We present a series of experiments conducted for the Last Glacial Maximum (~21 ka) over Europe using the regional climate Weather Research and Forecasting model (WRF) at convection-permitting resolutions. The model, with new developments better suited to paleo-studies, agrees well with pollen-based climate reconstructions. This agreement is improved when considering different sources of uncertainty. The effect of convection-permitting resolutions is also assessed.

Reconstructing past temperatures at regional scales during the Common Era is necessary to place the current warming in the context of natural climate variability. We present a climate reconstruction based on eight stalagmites from four caves in the Pyrenees, NE Spain. These stalagmites were dated precisely and analysed for their oxygen isotopes, which appear dominated by temperature changes. Solar variability and major volcanic eruptions are the two main drivers of observed climate variability.

In this study, we use climate modeling to investigate the relative impact of CO₂ and orbit on Early Eocene (~ 55 million years ago) climate and compare our modeled results to fossil records to determine the context for the Paleocene–Eocene Thermal Maximum, the most extreme hyperthermal in the Cenozoic. Our conclusions consider limitations and illustrate the importance of climate models when interpreting paleoclimate records in times of extreme warmth.

The climatic factors sustaining vegetation in the Sahara during the African humid period (AHP) are still not fully understood. Using biomarkers in a marine sediment core from the eastern Mediterranean, we infer variations in Mediterranean (winter) and monsoonal (summer) rainfall in the Nile river watershed around the AHP. We find that winter and summer rain enhanced during the AHP, suggesting that Mediterranean moisture supported the monsoon in sustaining the “green Sahara”.

The Maldives Inner Sea (northern Indian Ocean) offers an excellent study site to explore the impact of climate and sea-level changes on carbonate platforms. The sediments from International Ocean Discovery Program (IODP) Site U1467 have been studied to determine the drivers of carbonate production in the atolls over the last 1.3 million years. Even though sea level is important, the intensity of the summer monsoon and the Indian Ocean dipole probably modulated the production at the atolls.

The main aim of this paper is to present the summer vapor pressure deficit (VPD) reconstruction dataset for the last 400 years over Europe based on δ¹⁸O records by using a random forest approach. We provide both a spatial and a temporal long-term perspective on the past summer VPD and new insights into the relationship between summer VPD and large-scale atmospheric circulation. This is the first gridded reconstruction of the European summer VPD over the past 400 years.

We present transient simulations of the last glacial inception with the coupled climate–ice sheet model CLIMBER-X showing a rapid increase in Northern Hemisphere ice sheet area and a sea level drop by ~ 35 m, with the vegetation feedback playing a key role. Overall, our simulations confirm and refine previous results showing that climate-vegetation–cryosphere–carbon cycle feedbacks play a fundamental role in the transition from interglacial to glacial states.

We take advantage of a site in Alaska – where climate records are limited and a former alpine glacier deposited a dense sequence of moraines spanning the full deglaciation – to construct a proxy summer temperature record. Building on age constraints for moraines in the valley, we reconstruct paleo-glacier surfaces and estimate the summer temperatures (relative to the Little Ice Age) for each moraine. The record suggests that the influence of North Atlantic climate forcing extended to Alaska.

For better knowledge of the climate perturbation that occurred in the lattermost part of the Triassic (Norian–Rhaetian), we investigated the geochemical and rock magnetic properties of the limestones of the Pignola–Abriola section (Lagonegro Basin, Italy). Our investigation revealed at least a major episode of enhanced weathering occurring in the late Norian (~217–211 Ma), possibly related to the Cimmerian orogen and/or the northward motion of Pangea across the equatorial humid belt.

Climate and weather in spring are important because they can have far-reaching impacts, e.g. on plant growth, due to cold spells. Here, we study changes in climate and phenological indices for the period from 1763 to 2020 based on newly published reconstructed fields of daily temperature and precipitation for Switzerland. We look at three cases of extreme spring conditions, namely a warm spring in 1862, two frost events in 1873 and 1957, and three cold springs in 1785, 1837, and 1852.

 

 

In general, the variance and short-lag autocorrelations of the fluctuations increase in a system approaching a critical transition. Using these indicators, we identify statistical precursor signals for the Dansgaard–Oeschger cooling events recorded in two climatic proxies of three Greenland ice core records. We then provide a dynamical systems theory that bridges the gap between observing statistical precursor signals and the physical precursor signs empirically known in paleoclimate research.

Projecting the future evolution of the Greenland Ice Sheet is key. However, it is still under the influence of past climate changes that occurred over thousands of years. This makes calibrating projection models against current knowledge of its past evolution (not yet achieved) important. To help with this, we produced a new Greenland-wide reconstruction of ice sheet extent by gathering all published studies dating its former retreat and by mapping its past margins at the ice sheet scale.

The early 20th century warming – the first phase of global warming in the 20th century – started from a peculiar cold state around 1910. We digitised additional ship logbooks for these years to study this specific climate state and found that it is real and likely an overlap of several climatic anomalies, including oceanic variability (La Niña) and volcanic eruptions.

This study examines the transient response of the ocean carbon cycle to climate change since the last ice age by using an ocean general circulation model. Our carbon cycle model calculates atmospheric pCO₂ changes that are consistent with ice core records but whose magnitude is underestimated. Our analysis of carbon isotopes suggests that improving the expression of activated ocean ventilation and suppressing biological productivity are critical in simulating atmospheric pCO₂ changes.