Guest essay by Don Healy
During the past 100,000 years, human societies have witnessed the vast change in climate that has occurred as we have transitioned from a glacial period that ended about 20,000 years ago, into the current interglacial period. During the early stages of this period, human lived as hunter/gatherers, relying on a diet that was very heavily weighted towards meat from a wide variety of wild animals, but also included eggs, nuts, fruits and grasses, to the past 10,000 years or less, when agriculture became a much more dominate feature in society and allowed human populations to remain in the one area and create towns and small hamlets. With agriculture came the domestication of many of the wild meat sources.
As the agricultural model was perfected, much larger town and cities were created, society became more complex and the overall standard of living increased. In the past, it was assumed that societal changes were the prime driver in the change from the hunter/gatherer life style to the agricultural based society, but with the recent research into the change in the composition of the atmosphere over time from the various ice core research programs, another possibility emerges. From the ice core data we can now track the quantity of CO2 present in the atmosphere at various points in history, back to about 500,000 years ago. CO2 is one of the key ingredients in the photosynthetic process.
From : http://www.atmos.washington.edu/~dennis/Our_Changing_Climate.html
Numerous studies have shown the benefits from increasing CO2 levels on plant growth, but until recently, few studies have been conducted to understand how plants respond to the lower CO2 concentrations that were the norm during the glacial periods. Currently, CO2 levels are slightly above 400 ppm. However, during the last glacial period, ending about 20,000 years ago, CO2 levels were as low as 170 to 180 ppm. Below 200 ppm marks the very lowest level for CO2 since plants evolved and at these levels most plants are essentially starved for CO2.
The purpose of this paper will be to show that it is very likely that it was the increase in the CO2 content of the atmosphere, to levels above 250 ppm, that created the conditions for the plants that served as food sources to humans to thrive, and that made it worthwhile for humans to spend the time and energy in cultivating crops, which then allowed for the creation of cities and much more complex social orders. Prior to reaching this turning point, it was more efficient for humans to let wild animal species forage for the more limited vegetative offerings available, convert the plant material to protein and fat, and harvest the animals. Until about 8000 years ago, the human diet was composed primarily of meat from wild animals, supplemented with nuts, berries, mushrooms, and fungi in the local area. The transition from hunter/gatherer to agriculturalist was not necessarily a one-way process. Climatic changes could have necessitated a return to past methods when necessary for survival, such as occurred during the Younger Dryas.
However, as the following graphs will show, the viability of numerous plants drops considerably as CO2 concentrations diminish. Biomass and seed yield were only about 40% of current plant production rates during the glacial periods; levels that would make agriculture an inefficient use of time and energy in those early cultures.
From: http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2010.03441.x/pdf Pg. 682
To clarify, there are three different photosynthetic pathways: C3, C4 and CAM. For the purposes of this discussion, only the C3 and C4 pathways are of concerned. CAM is utilized by cacti and similar plants that are not a large component of the human diet. The C3 process evolved first, over 400 million years ago when CO2 levels where many times current levels and are utilized by about 85% of the existing plant species today. The C4 process evolved much more recently, about 30 to 40 million years ago, when CO2 levels had dropped to levels still above todays levels, but much lower than when C3 plants evolved.
It is believed that the C4 process was a natural adaptation to lower atmospheric CO2. With CO2 levels rising from levels of 180 ppm during the last glaciation to about 400 ppm currently, the C3 plants show a larger response, but the C4 plants also benefitted to a considerable degree, due to increased drought resistance and mycorrhizal colonization of plant roots. Examples of C3 plants are beans, rice, wheat, barley, rye, oats, soybean, peanut, cotton, sugar beets, spinach, potatoes, all woody trees and most lawn grasses. The C4 plants include corn, sugarcane, sorghum, millet, Bermuda grass and poa.
From: http://www.co2science.org/subject/b/summaries/biodivc3vsc4.php
A more graphic display of the effect of various CO2 levels on plant growth follows:
From: http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2010.03441.x/pdf Pg. 677
Higher concentrations of CO2 also have another beneficial effect upon plant growth. As CO2 levels increase up to certain limits, plants are able to use water more efficiently. The reason for this is that the stomata, the pores on the leaves of plants, must remain open longer at low CO2 concentrations to allow sufficient CO2 to enter the plant. CO2 is one of crucial ingredients in the photosynthetic process. While the stomata are open, water vapor escapes as transpiration. The longer the stomata remain open to allow sufficient CO2 to enter the leaf for photosynthesis to occur, the more water escapes. Thus, plants are more drought resistant at higher CO2 concentrations.
