**9. On relationship between climate variability found in widely separated regions**

Current studies show that climate variations recorded in geographically widely separated regions are strongly interrelated. In addition to the climate records analyzed above, there are many other climate proxy records (CPR) obtained from widespread regions of the Earth including coral cores from several oceans [36] and stalagmites from Soreq caves in the area of the ancient Levant [29]. Many CPR have been intercalibrated to obtain well-dated records of tracers of worldwide patterns in climate change [36, 32]. Comparisons of these records demonstrate the Northern Hemisphere wide extent of both millennium scale [38] and more rapid climate changes [39]. Thus, the abrupt termination of the YD cold-dry period has been detected throughout the Northern Hemisphere in Greenland, Western Europe, North America, and Central America, off the Venezuelan coast, in the Middle East, with some evidence from Central Africa and the Indian Ocean [35, 40–42].

The agreement of the climate variability found from the GISP2 data and the Cariaco data is an example of the climate tele-connections between distant regions of the Earth [43, 31] that have been demonstrated by ocean and atmospheric observational and modeling studies for both the Pleistocene [44] and Holocene [45]. Intercomparison of data shows that climate variations in the Arctic are linked to variations in Antarctic and to lower latitudes [37, 39, 46]. Here are some examples: Grootes and Stuiver [16] compared the ice core records with the deep ocean ∆18O records from Atlantic and Pacific Oceans and with tree-pollen land records in North America and Europe; Bond et al. [47] established correlations between climate records from North Atlantic Ocean and Greenland ice; Barlow et al. [34] established a link between stable isotope ratios (for deuterium) found from GISP2 ice cores data and the North Atlantic Oscillation (NAO) for the time period 1840–1970; and Wang et al. [48] linked the Asian monsoon in Southern China with the climate in the North Atlantic. Century-scale temperature variations in the Greenland Ice record [17] have also been related to the NAO [49]. The NAO is associated with a sea surface temperature anomaly having a meridional average tripole pattern: cool north of 55°N, warm in 20°–55°N latitudinal band, and cool south of 20°N in the positive phase of the NAO [50]. The Red Sea coral cores in an area close to the initial domestication of wheat also currently reflect variations in the North Atlantic Oscillation [36]. The Cariaco Basin data directly reflect the MesoAmerican rainfall during the summer and early fall in the Yucatan peninsula [50] near where corn was first domesticated. The NAO is one of several large-scale climate circulation patterns (such as Pacific Decadal Oscillation, Northern Annular Mode, Aleutian-Iceland Seesaw, and Cold Ocean-Warm Land patterns) that can be expressed as made up of different combinations of the current first and second Empirical Orthogonal Functions of the Northern Hemisphere winter sea-level pressure [45]. In these large-scale patterns, a climate variable, such as temperature, is above its mean value in one area of the coherent climate pattern and below its mean value in another geographically remote part of the pattern (and vice versa). The global mean is only weakly, if at all, affected, and the pattern temperature variability is not necessarily related to a change in global temperature. The pattern variability sometimes manifests itself as a prolonged statistical preference of one of the two basic states. For example, during the Little Ice Age, the temperature pattern tended to be in a state with a cold northern Eurasia more frequently than during more recent times [51, 52].

Studies such as these indicate that the climate variations observed in the GISP2 and Cariaco data reflect worldwide patterns that mankind would have experienced during the Pleistocene as well as the Holocene. It is not important for the development of agriculture, if these Pleistocene patterns are exactly the same as those we are familiar with from the Holocene. In fact, modeling suggests that they were not identical, but that the large-scale worldwide coherence was maintained [29, 42]. The large-scale coherence is an important feature because it strongly implies that the century-scale variations seen in Greenland and Cariaco Basin are parts of interrelated worldwide climate variations.

### **10. Conclusion**

When an agricultural society is developing, it may not be important if the local climate tends to be colder or warmer and dryer or wetter. What is important is that the local climate remains stable enough so that the crops and the livestock being domesticated continue to thrive.

It appears that from the time man left Africa about 50,000 ybp until 11,750 ybp there was essentially continuous climate variability in the period range of a century to a few centuries and no agriculture-based societies developed. These climate variations quieted at the beginning of the Holocene after the Younger Dryas terminated and were quickly followed by the development of several agricultural societies. It was the intense Pleistocene *climate variability* that prevented agriculture from developing until the onset of the relatively stable Holocene [8, 9]. This suggestion is supported by studies of the responses of already well-established agricultural societies to the relatively mild periods of climate variability that have taken place during the Holocene. For example, there was a weakly variable climate event at about 4000 years ago. This event strongly disrupted the Neolithic culture of Central China [48] as well as destroying the Egyptian Old Kingdom circa 4250–3950 ybp [53] and Akkadian in Mesopotamia 4170 ± 150 ybp [54]. A later period of climate variability observed in the Cariaco Basin sediments was accompanied by the fall of the classical Maya civilization in the Yucatan during the ninth century [55].

**13**

**Author details**

provided the original work is properly cited.

Joan Feynman and Alexander Ruzmaikin\*

*Climate Stability and the Origin of Agriculture DOI: http://dx.doi.org/10.5772/intechopen.83344*

systems were developed.

**List of abbreviations**

∼ approximate

ybp year before present (1950) Hss *Homo sapiens sapiens* YD younger Dryas

GISP2 Greenland Ice Sheet Project 2 EMD empirical mode decomposition SST sea surface temperature NAO North Atlantic Oscillation

PPN pre-pottery neolithic CPR climate proxy records

DO events Dansgaard-Oeschger climate events

We argued that the conditions required for the development of agricultural societies include about a millennium or more periods during which there are no largecentury-scale climate variations. We have presented evidence that this has been the case in the Northern Hemisphere since the end of the Younger Dryas but not during the last several tens of millennium of the preceding Pleistocene and suggested that this resulted in the failure to develop agricultural-based societies until after the termination of the Younger Dryas. We conclude that there is considerable evidence that climate variability inhibited the development of agriculture until ~11,000 ybp when relative climate stability was established and many independent agricultural

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

\*Address all correspondence to: alexander.ruzmaikin@jpl.nasa.gov

*Climate Stability and the Origin of Agriculture DOI: http://dx.doi.org/10.5772/intechopen.83344*

We argued that the conditions required for the development of agricultural societies include about a millennium or more periods during which there are no largecentury-scale climate variations. We have presented evidence that this has been the case in the Northern Hemisphere since the end of the Younger Dryas but not during the last several tens of millennium of the preceding Pleistocene and suggested that this resulted in the failure to develop agricultural-based societies until after the termination of the Younger Dryas. We conclude that there is considerable evidence that climate variability inhibited the development of agriculture until ~11,000 ybp when relative climate stability was established and many independent agricultural systems were developed.
