• ssu
    6k
    We don't take kindly to people inquirin' 'bout climate change 'round these places.Tzeentch
    :smile:

    The administrator will quickly take you out into the woods and before you know it...BANNED!!!

    (Or something like that, eh?)
  • Tate
    865
    But scientists appear to have little if any understanding of this magnetic field, or fields.Metaphysician Undercover

    I'm not sure what you're referring to. The sun's electromagnetic field is polarized like the Earth's. It doesn't extend too far into space. It doesn't reach Mercury, much less the Earth.

    Are you talking about solar winds?
  • Agent Smith
    6.2k
    increased CO2 could trigger reglaciation. — Tate

    :rofl: C'est la vie! :up:
  • Tate
    865
    Proceeding on with the history of climate change widening the horizon to 500 million years.

    450px-Phanerozoic_Climate_Change.png

    These fluctuations in climate are not cyclical like the the first graph I posted, which showed a parade of interglacials. This graph shows the dramatic change that one little lifeform called cyanobacteria caused, almost resulting in the final mass extinction due to the loss of atmospheric CO2.
    The whole globe was covered in ice. It shows the results of massive emissions of CO2 caused by volcanoes, which caused equatorial waters to steam and put palm trees on the poles. It's a fascinating saga.

    At the bottom of the graph you see four purple blocks representing events that some geologists call ice ages. it doesn't really matter what we call these larger scale cold spells. The point is: we're in one.
  • unenlightened
    6.8k
    At the bottom of the graph you see four purple blocks representing events that some geologists call ice ages. it doesn't really matter what we call these larger scale cold spells. The point is: we're in one.Tate

    The word "quaternary" refers to the idea that there were four ice ages in the past. We now call those glacial periods.Tate

    It bloody well does matter what we call them. You really need to stop waving "ice ages" about quite so carelessly. Do you not see how confusing you are making it for anyone reading the thread? I assume you are clear that the 4 ice ages you were talking about on page one don't even add up to the last of the 4 ice ages you are now talking about, because the quaternary period only covers the last 3 million years approx and just the last "cold spell" in your graph above covers 50 million years. But you certainly do not make it clear to the reader.
  • Tate
    865

    Sorry. Michael had already posted a blurb about how geologists call those larger scale cold events "ice ages", while in the public domain that term means woolly mammoths and saber tooth tigers, in other words, the last glacial episode.

    I responded to him that I've been compromising by calling them "large scale ice ages."

    Do you have advice for how to make it clearer?
  • unenlightened
    6.8k
    Do you have advice for how to make it clearer?Tate

    Well I put up links to help folks with terminology and timelines, and numbers of years ago are really useful for sorting things.

    This graph shows the dramatic change that one little lifeform called cyanobacteria caused, almost resulting in the final mass extinction due to the loss of atmospheric CO2.
    The whole globe was covered in ice.
    Tate

    The Snowball Earth hypothesis proposes that, during one or more of Earth's icehouse climates, the planet's surface became entirely or nearly entirely frozen. It is believed that this occurred sometime before 650 M.Y.A. (million years ago) during the Cryogenian period. Proponents of the hypothesis argue that it best explains sedimentary deposits that are generally believed to be of glacial origin at tropical palaeolatitudes and other enigmatic features in the geological record. Opponents of the hypothesis contest the implications of the geological evidence for global glaciation and the geophysical feasibility of an ice- or slush-covered ocean,[3][4] and they emphasize the difficulty of escaping an all-frozen condition. A number of unanswered questions remain, including whether Earth was a full snowball or a "slushball" with a thin equatorial band of open (or seasonally open) water.

    The snowball-Earth episodes are proposed to have occurred before the sudden radiation of multicellular bioforms known as the Cambrian explosion.

    But the Cambrian explosion started about 539 million years ago, so the first glaciation period in your graph is not a snowball earth event but the Late Ordovician glaciation and the whole globe was not covered in ice.

