound plant and animal migration strategies and programs that help ensure all species can adapt to a rapidly changing environment.
Climate Adaptation Strategy, California Government
Climate Change Adaptation Taskforce, The White House Council on Environmental Quality
Climate Change - Health and Impacts, U.S. Environmental Protection Agency
Landscape Conservation Cooperatives, U.S. Department of the Interior
Adaptation to Climate Change, UN Development Program
Climate Change, World Bank Group
Climate Change Adaptation, UN Environment Program
Climate Change Adaptation Program, Government of Australia
Climate Change Adaptation Strategy, City of London
Climate Change Impacts and Adaptation, Government of Canada
Various State Climate Change Action Plans, U.S. Environmental Protection Agency
Climate Adaptation Knowledge Exchange, Island Press
The Role of Adaptation in the U.S., Pew Center on Global Climate Change
Park 20/20, A Cradle to Cradle Inspired Master Plan, William McDonough + Partners
Rising Currents, Museum of Modern Art
Shanghai Houtan Park: Landscape as a Living System, Turenscape
Climate Resilient Communities
According to Peter Newman, a leading thinker on sustainability and cities, "a resilient city is sustainable in its economy, environment, and community, but it has a deeper quality which enables it to quickly adapt to challenges and rebuild itself for any challenge it faces." Resilient cities reduce their vulnerability to extreme events by responding creatively in advance of economic, social and environmental challenges. At the urban scale, these cities' climate adaptation plans focus on bolstering preparedness while investing in low-carbon transportation systems; dense, mixed-use neighborhoods; multi-use green infrastructure; and generating a sense of place.
Go to Green Infrastructure, Livable Communities, Sustainable Transportation, and Sustainable Urban Development Resource Guides to learn more.
C40 Cities, Clinton Climate Initiative
Climate Positive, Clinton Climate Initiative
Climate Resilient Communities Program, ICLEI Local Governments for Sustainability USA
"Climate Resilient Cities," World Bank Group, 2008
Interview with Jeb Brugmann, Author of "Welcome to the Urban Revolution: How Cities are Changing the World," ASLA
Interview with Peter Newman, Author of "Resilient Cities: Responding to Peak Oil and Climate Change," ASLA
Interview with Sadhu Johnston, Chief Environment Officer, City of Chicago, ASLA
A Civic Vision and Action Plan for the Central Delaware River, Philadelphia, Wallace Roberts & Todd
ChonGae Canal Source Point Park: Sunken Stone Garden, Seoul, Korea (Mikyoung Kim Design)
Greensburg Sustainable Comprehensive Plan, Kansas (BNIM)
Seattle Green Factor, Seattle (City of Seattle Department of Planning and Development)
Preparing for Sea level Rise
In addition to causing the flooding of inhabitated areas and destroying trillions of investments in housing and infrastructure, sea level rise would also affect freshwater quality by increasing the salinity of coastal rivers and bays and causing saltwater intrusion -- the movement of saline water into fresh ground water resources in coastal regions.
Adaptive capacity is the potential to adjust to minimize negative impacts and maximize any benefits from changes in climate. Highly populated communities on the coasts will require greater adaptive capacity than others if they are to adjust to or even benefit from sea level rise.
Landscape architects help build coastal adaptive capacity by constructing various forms of sea walls along with "soft" natural infrastructure like artificial sandbars to stem or absorb rising waters. Restored natural systems like wetlands provide critical green spaces and wildlife habitats while playing a central role in blunting the effects of sea level changes.
Coastal Zones and Sea Level Rise, U.S. Environmental Protection Agency
Conserving Coastal Wetlands for Sea Level Rise Adaptation, NOAA
River Corridor and Wetland Restoration, U.S. Environmental Protection Agency
Sea Levels Online, NOAA
"Coastal and Marine Ecosystems & Global Climate Change: Potential Effects on U.S. Resources," Pew Center on Global Climate Change
"Designing a Built Environment Resilient to Climate Change," The Dirt blog
Interview with Kristina Hill, Affiliate ASLA, on Climate Change, ASLA
Interview with Oz Schmidt, Oastler Professor of Population and Community Ecology, School of Forestry and Environmental Studies, Yale University, ASLA
"Major Tipping Points in the Earth's Climate System and Consequences for the Insurance Sector," WWF and Allianz, 2009
"The Netherlands Evolving Relationship with Water," The Dirt blog
"Point Reyes, Giacomini Wetland Restoration Project: What's the Long Term Future of the Restored Wetlands?", National Park Service
New Orleans Riverfront: Reinventing the Crescent, New Orleans (Hargreaves Associates)
Port Lands Estuary: Reinventing the Don River as an Agent of Urbanism, Toronto (Michael Van Valkenburgh Associates)
Increasing Density with Green Spaces
Given compact living reduces GHG emissions over the long-term, climate resilient communities are also focusing on increasing their density. Landscape architects aid in this process by adding green spaces like parks and plazas, along with infrastructure like green roofs and streets that reduce urban heat islands, improve public health, and increase water efficiency, making compact living easier and more attractive in the process.
Green spaces in themselves also act as carbon sinks, provide wildlife habitat, clean air and water, increase property values, and enhance wellbeing.