Many plants species evolved at much higher CO2 concentrations than we are experiencing currently. The predecessors to Gymnosperms, or evergreens, evolved about 360 million years ago when CO2 levels were about 4000 ppm, 10 times today’s levels. The Angiosperms, or flowering and deciduous trees, evolved about 160 million years when CO2 levels were about 2200 ppm, over five times current levels. So at the levels experienced during the last glacial period of 180 ppm, the plant kingdom was clearly under great stress. We are all quite aware that the survival of the more advanced members of the animal kingdom which includes humans, are clearly dependent upon the well-being of the plant kingdom. So it would appear that during recent glacial periods, much of the life on earth was in jeopardy.
Will rising CO2 levels enhance the growth of many plant species existing today? The answer is clearly yes. A note of caution is warranted here in that the burning of coal, oil and wood have been responsible for most of the increase in CO2 concentration in the modern era, and the burning of these fuels also releases many other toxic substances and pollution into the atmosphere, such as soot, nitric oxides, sulfur dioxides, and trace amounts of radioactive material. However, it would appear that within certain limits the increase in atmospheric CO2 has been beneficial to date, and very likely will continue to be for some time into the future. Please examine the graphs on the next page.
From: http://ibrarian.net/navon/paper/11__Evolution_and_Growth_of_Plants_in_a_Low_CO2_W.pdf?paperid=19948732 Page 236
Greening of the Globe: If the studies cited above are correct, then it would stand to reason that we should be able to detect a growth response in the vegetated portions earth and possibly see an expansion in the overall area occupied by vegetation. The abstract below indicates that this is occurring.
From: http://www.nature.com/nclimate/journal/v6/n8/full/nclimate3004.html
“Global environmental change is rapidly altering the dynamics of terrestrial vegetation, with consequences for the functioning of the Earth system and provision of ecosystem services1, 2. Yet how global vegetation is responding to the changing environment is not well established. Here we use three long-term satellite leaf area index (LAI) records and ten global ecosystem models to investigate four key drivers of LAI trends during 1982–2009. We show a persistent and widespread increase of growing season integrated LAI (greening) over 25% to 50% of the global vegetated area, whereas less than 4% of the globe shows decreasing LAI (browning). Factorial simulations with multiple global ecosystem models suggest that CO2 fertilization effects explain 70% of the observed greening trend, followed by nitrogen deposition (9%), climate change (8%) and land cover change (LCC) (4%). CO2 fertilization effects explain most of the greening trends in the tropics, whereas climate change resulted in greening of the high latitudes and the Tibetan Plateau. LCC contributed most to the regional greening observed in southeast China and the eastern United States. The regional effects of unexplained factors suggest that the next generation of ecosystem models will need to explore the impacts of forest demography, differences in regional management intensities for cropland and pastures, and other emerging productivity constraints such as phosphorus availability.”
During the 400 million or so years that plants have existed on earth, the average CO2 level has been about 1100 ppm, with a high near 4000 ppm when gymnosperms first evolved about 360 million years ago,, to a low of 180 ppm during the last glacial period. Agriculture did not become a practical enterprise for humans until 8,000 to 10,000 years ago when CO2 levels finally moved above 250 ppm during the current interglacial period. At today’s levels, just over 400 ppm we are seeing a significant increase in both the growth of individual plants and in their global distribution. The last 2.5 to 3 million years comprise an ice age in which the pattern has been 100,000 years of glacial advance, interspersed with interglacial periods of 10,000 to 20,000 years, give or take.
During the recent glacial advance, when CO2 levels dropped to 180 ppm, mark the very lowest levels of CO2 during the past 500 million years, and probably much longer. It should be noted, that below levels of 180 ppm, things become extremely dire. Were we to return to levels much below 250 ppm we would probably lose 70 to 80 percent of the human population to starvation and the societal turmoil that would ensue as we have to forgo the benefits of agriculture and go back to being foragers.
The IPCC warns us that at CO2 levels above 300 ppm we face dire consequences. It appears that the quandary we are facing is this: Do we allow CO2 levels to rise, face a modestly warming earth, but one with abundant plant growth, or try to lower CO2 levels which could have much more disastrous consequences for mankind? Ironically, if past geologic history is any indication, we could be approaching the end of the current interglacial and will then have to deal with the glacial narrative.
So, the question I put to you is this: After reviewing the information above, and perhaps doing your own research, what would be the ideal concentration of CO2?
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I do not believe there is an ideal CO2 concentration providing it is sufficient to create biomass (150ppm +??) and that any change from the status quo occurs over an appropriate time frame.
With human intervention selective breeding of both animals and plants can change characteristics and performance within a decade or two. Genetic science may reduce this to a few years. Combined farm and power station units may become synergistic to improve yields.
Similarly human populations can change rapidly. In the last 100 years world populations have trebled. But increasingly developed countries are no reproducing at below replacement rates.
The change in CO2 levels (even in these carbon profligate times) has been approx +40% over the last 150 years since pre industrial levels. There may be some rapid external forcing (volcanic, meteor etc) which could change the balance, but adaptation may be preferable to costly over reaction.t time to adapt
We are the most successful of Gods many creations. The ideal CO2 is the one we have. Lets go from there as we have since the blessed Enlightenment. Off your knees and on your feet people.
