6 ms·

Did plants cause one of Earth’s great extinctions?

37 points by sea6ear 9y ago

nategri 9y ago
> A more circular orbit of Earth around the sun — leading to years with no great difference between summer and winter — might have also helped doom most of the fish. Oh man please do not say this without additional clarification. People are confused enough as it is about what causes seasons.
- mirimir 9y ago
  It's sad that people who write such articles know so little science.
  - cryptonector 9y ago
    No, that's not at all a problem. The problem is how little they bother researching what they write about.
    - mirimir 9y ago
      When you lack requisite background, research doesn't help very much. It's like cramming for finals, when you've done no work during the semester.
- aaronblohowiak 9y ago
  For people who don't know -- earth's orbit is more like a circle than an elipse. The tilt of the earth is responsible for most seasonal variation we see on earth. IIRC, Mars has more of a difference between ahelion and perihelion and that impacts seasonal variation there much more.
  - mogigoma 9y ago
    The term here, if anyone wants to look into it, is "orbital eccentricity". Here's a table listing the eccentricities of the various planets: http://www.enchantedlearning.com/subjects/astronomy/glossary/Eccentricity.shtml http://www.enchantedlearning.com/subjects/astronomy/glossary...
- caymanjim 9y ago
  Earth's orbital eccentricity has nothing at all to do with its seasons. It's nearly a perfect circle right now. The reason Earth has seasons is because of the axial tilt relative to the plane of rotation. In the northern summer, the northern hemisphere is angled towards the sun, and in the northern winter, it's angled away. This repeated incorrect claim in the article is frustrating, because it's otherwise describing a fascinating theory.
- DrScump 9y ago
  I found a couple of papers about correlations between Earth-orbit perturbations and ice ages; submitted separately: https://news.ycombinator.com/item?id=16533837 https://news.ycombinator.com/item?id=16533837
mirimir 9y ago
Increasing atmospheric oxygen from early photosynthetic organisms did drive most anaerobes into extinction.
- pygy_ 9y ago
  The Great Oxygenation Event. Sounds like a fun party of massive death and extermination.
  - mirimir 9y ago
    Botulinum and Clostridium get their revenge sometimes, however.
    - cryptonector 9y ago
      Clostridium est dificil a batre.
      - mirimir 9y ago
        Oui :)
jandrese 9y ago
Seems like the culpret was a gigantic algae bloom using minerals liberated by newly evolved land plants that were breaking up rocks with their roots. This was exacerbated by poor ocean circulation from a highly circular orbit around the sun (but what about the tilt?). The same effect you get when fertilizer runs off into a stagnant pond or lake, except on a global scale.
- chiefalchemist 9y ago
  And when this algae died it eventually became oil?
chiefalchemist 9y ago
If correct (in some form), could this be used (in some way) to make Mars more human-friendly?
- qbrass 9y ago
  It might help on a habitat scale, but won't help Mars on a planetary scale. There's simply not enough atmosphere on Mars. While CO2 makes up 95% of Mars's atmosphere and 0.04% of Earth's. There's roughly the same amount of CO2 in the atmosphere of both planets. There's 500 times as much Oxygen in Earth's atmosphere than CO2. Even accounting for the size difference between the planets, you'd still need hundreds of times more oxygen than the current atmosphere could provide.
tzahola 9y ago
>A more circular orbit of Earth around the sun — leading to years with no great difference between summer and winter I recognize quality science journalism when I see it! And I see here none.
cryptonector 9y ago
The eccentricity of Earth's orbit doesn't make for more or less extreme summer/winter differences, but more or less extreme northern vs. southern hemisphere winter/summer differences. This is central to the theory of how the Milankovitch cycles are tied to glacial and interglacial periods of the current ice age. What makes seasons less extreme is a closer-to-right-angle angle of the axis of Earth's rotation to the ecliptic plane. This angle does vary a fair bit over time. In geologic time there are four astronomic parameters of Earth's movement, and one for the Sun's, that can affect the climate and life: - eccentricity of Earth's orbit - precession of the equinoxes - angle of the axis of Earth's rotation to the ecliptic - distance from the Earth to the Sun (which, besides eccentricity, varies over long geologic time due to interactions with Jupiter and other planets) When the northern hemisphere's summer coincides with the perigee of Earth's orbit around the Sun, insolation is at its highest over the most landmass, thus ensuring that ice does not accumulate on land over the summer and that any existing ice melts. This is likely the cause of the start of interglacials, while the opposite situation is likely the cause of the start of glacial periods. The angle of the axis of Earth's rotation to the ecliptic also plays a role, in this, obviously, since the smaller the angle the more extreme the seasonal differences. So goes the theory anyways. And, of course, the galactic neighborhood traversed by the Sun can make a difference. We don't want to be near stars about to go supernova...

