Will increased carbon dioxide levels actually benefit planet?
by William Happer
Did the world have just the right concentration of carbon dioxide at the pre-industrial level of 270 parts per million? Reading breathless media reports about CO2 "pollution" and about minimising our "carbon footprints", one might think that the earth cannot have too little CO2. Humans and most other animals would do fine in a world with no atmospheric CO2 - but most plants stop growing if CO2 levels drop much below 150 ppm, so we would starve to death without at least this minimal amount. We are probably better off with our current 390 ppm than with the preindustrial 270 ppm, and we would be better off with still more CO2. For example, there is evidence that California orange groves are about 30 percent more productive today than they were 150 years ago because of the increase of atmospheric CO2.
What atmospheric levels of CO2 would be a direct threat to health? Both the United States Navy and NASA have performed extensive studies of human tolerance to CO2. As a result of these studies, the navy recommends an upper limit of about 8,000 ppm for cruises of 90 days and NASA recommends an upper limit of 5,000 ppm for missions of 1,000 days. We conclude that atmospheric CO2 levels should be above about 150 ppm to avoid harming green plants and below about 5,000 ppm to avoid harming people.
That is a big range, and our atmosphere is much closer to the lower end than the upper end. We were not that far from CO2 anorexia when massive burning of fossil fuels began. At the current rate of burning fossil fuels, we are adding about 2 ppm of CO2 per year to the atmosphere, so getting from our current level of about 390 ppm to 1,000 ppm would take about 300 years—and 1,000 ppm is still less than most plants would prefer, and much less than either the NASA or the navy limit.
Yet there are strident calls to immediately stop further increases in CO2 levels and reduce levels back to the 270 ppm pre-industrial value that was supposedly "the best of all possible worlds". The first reason for limiting CO2 was to fight global warming. Since the predicted warming has failed to be nearly as large as computer models forecasts, the reason was amended to stopping climate change. Sancta simplicitas. Climate change itself has been embarrassingly uneventful, so another rationale for reducing CO2 is now promoted: to stop the supposed increase of extreme climate events like droughts, hurricanes or tornados.
But dispassionate data show that the frequency of extreme events has hardly changed and in some cases has decreased in the 150 years that CO2 levels have increased from 270 ppm to 390 ppm. Other things being equal, doubling the current CO2 level in the atmosphere will increase the surface temperature by about 1 C. This modest warming, together with documented benefits to plant life, would be an overall benefit. The supposed ill effects of more CO2 are from computer models in which water vapour and clouds multiply the modest direct warming by factors of three, four even 10. Observations show no evidence for these large ``positive feedbacks."
In the preface to the first edition of his Extraordinary Popular Delusions and the Madness of Crowds, Charles Mackay wrote: "The object of the author in the following pages has been to collect the most remarkable instances of those moral epidemics which have been excited, sometimes by one cause and sometimes by another, and to show how easily the masses have been led astray, and how imitative and gregarious men are, even in their infatuations and crimes." The contemporary crusade to demonize CO2 has much in common with the medieval crusades Mackay describes - with true believers, opportunists, cynics, money-hungry governments, manipulators of various types and even children's' crusades. The world has more important, real problems to tend to.
William Happer is professor of physics at Princeton University, in the US, and the author of The Truth About Greenhouse Gases – published by the Global Warming Policy Foundation
There are no references for any of your assertions - like orange groves being 30 per cent more productive now than 150 years ago, due to increased CO2 alone? Link to the study? Peer reviewed?
What has the safe limit for CO2 in humans got to do with anything? We're not suffocating the planet, we're overheating it. Nothing you've said addresses any of the key arguments, measurements of observations by the overwhelming majority of scientists working in the field of climate - total head in the sand stuff. Bravo.
Eddie Spaghetti - UK
Refreshing; a summary of CO2's effect on the planet from a writer who's not completely scientifically illiterate. Eddie, ask a botanist, not a political "climatologist" - CO2 is the furthest thing from pollution. Plants thrive on higher carbon dioxide levels, most prefer 1,200-1,500 ppm, and the effect is huge on growth and drought tolerance. Most plants evolved with far higher CO2 "pollution" levels- 7,000 ppm during the Cambrian.
Better still, do the experiment yourself. Unlike global warming, the fact that CO2 is good for plants is based on direct unambiguous observation, repeatable experiments with outcome prediction, quaint old-fashioned scientific principles like that. Not computer simulations.
