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4th National Climate Assessment shows extent of impacts from climate change

If you were busy last Friday shopping for Black Friday deals, you missed the release of the 4th National Climate Assessment (Part II), one of the biggest science news stories of the year. This report, which is mandated by Congress and released by the White House every four years, shows that the scientific evidence for climate change is real and incontrovertible. “The impacts and costs of climate change are already being felt in the United States, and changes in the likelihood or severity of some recent extreme weather events can now be attributed with increasingly higher confidence to human-caused warming,” according to the new report, the second volume of the fourth National Climate Assessment.

The whole report is very lengthy, not surprising considering the number of topics covered or the scope of the impacts that the report discusses.  You can read the Overview at It begins “Climate change, once considered an issue for a distant future, has moved firmly into the present. Corn producers in Iowa, oyster growers in Washington State, and maple-syrup producers in Vermont are all observing climate-related changes that are outside of recent experience. So, too, are coastal planners in Florida, water managers in the arid Southwest, city dwellers from Phoenix to New York, and Native Peoples on tribal lands from Louisiana to Alaska. This National Climate Assessment concludes that the evidence of human-induced climate change continues to strengthen and that impacts are increasing across the country.” In short, not only is climate change real, but it is undeniably caused mainly by  human action and it is already affecting life in the US in a number of ways and it will cause huge economic losses in the future if it is not halted.

Two specific chapters will be of the most interest to readers of this blog. The chapter on impacts of climate change on the Southeast can be found at The chapter on the impacts of climate change on agriculture can be found at

I am very proud of many of my climatologist friends who contributed to the report. Most of them volunteered their own time to make the report as truthful, complete and scientifically accurate as possible. There is no doubt that climate change is real, it is caused by us, it is bad, and scientists agree that it is happening. Even so, there is hope that we can change the future if we work together to minimize the effects of greenhouse gases on atmospheric temperatures by reducing their emission in economically responsible and inventive ways.

Even though the report was likely released on Black Friday with the hope that it would be missed in the general hubbub of Black Friday sales, it has received wide commentary in the national media. Here are some links to stories about NCA4 that caught my eye.

Florida Food & Farm: US Government releases “national climate assessment” report

AP Seth Borenstein: Government climate report warns of worsening US disasters

Weather Underground Bob Henson: A Report Not To Be Buried: Part II of the 4th National Climate Assessment

The Guardian: Climate-heating greenhouse gases at record levels, says UN

CNN: 15 takeaways from the US climate change report (many of these are ag-related) Three big takeaways from the major new US climate report

And finally, opinion pieces by Paul Krugman on climate deniers in the New York Times: The Depravity of Climate Change Deniers and by Enrique Dans in When Will We Accept That Climate Change Is Real?