Johan Nyberg - Academia.edu (original) (raw)

Papers by Johan Nyberg

Ancient Mesoamerica, 2007

Between A.D. 760 and 930, millions of Maya disappeared from the Earth. We examine changes in the ... more Between A.D. 760 and 930, millions of Maya disappeared from the Earth. We examine changes in the physical environment in which the Maya lived. The ice-core evidence from Greenland indicates that around the time of the Maya Collapse, a minimum in solar insolation and a low in solar activity occurred, accompanied by severe cold and dryness over Greenland, indicating hemispheric climatic conditions propitious for drought in the Maya Lowlands. In the northeastern Caribbean, sea-surface salinity (SSS) was lowered. The most severe drought of the past 7,000 years devastated the Yucatan Peninsula. Large Maya cities collapsed in four phases of abandonment spaced about fifty years apart around A.D. 760, 810, 860, and 910. A new core taken from Lake Chichancanab in Quintana Roo shows three peak episodes of brutal drought within a 150-to 200-year drought. A marine core from the Cariaco Basin off Venezuela precisely dates four severe drought episodes to 760, 810, 860, and 910, coincident with the four phases of abandonment of cities. The long-term drought appears to have lasted from 760 to 930 in the Cariaco Basin. The climatic changes were the most drastic the Maya had faced in the preceding 1,500 years and the most severe of the preceding 7,000 years. productivity and directly through vital rates." He also found that a 18C warming of winter temperature would reduce annual mortality by about 2% and a 18C cooling of summer temperature would reduce annual mortality by about 4%. In short, then, Lee found that mortality in England was increased by cold temperatures in winter and hot temperatures in summer, and fertility was decreased by the same conditions, a very clear and direct tie between climate and the fate of human populations (Ingram et al. 1981:28; Lee 1981 Lee : 398, 1987.

Ancient Mesoamerica, 2007

Between A.D. 760 and 930, millions of Maya disappeared from the Earth. We examine changes in the ... more Between A.D. 760 and 930, millions of Maya disappeared from the Earth. We examine changes in the physical environment in which the Maya lived. The ice-core evidence from Greenland indicates that around the time of the Maya Collapse, a minimum in solar insolation and a low in solar activity occurred, accompanied by severe cold and dryness over Greenland, indicating hemispheric climatic conditions propitious for drought in the Maya Lowlands. In the northeastern Caribbean, sea-surface salinity (SSS) was lowered. The most severe drought of the past 7,000 years devastated the Yucatan Peninsula. Large Maya cities collapsed in four phases of abandonment spaced about fifty years apart around A.D. 760, 810, 860, and 910. A new core taken from Lake Chichancanab in Quintana Roo shows three peak episodes of brutal drought within a 150-to 200-year drought. A marine core from the Cariaco Basin off Venezuela precisely dates four severe drought episodes to 760, 810, 860, and 910, coincident with the four phases of abandonment of cities. The long-term drought appears to have lasted from 760 to 930 in the Cariaco Basin. The climatic changes were the most drastic the Maya had faced in the preceding 1,500 years and the most severe of the preceding 7,000 years. productivity and directly through vital rates." He also found that a 18C warming of winter temperature would reduce annual mortality by about 2% and a 18C cooling of summer temperature would reduce annual mortality by about 4%. In short, then, Lee found that mortality in England was increased by cold temperatures in winter and hot temperatures in summer, and fertility was decreased by the same conditions, a very clear and direct tie between climate and the fate of human populations (Ingram et al. 1981:28; Lee 1981 Lee : 398, 1987.