Kingdom of Aksum

====Climate change hypothesis====
[[File:Balaw Kalaw (metera), stele axumita 06.JPG|thumb|Axumite Menhir in Balaw Kalaw (Metera) near [[Senafe]]]]
[[Climate variability and change|Climate change]] and trade isolation have also been claimed as large reasons for the decline of the culture.{{Citation needed|date=November 2019}} The local subsistence base was substantially augmented by a climatic shift during the 1st century AD that reinforced the spring rains, extended the rainy season from 3 1/2 to six or seven months, vastly improved the surface and subsurface water supply, doubled the length of the growing season, and created an environment comparable to that of modern central Ethiopia (where two crops can be grown per annum without the aid of irrigation).

Askum was also located on a plateau {{cvt|2000|m|ft}} feet above sea level, making its soil fertile and the land good for agriculture. This appears to explain how one of the marginal agricultural environments of Ethiopia was able to support the demographic base that made this far flung commercial empire possible. It may also explain why no Aksumite rural settlement expansion into the moister, more fertile, and naturally productive lands of Begemder or Lasta can be verified during the heyday of Aksumite power.

As international profits from the exchange network declined, Aksum lost control over its raw material sources, and that network collapsed. The persistent environmental pressure on a large population needing to maintain a high level of regional food production intensified, which resulted in a wave of soil erosion that began on a local scale {{circa|650}}, and reached crisis levels after 700. Additional socioeconomic contingencies presumably compounded the problem: these are traditionally reflected in a decline in maintenance, the deterioration and partial abandonment of marginal crop lands, shifts toward more destructive exploitation of pasture land—and ultimately wholesale, irreversible [[land degradation]]. This decline was possibly accelerated by an apparent decline in the reliability of rainfall beginning between 730 and 760, presumably with the result that an abbreviated modern growing season was reestablished during the 9th century.<ref name="butzer1981">{{Cite journal |last=Butzer |first=Karl W. |date=1981 |title=Rise and Fall of Axum, Ethiopia: A Geo-Archaeological Interpretation |url=http://sites.utexas.edu/butzer/files/2017/03/Butzer-1981-Axum.pdf |journal=American Antiquity |volume=46 |number = 3 |pages=471–495 |via=University of Texas at Austin |jstor = 280596 |doi = 10.2307/280596|s2cid=162374800 }}</ref>{{rp|495}}