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    How Humans Can Affect Nature
    By Patrick Lockerby | March 6th 2011 07:51 PM | 20 comments | Print | E-mail | Track Comments
    About Patrick

    Retired engineer, 60+ years young. Computer builder and programmer. Linguist specialising in language acquisition and computational linguistics....

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    Some people accept that the world's climate systems are changing, but try to argue that humans are too puny to be any part of the cause.

    The reason for putting forward such an argument in the face of a wealth of historical and scientific data seems to be a matter of political agenda: if humans are too puny to cause climate change then they must surely be too puny to put matters right.  It follows that 'right thinking people' should oppose any attempt to 'do something' about climate change - especially at the taxpayers expense.

    Concern for the environment is not a ploy recently invented by politicians to raise taxes or to impose a new world order.  From the earliest days of humanity our ancestors observed that depletion of resources can be fatal to the group.  With the dawn of agriculture came the simple observation that if you eat all the seed, you can't sow for next year: if you eat all the livestock there is nothing left to breed.  Before economics there was husbandry: the art of making best use of all natural resources.

    Prior to the industrial revolution fuels were burned for heating, cooking and small-scale metalworking.  The major sources of power for industry were wind and water mills.  The advent of the steam engine gave civilization a self-amplifying power source.  You can't burn wood to make forests and you can't use windmills to make wind.  But you can burn coal to make steam to power the engines to extract coal.  The ensuing rise in coal consumption was rapid.  As was the ensuing rise in pollution.

    As new coal fields were discovered across the planet, pit exhaustion was not considered to be a problem.  Long before the coal started to run out, science would undoubtedly have solved the problem of energy efficiency.  With each passing year we would use less and less coal, not more and more.
    Referring to your timely leader on the probable exhaustion of the English coal-fields, production can  never keep pace with the present wasteful use of coal. Science will yet come to the rescue, enabling us to utilise 100 per cent, of the energy stored up in the coal, instead of 15 per cent, in the steam engine mid 11 per cent, in the steam dynamos now gained. Electrical energy can be obtained direct from coal without the aid of steam or the ordinary combustion of that fuel.
    Reader's letter,
    The Mercury, Hobart Tasmania, May 1st 1901
    http://trove.nla.gov.au/ndp/del/article/12838744
    The best coal in the world for steam engines was Welsh steam coal.  It was exported all over the world at its peak.  It is now exhausted.

    Since the industrial era we humans have been extracting resources from the ground as if there is no tomorrow.  The effects of this are visibly damaging our environment.  In 1868, George P. Marsh wrote his book '
    The Earth as Modified by Human Action'.  Over 140 years later his writings on anthropogenic environmental changes remain largely ignored.

        The object of the present volume is: to indicate the character and, approximately, the extent of the changes produced by human action in the physical conditions of the globe we inhabit; to point out the dangers of imprudence and the necessity of caution in all operations which, on a large scale, interfere with the spontaneous arrangements of the organic or the inorganic world; to suggest the possibility and the importance of the restoration of disturbed harmonies and the material improvement of waste and exhausted regions; and, incidentally, to illustrate the doctrine that man is, in both kind and degree, a power of a higher order than any of the other forms of animated life, which, like him, are nourished at the table of bounteous nature.

    The Earth as Modified by Human Action
    George P. Marsh
    http://www.gutenberg.org/etext/6019


    The atmospheric blanket

    Since the time of George P. Marsh we have much more evidence of the environmental impacts of industrial scale activities.  We have also come to know that treating the atmosphere as a dumping ground for our waste gases is a very bad idea.

    Seeing snow on a mountain top was a puzzle to the ancients.  They knew that as you get closer to the equator it gets hotter, and as you move north it gets colder.  The Ancient Greeks even figured out that the far north should spend half the year in sunshine and half in darkness.  Some observers put the differences in temperature down to the curvature of the Earth which causes the equator to be nearer the sun than the poles.  If true, that would mean there should be no snow on mountain tops because they are nearer the sun, as noted by George Best.