Based on all my reading at this blog, I would have said around 1000 ppm CO2 would be “ideal”, if there is such a thing as “ideal”.
This way alamist whining would be amplified to greater proportions, giving more purpose to more alarmist lives, further inducing alarmist charities to fork over more dollars for more research revealing why 1000ppm CO2 is just this side of doomsday, thus, giving even more alarmist lives more meaning.
More CO2, thus, gives more lives more meaning. Oh, and there’s the plant-growth thing.
Previous advocates of AGW, like Arrhenius and Callendar, were right that it would be beneficial, even if they overestimated the effect on temperature of rising CO2 in the real climate system.
The first evidence of permanent settlements and agriculture started in the Levant with the Natufians. The start date was about 14,500 years ago and then the culture seems to have disappeared 12,400 years ago. It restarted later but that is much later.
https://en.wikipedia.org/wiki/Natufian_culture
I have a database of all the CO2 estimates and the 14,500 years ago date also coincides with the first time that CO2 got over 250 ppm after the last ice age.
It also then fell below 250 ppm again 12,400 years ago when the Natufian agriculture culture collapsed. This is also the Younger Dryas temperature decline period.
The next re-start of agriculture after the Natufians was in southern Turkey where the Gobekli Tepe first stonework temple is sited. The very first stone work anywhere and a surprisingly complex temple at the same time, 11,800 years ago.
https://tragicocomedia.com/2013/11/11/gobekli-tepe-the-origins-of-civilisation/
Wheat and barley grows wild here.
http://www.actaplantarum.org/floraitaliae/download/file.php?id=181741
The date of this restart is 11,800 years ago. Not surprisingly, this is also the next time CO2 got to 250 ppm again after the Younger Dryas decline.
The premise is that C3 pathway wheat and barley just does not grow well enough to support permanent settlement and farming until CO2 gets to 250 ppm. I think it holds.
Yup. Those plants can survive below 250 ppm, but they don’t thrive. They also need more water when CO2 is low, since they have to leave their stomata open longer.
Earth has greened as CO2 has climbed thanks to the water-savings from higher plant food concentrations in the air.
Yep. 280ppm and the accompanying mild, steady temps have been rather a salubrious, prosperous period for our species. Be a pity to spoil it.
Hey I know. Lets dump 30gt of co2 into the atmoshere and see what happens. What could possibly go wrong.
Sorry Tony,
Wheat and barley will grow ever more abundantly until CO2 gets into the 1,200 ppm territory. They will also progressively become more drought tolerant. Even if temps go up with more CO2, the C3 plants are going to grow up to 100% more productively. Yes, that is right.
The bad side is that C4 grasses (mostly tropical species) and CAMS pathway cactus will progressively get outcompeted by the C3 plants. But the C4 grasses will then move into the low vegetation desert regions like the Sahara and the US southwest and, well, that will probably be good anyway.
The downside is only for cactus.
Tony,
So far fertilizing the air with plant food has been a good thing, greening deserts and increasing food and fiber production.
All trees and most crops are C3 plants, which have been famished until humanity improved the environment, if indeed we can congratulate ourselves for increasing the essential trace gas CO2 in the air.
Bill and Chimp
Love your unalloyed optimism guys.
Tony, it is not optimism. This is what real science actually says. And in this case, real science is backed up by real studies and real evidence. Unlike climate science which is only backed-up by pessimistic “musings”.
No scientific, rational basis for alarmism.
The pioneers of the AGW hypothesis in the first half of the 20th century considered it beneficial, without even factoring in plant fertilization.
In the late 20th century, Hansen, et al, decided all of a sudden that AGW (assuming without evidence that it exists) had to be a terrible threat instead of a boon, because it suited their needs.
“Tony mcleod March 24, 2017 at 5:29 pm”
Daylight savings soon Tony, don’t let the milk turn sour or adjust your clocks, I know how you Queenslanders like to panic and worry over nothing.
Hello Bill:
Thank you so much for your comments. If you are willing to share your CO2 data base that you mentioned, I would greatly appreciate it. My email is dr.liz@frontier.com. Posting this article has created many good comments with which to pursue this idea further.
Thanks, Don Healy
MEGA! Make Earth Great Again! bring back CO2 to 4000ppm!
Great and green again.
One thousand ppm would be quite enough. Too bad that’s probably not possible given the Ice House in which our planet currently finds itself.
There are interesting questions that are not the same. One is what would be an ideal level of CO2 for Humans? Another is what would be an ideal level of CO2 for us, given that we are distributed as we are?
I am reasonably confident that humans would do very well with a CO2 level of 600 ppm, say. What I am not so sure about is whether we would do so well in the transition from 400 to 600ppm.
