GR: Editors at Futurism.com researched global warming and produced the infographic below. The names of the editors appear near the end of the graphic. We are fortunate that Robert Scribbler reviewed the graphic’s projections. His remarks follow the graphic.
[In general:] “A bit over the mark in some respects accurate in broad brush in others.
“1 C = present warming. Actually, we’re at 1.2 C now. We do have loaded dice for heatwaves capable of producing mass injury and mortality. So far, it appears that our heat readiness has increased as well. Damages to agriculture are on the rise. Threats to water supplies are also increasing. Severe weather is intensifying.
“1.5 C appears to be a threshold where we start to see some relatively considerable carbon store feedbacks — perhaps half a billion tons per year addition vs the 20th Century from the Earth System or about 4 percent of the present human emission. Maybe a bit more.
“2 C The statements for rates of sea level rise are tough to prove. That said, at 1.5 to 2.5 C there appears to be considerable risk of crossing various melt thresholds that produce multimeter sea level rise per Century. Extinction pressure from compounded factors including climate change makes the 1/3 number possible at 2 C. Climate pressure alone probably represents more than half of this. See:
“It will be tough to avoid 2 C warming by the end of this Century if we do not rapidly cut fossil fuel burning as the article suggests. The 492 CO2e number concerns me quite a bit because it implies 2.1 to 2.3 C warming by the end of this Century. If we get to zero fossil fuel burning by 2040, that still implies about 520 CO2e which perhaps drops back to 480 or 490 as methane falls out. That’s still very close to the mark. It looks to me like we have to both perform that rapid cut and look at atmospheric carbon capture by various means. In any case, these very high CO2e levels are highly unsafe, in my view.
“Passing 2 C probably implies about 800 million to 1 billion tons per year of carbon feedback from the Earth System by end Century. That’s about 7-9 percent of the present human emission.
“I think in this range we hit a bit of a warming speed bump as glaciers start going down more rapidly and seas begin to really rise. As a result, you’re probably looking at a number of decades and possibly Centuries of very severe storm impacts and very unstable and difficult to predict weather. The ice sheets dumping into the oceans and harming AMOC and other ocean circulation patterns will also tend to disrupt regional and global weather. So it’s here that you get into a period of rapid ocean stratification and extraordinarily bad weather conditions.
“I know I’ve said that we are on a path to 4 C under typical warming scenarios, but I think we also need to hold out what happens if ice sheet response becomes quite large.
“3 C: Traditional agriculture is going to be taking very hard hits even leading up to 3 C. Post 3 C probably does represent an decline threshold. Adaptation will require very extensive indoor vertical farming on the order of requiring national policy initiatives to support their build-out. Carbon feedbacks do become a bit more of a problem as you start pushing at stores that were laid down more than 5 million years ago. The sea ice and salt water incursion scenarios are in the ballpark.
“4 C: You’re probably well past major thresholds for a several glacier systems. 50 meters of long term sea level rise is probably locked in at this point, although you don’t get all that SLR all at once. Cities at 118 F — well, we have cities out west that are predicted to hit 116 this week. So that’s not too far fetched at all.Wet bulb at 35 C becomes pretty common in a number of regions during hot periods at this threshold. Agricultural collapse pressure is very high. A number of regions including Europe, the U.S. West, China, large parts of Africa, India and many more are all likely to be well outside of growing temperature ranges at this time. Loss of 500 billion tons of carbon from the Arctic at 4 C over 500 years is probably possible at this time. Total annual carbon feedback is probably edging into a range of 1.5 billion tons per year from the Earth System.
“5 C: It’s probably enough to completely bring down both Greenland and Antarctic ice over a number of Centuries if warming stopped at 5 C — faster if you keep warming beyond it. Economic damages are certainly quite severe due to very long term crisis. You’re basically looking at a much poorer world where natural resources are much more constrained. Unless the human system produces wealth internally, poverty will be quite rampant. 5 C warming is about 4-7 C cooler than peak PETM warming. It’s worth noting that a lot of the damages will come from a high velocity rate of warming in this scenario in which natural systems would usually have thousands of years to adapt to changes that could occur within a Century or so. Without a collective response, competition over resources would become quite difficult and potentially very vicious.
“6 C: Peak Permian Extinction warming was about 14 C warmer than 1880s. 6 C is not comparable to worst case Permian levels. That said, the level of greenhouse gas emission (approx 1200 ppm CO2e implied) that would achieve 6 C warming at end Century could produce a Permian type extinction event over longer periods (many centuries).
“At 6 C you’re not quite yet in the range where you’re worried about full-on Canfield Ocean type effects. [GR: Canfield Oceans produce deadly hydrogen sulfide. At the “full-on level, the gas rolls onshore and wipes out all animals and most (all?) plants.] However, you probably have regional dead zones that look a lot like a Canfield Ocean and are full of hydrogen sulfide producing bacteria. Sea creatures that enter these dead zones would mostly perish producing various ocean boneyards. I think at this point you probably have 50-60 percent of species threatened with extinction if this warming occurs very rapidly along a 1 Century to 150 year timescale. That said, if you achieve 6 C warming you are pushing at carbon stores that are 30 million years old or more. So you’ve probably set off a long term run up to a hyperthermal like the PETM or possibly the Permian if the carbon stores are deep enough and release long enough. In my opinion, you probably get something closer to the PETM if you peaked human fossil fuel based emissions to an 800 ppm CO2e level (implied 5 C warming at end Century and 10 C warming long term from the base forcing). If you keep burning fossil fuels, through end Century and achieve a base forcing of around 1,200 ppm CO2e or more (implied 6 C warming at end Century and 12 C warming long term from the base forcing) then what you get in the end may well resemble the Permian (or worse) due to combined human emission and Earth System feedbacks.” –Robert Scribbler.
Scribbler added this: “So the Permian killed off 90 to 95 percent of all species in the ocean and about 75 percent of all species on land. The various killing mechanisms didn’t kill off all plant life. But the world was very barren, lifeless, and toxic compared to the rich bounty we enjoy today.
It’s worth noting that the hydrogen sulfide venting effect likely produced a number of killing mechanisms for land forms. Some would include direct poisoning. But venting into the upper atmosphere would have harmed the ozone layer which would have hit land forms very hard as well.
“I think the direct testament to the danger of sulfur related compounds like hydrogen sulfide have been deeply ingrained in land forms to this day. Even a small amount of sulfur is detectable by the noses of mammals — to produce a danger response. This is probably an evolutionary mechanism that came up from the dangers of hothouse times.” –Robert Scribbler.