    In the 1800s, Horace de Saussure's experiments with hot boxes showed that mountain tops get far less benefit from the blanketing effect of the atmosphere than regions lower down.  Temperature is a matter of balance between heat inputs and heat outputs.  With a thermal blanket you can get a higher temperature from the same heat input or the same temperature from less heat input.  That's why we lag boilers and insulate houses.

    De Saussure’s hot box served as a model for nineteenth-century scientists demonstrating the relationship of the sun to the earth and its atmosphere. Like the glass covers of the hot box, our atmosphere allows most sunlight to strike the earth. About three quarters of the sun’s radiation reaches the earth’s surface when the sky is clear. The earth, like the bottom of the hot box, absorbs sunlight and releases heat. But this heat cannot readily escape through the atmospheric blanket—just as solar heat is trapped by the panes of glass in a hot box.
    http://solarcooking.org/saussure.htm

    Saussure statue at Chamonix - courtesy Wikimedia Commons.

    Water vapor is a 'greenhouse gas': it is a form of atmospheric 'lagging' which helps maintain temperatures within broad limits.  The amount of vapor in the atmosphere can vary substantially and rapidly at different locations depending on various factors.  Carbon dioxide - CO2 - is also a greenhouse gas.  The amount of CO2 in the atmosphere can vary with location but it does not vary rapidly.  Unlike H2O, CO2 can't precipitate out of the atmosphere.  It can only be absorbed by biological and geological processes, and that takes time.

    If CO2 goes into the atmosphere faster than it is taken out, then there will be a trend towards a planet which is ever warmer on average. Global warming doesn't mean that every single bit of the planet gets warmer.  It means that the globe, taken as a whole, is warming.  It means that the bits which are getting warmer are doing so faster than any other bits might be cooling.

    People have been putting CO2 into the atmosphere since the discovery of fire.  Following the invention of the steam engine, people burned the same fuels as previously but then burned coal additionally - mostly for industrial and transport purposes.

    With the invention of the electric motor and generator there was a further rise in industrial output.  A small scale enterprise which could not be run using a steam engine could be run using electric motors.  The spread of electrical power into every workshop and then every home in industrialized countries led to further demand for coal.

    We are now so used to having electrical power in the home that we take it very much for granted.  There is a basic fact that the ordinary consumer of electricity does not realize.  Burning coal to make electricity is very inefficient.  In effect, for every kilowatt you use, you throw away about four kilowatts.  Apply that economic model to buying a bag of potatoes, flour or rice.  You are required to buy five bags of food.  You are required to throw four bags on a bonfire before you are allowed to take the one bag home.  If anyone tried to run a store that way they would certainly get some interesting feedback from their customers.  But that is how coal-fired power stations work: we use roughly one bag of coal to get electricity and throw four away.  Oil and gas-fired power stations are also extremely inefficient.


    The subtlety of change

    It has often been remarked that we humans are not adapted to notice slow change.  Also, many people quite simply refuse to believe that the living things around us - and we humans as well - have evolved due to environmental pressures.  It seems hard for some people to imagine that micro-changes in environment can lead to micro-changes in living things and ultimately: new species.  Small wonder that people who won't acknowledge what we have changed on the human scale will not accept our ability to make changes on a global scale.

    Charles Darwin pointed out that our domesticated animals are a result of selective breeding - the selection of stock for breeding based on minor deviations from the average stock.  This is also true of our domesticated plants.  Domesticated plants and animals have been evolving over millenia through human influences, but often in a manner unremarked and hence unrecorded.
    As soon as the points of value are once acknowledged, the principle, as I have called it, of unconscious selection will always tend,—perhaps more at one period than at another, as the breed rises or falls in fashion,—perhaps more in one district than in another, according to the state of civilisation of the inhabitants,—slowly to add to the characteristic features of the breed, whatever they may be. But the chance will be infinitely small of any record having been preserved of such slow, varying, and insensible changes.