    This graph shows the dramatic change that one little lifeform called cyanobacteria caused, almost resulting in the final mass extinction due to the loss of atmospheric CO2.Tate

    Here you are unequivocally muddled; the cyanobacteria began photosynthesis about 3.5 Billion years ago and the oxygenation of the atmosphere about 2 billion years ago.
    https://en.wikipedia.org/wiki/Great_Oxidation_Event
  • Benkei
    5.7k
    Informative as was your previous post. I thought you were a psychologist? Hopefully @Tate you're getting "up to speed" and we can start discussing the climate crisis.
  • magritte
    460
    oxygenation of the atmosphere about 2 billion years ago.unenlightened

    Which means that before about 2 billion years ago iron rust was green but after that it became reddish. Should that colors be called greed or redeen?
  • unenlightened
    6.8k
    :rofl: Folks have been looking for a real world example ever since whichever pedant it was raised the 'grue' thing, and you have found it! My heartiest commiserations!
  • Tate
    865

    My goal is to get to articles. I think what you are telling me is that you want more depth. Would you like reading homework? Or excellent and trustworthy PBS documentaries? (it's called Eons, and it's great) Or do you want to talk about something specific? The cyanobacteria?

    I'm figuring you and I are the only ones reading this, so let's do it our way.
  • Tate
    865
    Well I put up links to help folks with terminology and timelines, and numbers of years ago are really useful for sorting things.unenlightened

    The times were on the graphs.
  • Tate
    865
    @unenlightened

    From here:


    "For cyanobacteria to trigger the rapid onset of a Snowball Earth, they must have had an ample supply of key nutrients like phosphorous and iron. Nutrient availability is why cyanobacterial blooms occur today in regions with heavy agricultural runoff.

    "Fortunately for the bacteria, Earth 2.3 billion years ago had already entered a moderately cold period, reflected in glacially formed rocks in Canada. Measurements of the magnetization of these Canadian rocks, which the Caltech group published earlier this year, indicate that the glaciers that formed them may have been at middle latitudes, just like the glaciers of the last ice age.

    "The action of the glaciers, grinding continental material into powder and carrying it into the oceans, would have made the oceans rich in nutrients. Once cyanobacteria evolved this new oxygen-releasing ability, they could feast on this cornucopia, turning an ordinary glaciation into a global one.

    "Their greater range should have allowed the cyanobacteria to come to dominate life on Earth quickly and start releasing large amounts of oxygen," Kopp says.

    "This was bad for the climate because the oxygen destabilized the methane greenhouse. Kopp and Kirschvink's model shows that the greenhouse may have been destroyed in as little as 100,000 years, but almost certainly was eliminated within several million years of the cyanobacteria's evolution into an oxygen-generating organism. Without the methane greenhouse, global temperatures plummeted to -50 degrees Celsius."

    There's another theory that snowball earth was caused by the break up of Rodinia which exposed basalt which absorbed CO2 and released sulfur which causes cooling.

    The cyanobacteria story is more poetic, though.
  • Tate
    865
    Informative as was your previous post. I thought you were a psychologist? Hopefully Tate you're getting "up to speed" and we can start discussing the climate crisis.Benkei

    Your attitude is unwarranted. By and large, everything I've said is true. If I happen to get facts muddled, I'm still well-meaning and don't deserve the scorn level you've been generating.

