- Joined
- Jan 28, 2013
- Messages
- 94,823
- Reaction score
- 28,342
- Location
- Williamsburg, Virginia
- Gender
- Male
- Political Leaning
- Independent
This is interesting work that puts current temperature trends in a larger and more informative context. Bottom line: warming and cooling are out of our hands.
Climate News / Paleoclimatology
Paleoclimate Cycles are Key Analogs for Present Day (Holocene) Warm Period
Guest Post By Renee Hannon
Abstract
Detailed pattern correlation of Earth’s temperature changes during the past 450 kyrs reveals observations about several cyclic climate patterns. The past four glacial cycles are increasing in duration from 89 kyrs to 119 kyrs. Within these glacial cycles, two warm periods occur about 200 kyrs apart and have strikingly similar temperature characteristics. These two warm patterns suggest processes modifying Earth’s temperature could be repeatable and predictable. In contrast, two other warm periods have different and distinct characteristics. These two warm periods occur during a predominantly elliptical orbit and a predominantly circular orbit, respectively, and on approximately 400 kyr cycles. . . .
Climate models need to include astronomical as well as oceanic and atmospheric forcing to reliably predict the duration and temperature changes of the future Holocene interglacial Warm period. . . .
Summary and Conclusions
A Glacial Cycle traverse illustrates that the duration of interglacial/glacial cycles progressively increases from past to present over the past 450 kyrs and are not a simple 100 kyr cycle. Eccentricity and its influence on summer insolation appears to play a dominant role in the duration of glacial cycles. Circular orbits tend to have shorter cycles (<100 kyrs) and more elliptical orbits tend to be longer (>100 kyrs).
Conceptual models are proposed using astronomical and oceanic processes described in the literature to explain repeatable patterns observed in past interglacial warm periods. Prioritizing dominant processes operating in different warm periods may provide general guidelines for future climate models.
Past Warm II and IV periods are well behaved and exhibit strikingly similar warming/cooling patterns suggesting a repeatable interplay of astronomical, oceanic, and atmospheric processes. These repeatable patterns occur every 200 kyrs during semi-elliptical eccentric cycles.
On the other hand, anomalous Warm III and V periods tend to have less predictable patterns and are unique. Warm III occurred during the most elliptical orbit and Warm V during the most circular orbit. Glacial cycles during elliptical orbits tend to have rapid onset and several warm/cool periods because obliquity is amplified and summer insolation dominates. Warm periods during circular orbits tend to have slower warm onsets and are more symmetrical. Oceanic processes may play a greater role during the warm periods but play a minor role in controlling the onsets or eventual cool periods.
During the last 450 kyrs, the five major warm onsets with rapidly increasing temperatures are triggered by increases in the eccentricity, obliquity, and precession of Earth’s orbit. The nearly concurrent increase in these three astronomical forces appears a necessary component for a major warm onset. Obliquity is the dominate control for ending these major warm periods and entering a cooling phase. Higher frequency procession/summer insolation appears to play a secondary role in overprinting the duration pattern with a stadial event such as the Holocene 8.2 kyr or extending a warm period like in Warm V. Oceanic processes dominate during periods of minor temperature changes (+/- 1.5 degrees C).
Dome C isotope ratios and their associated temperature estimates in combination with astronomical data provide ample evidence that astronomical forces control warming and cooling cycles. Because the astronomical processes affecting significant climate changes are beyond human control our focus should be on adaptation rather than climate manipulation. It is not a question if cooling will occur but simply a question of when.
Climate News / PaleoclimatologyPaleoclimate Cycles are Key Analogs for Present Day (Holocene) Warm Period
Guest Post By Renee Hannon
Abstract
Detailed pattern correlation of Earth’s temperature changes during the past 450 kyrs reveals observations about several cyclic climate patterns. The past four glacial cycles are increasing in duration from 89 kyrs to 119 kyrs. Within these glacial cycles, two warm periods occur about 200 kyrs apart and have strikingly similar temperature characteristics. These two warm patterns suggest processes modifying Earth’s temperature could be repeatable and predictable. In contrast, two other warm periods have different and distinct characteristics. These two warm periods occur during a predominantly elliptical orbit and a predominantly circular orbit, respectively, and on approximately 400 kyr cycles. . . .
Climate models need to include astronomical as well as oceanic and atmospheric forcing to reliably predict the duration and temperature changes of the future Holocene interglacial Warm period. . . .
Summary and Conclusions
A Glacial Cycle traverse illustrates that the duration of interglacial/glacial cycles progressively increases from past to present over the past 450 kyrs and are not a simple 100 kyr cycle. Eccentricity and its influence on summer insolation appears to play a dominant role in the duration of glacial cycles. Circular orbits tend to have shorter cycles (<100 kyrs) and more elliptical orbits tend to be longer (>100 kyrs).
Conceptual models are proposed using astronomical and oceanic processes described in the literature to explain repeatable patterns observed in past interglacial warm periods. Prioritizing dominant processes operating in different warm periods may provide general guidelines for future climate models.
Past Warm II and IV periods are well behaved and exhibit strikingly similar warming/cooling patterns suggesting a repeatable interplay of astronomical, oceanic, and atmospheric processes. These repeatable patterns occur every 200 kyrs during semi-elliptical eccentric cycles.
On the other hand, anomalous Warm III and V periods tend to have less predictable patterns and are unique. Warm III occurred during the most elliptical orbit and Warm V during the most circular orbit. Glacial cycles during elliptical orbits tend to have rapid onset and several warm/cool periods because obliquity is amplified and summer insolation dominates. Warm periods during circular orbits tend to have slower warm onsets and are more symmetrical. Oceanic processes may play a greater role during the warm periods but play a minor role in controlling the onsets or eventual cool periods.
During the last 450 kyrs, the five major warm onsets with rapidly increasing temperatures are triggered by increases in the eccentricity, obliquity, and precession of Earth’s orbit. The nearly concurrent increase in these three astronomical forces appears a necessary component for a major warm onset. Obliquity is the dominate control for ending these major warm periods and entering a cooling phase. Higher frequency procession/summer insolation appears to play a secondary role in overprinting the duration pattern with a stadial event such as the Holocene 8.2 kyr or extending a warm period like in Warm V. Oceanic processes dominate during periods of minor temperature changes (+/- 1.5 degrees C).
Dome C isotope ratios and their associated temperature estimates in combination with astronomical data provide ample evidence that astronomical forces control warming and cooling cycles. Because the astronomical processes affecting significant climate changes are beyond human control our focus should be on adaptation rather than climate manipulation. It is not a question if cooling will occur but simply a question of when.
