The Lateglacial interstadial at the southeastern limit of the Sonoran Desert, Mexico: vegetation and climate reconstruction based on pollen sequences from Ciénega San Marcial and comparison with the subrecent record

Abstract

The last glacial–interglacial transition encompassed rapid climate oscillations that affected both hemispheres. At low latitudes, the pattern of oscillations is not well established. To address this issue, pollen analysis was performed at Ciénega San Marcial, a monsoon‐influenced site located on the southeastern edge of the Sonoran Desert at the limit of the tropical thornscrub. The pollen record covers the Late Wisconsinan glacial termination II, from 15 650 to 13 400 cal. a BP, including GS‐2 and the Lateglacial interstadial, and a recent historical period (AD c. 1919 to 2004). We applied the modern analogue technique, in which pollen taxa are assigned to plant functional types (PFTs), to reconstruct the past climates. At the end of GS‐2, a Juniperus–Pinus woodland is indicative of annual temperatures 10±2 °C colder than present and higher annual precipitation dominated by winter rains. The onset of the Lateglacial interstadial occurs at c. 15 500 cal. a BP, resulting in a lower sedimentation rate and the spread of a xeric grassland. This period is associated with an increase in summer insolation. A weak signal of summer monsoon intensification is dated to 14 825 cal. a BP but is associated with colder winter temperatures. A wider spread of tropical taxa occurs after 13 800 cal. a BP, along with the loss of Juniperus, suggesting a temperature increase of approximately 3 °C. In spite of the earlier Lateglacial warming, the transition from glacial to interstadial conditions seems to be related to North Atlantic atmospheric variations. We conclude that during the last glacial–interglacial transition, the Sonoran Desert at 28.5° latitude was sensitive to climate variations originating in northern latitudes. The recent historical sequence displays summer‐dominant precipitation and additional drivers of climate change, including anthropogenic factors and El Niño, thus showing a stronger Pacific circulation influence in the subrecent period.

Stable Carbon and Oxygen Isotopes as Environmental Indicators of the Late Pleistocene in El Arenoso, Sonora, Northwest Mexico

“…Although there are no pollen data for El Arenoso, palynological, paleosoil, and Neotoma packrat analyses conducted in other sites of the Sonora and southern USA showed the presence of C 3 and C 4 grasses and xerophilous scrubs associated with low precipitation during the Late Pleistocene (Van Devender, 1990;Ballenger et al, 2011;Roy et al, 2012;Ortega-Rosas et al, 2016). This observation is also similar to the findings from carbon isotopic analyses of paleosoils and δ 13 C and δ 18 O values of herbivorous mammals from El Arenoso.…”

A pollen–climate calibration from western Patagonia for palaeoclimatic reconstructions

“…These methods are frequently used in climate reconstruction with their own set of advantages and limitations; they have been successfully used for Holocene climate reconstructions from terrestrial and marine records (e.g. Peyron et al , ; Mauri et al , ; Ortega‐Rosas et al , ). The MAT (Guiot, ) uses the squared‐chord distance to determine the degree of similarity between samples with known climate parameters (modern pollen samples) and samples for which climate parameters are to be estimated (fossil pollen sample).…”

Vegetation and climate changes over the last 30 000 years on the Leizhou Peninsula, southern China, inferred from the pollen record of Huguangyan Maar Lake

“…), whereas several events are not well established at low latitudes (Ortega‐Rosas et al . ). The Huguangyan area is one of the most suitable regions to address this issue.…”