Solar forcing comparison between the Holocene and Anglian interglacial periods related by eccentricity
An example of an interstadial similar to current climate events is an inter-glacial event that happend roughly 130,000 to 115kya years ago known as the Eemian. During the Eemian the global temperature were several degrees Celsius higher than it is today and the oceans were 20-30 feet deeper. This of course is not even considered an anomaly, it is estimated that all the inter-glacial periods might have had similar climate conditions as the Eemian during the Pleistocene. In attempts to understand the current interglacial period, known as the Holocene, scientists have observed that the Eemian period is not quite like the Holocene because it had a sharper temperature increase with no Younger Dryas effect, higher temperatures, and a temperature peak lasting less then 10,000 years. Some of the reasons for this are explained by eccentricity,
“The orbital eccentricity of an astronomical object is a parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit, and greater than 1 is a hyperbola.”
“Eccentricity is important because it regulates the strength of polar maximum summer insolation caused by precession of the equinoxes every 21,000 years. Precession determines the distance from the sun during a Polar summer. If summer coincides with the earth’s perihelion then summer insolation can be up to 20% higher than average. However if the earth’s orbit is nearly circular, as it is today, then precession has little effect at all. That is why we have about 12000 years left before cooling begins.” October 4, 2016 by Clive Best, When is the next ice age due?
In order to compare current climate changes to the past we need to look at an interglacial period with a similar eccentricity.
Two observations from these charts come to play. The first is the current interglacial period, Holocene, is only half over. And if the Holocene is anything like the Anglian interglacial period temperatures are set to continue to rise if they correlate with EPICA (European Project for Ice Coring in Antarctica) temperatures reported for the Anglian interglacial period.
"We can argue about how warm the peak temperature will get and CMIP5 models vary about this roughly between 2 and 5 degrees. However this manmade climate disturbance should last for not much more than 3000 years so long as our emissions are reduced before 2100. The real question is what level we should then try to keep CO2 to avoid another devastating glaciation in 13,000 years time? If we want to survive long term then probably we should never let CO2 fall below 300ppm ever again!"October 4, 2016 by Clive Best, When is the next ice age due?
Paleohydrological Events From the Late Pleistocene to the Holocene 30KYA to 1500AD