Take sea level as an instance. There is no reason at all that humans could not do very well if sea levels were 100 ft higher than today. We would have a different coastline, but it would not be intrinsically inferior to the one we have today. (this is an example – I am not saying sea level would rise by 100ft with CO2 at 600ppm. Maybe it would but that is not the point I am making)
However, if we ask the other question, how would we do if sea levels rose 100ft we get a very different answer. We would do very badly because most of our infrastructure would be under water. Our descendants would probably do fine, but there would be a huge cost in the transition.
Similarly, humans would do fine if Siberia was like the African Savannah and the Savannah was uninhabitable. However, we would do badly because lots of people require the Savannah to be productive. In a few generations, after the Africans and coastal dwellers have died, Humans will have established themselves in the new coasts and productive areas. However, millions may have died prematurely and caused massive disruption through forced migrations.
I think it is very important to recognize the distinction between these two questions. If you want to take the long view, then it does not matter too much. If you care about the welfare of people alive today and in the near future, then it does matter a lot.
However, if we ask the other question, how would we do if sea levels rose 100ft we get a very different answer. We would do very badly because most of our infrastructure would be under water.
===
We don’t have any infrastructure that’s going to last 1000 years anyway….no point
In a few generations…..you act like these people are too stupid to evolve
They can drive cars you know
1) No way could MSL going to rise 100 feet so rapidly that people could not adapt.
2) No way is MSL going to rise 100 feet.
During the prior interglacial, the Eemian, which was much warmer and lasted longer than our present Holocene, sea levels were previously pegged at four to six meters higher than today. Recent investigation raises that estimate, reporting peak Eemian sea levels peaked between 6.6 and 9.4 meters higher than now (~20 to 30 feet).
The long, hot Eemian caused the Southern Dome of the Greenland Ice Sheet to melt about 25% more than it has so far in the Holocene.
A thousand ppm would be better than 600 ppm. Commercial greenhouses operate at 1000 to 1300 ppm.
Please excise first “going to”.
There is absolutely no indication that this bad stuff would happen. Why would the savannah become uninhabitable when CO2 increases the ability of plants to use water? The Sahara is already greening! Why would you assume sea level will rise at some catastrphic rate? It has been going up at approximately 2mm/yr for 200 years or more, with no sign whatsoever that CO2 has or will effect that rate in any way. In reality, our coastlines would not look very different at all. Severe storms are the main reason for coastline damage and they have decreased. Think with your head-not your bad nerves!
Latitude and Chimp, putting aside the details for the moment, do you recognize the distinction between the two questions? Some outcomes might result in a world that is very conducive to human life, but would cause us great problems given our current distribution?
I was quite clear that I was not saying that sea level would rise by 100 ft, but that I was using this as an example of a situation that would not be intrinsically harmful to human life on Earth, but would present us with huge problems.
One could argue that an instantaneous rise of 100 ft would be fine because the new coastline is just as good as the old coastline as far as humans were concerned. However, it would leave a great many cities underwater, so there are good reasons why we might not want this sealevel rise.
Do you see the point I am making?
no……
These are West African Fulani nomads, nomads wander around to where the food and better conditions are….
….see the cell phone…they get the weather channel
http://c8.alamy.com/comp/CWA061/fulani-nomads-with-cell-phone-tamale-ghana-CWA061.jpg
Whether from manmade CO2 or natural causes, there is not going to be sea level rise too great and rapid for us to adapt.
Sea level fluctuates naturally and locally from human activity all the time on different time scales. Venice and New Orleans might not be able to adapt to sea level changes, but no one is going to perish as a result. Many cities have been built in what proved bad locations, as has happened throughout history.
Cutting fossil fuel use is far more dangerous than any possible continued sea level rise, which so far isn’t accelerating over the background rate from recovery from the LIA.
Certainly seaice — you are making the point that not only the absolute levels matter, but the velocity of change matters. Ocean levels rising 10 feet over a century can be easily coped with. Ocean levels rising 10 feet overnight could cause serious problems for many things, including humans at the coast.
But it wouldn’t cause serious problems for those coastal critters who are adapted to live in air or water — the coasts has plenty of mobile tidal critters who cope with a 10 feet rise in sea level (local) *every single day*, and have no problem with it occurring in a slightly different location overnight. In the case of CO2 concentration, the entire biosphere is full of things that function *just fine* at higher CO2 concentrations, in fact that prefer it substantially higher than it is now. And while the growth in annual concentration from anthropogenic may look scary, at a local level organism cope with much larger swings in CO2 concentration due to seasonal or biological effects.
CO2 isn’t sea level. Independent of climatic effects, there’s no reason to think that doubling CO2 from current levels over a period of decades would have a negative effect on humans or a net negative effect on the biosphere at large.
Thonis-Heracleion was not the end of the Egyptians
You are avoiding the question. Whether or not such things will or will not happen, do you recognize that that these are two very different questions? I am not saying here that these things will happen, but that the two questions are very different.