    Charles Robert Darwin (1809-1882)
    Origin of Species. Chapter I.  Variation under Domestication

    http://www.bartleby.com/11/0106.html
    Many people simply cannot - or will not - see that our domesticated breeds are descendants of wild ancestors and that they constitute an example of how subtle changes can produce something seemingly quite different to the previous norm.

    The process of evolution doesn't just apply to our stock, but to our urban environments.  Most people will know of local buildings demolished and new ones built; roads widened or newly built; rivers dammed; harbors enlarged; open land swallowed by new housing or industrial complexes - the list is endless.  This is evolution.  This is your local environment changing before your very eyes: your town - even your country - is likely to have changed greatly since your childhood.

    Change surrounds us in our daily lives, but the atmosphere appears constant and unchanging.  That is because the changes are small, subtle and long-term.  Also, the many gases we dump in our atmosphere are invisible.

    The globe's local climates have always changed, and always will for as long as our planet retains its oceans and atmosphere.  Our current problem lies not in change as such, but in a general blindness to such change and its potential consequences for the whole human race. 

    If people will open their eyes and see scientific and historical proofs that we humans have changed local climates in the pre-industrial past, then perhaps they will concede the virtual certainty that we industrial era humans are changing our whole planet-wide climate system.

    We are not too feeble to change the planet, so let us not be too feeble to undo any harm we may have done to formerly predictable natural cycles.

    Comments

    rholley
    Patrick,

    A lovely article.  Permit me to share a few thoughts that pop to the surface.

    Horace de Saussure is a most interesting figure.  Reading him up on Wikipedia, I find that he is Swiss; his achievements are wide and varied.  French Wikipedia gives a somewhat more detailed biography, including his interest in la montgolfière.

    It makes one wonder what a setback to science was the antipathy that developed, by and large, between British and Continental scientists and mathematicians in the 17th century and carried on well into the 18th.  Much of this can be traced back, perhaps, to the personality of Newton.  If I were able to fly back in time with a wet mackerel, I think that he would be a likely candidate (Descartes also, but for different reasons.)

    You mention Darwin.  One of the things that it not often appreciated is the difference balance between Wallace and Darwin over the mechanism of natural selection.  Wallace was more strongly into adaptation to the environment, while Darwin’s broader theory majored on competition between individuals of the same species.  I mention this, because the fuel companies may not be behaving well towards the environment, but those who take a simplistic view and say ‘ba-a-ad companies!’ seem blissfully unaware of the Darwinian struggle between companies.

    Back to de Saussure.  His hot box experiment is wonderful – admittedly, being perhaps the first alpinist, he was ideally placed to do these experiments.  But this one of a big family of experiments, most of which can easily be done at home.  From this viewpoint, I recommend two books by Craig Bohren, Clouds in A Glass of Beer: Simple Experiments in Atmospheric Physics and What Light Through Yonder Window Breaks?: More Experiments in Atmospheric Physics (both from Dover).




        Saussurea pygmaea,
        genus named after Horace de Saussure.

        (Wikipedia.)
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    logicman
    Robert:  many thanks for the added value you bring - as usual - to my article.
    Bonny Bonobo alias Brat
    Great article Patrick. Funnily enough I found this NASA article yesterday describing noctilucent or polar mesospheric clouds or 'night shining clouds' which form at very high altitudes—between 80 and 85 kilometers (50–53 miles) which positions them to reflect light long after the Sun has dropped below the horizon. The article claims that a possible increase in greenhouse gases and either water vapor or cooling in the atmosphere is causing polar mesospheric clouds to change and occur more frequently.
    My article about researchers identifying a potential blue green algae cause & L-Serine treatment for Lou Gehrig's ALS, MND, Parkinsons & Alzheimers is at http://www.science20.com/forums/medicine
    logicman
    Helen: thanks for a great link.  I browse that NASA site a lot - in fact I came to your comment from the NASA pages on the Pine Island Glacier - but I hadn't seen that article.

