Will there ever be a 2nd ice age?

  1. Is the ace age ever expected to return at any point in the distant future?

    Human beings survived the first ice age, so hypothetically speaking, what effect would it have on modern civilization if it occurred today?
  2. jcsd
    Earth sciences news on Phys.org
  3. russ_watters

    Staff: Mentor

  4. You should read the wiki article...It discusses this very point.

    Just a snippet:
  5. In other words, "we don't know." It could start tomorrow, it may not start for another 50,000 years. If the Yellowstone caldera erupts or some other VERY large volcanic event blows, we could have a mini-ice age precipitated by the volcanic dust, ash, and sulfur injected into the stratosphere. Pinatubo chilled the earth for a year.
    Thermodynamics tells us the sun's heat cannot last forever.
    10GYr from now?
  6. According to my open university module on exploring science, technically speaking we are still in an ice age but currently we are in an interglacial period - http://en.wikipedia.org/wiki/Interglacial
  7. Sure, we may not know, but as the way of the magic eight-ball, "All signs point to 'Yes'". I'd be willing to bet my life that there will be another one. When? That's a different question.
  8. Drakkith

    Staff: Mentor

    FYI for those who didn't read the linked article in post #2, but we are STILL IN AN ICE AGE.

  9. The earth seems to go through periods of warming and cooling and those periods of cooling can bring an ice age depending on the temperature change. We will go into another ice age, the correct answer is we don't know as we cannot predict the future but the most likely explanation is yes but the real question is when.
  10. Considering the volatile history of Earth, it's all but certain that the Earth will have many more ice ages long after we're dead.
  11. There have been 22 glacial/interglacial cycles. For the last 1.2 million years, the warm interglacial periods have a duration of roughly 10,000 to 12,000 years and the glacial periods have a duration of 90,000 years.

    Based on what has happened in the past the current interglacial period will end. As climatologists do not understand what causes the glacial/interglacial cycle and what causes the past abrupt climate change events in the climate record, the "predictions" of when the current interglacial period will end are fiction, media discussions.

    The last glacial period is called the Wisconsin glacial period as all of Canada and the Northern US states was covered by a 2 mile thick sheet of ice. Northern Europe has also covered by a massive ice sheet for roughly 90,000 years.

    The current interglacial period, the Holecene, has interrupted by the Younger Dryas abrupt climate change event, 12,900 years ago, at which time the Northern Hemisphere changed from interglacial warm back to glacial cold, with 70% of the cooling occurring in 10 years and the glacial cold remaining for 1000 years. There is a massive change in cosmogenic isotopes that correlate with the Younger Dryas event which indicates that there was a significant solar magnetic cycle change and something that abruptly changed the geomagnetic field at that time.

    The past interglacial periods ended abruptly. There is evidence in the paleoclimatic record of cyclic abrupt climate change (The large climate change events "Heinrich events" - 8000 to 10000 years, the Younger Dryas is an example of a Heinrich event - and the smaller climate change events the "Dansgaard–Oeschger" events which have a 1400 year period). There is evidence of solar changes at the time of the D-O cyclic changes and the Heinrich events, however, there is currently not consensus as to how a change to the sun could cause an abrupt climate change on the earth.

    Based on solar physics it is believed the sun cannot get significantly warmer or colder in a short period, so the explanation is not a change in the TSI (Total Solar Irradiation). The explanation (if the sun is the cause of past abrupt climate change events) is therefore likely related to an unexplained change to the solar magnetic cycle.


    Until the 1990s, the dominant view of climate change was that Earth’s climate system has changed gradually in response to both natural and human-induced processes. Evidence pieced together over the last few decades, however, shows that climate has changed much more rapidly—sometimes abruptly— in the past and therefore could do so again in the future.


  12. The following graph shows how planetary climate has changed over the last 5.5 million years, from the study of ocean sediments. As the graph shows the planet has gotten colder and colder.

    As the planet cooled, the Antarctic Ice sheet formed (12 million years ago). As the planet cooled further, roughly 2.6 million years, ice sheets started to form in the Northern Hemisphere with a cycle of glacial/interglacial of 41,000 years.

    As the planet cooled further, 1.6 million years ago the glacial/interglacial cycle changed from a 41,000 year cycle to a 100,000 year cycle.

