Fifth National Climate Assessment: Key Takeaways and Actions to Take
/In November of 2023, the U.S. released the Fifth National Climate Assessment (NCA5). Since the First National Climate Assessment in 2000, the U.S. Global Change Research Program (USGCRP) has led a team of climate scientists and subject matter experts from a wide variety of backgrounds and institutional sectors to develop this assessment of the best available science. NCA5 is complemented by a new web-based NCA Atlas that allows people to explore climate projections in U.S. states and counties. In addition, a Spanish language version of NCA5 was just released earlier this year.
Key Takeaways from NCA5
1. The U.S. is experiencing more frequent and more severe climate events.
Approximately three-quarters of total greenhouse gas emissions have happened since 1970, and the same is true of global warming with most global temperature increase occurring since 1970.
Data also indicated that the U.S. is warming faster than the global average. Global temperatures have increased faster in the past 50 years than at any time during the past 2,000 years.
The rate of sea level rise experienced during the 20th century was faster than in any other century in the previous 3,000 years.
Total global greenhouse gas emissions continue to increase causing rapid warming and changing precipitation.
The U.S. experiences a billion-dollar climate-related disaster on average every three weeks. In the 1980s, this was once every four months.
2. Everyone in the U.S. and around the globe will feel the effects of climate change.
Climate change is projected to increase risks of natural disasters and lead to rising costs of healthcare, food, insurance, construction, and infrastructure, including home repair. NCA5 is the first to include a chapter on economics for just this reason.
Historically disadvantaged, overburdened, and underserved communities continue to face disproportionate climate change impacts and risks. These communities have higher inland flood, heat, and other exposures that exacerbate existing economic and social inequities. NCA5 includes a new chapter discussing social systems and justice that considers effects on and adaptation strategies to help these historically disadvantaged communities, including indigenous communities.
Indigenous communities are seeing their ability to maintain their traditions and way of life undermined by climate impacts that cause loss of access to water resources, plant and animal species, and other landscape features on which they have historically depended.
3. There is hope, but we need to take action.
U.S. greenhouse gas emissions have declined, by around 1% per year, since a peak in 2007. Renewable, zero- and low-carbon energy options are becoming more affordable and available transforming the U.S. energy system through cleaner and more efficient technologies.
Nearly every region of the U.S. is taking action to address climate change. New city- and state-level climate adaptation plans increased by 32% from 2018 to 2023. New state-level adaptation mitigation activities also increased 14% during that same period.
Maybe the most important insight that has evolved from recent research and climate related activities is that we can influence how much climate changes with the choices we make now. Most people have heard that the climate change goal is to limit global warming to 1.5°C (2.7°F), which requires net-zero greenhouse gas emissions by 2050. While declining U.S. emissions are helping, it is not enough. U.S. greenhouse gas emissions need to decrease by 6% per year to help meet this target. This then requires us, as an industry and as individuals, to ask “what can we do?”
Climate change is requiring us to plan to make our cities, businesses, and homes more resilient and better able to withstand or mitigate the effects. We can also apply adaptation strategies in our actions that help with resilience and mitigate current issues that are contributing to climate change. Examples include:
Finding ways to conserve and reuse water, such as turning off faucets when brushing your teeth and installing low flow plumbing fixtures, are easy ways to help.
Another fairly simple way for many individuals to contribute to a more resilient landscape that is better able to mitigate greenhouse gas emissions is to conserve native vegetation and use only native plants in landscaping your property.
Native plants evolved to live where you live, and they are a vital part of a healthy ecosystem.
Thriving native ecosystems better capture carbon emissions (the primary greenhouse gas).
Using nature-based solutions, including green infrastructure like grass-lined swales, bioretention basins, green roofs, and pollinator or rain gardens in designs, maintaining urban greenspace, and requiring nature-based solutions in municipal codes and ordinances also help support our ecosystems.
A rain garden (left), an urban greenspace (center), and a green roof (right). Source: U.S. Federal Emergency Management Agency (FEMA)
Municipalities can conduct code audits to ensure that their current codes and ordinances allow for and promote nature-based solutions.
Updates to comprehensive plans and other plans, including new pursuits like greenway, trail, and wildlife corridor plans, should include requirements to preserve, use, and promote native and natural habitats.
Municipalities and regions can also invest in resilience plans that outline implementable adaptation measures. A variety of funding mechanisms are available to assist with these efforts.
Finding ways to conserve energy and promote the use of cleaner, renewable energy sources should be integrated into normal practices.
Finally, ensure that infrastructure designs are based on updated climate inputs, such as recent precipitation numbers and projections.
Efforts such as these are vital to helping reduce greenhouse gas emissions and ensuring that our communities are resilient in the face of current and looming climate changes.
Potomac-Hudson Engineering, Inc. (PHE) has been providing environmental consulting services to the government and private sector for over 35 years. Our expertise includes environmental planning and analysis, and environmental compliance, with a focus on greenhouse gas emissions and climate change. We have conducted lifecycle greenhouse gas emission and climate change impact assessments for large and small infrastructure projects, including carbon sequestration and storage (CSS) projects, power plants, pipelines, wastewater treatment plants, sewer collection systems, and others. Our team has conducted environmental analyses for clean energy projects, including geothermal, solar photovoltaic systems, and wind energy. PHE staff include experienced grant writers and grant compliance experts, and planners, that can assist with funding applications for and completing code audits, resilience plans, adaptation strategies, and other planning needs. To learn more about how PHE can help you reduce your greenhouse gas emissions, improve your sustainability posture, and prepare to respond to the challenges posed by climate change, please contact Dawn Schilling, PE, AICP, Senior Project Manager, at dawn.schilling@phe.com.
