Planning for Climate Mitigation and Adaptation

Climate change is a global challenge that demands global solutions combined with local action. This includes mitigating future climate change through the reduction of greenhouse gas (GHG) emissions and adapting the built and natural environments to the changes already taking place or anticipated to take place in the future.

Effective responses will require a fundamental and systemic shift in how people manage the resources and ecosystems required to sustain life on this planet. Aggressive climate policies and projects in communities from rural towns to major metropolitan areas must be adopted and implemented within this country and aligned with actions around the world.

Success can only be achieved through a comprehensive, interdisciplinary approach, which starts with planning for sustainable and resilient outcomes that meet the needs of today while anticipating the requirements of future generations. Planners in all sectors will be required to not only be a part of the solution, but to lead it.

PAS Report 601, Planning for Climate Mitigation and Adaptation, provides an overview of the necessary information and tools needed by planners to take leadership roles in helping our communities respond to climate change. It summarizes essential historical and scientific background information so that planners can be informed participants in future collaborative discussions about climate change, and it offers comprehensive guidance on climate mitigation and adaptation so that planners are better prepared to advance climate resilience in our communities.

A CLIMATE EMERGENCY

In August 2021, the International Panel on Climate Change (IPCC) issued its Sixth Assessment Report (AR6) on climate change, calling it a "code red for humanity." The planet is warming at an unprecedented and intensifying rate — a climate emergency that is unequivocally caused by anthropogenic, or human, activities. Unless rapid and deep reductions in carbon dioxide (CO₂) and other GHG emissions are achieved in the coming decades, there will be little chance of meeting the commitments set out in the 2016 Paris Agreement, the United Nations' legally binding international treaty on climate change. It calls for limiting global warming to well below 2°C (3.6°F), and preferably to 1.5°C (2.7°F), compared to pre-industrial levels.

Climate change refers to changes in long-term temperature, precipitation, and wind patterns resulting from higher levels of CO₂ and other GHGs in the atmosphere. GHGs are a natural and critical component of regulating the conditions required to sustain life on this planet. However, the burning of fossil fuels, deforestation, and intensive agriculture production since the Industrial Revolution has caused levels of CO₂, methane, and other GHGs to increase, accelerating global warming.

This warming of the planet has caused unprecedented increases and variability in global temperatures, resulting in extreme heat; melting permafrost; warmer ocean temperatures, declining sea ice, and subsequent sea level rise; more frequent and intense storm events and inland flooding; acidification of the Earth's oceans; drought and threatened water supplies; increased fire activity; and declining biodiversity, among other climate-induced impacts to the natural and built environments. This PAS Report reviews the science behind climate change, explains the impacts of global warming on the earth's systems, and summarizes the coming changes planners and their communities can expect across the different U.S. regions.

THE ROLE OF PLANNING

There is widespread recognition that patterns of development have significant implications regarding global emissions and resulting consequences. In particular, rethinking the spatial configuration and systems that enable cities to function (e.g., increasing densification; reducing sprawl and vehicle miles traveled; localizing production and distribution of renewable energy; taking full advantage of ecosystem services and green infrastructure solutions; and implementing life-cycle thinking regarding production, consumption, and reuse of resources) may prove to be some of the most effective and impactful opportunities to rapidly reduce GHG emissions and mitigate climate change.

Past GHG emissions have already changed global climate conditions and will continue to do, even if current and future emissions are mitigated. Communities are increasingly turning to climate adaptation actions and projects to reduce their vulnerability to climate impacts from climate variability and extreme weather events. However, these efforts may not be part of a comprehensive and far-sighted approach, instead only responding to a single climatic impact or addressing today's problems rather than anticipated future conditions. This needs to change. Successful climate adaptation requires the comprehensive, long-range, and interdisciplinary perspective that planners offer.

Addressing climate change will be the defining challenge for our generation and subsequent generations. And as climate impacts continue to worsen, a larger burden will be placed on those who are least able to adapt — those with the fewest resources, the least access to information, and the least likelihood of being heard. This requires planners to simultaneously advance both mitigation and adaptation actions while working within the framework of sustainable development, embracing and integrating factors of social equity and inclusion as part of all climate-related decision-making.

THE ELEMENTS OF CLIMATE ACTION

To help their communities move towards a climate-resilient future, planners need to rapidly advance their knowledge regarding climate mitigation and adaptation planning and implementation.

Climate mitigation involves actions that reduce the levels of GHG emissions in the atmosphere or enhance systems that absorb more GHGs than are emitted (e.g., sequestration through afforestation and other nature-based solutions). Mitigation actions predominantly focus on keeping climate change from getting worse. This requires rapid emissions reductions across all sectors, including transportation, energy production and transmission, industrial operations, agriculture and food production systems, building construction and operations, and materials and waste management, while transitioning to a more circular and sustainable economy. This report identifies the principal sources of emissions that planners need to be aware of to advance climate mitigation, and it highlights strategies and recommended practices planners can use to reduce GHG emissions in their communities.

Climate adaptation involves the anticipatory process of adjusting natural and built systems to accommodate and withstand actual or expected climate impacts. Adaptation actions stem from the need to reduce risk and vulnerability with regard to human health and well-being and the assets, resources, and ecosystems that sustain community viability. While climate adaptation actions will always be implemented locally, the extent to which adaptation actions are required will largely depend on the extent and speed with which mitigation policies are implemented globally. To better equip planners to advance climate adaptation action, this report reviews the impacts that climate change will have across key urban sectors — energy, transportation, land use, housing, waste management, the natural environment, and food systems — and the responses available to communities to manage and adapt to those impacts.

As planners, it is critical to become educated on the likely consequences of climate change. A greater understanding of climate vulnerability and communities' adaptive capacity to withstand the most severe impacts is imperative. To mobilize our communities to respond to a growing and intensifying list of climate impacts, planners must work on an interdisciplinary basis with allied professions (e.g., architects, landscape architects, and engineers) to advance strategies both structural (i.e., physical projects) and nonstructural (i.e., policies and regulations). Climate action has already begun in many communities across the country; this report offers case studies highlighting a range of climate mitigation and adaptation actions at the state and local levels.

THE TIME IS NOW

The climate is changing rapidly and the rate of change is accelerating. Getting to action fast must be a planner's imperative. Cities are major population centers and economic hubs. They are responsible for generating much of the world's GHG emissions, and they are also the most vulnerable to increasing natural disasters and extreme weather events. This places urban areas at the forefront of climate response.

Unlike traditional planning and development actions that can be easily implemented as part of siloed responses, implementation for climate mitigation and adaptation action will require fundamental shifts in governance, community growth and redevelopment, and essential services. Because planning is the only profession working at the nexus of transportation, development, and land use — the sectors most critical to climate mitigation and adaptation — planners need to rise to the challenge to help guide their communities to a climate-resilient future.

This transformation necessitates actions that will fundamentally change the built environment, local and regional economies, and social norms. To ensure sustainable, resilient, and equitable outcomes, planning for climate mitigation and adaptation will require a comprehensive, visionary, and systems-oriented response based on robust and informed community engagement and facilitation, consensus building, and prioritization — placing planners as uniquely qualified to take a leadership role in this process.

This PAS Report offers planners a comprehensive overview and approach to the complexity and interconnectedness of climate mitigation and adaptation. It sets the stage for an ongoing journey that planners will need to embrace for the rest of their careers and weave into everything that they do. Additional research, tools, and strategies are still needed to advance every component of climate response — from mitigating future GHG emissions to adapting to its impacts. But the time for action is now.