Summaries (mostly by the Press)

     Paraphrasing: We are well on the way to 1.5°C hotter than 1880; damages will get even worse above 1.5°C.  We need net-zero by 2050 to limit warming to 2°C.  The changeover to renewables has been slow.  Solar radiation management (SRM), by imitating major volcano eruptions, has the bad side effect of moving monsoon rain offshore.  It is also expensive.  For CO2 removal (CDR), CCS has proven to be too expensive - as well as ineffective, because it is mostly used for enhanced oil recovery.  Direct air capture is also too expensive so far, as it uses a lot of energy.  Removing our legacy CO2, even at a hoped-for $100 / ton, would exceed the Gross World Product (GWP).  Trees are cheaper, but impermanent; forests burn.  “The arithmetic highlights the tremendous need to cut emissions.  There is no viable workaround.”

     Dr. Fry’s comments: Achieving net zero would be wonderful, but it is very far from sufficient to hold global heating to 2°C.  When Earth last wore 420 ppm CO2, millions of years ago, global temperatures were 4-8°C above 1880’s.  This further (past and future, beyond 2°C) heating was, is and will be driven mostly by feedbacks from albedo (reflectivity) changes from snow, ice, and sulfates, plus their water vapor and clouds multiplier.  The impacts of 5°C are far worse (several multiples of world GWP) than the cost of SRM and CDR.  We indeed have a tremendous need to cut greenhouse gas (GHG) emissions, but cutting them to zero, even immediately, is way not enough.  Small companies, recent start-ups, are devising ways (no fans, no heat to regenerate catalysts) to cut DAC energy use (and cost) by 95% or so.  For SRM, the costs are measured in billions rather than trillions of dollars.  Perhaps better SRM than imitating volcanoes is marine cloud brightening (MCB), targeted in the Arctic.  There, warming has caused the polar jet stream to meander, bringing long dry hot spells, long rainy spells (floods), and deep excursions of polar air into temperate zones in winter.  MCB probably would not affect monsoons much

     “China faces extremely grim ecological and environmental conditions, under the impact of continued global warming and changes to China's regional environment.”  Assuming no measures to counter global warming, grain output in the world's most populous nation could fall from 5 to 20% by 2050.  "But steadily, as the temperatures continue to rise, the negative consequences will be increasingly serious….  For a certain length of time, people will be able to adapt, but costs of adaptation will rise, including for agriculture.”
    "Climate change will lead to severe imbalances in China's water resources, within each year and across the years.  In most areas, precipitation will be increasingly concentrated in the summer and autumn rainy seasons, and floods and droughts will become increasingly frequent….  Without effective measures in response, by the latter part of the 21st century, climate change could still constitute a threat to our country's food security,"