6 May 2014: The US Global Change and Research Program (USGCRP) released the Third National Climate Assessment (NCA), which, to date, is the most “comprehensive, authoritative, transparent scientific report on US climate change impacts ever generated.” The report, a key deliverable of US President Barack Obama’s Climate Action Plan, confirms that climate change is not a distant threat but is currently occuring and has immediate impacts, and that most of the warming over the past 50 years is due to human activities.

The report confirms climate change is affecting every region of the country and key sectors of the US economy and society, and emphasizes the need to tackle climate change threats and increase community preparedness and resilience throughout the country.

Key findings of the report include that: extreme weather and climate events have increased in recent decades, some of which are related to human activities; human-induced climate change is projected to continue, and will accelerate significantly if global emissions keep increasing; climate-related impacts are evident in many sectors and are expected to become increasingly disruptive; climate change threatens human health and wellbeing, including through extreme weather events and wildfires, decreased air quality, and diseases transmitted by insects, food and water; sea-level rise, heavy downpours and extreme heat are damaging and will continue to damage infrastructure with ongoing climate change; climate change is jeopardizing water quality and water supply reliability, which is affecting ecosystems and livelihoods; climate disruptions to agriculture have been increasing and their severity is projected to increase; climate change poses particular threats to Indigenous Peoples’ health, wellbeing and ways of life; the capacity of ecosystems to withstand the impacts of extreme events, such as fires, floods and severe storms, is being overburdened; oceans are warming and increasing in acidity, which is affecting ocean circulation, chemistry, ecosystems and marine life; and while adaptation and mitigation planning is increasing, implementation efforts are inadequate to avoid the negative social, environmental, and economic consequences of climate change.

The NCA was: developed over a four-year period by hundreds of climate scientists and technical experts; guided by a 60-member Federal Advisory Committee; and informed by input gathered through town hall meetings, public comment opportunities and technical workshops. The NCA is available for download or can be explored through an interactive website, which was launched to coincide with the report’s release. [Publication: Third National Climate Assessment] [USGCRP Press Release]