But there are some good exceptions. Two days ago, ex-moonwalker Harrison Schmitt and physics professor Will Happer of Princeton wrote an opinion article for the Wall Street Journal from which I could have learned some new things:
Harrison H. Schmitt and William Happer: In Defense of Carbon DioxideThe basic theme of the article is simple and most of us learned it as fifth-graders: CO2 is primarily the plant food while its other implications for Nature are negligible in comparison. Humanitarian organizations should work hard to help the mankind to increase the CO2 concentration and it's surprising that virtually all of them are failing to do so.
The demonized chemical compound is a boon to plant life and has little correlation with global temperature.
Needless to say, the article was greeted with a highly nervous reaction from the anti-scientific left-wing extremist sources. They must think it's a blasphemy to remind anyone that CO2 is the key compound that plants need to grow – and, indirectly, that every organism needs to get the food at the end. See, for example, the hysterical reactions by Climate Science Watch, the lousy and badly biased astronomer Phil Plait, anti-Fox-News attack dog organization Media Matters for America, and many others. Many of them seem to literally say that it's been disproven that plants need CO2 to grow; I kid you not. The insanity of certain people who put ideology (and not just any ideology: I mean a highly pathological ideology) on the first place has no limits.
Mr Plait and others, please, try to gradually get used to the fact that we are past the peak global warming hysteria. The elementary parts of common sense, e.g. the realization that carbon dioxide's impact on Nature as a plant food is many orders of magnitude more important than the role of carbon dioxide as a greenhouse gas, will be returning to all segments of the society and you will be increasingly recognized as kooks if you deny such facts about 101 botany, 101 economy, and 101 ecology, even among the people whom you expect to be "ideologically obedient". Your position is totally unsustainable in the long run and even the medium run.
The (for me and others) new insights that the authors presented were differences between C3 plants and C4 plants. The latter evolved to cope with lower CO2 concentrations but they still have to pay some price.
In both cases, plants absorb CO2 through stomata in their leaves and they need a very large amount of water to grow. A higher CO2 concentration allows them to reduce the number of stomata and save water, if I simplify things a bit. So one may say that a higher CO2 helps the plants to deal with the shortage of water.
Today, the average CO2 concentration reached 400 ppm or 0.04% of the volume (or, equivalently, of the number of the molecules in the air because the air is a nearly ideal gas) "today". The mankind will reach a maximum that is much higher, perhaps 600-1,500 ppm between 2050 and 2300. I don't know any details. No one knows them.
But if those future generations stop pumping CO2 into the air, its concentration will drop dramatically. These days, Nature absorbs about 2 ppm worth of CO2 every year from the atmosphere; it's because the "excess CO2" above the equilibrium value which is about 280 ppm for our temperature is about 120 ppm. If the excess is gonna be 600 ppm, like in 880 ppm, it's very plausible that Nature will be eager to absorb five times more, i.e. 10 ppm from the atmosphere every year. That could be described as a nearly 1% drop of CO2 in the atmosphere per year which could reduce the efficiency of agriculture by 0.5% or so per year.
It's not too much but it's not negligible, either. If their technological tricks are already maximized, they could easily find out that the dropping CO2 is an order from Mother Nature that the population should drop by 0.5% a year. The Earth's ability to feed the mankind may start to drop at that point. 0.5% isn't a cataclysmic population decrease and it may be respected without mass starvation, by a lower birth rate. But it would still be annoying.
Nowadays, we enjoy CO2 concentrations growing by 2 ppm i.e. 0.5% a year and this increase contributes a non-negligible part to the increasing efficiency of the agriculture. I hope that when people are forced to get used to the dropping CO2, they will either find a way to mitigate this unwelcome evolution – e.g. by burning lots of biomass or something else – or they will have some other tricks.
For example, in 100 years, most of the agriculture may take place in some huge "greenhouses" (which are more useful if the CO2 concentration in them is kept at elevated levels). What some nations are doing about beating Nature's limitations on agriculture is impressive. Open the new Google Earth Engine with the Landsat Annual Timelapse 1984-2012. You may see the satellite pictures of any region on the globe to check how it was changing during the last three decades. You are offered some real local catastrophes, like drying of the Aral Sea (or a lake in Iran), some changes that are overinterpreted as tragedies although they're really not, like Amazon deforestation and the retreat of a glacier in Alaska, but also examples of some impressive human activities.
They include expanding coal mining in Wyoming – I don't like it too much; and Dubai coastal expansion which is impressive at any rate. But my winner is the Saudi Arabia irrigation. What these Saudis managed to do with the desert is amazing. Look at the nicely ordered crop circles! The diameter of these circles is almost 1 kilometer. Cool. With enough energy, similar things can be built in Sahara and elsewhere, too. I see no reason why the average population density sometime in the future shouldn't exceed the current population density in the Netherlands – 500 people per square kilometer – which would mean that the world population may rather easily surpass 50 billion at some point (many centuries in the future).
I don't claim that I like the idea – large fields and forests where no one annoys me for hours in the afternoon usually seem more pleasing to your humble correspondent than overcrowded, loud areas ;-) – but liking something is a totally different issue than expecting something to take place!