    The graph on the page you link is a close match - if inverted - to solar activity.  The 'double troughs' correspond well with the double peak pattern seen when increased solar activity is revealed in geomagnetic storms which cause induced currents in power transmission systems.

    Where you following links on geomagnetism, or was it a case of serendipity?  :)
    Bonny Bonobo alias Brat
    It was serendipity Patrick, I also browse that site a lot, its a real treasure trove.
    My article about researchers identifying a potential blue green algae cause & L-Serine treatment for Lou Gehrig's ALS, MND, Parkinsons & Alzheimers is at http://www.science20.com/forums/medicine
    Rick Ryals
    But are we detached from, or a part of the natural evolution of the eco-balance that brought us into existence, and whose ongoing thermodynamic process we may well simply serve to enhance?  Evolution. that is, true evolution to higher order of complexity and function, is strongly guided by the environment, so who says that we aren't helping like we're supposed to?

    I think that this is where ideology supercedes science on both sides of the debate.

    I think that there are good reasons to believe that the Earth would look like the runaway greenhouse condition that is observed on Venus if the political right had things totally their way, but there are just as many good reasons to think that it would look like Mars if the equally misguided ideals of the "left" were left unchecked... stagnate, cold, and equally dead.

    And I think that it requires a lot of arrogance to *automatically* assume that we are detached from the process and are only destructive to it.  The kind of arrogance that you can only get by way of worldviews that are equally religious and just as vehemently practiced, God vs. Copernicanism, so we can't even hope for the understanding that exists in the middle that I have described, yet that is most probably where the real science is.
    Gerhard Adam
    And I think that it requires a lot of arrogance to *automatically* assume that we are detached from the process and are only destructive to it.
    I think you have to be careful in how you phrase this to distinguish between some objective scientific information versus information that is pertinent to human survival.

    When we engage in activities that modify the environment from what we are used to, we are effectively rolling the dice regarding the impact on humans.  This is little or nothing to do with the planet, but rather it relates to the affect it will have on human society and our current existence.

    If weather patterns change, or insect migrations (or disease vectors) vary, then it will be something that we will have to adjust to if we can, while those species affected will accommodate things as best as they can also.

    The environment is always changing based on the presence of any organism.  Just as microbes gave rise to the oxygen atmosphere we now enjoy, I suppose one could imagine a similar type of debate [among the microbes] at that time suggesting that the release of that much oxygen would be detrimental to their species (and it was). 

    Regardless of how one feels about it, the underlying problem is that we don't actually know what constitutes a solution.  While we love our doomsday scenarios, the reality is that it is highly unlikely that any impact we have (regardless of how radical) will affect much beyond the "higher" life forms.  Therefore, even if we brought on a great extinction, that will hardly be the demise of planet Earth, although we may well end up being another failed "evolutionary experiment", life isn't likely to be decimated.

    Essentially, I believe that Patrick is correct in arguing that humans can affect nature, but I don't believe that effect is strong enough to undo nature.  It is strong enough to undo ourselves though.
    Mundus vult decipi
    Rick Ryals
    When we engage in activities that modify the environment from what we are used to, we are effectively rolling the dice regarding the impact on humans.

    This is an unproven assumption.  We don't know that we don't do just exactly what we're supposed to do and it requires arrogance to automatically assume that we are detached from the process, (that we have the ability to "roll the dice")... was my point.  If we are necessary to the process, then you can bet your last buck that we can't.
    Gerhard Adam
    It is NOT an unproven assumption, since we already know that there are finite population limits for all animals before resource constraint becomes a factor in their ability to survive.  Therefore when we use technology to stretch the boundaries of normal human/mammal survival beyond those that "nature" would provide, we are definitely "rolling the dice" regarding the effect we will have, since it is clear that "natural selection" would have long ago limited how many humans were occupying the Earth's surface.

