On May 6, 2014, the U.S. Global Change Research Program released the Third U.S. National Climate Assessment, titled "Climate Change Impacts in the United States" ("the Assessment"). The Assessment was three years in the making and was based on the work of more than 300 experts from academia, government, business, and NGOs.
The 800-plus page Assessment contains twelve overall findings, which are incorporated into six chapters on various environmental or societal sectors, such as urban systems and Indigenous Peoples. The Assessment also evaluates climate change impacts by region of the country, including a discussion of effects on the coasts of ocean and internal waterways. The twelve key findings are:
- Global climate is changing and this is apparent across a wide range of observations.
- Some extreme weather and climate events have increased in recent decades, and new and stronger evidence confirms that some of these increases are related to human activities.
- Human-induced climate change is projected to continue, and it will accelerate significantly if emissions of heat-trapping gases continue to increase.
- Impacts related to climate change are already evident in many sectors and are expected to become increasingly disruptive across the nation throughout this century and beyond.
- Climate change threatens human health and well-being in many ways.
- Infrastructure is being damaged by sea level rise, heavy downpours, and extreme heat; damages are projected to increase with continued climate change.
- Water quality and water supply reliability are jeopardized by climate change in a variety of ways that affect ecosystems and livelihoods.
- Climate disruptions to agriculture have been increasing and are projected to become more severe over this century.
- Climate change poses particular threats to Indigenous Peoples' health, well-being, and ways of life.
- Ecosystems and the benefits they provide to society are being affected by climate change. The capacity of ecosystems to buffer the impacts of extreme events like fires, floods, and severe storms is being overwhelmed.
- Ocean waters are becoming warmer and more acidic, broadly affecting ocean circulation, chemistry, ecosystems, and marine life.
- Planning for adaptation…and mitigation…is becoming more widespread, but current implementation efforts are insufficient to avoid increasingly negative social, environmental, and economic consequences.
Key response steps recommended by the Assessment include adaptation, mitigation, additional research, and decision-making integrating adaptation and mitigation measures. This Assessment also recommends a "sustained assessment process," rather than developing reports periodically, as has happened in the past.
After detailing the significant negative impacts of climate change throughout the country, the Assessment's companion "Highlights" report concludes more optimistically that "the amount of future climate change and its consequences will still largely be determined by our choices, now and in the near future. There is still time to act to limit the amount of climate change and the extent of damaging impacts we will face."
The Assessment was prepared under the oversight of the National Climate Assessment and Development Advisory Committee, which was established at the end of 2010 by the U.S. Department of Commerce. A National Climate Assessment must be conducted every four years pursuant to the 1990 Global Change Research Act, which has resulted in prior assessment reports being released in 2000 and 2009.