    If you don't want to contribute meaningfully to my thread, could you at least go elsewhere?
  • Metaphysician Undercover
    10.2k
    I'm not sure what you're referring to.Tate

    The point was that radiant heat from the sun has the biggest influence over the earth's surface temperatures, and scientists seem to know very little about the sun's capacity to radiate heat. I suppose I'm off topic, and we need a different thread about the sun's influence on the earth's climate.
  • Tate
    865
    The point was that radiant heat from the sun has the biggest influence over the earth's surface temperatures, and scientists seem to know very little about the sun's capacity to radiate heat. I suppose I'm off topic, and we need a different thread about the sun's influence on the earth's climate.Metaphysician Undercover

    It is the biggest influence. Easily overlooked, you're right. There's the grand solar minimum (solar minimum) that some say started two years ago and will cause cooling until around 2050? I don't know much about.
  • L'éléphant
    770
    @Olivier5
    In fact, we're in interglacial period. Which means, sooner or later, we're going to enter the ice age. But not yet. — L'éléphant


    That is not happening: the ice caps are fast melting. The Artic one will be history soon, by 2040 or so. Then, in the absence of the moderating factor that the artic ice cap represents, summer temperatures in the northern hemisphere will most certainly shoot up.

    Antarctica is a bigger piece but all models predict that summer ice there will be gone in a few centuries.

    Tate's "ice age" (defined by the presence of ice caps) is ending. Because of us. -- Olivier5

    I took the liberty of copying your comment here because the other thread is closed.

    My response is this:

    In terms of the ebb and flow of the Earth’s climate over the course of its history, the next Ice Age is starting to look overdue. Periods between recent Ice Ages, or ‘interglacials’, average out to be around 11 thousand years, and it’s currently been 11, 600 since the last multi-millennial winter. Although it is almost impossible to predict exactly when the next Ice Age will occur (if it will at all), it is clear that a global freeze is not on the horizon; the amount of CO2 emitted by human activity and the enhanced greenhouse effect that results all but preclude it. But what if we weren’t around and CO2 was lower?

    In a paper published in Nature Geoscience this week, new research proposes that the next Ice Age would have been kick-started sometime in the next thousand years, just round the corner in the context of the Earth’s lifespan, if CO2 was sufficiently low.

    By looking at the onset of abrupt flip-flops in the temperature contrast between Greenland and Antarctica (extreme climate behaviour that would have only been possible if vast and expanding ice sheets were disrupting ocean circulation), the researchers believe they have been able to identify the fingerprint of an Ice Age activation, or the ‘glacial inception’.

    By applying this fingerprinting method to an interglacial period with nearly identical solar radiation, or ‘insolation’, to our own - some 780 thousand years ago - the researchers have been able to determine that glacial inception would indeed be expected to occur sometime soon.

    “The mystery of the Ice Ages, which represent the dominant mode of climate change over the past few million years, is that while we can identify the various ingredients that have contributed to them, it’s the arrangement of these ingredients, and how they march to the beat of subtle changes in seasonality, that we lack an understanding of,” says Dr Luke Skinner from the Department of Earth Sciences, who helped to conduct the research with Professor David Hodell and their colleague Professor Chronis Tzedakis from University College London.

    Insolation, the seasonal and latitudinal distribution of solar radiation energy, changes over tens of thousands of years due to the variations in the Earth’s orbit around the sun. It has long been apparent that insolation changes have acted as a pace-maker for the Ice Ages. But, like a metronome paces music, it sets the beat of climate change but not its every movement. The changing concentrations of greenhouse gases, CO2 in particular, are evidently what determine when a shift in insolation will trigger climate change.

    “From 8,000 years ago, as human civilization flourished, CO2 reversed its initial downward trend and drifted upwards, accelerating sharply with the industrial revolution,” says Skinner. “Although the contribution of human activities to the pre-industrial drift in CO2 remains debated, our work suggests that natural insolation will not be cancelling the impacts of man-made global warming.”
    From Ice Age, Interrupted article link

    Note that while the man-made CO2 certainly has interrupted the trajectory of the climate change, it did not, and could not destroy the insolation changes that are responsible for the ice ages. Also note that this article uses the words "metronome" and "pace maker" as an analogy to the functioning of isolation changes. I'm sure you get the point.
  • Olivier5
    5.4k
    I'm sure you get the point.L'éléphant

    The point I get is that natural insolation will not be cancelling the impacts of man-made global warming. Another point is in the tittle: ice age, interrupted. Compare with:

    Tate's "ice age" (defined by the presence of ice caps) is ending. Because of us. -- Olivier5

    So your article agrees with me, or rather, my take on CC is far closer to current science than Tate's crypto-denialism.