    I'm not arguing for some return to the land, or natural type of lifestyle, I'm simply pointing out that we (as humans) have exceeded any natural limits that might have existed because we have the ability to do so.  We are NOT necessary to the process, since no animal can be "necessary" for the process.  We affect the process but one can't argue necessity.  Were oxygen producing microbes "necessary" to the atmosphere?  No, although in hindsight, we can see how their modification to the atmosphere allowed evolution to follow a different path ultimately giving rise to humans.

    Necessity implies a purpose and there is none.  When I say "roll the dice", I'm merely acknowledging that whatever we do will have an environmental impact.  It can't be helped, since it occurs whenever any organism occupies some space and interacts with that environment.  However, we cannot think that all of the possible outcomes will necessarily be favorable to us simply because they might do so in the short term. 

    Our mere existence is a "roll of the dice" regarding Earth's long-term prospects.  Therefore we cannot know what possible impact we may have on our future, and the more we do, the more we "roll the dice" since we don't know what the consequences of any particular course of action are.  Therefore when we modify the environment (in any form), we are always going to be unsure whether a sequence of events is occurring that will favor us, or destroy us.  Arguing that we are "necessary" simply makes it worse, since if we don't know the outcome, then we don't know what we're supposed to do that you might consider "necessary".
    Mundus vult decipi
    Rick Ryals
    It is NOT an unproven assumption, since we already know that there are finite population limits for all animals before resource constraint becomes a factor in their ability to survive.

    Sorry, but you do no know that nature won't regulate our population accordingly if/when it becomes necessary.  It is an assumption, and looking at the rest of what you wrote, I see many more similar assumptions.

    We are NOT necessary to the process, since no animal can be "necessary" for the process.

    Assumption.  You, I, maybe nobody even knows what the whole of the process involves.  You cannot know this without some kind of complete or final theory and you don't have one.

    Necessity implies a purpose and there is none.

    And your assumptions are all very "copernicanism" oriented...

    On your knees when you say that, Gerhard... ;)
    Gerhard Adam
    Actually the only assumption is that there can be no causal relationship between any animal and an "expected" outcome since that would entail having complete knowledge and potentially even describe a "purpose" or objective.  Since there is no such relationship, then we can safely use the null hypothesis to argue that we are attributing no special purpose or intent to human actions and therefore whatever occurs will be in response to whatever unknown, ordinary, and/or non-specific interactions we have with our environment.

    As a result, since none of these are known, then we can't claim that they are "necessary" since that would be tantamount to attributing a purpose to those actions.

    Therefore without knowing the effect and without claiming any purpose then, by definition, any action we take is a "roll of the dice" since we cannot know that our actions (or outcomes) will not be detrimental (or advantageous) to our future existence.

    What we do know is that as any species population size increases, then competition for resources increases which makes sustaining a large size more difficult.  We also know that one of the hurdles to a large population size is that the byproducts (or waste) of a large population may become detriments to the continued growth and/or survival of the species being examined.  It is therefore also quite reasonable to conclude that humans do not represent an exception to this case.  While we can certainly consider that human technology may help change some of the basic parameters, we must also consider that there may be some problems that are simply intractable or exacerbated by our technology.

    Putting these points together suggests that we may be introducing problems and unintended consequences as a result of technology use and population growth.  This is not a conclusion, but only a possible outcome.  It could equally be beneficial to us, however, this needs to be weighed against the number of exceptions we've seen in other species encountering similar circumstances.  If there are no well known exceptions, then the only conclusion left, is that if we are faced with the same threat of extinction, but it is only our "faith" in a technological solution that differentiates us from any other species in a similar predicament.
     
