Changes

There is evidence of increased drought during or around 900 AD, with scholars often attributing the "collapse" period as being between 800-1000 AD. The Yucatecan lake sediment cores show very severe droughts that not only meant less rainfall , but the thin soils that Maya agriculture were was dependent on were particularly vulnerable to sudden change as they were also relatively less fertile. Tree ring data and climate modeling have also been conducted, helping to show that there is are multiple lines of evidence that likely drought occurred. In fact, in the northern hemisphere at around 800-1000 AD, increasing cold temperature are evident. Those colder temperatures would have had the effect of creating more drier conditions to the south in Mexico and Central America.<ref>For more on the role of climate in this collapse, see: Hodell, D. A., Curtis, J. H., & Brenner, M. (1995). Possible role of climate in the collapse of Classic Maya civilization. <i>Nature</i>, 375(6530), 391–394.</ref>

More recentlyIn fact, more precise information on isotopic changes in sediments has allowed a more direct quantification on how much rainfall the northern hemisphere at around 800-1000 AD, increasing cold temperature is evident. Those colder temperatures would have had to change to lead to the collapse effect of the Maya. Recent work has shown that between 41% and 54% (with intervals of up creating more drier conditions to 70%) of rainfall reduction in the Mayan regions likely occurred. In other words, reduction south in rainfall was drastic Mexico and there was an accompanied decline in humidity, which likely led to more rapid drying with rainfall that fellCentral America.<ref>For more on the change role of climate in rainfall and how much this can be quantified to becollapse, see: EvansHodell, ND. P., Bauska, T. K., Gázquez-Sánchez, F., Brenner, MA., Curtis, J. H., & HodellBrenner, D. AM. (20181995). Quantification Possible role of drought during climate in the collapse of the classic Classic Maya civilization. <i>ScienceNature</i>, 361375(64016530), 498–501391–394.</ref>

More recently, more precise information on isotopic changes in sediments has allowed a more direct quantification on how much rainfall had to change to lead to the collapse of the Maya. Recent work has shown that between 41% and 54% (with intervals of up to 70%) of rainfall reduction in the Mayan regions likely occurred. In factother words, reduction in rainfall was drastic, relative and there was an accompanying decline in humidity, which likely led to more rapid drying with rainfall that fell.<ref>For more on the change in rainfall and how much this can be quantified to be, see: Evans, N. P., Bauska, T. K., Gázquez-Sánchez, F., Brenner, M., Curtis, J. H., & Hodell, D. A. (2018). Quantification of drought during the collapse of the classic Maya civilization. <i>Science</i>, 361(6401), 498–501.</ref> Relative to today, the region the Maya occupied was very different. It had been assumed the Maya created cities within jungles. However, the regions the Maya occupied were often drier, seasonally wet places that had cyclical rains that the Maya likely increasingly became dependent on. Only later after the cities were abandoned , they became jungles. That pattern of climate began to change between 800-1000 AD, which likely disrupted the agricultural system the Maya depended on. The agricultural system, composed of canals, terracing, raised fields, and other systems began not to not be sustainable relative to the new, emergent climate. Wider environmental decline may have accompanied climatic change that affected the success of agriculture, such as a decline in the complex agricultural system created.<ref>For more on wider environmental change, including the ecology, see: Kuil, L., Carr, G., Viglione, A., Prskawetz, A., & Blöschl, G. (2016). Conceptualizing socio-hydrological drought processes: The case of the Maya collapse: Socio-Hydrological Drought Processes. <i>Water Resources Research</i>, 52(8), 6222–6242. https://doi.org/10.1002/2015WR018298 </ref>