Do you see the point I am making?
Seaice,
Sea level rise is simply not going to be fast enough to leave cities underwater such that people can’t adapt. Some cities would survive with public works as the Netherlands has done for centuries. Others might have to be abandoned, as has so often happened in the past, when sea level was higher than now, as during the Holocene Optimum (when there already were coastal cities), Egyptian, Minoan, Roman and Medieval Warm Periods. MSL fluctuates all the time, dropping during cold phases and rising during warm ones.
Buildings which were by the sea during the Roman and Medieval WPs are now high and dry. Maybe they’ll be coastal again if the Modern WP lasts long enough.
Which is why mentioning 100 feet doesn’t make for a useful analysis. If at most MSL might rise 30 feet over the next century (which it won’t), then people would have to adapt to only 3.6 inches per year rather than a foot.
In fact, there is no reason to expect more than three mm per year, ie maybe a foot in a century, although probably less than that. Two mm a year is more likely.
So, no worries.
You are avoiding the question. Whether or not such things will or will not happen, do you recognize that that these are two very different questions? I am not saying here that these things will happen, but that the two questions are very different.
Do you see the point I am making?
Seaice,
No, I don’t see your point.
That climate change might happen quickly doesn’t matter if we can adapt to it. But it won’t in any case.
Whether sea level rises a foot in a century or 30 feet, it’s not a catastrophe. Whole cities have been destroyed during wars, continents laid waste, tens of million of people killed in a matter of years, yet humanity has adapted and overcome. Up to half of all Europeans died in the Black Death, in just a few years.
CACA is a myth, but even if alarmism were justified, it would be nothing we can’t handle. A “catastrophe” it wouldn’t be. Not even his fellow alarmists buy Hansen’s “Venus Express”.
Chimp.
“That climate change might happen quickly doesn’t matter if we can adapt to it. But it won’t in any case.
Whether sea level rises a foot in a century or 30 feet, it’s not a catastrophe. Whole cities have been destroyed during wars, continents laid waste, tens of million of people killed in a matter of years, yet humanity has adapted and overcome.”
I argue that it does matter. Are you saying that if cities were destroyed and tens of millions of people killed it doesn’t matter because humans will survive?
Dale S acknowledges that there could be problems in the short term, but then says that critters will survive OK. That is fine, but I am more concerned with the people.
“Take sea level as an instance.” Why? Other than the fact that it is a fave Alarmist talking point that is. There is no reason to believe (other than wishful thinking on your part) that SLR is going to speed up, and pure fantasy on your part that it might rise 100 feet.
I’ll speculate that CO2 level of 600-800ppm would be s good range. The question then becomes what happens to CO2 during an 100Kyr glacial period then humanity might need it to be 1000-1200om entering the glacial period.
Maybe the 400 million year old evolution of the C3 process refers specifically to vascular land plants, but green algae, the ancestors of plants, also employ C3 photosynthesis, so the process itself is much more ancient than 400 Ma. The main difference between C3 processes in algae and land plants is that unicellular green algae avoid photorespiration via a CO2-concentrating system. Biochemically, photosynthesis and photorespiration in the green algae are similar to C3 higher plants. There is a difference, however, in the mechanism of inorganic carbon uptake prior to the actual fixation of CO2.
Algae has two sources of CO2. It can extract it for the gas dissolved in water. It can also get it from carbonates such as calcium carbonate CaCO3 which is also dissolved in water. (I have seen PH and KH changes in my aquarium that indicate this does happen. Plants can also extract carbons from carbonates. However they generally have to be in very wet environment to have access to enough carbonate.. Wet territorial environments typically have a lot of rain which will wash away carbonates. So most terrestrial plants don’t have enough access to carbonates to compensate for CO2 depletion in the air.
Why don’t we let it rise- correct that-make it rise until we have some indication that the pause is not a stop or that CO2 is actually affects temperature and is not some fevered environmentalist nightmare. Then we can decide whether we like that world better or not, whether we are in danger of slipping back into glaciation or not and what sort of technical options we have to deal with our CO2 issue at reasonable cost. The IPCC says that a global temperature rise of 1.8C is beneficial to the planet. Why is it “critical” that we limit it to 1.5C?
Earth suffered an ice age or glacial episode when CO2 was four to five thousand ppm during the Ordovician. Solar power was some four percent lower, but that’s not enough to explain ice sheets under CO2 more than ten times higher than now.
That’s the problem right there! CO2 explains everything until you start to drill down. Then it explains nothing!
Don, your essay is perfect timing. Two evenings ago on the 22nd, I attended a Vancouver lecture by Gwynne Dyer. Dyer, known to most older Canadians for his seminal 1980’s broadcasted NFB series “War,” has taken on Climate Change as author of “Climate Wars: The Fight For Survival as the World Overheats.”
