Climate threatsU.S. gov.’s climate assessment: U.S. already suffering severe consequences of climate change
The Fourth National Climate Assessment (NCA4)—a quadrennial report mandated by Congress since 1990—was released Friday. Thirteen federal agencies develop the NCA using the best available science to help the nation “understand, assess, predict and respond to” climate change. The 1,500-page report examines the climate and economic impacts U.S. residents could expect if drastic action is not taken to address climate change. The consequences of global warming for the U.S. economy, infrastructure, food production, water, and public health are already severe, as flooding, droughts, wildfires, rain storms, and hurricanes intensify. Unless warming is arrested, to consequences are only going to get worse.
The Fourth National Climate Assessment (NCA4)—a quadrennial report mandated by Congress since 1990—was released today. Thirteen federal agencies develop the NCA using the best available science to help the nation “understand, assess, predict and respond to” climate change. The 1,500-page report examines the climate and economic impacts U.S. residents could expect if drastic action is not taken to address climate change.
Brenda Ekwurzel, the director of climate science at the Union of Concerned Scientists (UCS) and one of the NCA4 report authors, said:
This report makes it clear that climate change is not some problem in the distant future. It’s happening right now in every part of the country. When people say the wildfires, hurricanes and heat waves they’re experiencing are unlike anything they’ve seen before, there’s a reason for that, and it’s called climate change.
U.S. residents are now being forced to cope with dangerously high temperatures, rising seas, deadly wildfires, torrential rainfalls and devastating hurricanes. The report concludes that these climate-related impacts will only get worse and their costs will mount dramatically if carbon emissions continue unabated. Annual losses in some sectors are projected to exceed $100 billion by the end of the century and surpass the gross domestic product of many states.
Rachel Cleetus, UCS’s Policy Director and Lead Economist, Climate & Energy, summarizes the report’s main findings:
Climate change is already imposing economic costs
The NCA reiterates that human-caused emissions of heat-trapping gases are the dominant cause of observed global warming over the last century; there is no other credible explanation for it. Observations show that annual average temperatures across the contiguous United States have risen by 1.8°F since the beginning of the 20th century.
The NCA explains that as temperatures rise, the latest science and data point to a range of worsening impacts. For example, as oceans have warmed and expanded and as land-based ice has shrunk due to warming temperatures, the annual medial sea level along U.S. coasts (with land motion removed) has increased about nine inches since the early twentieth century. Warmer, drier conditions have contributed to an increase in wildfire activity in the western United States and Alaska over the past several decades.
