Our current understanding of dryland forests and their contribution to the climate system is very much shaped by the groundbreaking research coming out of the Yatir research station, in central Israel. The first flux tower in a dryland forest was established in 2000 by Prof. Dan Yakir of the Weizmann Institute of Science. Dan realized the large knowledge gaps existing in biogeochemistry and ecology in arid and semi-arid regions, and the research bias towards temperate ecosystems, in Europe and North America. In 20 years of laborious research, studies at the Yatir pine forest revolutionized almost everything we know about dryland ecosystems. For example, we learnt about the large potential in carbon sequestration in the semi-arid zone; about the albedo-related warming effect and the tradeoff with the long-term cooling potential; and the role of soil in buffering periods of drought that put the trees at risk. The session will highlight some of these discoveries, while bringing topics of current discussions and open questions.