Go to Livable Communities and Sustainable Urban Development Resource Guides to learn more.
Combating Urban Heat Islands
Urban heat islands, which are caused by dark, impervious surfaces, lead to higher temperatures, up to 6 degrees Fahrenheit during the day and 22 degrees in the evenings. Vulnerable populations also face greater risks of heat exhaustion. The Center for Diseases Control estimates that excessive heat has led to 8,000 premature deaths over the past 25 years in the U.S. alone.
Landscape architecture guide the development of ecologically-sound urban forestry campaigns and green roofs and walls that help cool cities by shading people and building roofs and sidewalks. Through their leaves, trees evapotranspire or provide evaporative cooling, which increases air humidity. Shaded surfaces may be 20-45 degrees cooler, and evapotranspiration can further reduce peak summer temperatures by 2-9 degrees. Green roofs and walls also provide significant evapotranspiration benefits.
Go to Green Infrastructure and Maximing the Benefits of Plants Resource Guides to learn more.
Increasing temperatures are expected to intensify the climate's hydrologic cycle, the movement of water between the land surface, oceans and atmosphere, as well as melt snowpacks more rapidly (IPCC, 2007). The frequency and intensity of floods and droughts will most likely increase in different areas and affect water quality and supply according to the timing, intensity, and duration of precipitation. Significant flooding can overload storm and wastewater systems and transport contaminants into water bodies. Higher temperatures and decreases in precipitation as well as earlier snowmelt could increase risk of drought and limit access to fresh water. As climate patterns change, it will become increasingly critical to develop water management strategies to retain, reuse, and recycle water.
Landscape architects play a central role in developing highly water-efficient green infrastructure like parks, bioswales, and green roofs that offer green space yet minimize water use. In addition, landscape architects help devise complex water recycling and reuse systems that use building wastewater to maintain landscapes.
Go to Improving Water Efficiency Resource Guide to learn more. Also, see an animation, "Leveraging the Landscape to Manage Water."
Kresge Foundation Headquarters, Michigan (Conservation Design Forum)
Mount Tabor Middle School Rain Garden, Oregon (Kevin Robert Perry)
NE Siskiyou Green Street, Oregon (Kevin Robert Perry)
Nueva School, California (Andrea Cochran Landscape Architecture)
Tianjin Qiaoyuan Park: The Adaptation Palettes, China (Turenscape)
Underwood Family Sonoran Landscape Laboratory, Arizona (Ten Eyck Landscape Architects)
Human and natural systems must develop resiliency in tandem. Humans are an integral component of all ecosystems. However, our resiliency depends on ensuring that other species are able to thrive alongside us, even in densely populated cities. Climate change and urbanization pose an increasing threat to many plant and animal species. Communities must therefore ensure that efforts to improve urban infrastructure and open space also provide adequate habitat areas for species trying to survive and adapt in otherwise hostile conditions. These habitat areas should also provide a core habitat area, or “habitat backbone” that enables migration, as well as a “shifting mosaic”, a series of habitat zones available during different seasons or time periods. These habitat areas should be connected across regions and include migration corridors that enable species to migrate northward to cooler climates when necessary.
Landscape architects design transporation systems, parks, and shoreline structures that incorporate wildlife habitat and enable different species to more safely coexist with humans. Landscape architects also work with arborists, horticulturalists, and other biologists to plan for shifting plant hardiness zones, enabling a range of plant species to survive and adapt to the effects of rising temperatures. Special consideration is often given to native plant species that are drought resistant and heat tolerant and require less water and maintenance.
Go to Maximizing the Benefits of Plants Resource Guide to learn more.
Climate Smart Habitat Conservation, NOAA
Habitat, U.S. Fish and Wildlife Service
Strategic Habitat Conservation, U.S. Fish and Wildlife Service
Habitat Conservation, Defenders of Wildlife
Interview with Carolyn Fraser, Author of "Rewilding the World: Dispatches from the Conservation Revolution," ASLA
Interview with Kristina Hill, Affiliate ASLA, on Climate Change, ASLA
Interview with Nina-Marie Lister, Affiliate ASLA, on Ecological Urbanism, ASLA
Legacy of the Cold War: Germany's Green Belt, The Dirt blog
Restoring the Balance Between People and Nature Through Wildlife Habitat Design and Recreating Wildlife Habitat in Cities, The Dirt blog
Brays Bayou Greenway Framework, Texas (SWA Group)
Isla Palenque, Panama (Design Workshop)
The Floyds Fork Greenway Master Plan, Kentucky (Wallace Roberts & Todd)
FreshKills Park, New York (James Corner Field Operations)
James Clarkson Environmental Discovery Center, Michigan (MSI Design)
Lost Dog Wash Trailhead, Arizona (Floor Associates)
Orange County Great Park Comprehensive Master Plan "A Vision for the Great Park of the 21st Century", California (Ken Smith Workshop West and Mia Lehrer Associates)
Orongo Station Conservation Master Plan, New Zealand (Nelson Byrd Woltz)
The Sungei Buloh Wetland Preserve Master Plan, Singapore (National Parks Board)
If you know of useful resources we've missed, please send recommendations to email@example.com