Scientific paper warns of continuing rise in sea levels, wildfires, heavy rains.As President Donald J. Trump left for Asia, his White House signed off on a report that pins climate change and global warming on humanity.
The report, unveiled Friday by 13 federal agencies, contradicts much of the Trump administration’s position on climate change, the New York Times noted. Trump pulled the United States out of the Paris Accord earlier this year.
“Global annually averaged surface air temperature has increased by about 1.8°F (1.0°C) over the last 115 years (1901–2016),” states the U.S. Global Change Research Program Climate Science Special Report. “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.”
The report, which was mandated by a 1990 law, claims 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,” it says.
The report said that “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.
“For example, global average sea level has risen by about 7–8 inches since 1900, with almost half (about 3 inches) of that rise occurring since 1993,” the document states. “Global sea level rise has already affected the United States; the incidence of daily tidal flooding is accelerating in more than 25 Atlantic and Gulf Coast cities.”
Alarmingly, the report predicts that global average sea levels will to continue to rise—by at least several inches in the next 15 years and by 1 to 4 feet by 2100. Sea level rise will be higher than the global average on the East and Gulf Coasts of the United States, it says.
In what will come as little surprise to those who lived through Hurricane Harvey in and around Houston this summer, the report notes that heavy rainfall is increasing in intensity and frequency across the United States and globally and is expected to continue to increase.
Further, as residents of California and other western states have experienced this year and in recent years, the report acknowledges that the incidence of large forest fires in the western United States and Alaska has increased since the early 1980s and is projected to further increase in those regions as the climate changes.
The report urges a reduction in greenhouse gas and carbon dioxide emissions:
Without major reductions in emissions, the increase in annual average global temperature relative to preindustrial times could reach 9°F (5°C) or more by the end of this century. With significant reductions in emissions, the increase in annual average global temperature could be limited to 3.6°F (2°C) or less.
The global atmospheric carbon dioxide (CO2) concentration has now passed 400 parts per million (ppm), a level that last occurred about 3 million years ago, when both global average temperature and sea level were significantly higher than today. Continued growth in CO2 emissions over this century and beyond would lead to an atmospheric concentration not experienced in tens to hundreds of millions of years. There is broad consensus that the further and the faster the Earth system is pushed towards warming, the greater the risk of unanticipated changes and impacts, some of which are potentially large and irreversible.