Dyer’s main thesis was that we are all doomed by feedback mechanisms if the temperature exceeds about 2 degrees, beginning with the death of “all non-native (ie: most)” food plants around the Earth’s tropic band resulting in massive numbers of nourishment refugees moving into the temperate areas in order to feed themselves.
I asked the first post-lecture question: How do you reconcile 2 degrees to doom when we already know the Vikings enjoyed decent temperatures in Greenland as evidenced by discovery of crop seeds, subsurface burials, grapes in northern Britain on Vine Street… And how to reconcile tropic food crop destruction to the benefits of life-giving CO2 increases producing measurable greening of the Earth including forests and food plants.
Without directly answering my questions, Dr. Dyer simply replied that there has always been climate fluctuations before the Little Ice Age; and that any benefit attributable to CO2 plant fertilization is currently, and will continue to be, negligible.
But I think he may have jumped the shark with his serious promotion of a plan for global salvation in the form of seeding the upper atmosphere with sulphur compounds to stave off human destruction for a little while longer at least. (After proper testing, of course.)
Why would anyone listen to what Gwynne Dyer has to say on “climate change”?
Here are links to his “War” series. Thanks.
https://en.wikipedia.org/wiki/Gwynne_Dyer
“So, the question I put to you is this: After reviewing the information above, and perhaps doing your own research, what would be the ideal concentration of CO2?”
I think that is the wrong question. There is a threshold below which life becomes difficult, but above it many other factors become more influential, until a higher threshold above which life is again, impossible. In between the concept of an ideal concentration is not very useful, except in an environment in which all other factors are controlled, such as a nursery – or spacecraft, come that. I suspect also that the ideal is itself dependent on the other factors, too.
Perhaps it is a tongue in cheek shot at the AGW alarmists, who have precisely this problem – impossible to define an ideal temperature.
Since all plants benefit from CO2, your supposition needs to include an explanation of what the low CO2 animals were eating. The history of human advances can be attributed to a very small number of remarkable births. We know that a large number of important crops, viz., potatoes, tomatoes, and peppers were unknown in Europe and Asia before the Americas were “discovered”.
My point, agricultural technology likely played a primary role in the shift from subsistence to agrarian societies.
C4 and CAM plants can survive on remarkably low levels of CO2. But the vast majority of plants achieve optimum growth at around 1200-1300 ppm. They can flourish however upwards from 800-900 ppm.
Don’t forget maize (corn), the leading grain crop, world production of which almost equals the mass of numbers two and three wheat and rice together. Much of that however is field corn for animal feed or ethanol rather than sweet corn for corn syrup or direct human consumption.
Chimp, the main reason maize (corn) is such a large global crop is its ‘harvest index’. That is the ratio of grain to everything else above ground (corn stover). The harvest index ignores roots, so exludes the more scientifically correct total biomass. But it is easy to measure in the field by harvesting thengrain, then harvesting the straw or soy stubble. Corn is incredibly ~55% food grain, 45% everything else above ground (dry biomass basis). US harvest index ~0.55. Borlaug’s dwarfing of wheat (that and rust resistance were his original green revolution and Nobel Prize basis) is a cultivar dependent ~0.5 HI. About the same for dwarfed rice, also cultivar dependent. Soybeans are only about 0.4 HI, but more highly cultivar dependent. So for a given amount of land, corn simply produces more food. Of course, wheat produces more protein and soy produces more oil. Corn produces more calories, which is why it is the principal poultry/pork feedgrain.
The production figures I cited were for tonnage of grain alone, not all harvested biomass.
I grew up on a 1400-acre family wheat ranch near one of the ag experiment stations where modern varieties of soft white wheat were bred, and ran it until 2001. Nowadays even the short straw of modern varieties often gets harvested, too. As with corn, of course, the roots get tilled up.
It has been so wet this spring that ranchers are planting barley on their summer fallow.
The enhanced biomass and increased diversity of the current age should be celebrated. Thanks to the climate obsessed fanatics we are instead destroying the environment with industrial wind farms, solar farms and idiocratic ideas they may succeed in wrecking it all.
Yes a good point one that needs to be expanded upon….
This excellent summary by André Bijkerk copied from http://www.climategate.nl
In short, in order to survive we need to continue recovering carbon from its natural sinks to the atmosphere as we do through fossil fuel combustion:
Recently I posted this somewhere and for the first time no alarmist came around attempting to trash it:
Carbon dioxide, soda water, sugar, limestone, mice, roses, marble, all have one thing in common, the element carbon (C). It’s the most versatile element, because you can make a lot of very different things of it. Carbon goes around in a big carbon cycle. Green plants make sugars out of carbon dioxide, the very base of life. Eventually with the death of life, carbon returns to more simple forms like methane and carbon dioxide, completing the organic carbon cycle. But the bottom line is: carbon=life and CO2 is its major primary building block. Essentially this also means that the available amount of carbon in the biosphere determines the total amount of biomass
There is another cycle, the inorganic cycle. Carbon has a nasty habit to bind with calcium to form calcium (bi-) carbonates in marbles and limestone and calcium shells. This is a very stable compound which hardly dissolves and just forms rocks, mountains etc. This carbon would be lost for the organic carbon cycle of life and hence for the total biomass on earth, if it wasn’t for volcanoes. The high temperatures >1000 degrees Celsius dissect the carbonates back into CO2 and calcium oxides, adding CO2 again to the atmosphere, and useable for plants to grow again.
