In spite of the current US government’s denial of climate change and all the actions that have recently been taken to reinforce that idea, 13 Federal Agencies have just released the First Volume of an authoritative assessment of the science of climate change, mandated by the Global Change Research Act of 1990:
The report clearly documents the following:
“Global annually averaged surface air temperature has increased by about 1.8°F (1.0°C) over the last 115 years (1901–2016). This period is now the warmest in the history of modern civilization. The last few years have also seen record-breaking, climate-related weather extremes, and the last three years have been the warmest years on record for the globe. These trends are expected to continue over climate timescales.
This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.
In addition to warming, many other aspects of global climate are changing, primarily in response to human activities. Thousands of studies conducted by researchers around the world have documented changes in surface, atmospheric, and oceanic temperatures; melting glaciers; diminishing snow cover; shrinking sea ice; rising sea levels; ocean acidification; and increasing atmospheric water vapor…”
While the focus is the United States, there is much information contained within that is worthy of global dissemination and review, e.g. for those of us concerned with the dramatic shift climate change will have on our urban tree planting palettes, Chapter 10 may be of special interest.