    As noted in my above comment there is no explanation as to what causes the glacial/interglacial cycle (the timing of the glacial/interglacial cycle is related to the earth's orbital position, however detailed analysis shows that there is some cycle abrupt climate change event that is causing the glacial/interglacial and the mechanisms of that event is modulated by the earth's orbital configuration as opposed to the glacial/interglacial cycle being caused by amount of summer sunlight at N65) and what causes the cyclic abrupt climate change events - Heinrich events (6000 to 8000 year periodicity) and Dansgaard–Oeschger events (1400 year periodicity), however it appears based on observations that what ever causes the Heinrich events and the D-O events also causes the glacial/interglacial cycle.

  13. Drakkith

    Staff: Mentor

    Betzalel, in your link in the post above this one, it appears the fluctuations in the temperature because drastically higher as we get closer to the present. Any idea why? Is it just due to the increased time each cycle takes?
  14. http://upload.wikimedia.org/wikipedia/commons/f/f7/Five_Myr_Climate_Change.svg

    Your question is astute. You are looking at the paleo ocean sediment temperature data and asking for a physical explanation for what is observed. The analysis and research as to what has happened in the past has started to converge. There is general agreement among the specialists as to what has happened in the paleoclimatic past (certainly for the last 5 million years.)

    What is missing is a physical explanation, a cause to explain the glacial/interglacial cycle, abrupt climate change, and other larger term changes.

    The data shows the planet has been cooling for 20 million years. Differing to another thread what is causing the planet to gradually cool for 20 million years and also differing the question what controls the amount of CO2 in the atmosphere which is surprisingly difficult to explain.

    When the planet was warmer there was no glacial/interglacial cycle. The planet’s internal systems (cloud cover) stabilizes planetary temperature when it is warmer. This statement is supported by recent top of the atmosphere analysis of radiation Vs ocean surface temperature which shows planetary clouds in the tropics increase or decrease to resist forcing changes by reflecting more or less sunlight off into space.

    As the planet cools ice sheets start to form which upsets the planet’s temperature regulating systems as the ice sheets reflect sunlight off into space in summer and winter. Ice sheets take hundreds and thousands of years to melt and as they become thicker, it becomes more difficult for the ice sheet to melt, as their upper surface is colder due to the the higher elevation of the top of the ice sheet (there is cooling of roughly 3C for every 1000 feet gain in elevation).

    A basic energy balance calculation indicates if the polar cap ice sheet’s lower latitude extent on the planet reaches around 30 degrees sufficient sunlight is reflected off into space to push the earth to full glaciation (oceans freeze). Also as the ice sheets move to lower latitudes there is more moisture to form snow in the winter, spring, and fall which accelerates the formation of the ice sheet.

    As the planet continues to cool the glacial phase becomes more extreme, colder. As the extent of the ice sheet increases there are ice sheets at lower latitudes which reflects higher intensity sunlight (sunlight at lower latitudes off into space), which results in increased cooling.

    It is interesting as you note, however, that as the planet has cooled, the short (10,000 to 12,000 year duration) interglacial periods have become warmer. To explain physically why that is the case it is necessary to have a strawman working hypothesis to explain what is causing the glacial/interglacial cycle and the cyclic abrupt climate change events (Heinrich and D-O) that are observed in the paleo climate record.

    As noted above the cause of the glacial/interglacial cycle and the cause of abrupt climate change is not the varying amount of summer sunlight at 65N caused by orbital changes.
    I have looked at this subject in detail and can provide a working hypothesis based on recent breakthroughs in geomagnetic research and paleoclimate analysis.

    The geomagnetic researchers have found that there is a 3 to 5 times increase in the geomagnetic field intensity during the interglacial periods. A working explanation for why the planet is warmer when the geomagnetic field intensity is stronger is Svensmark’s ion mediated cloud formation theory (the amount of ions in the atmosphere particularly over the ocean which is particulate poor determines how clouds from, the lifetime of the cloud, and the albedo of the cloud. ) When the geomagnetic field strength is higher the geomagnetic field deflects more cosmic rays (cosmic rays are mostly high energy protons) which reduces the number of ions that are produced in the atmosphere. (Less cloud cover warmer planet).

    The explanation for why the warm interglacial period is warmer even as the planet continues to cool can be explained by the physical reason for what is causing the cyclic abrupt changes to the geomagnetic field. (i.e. It has been found that geomagnetic field intensity is stronger during the interglacial period as the glacial periods became colder. There needs to be an explanation as to what is physically causing the cyclic geomagnetic field intensity changes.)

