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Thursday, September 2, 2021

"Clarion Call?" One continuing to fall on deaf ears?

Clarion call from climate panel (from a recent AAAS editorial)

Unprecedented flooding, searing temperatures, and raging fires across Europe, Asia, and North America this summer have created a stark backdrop for this week's release of the sixth physical science assessment report (AR6) of the Intergovernmental Panel on Climate Change (IPCC). These reports, initiated in 1990, arrive about every 7 years at the request of the countries of the United Nations Framework Convention on Climate Change. They form the basis for UN discussions and have become a crucial means to take stock of the latest scientific developments. The reports' future projections about climate change have remained fairly stable over the years and have, sadly, proven quite accurate. So, what does the new report add?

Above all, AR6 expresses greater confidence in familiar findings, owing to stronger evidence. A notable example concerns “equilibrium climate sensitivity,” a measure of how much global warming ultimately occurs if the atmospheric carbon dioxide (CO2) concentration doubles. Based on improved understanding of cloud processes and climate changes that have already occurred, AR6 concludes that this figure is “likely” (a two-thirds chance or greater) to lie between 2.5° and 4°C—halving the spread of 1.5° to 4.5°C in previous reports. Global temperatures had stalled in the period before the 2013 assessment (AR5) but have since surged, reaching 1.1°C above that of preindustrial times. Atmospheric CO2 has reached concentrations not seen for at least 2 million years, and the new report expresses high confidence that oceans, plants, and soils will become less efficient at absorbing future carbon emissions...

The report also provides new clarity on aspects like changes in extreme rainfall and drought. Almost all robustly observed regional trends in these events are upward and are projected to continue. One sobering finding is that even if global warming is limited to 2°C, heat events that once occurred twice per century will happen every 3 to 4 years—and will tend to coincide with droughts, compounding the impacts. Much better regional information is provided than in previous reports. However, the lack of adequate data in many regions, including most of Africa, is apparent and should be addressed...

Although the IPCC reports provide an invaluable resource and periodic wake-up call, they come at a price. This report was written by 234 authors over 3 years, with similar effort invested in two more reports on adaptation and mitigation due next year. The process is arduous: Over 75,000 review comments were individually addressed. The world's climate modeling centers invest heavily in simulations following common protocols, which is growing steadily more taxing for them.

If another assessment is commissioned on schedule, it will arrive not much before 2030. By then, if emissions persist at current rates—that is, even if emissions growth is halted—nearly all the remaining “global carbon budget,” which gives a 50-50 chance of keeping global warming below 1.5°C, will have been exhausted. So, this may be the last report that can meaningfully influence policy to keep the climate targets of the 2015 Paris Agreement within reach. AR6 is intended to inform discussions at the UN Climate Change Conference of the Parties (COP26) meeting in November. Our children and grandchildren are waiting to see what comes out of it.
My 19.5 months-old grandson Calvin at my house yesterday, chillin' watching PBS Kids. Continuing willful deaf ears is existentially criminal.

Climate and Environment

Nearly 1 in 3 Americans experienced a weather disaster this summer
Climate change has turbocharged severe storms, fires, hurricanes, coastal storms and floods—threatening millions

Serious tornadoes touch down in Annapolis, MD. About 30 miles from our house.
My nephew Austin is here from Las Vegas. He turned me on to this on Netflix. We watched it together. Very intriguing.

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