- #1
keepitmoving
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at the end of these 100,000 year cycles of temperature, what causes the peak temperature to fall?
At the end of these 100,000 year cycles of temperature, what causes
- Thread starter keepitmoving
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Discussion Overview
The discussion centers on the factors influencing the peak temperature at the end of 100,000-year cycles, particularly in relation to Earth's orbital changes and climate dynamics. It explores the interplay of various elements such as greenhouse gases, albedo, and historical shifts in temperature cycles.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- Some participants suggest that changes in Earth's orbit drive long-term climate changes, which are further influenced by greenhouse gas levels and albedo effects.
- Others note that the cycle length has varied historically, with a significant period exhibiting a 41,000-year cycle, raising questions about the consistency and causes of these cycles.
- One participant highlights discrepancies between solar forcing patterns and glaciation stages, indicating that additional factors may be involved in climate changes beyond those explained by Milankovitch cycles.
- There is mention of challenges to the Milankovitch hypothesis, suggesting ongoing debate regarding the mechanisms behind climate cycles.
Areas of Agreement / Disagreement
Participants express multiple competing views regarding the causes of temperature peaks and the validity of the 100,000-year cycle, indicating that the discussion remains unresolved.
Contextual Notes
Limitations include the unclear causes of historical shifts in cycle lengths and the dependence on specific proxies for climate data, which may not fully capture the complexity of the climate system.
- #2
DrClapeyron
http://en.wikipedia.org/wiki/Milankovitch_cycles"
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- #3
Xnn
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Changes in Earth's orbit normally drive long term climate changes (warming and cooling) and are amplified by changes in greenhouse gases (CO2 and CH4) along with changes in snow and ice coverage (albedo).
http://stephenschneider.stanford.edu/Publications/PDF_Papers/Ruddiman2003.pdf
BTW, it wasn't always a 100,000 year cycle. For a significant period of time, the temperature cycle was 41,000 years. It's not entirely clear what caused that shift or if there really is a 100,000 year cycle as opposed to a series of 82,000 and 123,000 year cycles that happen to average out at 100,000 years.
- #4
keepitmoving
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thanks.
- #5
Andre
- 4,296
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Not done yet,
Another problem is that the 413,000 years eccentricity cycle clearly shows up in the insolation cycles as amplitude modulation here, but it does not show up in the oceanic benthic foraminifera isotope proxies as well as the ice cores.
The graph shows that the total resulting solar forcing at 65 degrees north in the summer does not resemble the stages of glaciation a lot. Note especially that 400,000 years ago we see one of the biggest spikes in the glaciation together with the one of the least variation in summer forcing compared to 200,000 years ago when one of the strangest variation in summer forcing is seen together with only a small spike.
Apparantly there is some more to it, although this wasn't even the reason why Karner and Muller challenged the Milankovitch idea http://sciencemag.org/cgi/content/summary/288/5474/2143.
full text
Another problem is that the 413,000 years eccentricity cycle clearly shows up in the insolation cycles as amplitude modulation here, but it does not show up in the oceanic benthic foraminifera isotope proxies as well as the ice cores.
The graph shows that the total resulting solar forcing at 65 degrees north in the summer does not resemble the stages of glaciation a lot. Note especially that 400,000 years ago we see one of the biggest spikes in the glaciation together with the one of the least variation in summer forcing compared to 200,000 years ago when one of the strangest variation in summer forcing is seen together with only a small spike.
Apparantly there is some more to it, although this wasn't even the reason why Karner and Muller challenged the Milankovitch idea http://sciencemag.org/cgi/content/summary/288/5474/2143.
full text
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