Science is a method, not an institutionalised consensus. I think Darwin, Galileo and Einstein would tell you that? But if you must go with consensus - I'd go with the tens of thousands of independent qualified scientists, who consider AGW garbage, over a handful of discredited political groups.
Therepwood - Michigan
How can a supposedly serious scientist talk about the dangers of global warming, or any other global environmental change, without mentioning ecosystems? While it might be true that many plant species would prefer a higher CO2 concentration, this does not alter the fact that eco-systems worldwide might drastically change, in ways that we are unlikely to want.
The author admits that global warming will favour some species over others. But unfortunately, the author does not understand that this might be problematic. Fast environmental changes will bring habitat changes, decline in biological variation and might very well bring drastic reductions in vital environmental services that we rely on, before a new ecological balance will be established. Habitat changes, extinction of key species and reduced variation is already happeing at paces faster than anything seen in human times. Ecosystems are stable right up to the point where they are not, environmental change is not linear, we do not want to know what happens beyond the tipping point.
It is quite ignorant to think that we have the knowledge and power to change our global ecosystem in a favourable direction in a controlled way. As admitted by the author, we have a poor understanding of the global climate. In such a situation, the prudent thing is to keep the status quo, not jump of a cliff simply because the grass might be greener down there.
Henrik Hermansson - Trinity College Dublin
Not "might", the grass (and the entire planet) literally will be greener.
Threepwood - Michigan
Not science. This is a religious screed.
R Pauli - USA
This opinion piece is insulting. The negative consequences of CO2-driven climate change vastly outweigh the few positives. Over all, plant production world-wide has decreased and will continue to decrease as CO2 increases; only a sub-set of flora benefit from increased atmospheric CO2. Also, increased drought has occurred and will continue to occur as increasing CO2 warms the planet.
Worse yet, as our CO2 increases, supplies of fresh water for billions of human beings (and other species) has decreased and will continue to decrease: it isn't something that will happening in the near future. it is already happening. Sea levels continue to rise, which will dislocate hundreds of millions of people.
David Rice - Desertphile
"Sea levels continue to rise, which will dislocate hundreds of millions of people". Actually, sea levels have been rising and ice shrinking since the last glacial maximum around 18,000 years ago. Pray this does not stop/reverse in our lifetimes or we may really have something to worry about.
The rate has not increased; In 2007, IPCC notes stated: "Global average sea level rose at an average rate of 1.8 [1.3 to 2.3] mm per year over 1961 to 2003. The IPCC concluded that there was "no significant acceleration in the rate of sea level rise during the 20th century has been detected".
Co2 is an integral part of photosythesis, it benefits almost every green plant on earth. Again- ask a botanist or do the experiment yourself.
Threepwood - Michigan
I read another article , which says that the human brain has stopped evolving due to lack of oxygen.From your research, it indirectly means you want to make my brain dumb.
Aravind - Chennai, India
Nice article and debate. I am very much inclined to go with Therepwood, if there is enough evidence and facts behind his claims. Yes I would like to see a greener earth, may not be in my lifetime - but who knows, as a Hindu, I believe in re-incarnation. So may be in a couple of thousand years I would like to born again in a greener world. if not poached by concrete jungles.
Avijit Nag - Mumbai, India
David Rice. Relax, there's been no warming for the last 13 years. If you're that worried about your fellow man, then you should be troubled by ruinous, idiotic, "green" taxation and environmental policy - currently, rolling over the economies of the west. Just when we least need it.
Big Paul - UK
As a horticulturist, I can tell you that some commercial greenhouses use CO2 as a plant growth agent - therefore, it is literally a "greenhouse gas." If water vapour is 90 per cent + of the atmospheric greenhouse gases as he suggests, and evaporation relates linearly to sun flares, etc - I question whether CO2 matters next to solar activity - except to the plants.
Danny Boy - Boston, US
No one credible is predicting more than 1-2 deg increase this century, right? The catastrophic scenarios don't come into play unless we have 12-25 deg increases. I understand that we should be concerned about human generated warming, but why do environmentalists always seem to use panic inducing comments?
Seems to me that we have plenty of time for market driven adjustments in our lifestyle. The real catastrophe would be to channel our ever decreasing resources and ever growing deficits from our main problem - namely economic growth.
Joseph Greene - Los Angeles, CA, USA