    Mundus vult decipi
    Rick Ryals
    I actually think that this is a road that we've already been down, Gehard.  I would invoke Snyder and Sagan, maybe James Kay and Scott Sampson too, who all believe that they have hard evidence that supports the idea for "purpose" in nature:

    http://www.taipeitimes.com/News/editorials/archives/2004/09/30/2003204990

    Now, that is just a popularization and it has plenty of flaws, but that doesn't mean that they aren't on the right track and it establishes that you cannot *know* that there is no "purpose", so you are practicing "copernicanism" when you *automatically* assume otherwise.

    FYI, I do not intend to argue the merits of Snyder and Sagan's observation, it is only meant to offer a single plausible evidenced scenario for purpose in nature and it does.  One single example of numerous similarly plausible and evidenced possibilities that only pre-conceived conviction can *automatically* dismiss.
    Gerhard Adam
    ...you cannot *know* that there is no "purpose", so you are practicing "copernicanism" when you *automatically* assume otherwise.
    No, the null hypothesis requires that we must not assume that there are special conditions until evidence suggests that there are.  In the absence of such evidence, the only reliable explanation is that there is no "purpose".   This doesn't mean that there may not be, it simply means that in the absence of such evidence or reason to suspect that there is, any different conclusion must be considered speculative.

    This is also the conclusion drawn by Occam's Razor in removing or eliminating any unnecessary explanations until there's some evidence to suggest that it must be considered.
    Mundus vult decipi
    Rick Ryals
    Yeah, but you missed the word evidenced, twice.

    Wow

    Now for the denial, but Judas, I do not believe you... ;)
    Gerhard Adam
    The concept of "purpose" in this context doesn't lead to "necessity".  There's no question that (in the sense used in the article) that "purpose" or increased complexity is a result of life.  However, another way to look at that is to simply argue that physics and chemistry provide explanations for processes that occur in nature, while life utilizes those processes to maintain and perpetuate itself.

    In that respect there is certainly a "purpose" or "intent", but it doesn't rise to the level of some higher meaning which is suggested when you consider our actions as a species.  So, in the sense that we will behave as humans, then perhaps you could use the word "necessity" although it seems to be stretching the meaning.  Even in that sense, and with the idea of evolution proceeding to increased complexity (which isn't actually true), it says nothing about the fate of humans.  In fact I would argue that the idea of "increased complexity" is actually an artifact of increased specialization because fewer opportunities or "niches" exist for life to exploit. 

    So, to get back to the original point which related to humans modifying their environment and potentially introducing unintended consequences (i.e. rolling the dice), I don't think there's any basis for asserting that the "purpose" you might assign to life correlates to the actions such life takes as being "necessary".  They are simply what it does, for good or ill and there is no indication that such actions serve a "purpose" in the causal chain of events that determine success or failure.
    Mundus vult decipi
    Rick Ryals
    There's no question that (in the sense used in the article) that "purpose" or increased complexity is a result of life.

    Eh, there is no question that (in the exact terminology used in the article) that "purpose" is from the necessity of the thermodynamic process.

    That was even worse than I'd expected and your follow up attempt to dismiss me in order to "get back to the original (lame) point"... tells me that it's time to say bye bye to you Gerry, before I say something that Hank would not appreciate...

    Buh bye... ;)
    Patrick,

    First, not everyone considers CO2 to be a pollutant.

    Second, for the last 2 million years or so, we have been stuck in a cycle of 100,000 year periods of glaciation (ice ages) with up to 20,000 years of moderate global temperatures (as we are seeing now). Prior to 2 million years ago (from 2 million to 250 million years ago), our planet had CO2 levels higher than 400 parts per million and did not typically cycle through these ice ages. The flora and fauna on the planet flourished during these periods. During glacial periods, our planet has seen CO2 levels between 180 and 300 parts per million. But during these long cold periods, life on the planet is really stressed and many species disappear completely.

    Third, many green houses will purposely raise the CO2 levels to 1500 to 2000 parts per million, to improve the growth of the plants. These levels of CO2 do not harm humans or most animals on the planet.

