As so often in life and science, the scale matters (in this case, the time scale)!
Or in other words, be glad to live on a warming planet!
There is so much about our climate, we still do not understand very well! Global Warming is a hoax and Climate Change a religion!
From the editor's summary and abstract:
"Editor’s summary
Global climate has cooled considerably over the past 4.5 million years, but by exactly how much and following exactly what trajectory is difficult to specify because of uncertainties in the proxy methods commonly used to measure temperatures. Clark et al. present a temperature reconstruction for that period that avoids some of those uncertainties and provides a more reliable temperature curve. Their findings should help to provide a better understanding of the interactions and feedbacks of the climate system that caused the global temperature changes. ...
Abstract
Much of our understanding of Cenozoic climate is based on the record of δ18O measured in benthic foraminifera. However, this measurement reflects a combined signal of global temperature and sea level, thus preventing a clear understanding of the interactions and feedbacks of the climate system in causing global temperature change. Our new reconstruction of temperature change over the past 4.5 million years includes two phases of long-term cooling, with the second phase of accelerated cooling during the Middle Pleistocene Transition (1.5 to 0.9 million years ago) being accompanied by a transition from dominant 41,000-year low-amplitude periodicity to dominant 100,000-year high-amplitude periodicity. Changes in the rates of long-term cooling and variability are consistent with changes in the carbon cycle driven initially by geologic processes, followed by additional changes in the Southern Ocean carbon cycle."
Global and regional temperature change over the past 4.5 million years (no public access)
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