37 points by sea6ear 9y ago

> A more circular orbit of Earth around the sun — leading to years with no great difference between summer and winter — might have also helped doom most of the fish. Oh man please do not say this without additional clarification. People are confused enough as it is about what causes seasons.

mirimir 9y ago
It's sad that people who write such articles know so little science.
- cryptonector 9y ago
  No, that's not at all a problem. The problem is how little they bother researching what they write about.
  - mirimir 9y ago
    When you lack requisite background, research doesn't help very much. It's like cramming for finals, when you've done no work during the semester.
aaronblohowiak 9y ago
For people who don't know -- earth's orbit is more like a circle than an elipse. The tilt of the earth is responsible for most seasonal variation we see on earth. IIRC, Mars has more of a difference between ahelion and perihelion and that impacts seasonal variation there much more.
- mogigoma 9y ago
  The term here, if anyone wants to look into it, is "orbital eccentricity". Here's a table listing the eccentricities of the various planets: http://www.enchantedlearning.com/subjects/astronomy/glossary/Eccentricity.shtml http://www.enchantedlearning.com/subjects/astronomy/glossary...
caymanjim 9y ago
Earth's orbital eccentricity has nothing at all to do with its seasons. It's nearly a perfect circle right now. The reason Earth has seasons is because of the axial tilt relative to the plane of rotation. In the northern summer, the northern hemisphere is angled towards the sun, and in the northern winter, it's angled away. This repeated incorrect claim in the article is frustrating, because it's otherwise describing a fascinating theory.
DrScump 9y ago
I found a couple of papers about correlations between Earth-orbit perturbations and ice ages; submitted separately: https://news.ycombinator.com/item?id=16533837 https://news.ycombinator.com/item?id=16533837

mirimir 9y ago

Increasing atmospheric oxygen from early photosynthetic organisms did drive most anaerobes into extinction.

pygy_ 9y ago
The Great Oxygenation Event. Sounds like a fun party of massive death and extermination.
- mirimir 9y ago
  Botulinum and Clostridium get their revenge sometimes, however.
  - cryptonector 9y ago
    Clostridium est dificil a batre.
    - mirimir 9y ago
      Oui :)

jandrese 9y ago

Seems like the culpret was a gigantic algae bloom using minerals liberated by newly evolved land plants that were breaking up rocks with their roots. This was exacerbated by poor ocean circulation from a highly circular orbit around the sun (but what about the tilt?). The same effect you get when fertilizer runs off into a stagnant pond or lake, except on a global scale.

chiefalchemist 9y ago
And when this algae died it eventually became oil?

chiefalchemist 9y ago

If correct (in some form), could this be used (in some way) to make Mars more human-friendly?

qbrass 9y ago
It might help on a habitat scale, but won't help Mars on a planetary scale. There's simply not enough atmosphere on Mars. While CO2 makes up 95% of Mars's atmosphere and 0.04% of Earth's. There's roughly the same amount of CO2 in the atmosphere of both planets. There's 500 times as much Oxygen in Earth's atmosphere than CO2. Even accounting for the size difference between the planets, you'd still need hundreds of times more oxygen than the current atmosphere could provide.

tzahola 9y ago

>A more circular orbit of Earth around the sun — leading to years with no great difference between summer and winter I recognize quality science journalism when I see it! And I see here none.

cryptonector 9y ago

The eccentricity of Earth's orbit doesn't make for more or less extreme summer/winter differences, but more or less extreme northern vs. southern hemisphere winter/summer differences. This is central to the theory of how the Milankovitch cycles are tied to glacial and interglacial periods of the current ice age. What makes seasons less extreme is a closer-to-right-angle angle of the axis of Earth's rotation to the ecliptic plane. This angle does vary a fair bit over time. In geologic time there are four astronomic parameters of Earth's movement, and one for the Sun's, that can affect the climate and life: - eccentricity of Earth's orbit - precession of the equinoxes - angle of the axis of Earth's rotation to the ecliptic - distance from the Earth to the Sun (which, besides eccentricity, varies over long geologic time due to interactions with Jupiter and other planets) When the northern hemisphere's summer coincides with the perigee of Earth's orbit around the Sun, insolation is at its highest over the most landmass, thus ensuring that ice does not accumulate on land over the summer and that any existing ice melts. This is likely the cause of the start of interglacials, while the opposite situation is likely the cause of the start of glacial periods. The angle of the axis of Earth's rotation to the ecliptic also plays a role, in this, obviously, since the smaller the angle the more extreme the seasonal differences. So goes the theory anyways. And, of course, the galactic neighborhood traversed by the Sun can make a difference. We don't want to be near stars about to go supernova...