However in the late Cenozoic more and more carbon became trapped in the inorganic carbon cycle, leaving the atmosphere with less and less carbon. Maybe volcanic activity was decreasing gradually, suppressing the carbon return in the inorganic cycle. In the late Pleistocene a mere 180 ppm remained, hardly enough for many trees, causing steppes to dominate the landscape. But also 150 ppm is the limit of life. Below that, plants are unable to take in CO2 anymore and life on Earth was on the brink of disaster, if it wasn’t for a temporary carbon injections during stages which are known as interglacials. But how much longer would it last?
This leads to three important conclusions:
1: if there weren’t volcanoes, life would cease to exist on earth with all carbon being sequestered in limestones and shells eventually.
2: humans are doing a great job, bringing fossil fuel carbon, lost in the earth, back into the organic carbon cycle and thus prolonging the era in which life is possible on Earth.
3. Curbing CO2 is the single most largest stupidity of mankind ever and for ever to come.
I believe most scientist agree that volcanoes are a key part in recycling carbon back into the atmosphere. So yes there is an inorganic carbon cycle, There is also a second aspect to the carbon cycle you may have note realized. In order for carbonates to continuously increase you must add continuously calcium, or magnesium to the water. There is a theory out there that the creation of the himalayan mountains started the ice age cycles. As the mountains grew, erosion and carbonate production increased leading to the lower CO2 levels we have today.. Prior to the formation of the mountains CO2 levels were about 1000ppm. Eventually the uplift of the mountains will end and if the theory is right CO2 levels should start to increase buy that is at least 50 million years away.
The problem is that falling CO2 didn’t cause our present Cenozoic ice age or ice house. Eocene CO2 has been estimated at 700 to 2000 ppm, but those levels were because it was warm then. CO2 is more effect than cause of warmth.
Neither did the Azolla Event cause the Cenozoic ice age.
https://en.wikipedia.org/wiki/Azolla_event
Ice sheets started to form on Antarctica in the Oligocene when that continent was separated from South America and Australia by deep oceanic channels. They retreated some in the Miocene when the paleo-Drake Passage between the South American and Australian plates temporarily grew shallower. In the Pleistocene, they grew again. (Not sure about the intervening, short Pliocene Epoch.)
http://theresilientearth.com/files/images-2011/cenozoic_d18O.jpg
Cold already returned late in the long Miocene, then earth enjoyed a brief last blast of warming in the Pliocene, against the long-term trend.
As usual I am confused, it doesn’t take much. Anyone who has accidentally frozen a can of coke knows that when you freeze water it outgasses all dissolved CO2. If sea levels are down 20 meters because the water has frozen then you would think that all that outgassing would have put atmospheric CO2 up, not down.
I’m not sure about the outgassing part, does most of it remain trapped in ice as bubbles?
However the other part is that the oceans across the globe cool and more CO2 taken from the atmosphere. Water and CO2 react chemically, to form Carbonic Acid, this is aided by lower temperatures. O2 and N2 do not react in the same way but just occupy the intermolecular spaces, In the case of O2 this is handy for fish who extract Oxygen with their gills.
That’s how I remember it from school 50 years ago.
Robin,
Sea ice indeed doesn’t retain CO2 and other gases in the ice, that doesn’t change the atmosphere that much as that is only a small part of the carbon cycle. Most CO2 is going down with the heavier waters at the edge of the sea ice fields. Heavier in part due to the cold temperatures and the fact that freezing waters also expels its salts which makes the surrounding waters saltier and thus heavier…
This is the issue people seem to miss most, societies thrive during warming periods, they die during ice ages. We are blessed with the warming. We should be spending money to prepare for the next ice age, not for continued warming.
Just How Much Does 1 Degree C Cost?
https://co2islife.wordpress.com/2017/01/25/just-how-much-does-1-degree-c-cost/
In 100 years we have discovered genetics and have developed tools that allow use to change DNA in plants and animals. We have also developed ways to make and break chemical bonds between atoms. It will take at least a 1000years for the next ice age to start. By then we may already have converted using genetic engineering C3 food plants into C4 plants which can tolerate very low CO2 levels. We can also today convert calcium carbonate to CO2 and calcium metal young only electricity. So I think our ancestors will handle the next ice age better than our ancestors.
