and with the world’s population nearing 7 billion, greater costs to deal with them.
A soon to be released report from the Intergovernmental Panel on Climate Change marks a shift in climate science from focusing on subtle changes in average temperatures to concentrating on events that grab headlines, hurt economies and kill people, saying that extremes caused by climate change could eventually grow so severe that some areas will become “increasingly marginal asplaces to live.”
The final version of the report will be issued in a few weeks. The draft says there is at least a 2-in-3 probability that climate extremes have already worsened because of human-made greenhouse gases.
By the end of the century, the intense, single-day rainstorms that typically happen once every 20 years will probably happen about twice a decade, the report said.
The opposite type of disaster – a drought such as the stubbornly long dry spell gripping Texas and parts of the Southwest – could also happen more often as the world warms.
The Texas State Climatologist John Nielsen-Gammon, taking a cue from the state leadership is not is not committing to how much the current drought, Texas’ worst single-year one on record, is connected to climate change. But he does acknowledge that the drought is caused by a lack of rainfall and record heat; and at least part of the heat is due to global warming.
In the future, climate change will make droughts even more severe, with higher temperatures causing more evaporation and thus putting a greater strain on water resources.
The report does say scientists are “virtually certain” – 99 percent – that the world will have more extreme spells of heat and fewer of cold. Heat waves could peak as much as 5 degrees higher by midcentury and even 9 degrees by the end of the century.
In the United States this year, we set 2,703 daily high temperature records, compared with only 300 cold records during that period, making it the hottest summer in the U.S. since the Dust Bowl of 1936, according to Weather Underground.
The report’s summary chapter didn’t detail which regions might suffer extremes so severe that they become only marginally habitable, but we may learn more once the report is released.