    As for metronomes... sometimes they break. Gime a sledgehammer and a metronome, and I'll show you how it might happen. The metronome is our climate, the sledgehammer is greenhouse gases.
  • unenlightened
    6.8k
    The story so far.

    We have solar cycles, about which not much is known over the long term, because the records cannot be read through the inferred influences of the atmosphere. We know that solar radiation varies with the eleven year sunspot cycle, and another 100 year cycle, and we infer from. We also know from astronomical study of main sequence stars, that the sun is getting hotter, by about 25% over 3billion years or so.

    Insolation of Earth is further modified by Milankovitch cycles. These have periods of 26000, 41,000, and 100,000 yrs. The reason why the North polar region is the influential one for these cycles is that most of the land mass is in the Northern hemisphere and the land heats and cools more quickly than the sea, and ice forms more easily on land, because sea has salt as antifreeze. So the Antarctic is more stable.

    The temperature of Earth's surface is produced by insolation modified by transparency and insulation effects of the atmosphere, and the reflectivity of the surface itself, and by the absorption of heat by photosynthesis. (Forests also have a large cooling influence through transpiration and associated cloud production.)

    The lesson I take from the 2 billion yr old story of cyanobacteria poisoning the atmosphere with oxygen and producing a snowball Earth, which might have remained stable until the present because of the reflectivity of ice, but for some vulcanism restoring a bit of CO2 and maybe darkening the ice a bit with ash, is that the Gaia hypothesis is not true. The living planet is not self regulating.

    Rather, there have been wild fluctuations of climate through geological time far larger than can be accounted for by variations of insolation. The history of humanity has been one of unusual climate stability sufficiently long for the effects of milankovitch cycles to become noticeable.

    When Prime Minister Harold Macmillan was asked what was the greatest challenge for a statesman, he replied: 'Events, dear boy, events'.

    Vulcanism, asteroids, continental drift, and changes to the biome. Human civilisation is a change to the biome that has affected every region and every species. It is events that destabilise the climate and send it careering off to a heating or cooling until it arrives at a new semi-stable climate maybe tens of degrees hotter or cooler. This happens because of positive feedback and tipping points, which complex systems analysts will be familiar with.
  • Agent Smith
    6.2k
    poisoning the atmosphere with oxygen — unenlightened

    :rofl:

    One man's food is another man's poison, oui monsieur?

    Life has a dark history - we need to deep-six this investigative, detective mentality lest we discover the awful truth behind our so-called evolutionary success, our bloodlust to put it mildly.

    For some reason being alive doesn't make me as happy as it used to!
  • Olivier5
    5.4k
    The living planet is not self regulating.unenlightened

    :up:
  • Tate
    865

    :up: :up: :up: :up:
  • Metaphysician Undercover
    10.2k
    It is the biggest influence. Easily overlooked, you're right. There's the grand solar minimum (solar minimum) that some say started two years ago and will cause cooling until around 2050? I don't know much about.Tate

    The standard, observed sunspot cycle is approximately eleven years, we are heading into a maximum period right now.

    At the minimum period, the sun's magnetic field is an organized dipolar field, extending far into interplanetary space. The dipolar field allows particles to move rapidly along field lines, and this is the solar wind. The earth, being currently on a different plane is not exposed to this rapid solar wind of the minimum period.

    At the maximum period, the magnetic field breaks down, and is randomized. This allows more random coronal ejections of particles, in random directions, in a slower solar wind. Some of these solar flares may be directed toward the earth.

