Coupled CO2-climate response during the Early Eocene Climatic Optimum

Was the Arctic Eocene ‘rainforest’ monsoonal? Estimates of seasonal precipitation from early Eocene megafloras from Ellesmere Island, Nunavut

“…Recent studies of modern monsoonal sites have shown that leaf physiognomy can be used in identification of summer-precipitationdominated monsoonal climates (Jacques et al, 2011(Jacques et al, , 2014. This same signal would also be present in ecosystems that would become dormant during the long dark winters of high latitude regions (Royer et al, 2003;Jahren and Sternberg, 2008).…”

“…These types of monsoonal precipitation regimes have been proposed using both proxies and modeling data to characterize Eocene hyperthermal conditions in several regions of the earth, including the Arctic and Antarctic (Huber and Goldner, 2012;Schubert et al, 2012;Jacques et al, 2014). However, in polar regions proposed summer-wet precipitation regimes are contradicted by other proxy evidence (Greenwood, 1996;Eberle and Greenwood, 2012).…”

“…High latitude environments that were temperate and wet, such as the Canadian High Arctic, Spitzbergen and North Sea, instead experienced an increase in both temperature and precipitation (Uhl et al, 2007;Greenwood et al, 2010;Eldrett et al, 2014). The north polar region of the early Paleogene represents an environment that has no satisfactory modern analogue, relegating it to fossil environment status, as defined in Jacques et al (2014), although the winter-wet west coast forests of North America and the coastal forests of east Asia have been suggested as possible analogues (Greenwood et al, 2010;Schubert et al, 2012). Extensive studies in the literature document the presence of flora and fauna in the early Cenozoic that exist nowhere near these latitudes today (e.g., Hickey et al, 1983;Dawson et al, 1993;Basinger, 1991, 1995;McIver and Basinger, 1999;LePage, 2001LePage, , 2007Lepage, 2003;Eberle, 2005;Eberle et al, 2014;Harrington et al, 2012).…”

“…Based on both paleoclimate proxy evidence and climate model sensitivity experiments, highly seasonal 'monsoon-type' summerwet precipitation regimes seem to have characterized the early Eocene hyperthermal conditions in several regions of the earth (e.g., Greenwood, 1996;Hubert and Goldner, 2012), as well as the Arctic and Antarctic (e.g., Huber and Goldner, 2012;Schubert et al, 2012;Jacques et al, 2014;Krishnan et al, 2014). However, other proxy and modeling data for Arctic regions implies Eocene polar rain forests consistent with no or low precipitation seasonality (Eldrett et al, 2009;Greenwood et al, 2010;Eberle and Greenwood, 2012;Huber and Goldner, 2012).…”

Estimation of late Eocene (Bartonian–Priabonian) terrestrial palaeoclimate: Contributions from megafloral assemblages from central Germany

“…Maximum ocean water temperature curves calculated from oxygen isotopes of benthic foraminifera (Zachos et al, 2001(Zachos et al, , 2008 are often correlated with global climate evolution McInerney and Wing, 2011;Favre et al, 2014) and global atmospheric CO 2 changes McInerney and Wing, 2011). The terrestrial record, however, is not so well understood and indicates partly distinct and different developments (Mai, 1995) which means that averaged global ocean water temperature values and changes may not necessarily faithfully mirror continental palaeoclimate especially on a regional scale (Hyland and Sheldon, 2013).…”