[U-03] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia

[U03-06] Seasonal origin for the Holocene and last interglacial thermal maxima

★Invited Papers

*Yair Rosenthal¹, Samantha Bova², Zhengyu Liu³ (1.Rutgers University, 2.San Diego State University, 3.Ohio State University)

Keywords:Holocene, Temperature, proxies

Proxy reconstructions, interpreted to reflect mean annual temperatures, indicate peak temperatures in the first half of the last and current interglacials (a.k.a. the Holocene and last interglacial thermal maxima), arguably exceeding modern temperatures. In contrast, climate models simulate monotonic warming throughout both periods. This significant model-data discrepancy, known as the Holocene temperature conundrum, has undermined confidence in proxy reconstructions and climate models. Our recent studies have suggested that global reconstructions of the Holocene and last interglacial (LIG) periods reflect the evolution of seasonal rather than mean annual temperatures. To overcome this bias, we have developed a Seasonal to Annual mean Transformation (SAT) method. Using this transformation, we demonstrate that in contrast with previous reconstructions, global mean annual temperatures have been increasing since the early Holocene, first in response to retreating ice sheets (12 to 6.5 thousand years ago), then due to rising greenhouse gas concentrations (0.25 ± 0.21°C over the last ~6.5 thousand years). The SAT has been challenged as a robust solution to this problem. In this presentation, we will discuss the method, its implications to global climate during the Holocene and other interglacials, and address some of the common critiques of the method, as well as provide an outlook on future development of SAT.