Weather Underground "Blockbuster Assessment: Humans Likely Responsible For Virtually All Global

Warming Since 1950s

https://www.wunderground.com/cat6/blockbuster-assessment-humans-likely-responsible-virtually-all-global-warming-1950s

by Bob Henson

Humans are likely responsible for 93 - 123% of Earth’s net global warming after 1950, says a blockbuster climate report issued on Friday. The Climate Science Special Report is the first product released by the Fourth National Climate Assessment (NCA); the core assessment itself, focusing on impacts, will be released in 2018. The NCA is an congressionally mandated quadrennial effort by hundreds of U.S. scientists to assess how the climate is changing in the United States. The project is carried out by the U.S. Global Change Research Program. Preparation of the report included workshops around the nation, a public-comment period on the draft, and a technical review spanning 13 agencies.

A strong answer for climate-science-denying politicians
Ever since the Earth recorded three consecutive warmest years on record—2014, 2015, then 2016—the mantra of climate-science-denying politicians has shifted from “it hasn’t warmed since 1998” to “Earth’s climate has always changed, and we are not sure how much humans are to blame for the current warming.” At least three members of President Trump’s cabinet gave a variation of this message in their Congressional confirmation hearings. Well, we now have a new authoritative range on what the human contribution to global warming is: 93 – 123% of the warming since 1951. Chapter 3, Detection and Attribution of Climate Change (p.160) of the new report states:

“The likely range of the human contribution to the global mean temperature increase over the period 1951–2010 is 1.1° to 1.4°F (0.6° to 0.8°C), and the central estimate of the observed warming of 1.2°F (0.65°C) lies within this range (high confidence). This translates to a likely human contribution of 93%–123% of the observed 1951–2010 change.”

In other words, Earth might well have cooled slightly during this period if it were not for human activity; this makes Earth’s recent record-high temperatures even more startling. The report adds:


snip - much more at the link including lots of scenario maps