We continuously hear from political and media activists that we're experiencing a great climate disruption and the Earth is facing a so-called 'Sixth Mass Extinction event' as a result of our use of hydrocarbons..I will show a contrarian perspective, which used to be mainstream. As to whether climatic changes measured in the 20th century constitute a true state of emergency warranting a totalitarian lockdown on society, you be the judge..Approximately 8,000 years ago, the Sahara Desert was a lush green grassland with extensive lakes and rivers. (This is not disputed.) Then gradually, this region transitioned to the arid desert that it is today. Why did this happen and what can we take from this knowledge and apply to our current dilemma on matters relating to climate hysteria?. Neoglacial phase .The desertification of Northern Africa was part of a global phenomenon that paleoclimatologists refer to as the transition into a neoglacial phase. Immediately prior to the transition to the current neoglacial phase, the state of the global climate system was referred to as the Holocene Climate Optimum (HCO) or the Holocene Thermal Maximum..Isn't it intriguing that classical climatology refers to a warmer climate as 'optimal?'.Javier Vino's illustration highlights some of the defining characteristics of this transition to include the emergence of the major global deserts along the Horse Latitudes (i.e. the Sahara, middle eastern and Gobi deserts,) the rapid cooling of Greenland and the migration of the Intertropical Convergence Zone (ITCZ) towards the Southern Hemisphere, just to name a few notable effects..In my previous article titled Tired of the Fear Mongering, I introduced the topic of the ITCZ as a critical climate indicator and showed the arrival of the tropical summer monsoon in the tropics coincides with its migration towards whichever hemisphere is warming relative to the other hemisphere..I demonstrated that this occurs during both the Seasonal Cycle and the 60-year solar cycle..Javier Vino's illustration shows that the ITCZ was much higher in the northern hemisphere during the Holocene Climate Optimum than today, because the higher latitudes of the northern hemisphere were themselves four to eight degrees centigrade warmer than at present..Lasher et al's reconstruction of the changes in air temperatures in northwestern Greenland 8,000 years ago, shows at the height of the Holocene Climate Optimum, this region was 4 to 6 degrees Centigrade warmer than today. Lasher et al's study demonstrates that a gradual cooling of the current neoglacial phase of the Holocene Interglacial has been underway for thousands of years..With this cooling, Greenland's icefields returned and the ITCZ began is millennial migration towards the Southern Hemisphere. It is generally accepted this transition from the Holocene Climate Optimum to the current neoglacial phase is due to changes in the Earth's orbit caused by larger-scale cyclical changes in the local gravitational environment of the solar system, which collectively are called the Milankovitch Cycles.. Northwest Greenland .One of the best representations of the migrations of the ITCZ over the entire course of the Holocene Interglacial is published by Tapio Schnieder et al in the work titled Migrations and Dynamics of the Intertropical Convergence Zone..The x-axis is in thousands of years before present (i.e. kyr BP) and the y-axis include metrics specific to the Indian Summer Monsoon rainfall, the temperature difference between hemispheres and a relative scale for precipitation in either hemisphere..I have taken the liberty of adding acronyms for the approximate historical timing of the Holocene Climate Optimum, the Roman Warm Period (RWP) and the Medieval Warm Period (MWP)..The rise to the peak of the Holocene Climate Optimum coincides with the exit from the last glacial maximum, also called the Eemian Ice Age. As shown, this resulted in warming and increased precipitation across the Northern Hemisphere relative to the Southern Hemisphere. Conversely, the current neoglacial phase of the Holocene Interglacial is resulting in the reversal of all those major climatic features, as once again Earth is moving towards the next glacial maximum..By including the acronyms for the RWP and the MWP at 1,000 and 2,200 years before present, I am intentionally highlighting evidence I believe places these historical periods as the equivalent of what is known in paleoclimatology as Interstadial events.. Migrations .Interstadial events commonly occur during neoglacials and are defined by sudden migrations of the ITCZ towards the northern hemisphere, as the latter rapidly warms relative to the southern hemisphere. These brief excursions from the cooling trend of the neoglacial commonly last for a few centuries before returning to the neoglacial trend..Conversely, sudden displacements of the ITCZ towards the southern hemisphere are called Stadials and the Little Ice Age that occurred prior to the Current Warm Period (CWP) and after the Mediaeval Warm Period is a prime example..Finally, in my last article titled Tired of the Media Fear Mongering I featured additional data from Tapio Schnieder et al, which shows that the migrations of the ITCZ in the 20th century does not support the argument that our use of hydrocarbons is resulting in a Great Climate Disruption. Instead, what was observed is two periods of rapid warming of the Northern Hemisphere relative to the Southern Hemisphere in the 20th century caused the ITCZ to oscillate between the peak warming periods of the 1940s and 2000s..Those who argue the CWP is exceptional and the measured changes in climate in the 20th century represents an existential threat, do so by ignoring the immense body of evidence specific to the neoglacial record. The neoglacial backdrop to the CWP shows large scale desertification of the Northern Hemisphere developed as it cools relative to the HCO and as the ITCZ migrates towards the Southern Hemisphere..The evidence is clear, in our climate system is advancing towards the Holocene Ice Age. The questions that remain unanswered are how long will the Current Warm Period last before returning to the neoglacial trend and how will humanity adapt in view of the approaching Holocene Ice Age?.And a Sixth Great Extinction? If it happens, blame the natural warming-cooling cycles.