    It appears an abrupt change to the solar magnetic cycle (there are cosmogenic isotope changes that correlate with the geomagnetic excursion and there are smaller geomagnetic field changes (archeomagnetic jerks) where the geomagnetic field’s tilt abruptly changes by 10 to 15 degrees which also correlates with solar magnetic field changes. There are burn marks on the surface of the earth that coincide with the timing of the Younger Dryas abrupt climate change event. There is a geomagnetic excursion that correlates in time with Younger Dryas abrupt cooling event) causes the small and large abrupt changes to the geomagnetic field.

    The modulation of the geomagnetic field by a rare, cyclic solar event, explains how a short duration solar event say over a number of months, can cause an abrupt cooling event such as the Younger Dryas where the planet when from interglacial warm to glacial cold with 70% of the cooling occurring in 10 years and remaining cold for 1000 years. As the geomagnetic field takes hundreds and thousands of years to equalize after the abrupt solar forcing event alters geomagnetic field on the surface of the planet, as the field in the liquid core reaches a minimal energy state which is a simple polar field aligned with the earth’s axis of rotation.

    The solar forcing mechanism also explains why orbital eccentricity, the tilt of the planet, and the seasonal timing of perihelion correlate with the glacial/interglacial cycle. Following the logic of the hypothesized mechanism, the largest magnitude solar magnetic cycle restart would need to occur with a periodicity of 8000 to 10000 years to explain the periodicity of the Heinrich events. The affect of the solar magnetic cycle restart on the geomagnetic field strength is depend on the orbit configuration at the time of the solar magnetic restart and dependent on whether there is insulating ice sheets covering the earth at the time of restart.

    Assuming that is what is forcing the geomagnetic field (i.e. following the logic of the assumed mechanism) then the extent of the ice sheets at the time of the abrupt change to solar magnetic cycle (it appears the solar magnetic cycle is interrupted and when it restarts what happens can cause a geomagnetic excursion.) determines how that solar abrupt change modulates the geomagnetic field as does the orbital configuration at the time when the solar magnetic cycle restarts.

    Recent geomagnetic field analysis has found geomagnetic excursions (excursion is the name for a failed geomagnetic reversal at which time the geomagnetic field intensity drops by a factor of 7 to 10 times) occur during the Heinrich events and during interglacial termination.



    Paleoclimatic context of geomagnetic dipole lows and excursions in the Brunhes, clue
    for an orbital influence on the geodynamo?

    Last edited: Feb 16, 2013
  15. Drakkith

    Staff: Mentor

    Interesting. Thanks!
  16. The explanation for the periodicity of the ice ages during the Pleistocene is probably the best known and most widely accepted of all the climate-forcing hypotheses. It involves orbital-forcing (the Milankovich Theory). I refer you to this excellent NASA online explanation: http://earthobservatory.nasa.gov/Features/Milankovitch/

    Over the last approximately 1.2 million years of the Pleistocene, there have been roughly 102 ice ages, each occurring at roughly 100,000-year intervals. We are currently some 20,000 years into the 50,000-year very irregular warming portion of the current cycle. This will be followed by some 50,000 years of equally irregular cooling and another onset of continental glaciation.

    Homo sapiens first appeared during the last interglacial, and withstood the last continental glaciation. It might be interesting to note that during this last interglacial, surface temperature are estimated to have been from 0°C (Equator) to 10°C (about 65°N) warmer than at present. Sea levels were some seven meters higher than at present.

    Both the Antarctic and Greenland icecaps continued through all of these interglacial periods, although obviously somewhat reduced.

    It is hypothesized that ice ages occurred during geological eras other than the Pleistocene, but the evidence is weak.
  17. SteamKing

    SteamKing 8,349
    Staff Emeritus
    Science Advisor
    Homework Helper

    "Over the last approximately 1.2 million years of the Pleistocene, there have been roughly 102 ice ages, each occurring at roughly 100,000-year intervals.", quoted from klimatos

    102 * 100,000 = 10,200,000 years

    Can you provide a reference for the 102 ice ages figure?
  18. SteamKing,

    The 1.2 million year span of the Pleistocene was a simple, late-night brain fart. The current estimated span of the Pleistocene is, of course, roughly 2.5 million years. I have no excuse. I should have caught it before I posted.

    The "102" number can be found in http://en.wikipedia.org/wiki/Pleistocene . Look under "Oxygen isotope ratios".
    Whether you count all 102 advances as true "ice ages", of course, will depend upon your definition of that term. I should also have mentioned that the 100,00 year interval only applies to the most recent series of glacial episodes, as betzalal did in post 12. The earlier episodes had shorter cycles.
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