Carbon dioxide was measured at 400 parts per million at the oldest monitoring station which is in Hawaii sets the global benchmark. The last time the worldwide carbon level was probably that high was about 2 million years ago, said Pieter Tans of the National Oceanic and Atmospheric Administration. That was during the Pleistocene Era. "It was much warmer than it is today," Tans said. "There were forests in Greenland. Sea level was higher, between 10 and 20 meters (33 to 66 feet)." http://weather.yahoo.com/greenhouse-gas-milestone-co2-levels-set-record-193012833.html
Thanks John It is sad, depressing and shameful...for this generation. Any idea where it will max out? Andrew
If we continue the global policy of 'drill, baby, drill', and burn all possible coal, oil, and gas reserves, it'll easily climb well above 1,000ppm. The permafrost will melt, which could easily double the amount of carbon in the atmosphere, and undersea frozen methane on the continental shelves will also melt. The feedback from those two effects might drive it well over 1,5000ppm (but few humans will be around to observe that). On the other hand, if we aggressively shift away from fossil fuels and address efficiency head-on, we might top out at 500ppm before the numbers start to drop back to safe levels. (International negotiations have set 450ppm as a target peak, but we're already failing to take the actions needed to halt at 450) Of course, it's possible that the melting permafrost and undersea methane will kick in while our aggressive actions are still taking effect, which might mean that stopping at 500ppm is impossible and we're going to reach 7-800ppm no matter what we do. The 350ppm benchmark is the last 'safe' value we know of, anything higher than that has a risk of dramatic positive feedback making it extremely difficult to halt the rise. We're already seeing melting permafrost and arctic amplification, but we don't yet know how fast or at what threshold it'll start to become a dominant influence. Most likely, if civilization is going to survive, we'll have to start a massive project of geoengineering and scrub excess CO2 from the atmosphere directly. The cost of this will be horrendous, but there won't be any viable alternative left.
Heck If we get extreme consequences No doubt BIG SCIENCE will come up with a POSSIBLE CURE Something pretty dangerous-like HUGE amounts of something to reflect light solar energy back into space Maybe send us into an ice age!!
Thanks John Good Summary of predictions. My analogy is that ; She is a very big ship, we have had our steering wheel ( CO2) stuck at high and she has started to move (temperature). Trying to swing back will have very little affect for a very long time. As you point out. permafrost melting will now take over. I expect 1000ppm max. i.e. all fossil fuels used up. I expect Human civilzation will continue.....but I am sure our descendants will not hold us in any high regard. Best of luck Andrew
The solution is stop burning fossil fuels. There are no magic bullets - the risk of unintended consequences of some hastily conceived scheme is just not worth it. We know how to get plenty of energy from renewable sources and we just have to to do it. Four fifths of the known reserves of fossil fuels must stay in the ground, or we are toast.
A couple of years ago it looked like we'd tapped out the cheap oil and CO2 would level off because we'd hit Peak due to supply constraints. No longer. The rise in crude prices triggered massive exploration and development efforts, and we're back to having enough oil to meet current demand for a loooong time. So now the only way to seriously rein in CO2 output is going to be self-restraint, possibly in the form of some sort of energy or carbon tax. And I don't think THAT is going to happen unless (er, until) GCC starts causing sustained severe economic damage in the US. Until then, we will still keep driving cars bigger than we need, faster than we need, and more miles than we need. We're going to keep building sprawling developments out in the middle of nowhere, and too many people will continue to put up with an hour or more of extra commuting so that they can buy "cheaper" housing, which all too often really means buying way more house and yard than they need for basically the same price they would have paid for a modest but big-enough house closer in. And the pattern of jobs decentralizing to the suburbs too will continue, forcing too many people to drive even if they've taken the initiative to live where they don't have to drive miles and miles to get to their stores, schools and churches. We'll continue to make fun of people who do manage ride the bus or get around by bike, and complain about (mostly alleged) "free ride" those folks are getting when they're actually saving the ASSES of those who drive their own asses around alone all the time. Believe it or not, by nature I'm an optimist. But not on this issue.
https://gml.noaa.gov/webdata/ccgg/trends/ch4_trend_gl.pdf The website graphs just above for increasing global atmospheric methane and the post above that showing increasing global atmospheric CO2, actually show decreases in GHG emissions caused by major shutdowns of productivity plants due to ccp coronavirus spreading around the World. Man, there is almost no effect to GHG emissions reductions due to the disease!!! It is clear AND scary to death, that the World’s ability to meaningfully cut GHG emissions is impossible, except only by a major collapse in World productivity that makes ccp coronavirus productivity reductions look like little kids playing with toy trucks in the backyard!!!
https://earthobservatory.nasa.gov/images/150967/why-methane-surged-in-2020 The above article indicates why shutdowns in ccp coronavirus related man-made reduced emissions, showed little to no reductions in over-all World GHG emissions. PS….I’ll let others determine the accuracy of the studies. Over my head.
Had to read that article a couple times to fully understand it, but now I get it. Reducing combustion for those months in 2020 also reduced NOx emissions, which normally break down into OH and scrub methane out of the atmosphere. And with methane a vastly more powerful GHG than CO2, that increased methane enough to offset the reduction in CO2 output that came from reducing combustion in the first place. Wow. Scary and depressing. But it also leads to the question: While we normally regard NOx as a (ground-level) pollutant if it's that powerful of a methane neutralizer, as we become more aware of the effects of methane emissions might it make sense to release NOx (or OH) strategically as we reduce the carbon emissions that normally accompany it? Maybe dispersed and not concentrated in populated areas, so as to avoid health effects? Of course I realize this scale of climate engineering carries enormous risks, and is not something we would want to do lightly.
At least five independent studies conducted during the coronavirus lockdown in 2020 documented that ambient NO2 levels decreased significantly (as a result of decreased NOx emissions), but ambient ozone levels either stayed the same or increased in all cases, some dramatically: https://www.greencarcongress.com/2020/05/20200512-grl.html https://www.greencarcongress.com/2020/12/20201227-york.html https://www.greencarcongress.com/2020/07/20200729-leeds.html https://advances.sciencemag.org/content/7/3/eabd6696 https://cdn.coverstand.com/43726/704234/e344283c3c88b9ee47a8433be916e61a375b36fe.3.pdf [Page 238] Secondary organic aerosol (SOA) production may dramatically increase as NOx emissions are decreased according to a study by Carnegie-Mellon University - Yunliang Zhao et al. "Reducing secondary organic aerosol formation from gasoline vehicle exhaust," Proceedings of the National Academy of Sciences, May 2017, http://www.pnas.org/content/early/2017/06/13/1620911114 (Figure 3a). Medium-high ambient NOx levels may inhibit sulfate formation (https://www.greencarcongress.com/2019/12/20191225-nox.html) A European study found that health risks associated with PM2.5 were estimated to be lower in countries where nitrates were high in the concentration mix (https://www.greencarcongress.com/2021/12/20211228-lshtm.html). NOx emissions are sort of a double-edge sword and caution should be taken in massive reductions, in my opinion.