    When the magnetic field reestablishes itself as dipolar, at the next minimum period, it has reversed polarity from the last minimum period. So the entire cycle, to return to the same polarity, is approximately twenty two years.

    https://www.sciencedirect.com/topics/earth-and-planetary-sciences/solar-magnetic-field#:~:text=The%20solar%20magnetic%20field%20is%20highly%20variable%2C%20which%20makes%20the,like%20that%20of%20the%20earth.
  • Metaphysician Undercover
    10.2k
    The earth's magnetic field also reverses, but over a long time period of time, hundreds of thousands of years, and not in an organized cycle. Magnetic north has been drifting since it was first accurately located. The speed of the drift has varied. In recent times it has accelerated. If you use a compass you may have noticed that the adjustment for declination has changed in some places. The relationship between the shift in magnetic north, and global climate change is unknown.

    https://earthsky.org/earth/magnetic-north-rapid-drift-blobs-flux/
  • SophistiCat
    1.9k
    Rather, there have been wild fluctuations of climate through geological time far larger than can be accounted for by variations of insolation. The history of humanity has been one of unusual climate stability sufficiently long for the effects of milankovitch cycles to become noticeable.unenlightened

    You are losing track of the relative time scales here. The history of humanity is a point on the geological timescale. We could be living right smack in the middle of one of those "wild fluctuations of climate" that you mentioned and not notice it.
  • Tate
    865


    Not always. This interglacial started with an abrupt change called the Younger Dryas. We would notice if that happened. A shutdown of the oceanic heat conveyor is believed to have caused it and scientists are watching that current now because it's slowing down due to global warming.
  • unenlightened
    6.8k
    You are losing track of the relative time scales here. The history of humanity is a point on the geological timescale. We could be living right smack in the middle of one of those "wild fluctuations of climate" that you mentioned and not notice it.SophistiCat

    Perhaps I wasn't clear. The history of humanity spans roughly the Quaternary period, which consists of alternating glaciations and interglacials over the last 3 million years or so; the beginning of the stone age is a little further back into the Pliocene Epoch. That is what I call a period of stability relative to the much larger climate variations over geological time. Note that i call the mere covering of Northern Europe and Canada with an ice sheet benign stability in the context of major disruptive events.
  • unenlightened
    6.8k
    To make it clearer, my reason for calling the time of the evolution of humans a period of stability is the Antarctic ice sheet which started developing 33.9 million years ago at the Eocene-Oligocene boundary and this is the 'icehouse period' that we are still in. But manmade global warming is likely to tip us out of the icehouse and into the hothouse which neither humans nor apes have ever experienced.
  • Tate
    865
    You're obviously well informed.

    Why don't we look at some of the research behind this:

    But manmade global warming is likely to tip us out of the icehouse and into the hothouse which neither humans nor apes have ever experienced.unenlightened

    Specifically, let's look at the support for this Wikipedia statement in it's article entitled "Ice Ages":

    "The amount of anthropogenic greenhouse gases emitted into Earth's oceans and atmosphere is predicted to prevent the next glacial period for the next 500,000 years, which otherwise would begin in around 50,000 years, and likely more glacial cycles after.[4][5][6]"

    I have university access to scientific papers today, so I'll print out the articles referenced by the Wikipedia article and we can discuss them. Sound good?
  • Tate
    865
    This is the first article:

    Live Science

    This is a report on a computer model. The article states:

    "Even if we burn only a quarter of the Earth's total reserves of fossil fuels (currently we have burned less than one tenth of reserves), the carbon dioxide remaining in the atmosphere could cause the next ice age to be skipped because ice sheets and glaciers will have melted and won't be able to reform substantially, Tyrrell found."

    "In fact, burning up all of Earth's reserves would prevent the next five ice ages, the model shows, he said."

    So one of the problems with Wikipedia's article is

    "The amount of anthropogenic greenhouse gases emitted into Earth's oceans and atmosphere is predicted..."

    What amount? The amount we've emitted so far? No. That amount is not predicted to cause a miss of coming glacial triggers.

    Burning all the fuel we can access probably would, as I've previously noted, twice.
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