    Fourth and final, if we continue to increase CO2 levels in our atmosphere, but don't go over 2000 parts per million, we will more than likely increase the global temperature and we will melt more glaciers. If we were to melt ALL the ice on the planet, we could expect sea level to rise 50 to 60 meters (some areas more and others less). That would not be good for people living near the coasts, but it would not wipe out life on the planet. Also, with warmer climates, life would move further north in America, Europe and Asia and perhaps south into Antarctica. We might have to abandon many of our coastal cities, but we can build new ones on higher ground. But this seems like a better alternative than to go through another ice age with kilometers of snow and ice covering much of North America, Europe and Asia.

    Thus, increasing levels of CO2 in the atmosphere to values above 400 ppm and below 2000 ppm, might have the effect of eliminating our ice age cycle (if our sun behaves, our planet does not go into a more elliptical orbit, we don't get hit by an asteroid, the number of volcanoes erupting does not quadruple, etc.).

    Rick Ryals
    I agree with most of what you say, but I don't think that you've accounted for the point of no return for the runaway greenhouse effect.  I've noticed that this quantifiable point has conveniently disappeared from the "climate change" debate, as well, because we could nail them to the wall if they were to define it... and they know it.  As with glaciation, there is a cumulative, exponentially accelerating effect, in other words.

    I agree with most of what you say, and I'd go as far as to argue that we may very well be the sole reason that glaciation is overdue.  We *are* the "homeorhetic" mechanism that keeps the Earth from become like Mars, in this scenario.

    And yet... we are still here...
    --Morpheus
    logicman
    not everyone considers CO2 to be a pollutant.
    A classic climate change denial argument!

    If CO2 is not a pollutant, what other factor kills off yeast in the brewing of alcohol?

    A pollutant is anything whatsoever which by its presence in excess in a specific environment harms the survival prospects of the life-form/s which thrive in the given environment.

    CO2 in soil kills most plants, since roots, like mammals, need oxygen.  CO2 in soil in excess is a pollutant q.e.d.

    CO2 in the atmosphere in sufficient excess would wipe out many species - including humans - through dramatic climatic effects.  Your suggested 2000 ppm would be a sufficient excess, but there would be no humans left alive to measure that level of atmospheric pollution.  Due to our having evolved to cope with a specific range of temperatures, we humans could not possibly survive outdoors in a high temperature, high humidity climate.

    Thus, increasing levels of CO2 in the atmosphere to values above 400 ppm and below 2000 ppm, might have the effect of eliminating our ice age cycle ...

    Thus raising sea levels by such an amount as to make most of our present coastal lands uninhabitable.  Let me use Greece as an example of what that means.  The famed pass at Thermopylae where 300 Spartans held up the Persian army is now over 2 miles from the edge of the sea, due to land having been reclaimed.

    If the 'elimination of our ice age cycle' raised sea level by only 50 meters - a very conservative estimate - most of the land in Greece currently usable for agriculture would most definitely be underwater.

    A rise of 'only' 1 meter can pose severe problems.  For example, a slope of 1 in 100 would give a 100 meter incursion in the absence of (very expensive) flood defences.

    That is most definitely something to think about, I would say.
    Being a home brewer, I definitely understand how yeast can produce alcohol and CO2 in amounts that will eventually kill them.

    If we increase CO2 in the atmosphere to levels that will kill us (approximately 6% or 60,000 ppm), we will be in dire straits.

    But what if plants and coral have been working too efficiently storing away carbon that our atmosphere was getting to the point where they could no longer survive. By your yeast argument, plants were overdoing their job. If our atmosphere were to drop below 150 ppm, plants would be in dire straits.

    If we push CO2 to levels approaching 10,000 ppm, then it will definitely be in excess and unfavorable. I am still not convinced that we are close to those levels yet.

    However, I do agree that we have an impact on our environment (both good and bad).