Our descendants indeed should be able to survive the inevitable, coming cold, but our ancestors did alright, too. Their numbers exploded with agriculture, then the Industrial Revolution, during our current balmy interglacial, but our modern human, hunter-gatherer ancestors managed to live through one glaciation by staying in Africa (although H. erectus-grade people lived in Asia and even Europe then), and during the next spread everywhere (depending upon the date you assign to their entry into the Americas south of the ice sheets).
Humans are adaptable. Increasing CO2 presents no threat.
Am I the only one who thinks that its strange that a few percent extra of emissions from fossil fuel use could increase levels by 100ppm but levels at the limit of sufficient for terrestrial plants to survive did not lead to large swings?
How many laboratories would risk their reputation by reporting gas analysis results at <0.0005% precision, even for a hermetically sealed sample, under strictly controlled conditions in their own premises?
Outside air concentrations at the same precision 158 000 BC requires paranormal talent. Good enough to claim the M$ offer from Randi et al.
jaakkokateenkorva,
Still a challenge, but they even measure changes in O2 in outside air to a precision of better than 0.0001% (less than 1 ppmv on 210,000 ppmv)…
The CO2 levels in ice cores are measured using either the grating technique: grating the ice just below freezing point under vacuum where water vapor is frozen out of the gas in a cold trap, or the sublimation technique: again just under the melting point with an IR lamp where everything is sublimated and cryogenic frozen out and later separately released. The latter is used to measure the isotopic composition on a mass spectrometer.
Average repeatability of samples taken at the same ice depth for CO2: 1.2 ppmv (1 sigma). Maximum deviation for the same average gas age between cores with extreme differences in temperature and accumulation rate: 5 ppmv.
See further:
http://courses.washington.edu/proxies/GHG.pdf
Any news from OCO-2? No? For this reason, the story is good otherwise, but the average global outside air composition from the homo neanderthalensis period at 0.0005% precision is excellent entertainment in Star Trek.
This cannot be. Intelligent carbon based life cannot possible evolve on Earth. Elsewhere in the universe carbon scores the 4th most common chemical element. On Earth it’s only the 15th. Even chromium, sulphur, nickel and cobalt are more common. And, according to the settled models of the scared scientists, have already poisoned our ancestors./sarc
It is reasonable to speculate on the effects of changing atmospheric CO2 concentration. However, as soon as an ‘ideal’ concentration is specified (by scientific consensus, of course), the pressure will be on to achieve it. The prostitutes and parasites who presently infect the more speculative branches of science will have another lucrative honeypot with which to SAVE THE PLANET. This should not be encouraged.
Given a reasonably slow rate of change, it is likely that most forms of life will either adapt or mutate to cope. As there is presently no convincing method of distinguishing anthropogenic CO2 from the natural stuff, and given the fact that atmospheric CO2 concentration has varied widely over the aeons with no anthropogenic influence whatsoever, I don’t see much point in worrying about the matter.
Please do not be too hard on Doctor Suzuki. He has done some world class, ground breaking research on why fruit fly genitalia are larger than his.
This thesis was proposed 9 months ago:
https://wattsupwiththat.com/2016/06/25/why-did-agriculture-start-13000-years-ago/
The problems have not gone away:
1) If the invention of agriculture were simply waiting for edible grains to grow bigger, faster we might expect it to happen nearly simultaneously in various parts of the inhabited globe, in Eurasia, Africa,
Australia, and the Americas. As far as we know it happened just once, in the Levant or thereabouts.
2) No direct evidence is presented or mentioned here connecting the prevalence of any plant species to CO2 concentration, that is, in an environment where climate could otherwise be controlled for. Can a single plant extinction be attributed to CO2 starvation?
3) Non-anthropologists are prone to project their world view into the mind of primitive man. Just as humans could never invent technological fundamentals like writing or the phonetic alphabet, but could only discover them through a series of accidents, so humans could only discover by accident how plants and animals reproduce. The most primitive people on earth in the first half of the 20th century, the Tiwi of Melville and Bathurst Islands north of Australia, had remained sufficiently isolated to allow their largely uncontaminated Paleolithic technology and culture to be studied independently by two
anthropologists a quarter of a century apart. The two eventually collaborated in a book, “The Tiwi of North Australia.” One point that was abundantly clear through many aspects of their culture, from marriage practices to naming customs, was that the Tiwi did not know where babies came from. This anthropological discovery leads directly to the conclusion that just as Austrialian-Tiwi isolation
prevented their introduction to the bow, animal domestication and agriculture, so it prevented their learning of biological reproduction: Paleolithic man did understand paternity.
4) Accordingly seed function and incipient agriculture would only be discovered by accident, and the proper question becomes, what circumstances would most likely lead to the discovery in the apparently unique time and place it occurred, while at the same time explaining its uniqueness–not in Africa, America, China, or Australia. CO2 abundance does not seem a likely candidate. –AGF
That should read, “Paleolithic man did NOT understand paternity.”