Multiple proxies for the XSZ planation surface reveal that the climate was dry and stable during the late Miocene but became intermittently humid with more seasonality at 4.7–3.9 Ma. Regional climatic differences between the central and western CLP reveal that expansion of the paleo-EASM occurred during the early Pliocene. The warming of the high northern latitudes in response to the closure of the Panama Seaway may have been responsible for the thermodynamical enhancement of the paleo–EASM.

The New Zealand subantarctic islands, in the Pacific sector of the Southern Ocean, provide valuable records of past environmental change. We find that the Auckland Islands hosted a small ice cap around 384 000 years ago, but that there was little glaciation during the Last Glacial Maximum, around 21 000 years ago, in contrast to mainland New Zealand. This shows that the climate here is susceptible to changes in regional factors such as sea-ice expanse and the position of ocean fronts.

Insolation is thought to drive monsoons on orbital timescales. We find that insolation can be a trigger for changes in precipitation, but surface energy and vertical stability play an important role too. These feedbacks are found to be dominant over oceans and can even counter the insolation forcing, thus leading to a land–sea differential response in precipitation.

Based on a Holocene oxygen stable isotope record from Lake Sidi Ali (Morocco) we correlate Western Mediterranean precipitation anomalies with North Atlantic ice-rafted debris (Bond) events to identify a probable teleconnection between Western Mediterranean winter rains and subpolar North Atlantic cooling phases. Our data show a noticeable similarity between Western Mediterranean winter rain minima and Bond events during the Early Holocene and an opposite pattern during the Late Holocene.

Historical documents are full of untapped data on past climate conditions. Our paper sets out a method for extracting this information into a database that is easily utilized by climate scientists. We apply this method to a document from Shirley Plantation covering the years 1816–1842. We then provide two case studies to demonstrate the validity and utility of the new method and database.

In geology and in paleoclimate science, most changes are caused by well-understood forces acting slowly over long periods of time. However, in highly nonlinear physical systems, mathematical bifurcation theory predicts that small changes in forcing can cause major changes in the system in a short period of time. This paper explores some sudden changes in the paleoclimate history of the Earth, where it appears that bifurcation theory gives a more satisfying explanation than uniformitarianism.

We empirically estimate signal-to-noise ratios of temperature proxy records used in global compilations of the middle to late Holocene by comparing the spatial correlation structure of proxy records and climate model simulations accounting for noise and time uncertainty. We find that low signal contents of the proxy records or, alternatively, more localised climate variations recorded by proxies than suggested by current model simulations suggest caution when interpreting multi-proxy datasets.

Understanding how atmospheric CO₂ has affected the climate of the past is an important way of furthering our understanding of how CO₂ may affect our climate in the future. There are several ways of determining CO₂ in the past; in this paper, we ground-truth one method (based on preserved organic matter from alga) against the record of CO₂ preserved as bubbles in ice cores over a glacial–interglacial cycle. We find that there is a discrepancy between the two.

The Mediterranean region has returned some of the clearest evidence of a climatically dry period occurring approximately 4200 years ago. We reviewed selected proxies to infer regional climate patterns between 4.3 and 3.8 ka. Temperature data suggest a cooling anomaly, even if this is not uniform, whereas winter was drier, along with dry summers. However, some exceptions to this prevail, where wetter condition seems to have persisted, suggesting regional heterogeneity.

We present the first black carbon (BC) ice-core record from the Andes (Illimani, Bolivia). It spans the entire Holocene and reflects biomass burning emissions from the Amazon Basin, with high (low) concentrations during warm–dry (wet–cold) periods. The highest fire activity occurred during the Holocene Climatic Optimum (7000–3000 BCE). Recent BC levels, increasing since 1730 CE, do not exceed those of the Medieval Warm Period. The contribution from industrial and traffic emissions remains minor.

By using a 3-D hybrid ice-sheet–shelf model, we investigate the impact of millennial-scale oceanic variability on the Greenland Ice Sheet (GrIS) evolution during the last glacial period (LGP). We show that the GrIS may have strongly reacted to oceanic temperature fluctuations associated with Dansgaard–Oeschger cycles, contributing to sea-level variations of more than 1 m. Our results open the chance for a non-negligible role of the GrIS in millennial-scale oceanic reorganisations during the LGP.

This PAGES (Past Global Changes) 2k (climate of the past 2000 years working group) special issue of Climate of the Past brings together the latest understanding of regional change and impacts from PAGES 2k groups across a range of proxies and regions. The special issue has emerged from a need to determine the magnitude and rate of change of regional and global climate beyond the timescales accessible within the observational record.

Approximately 600 million years ago, major environmental changes set the course for the emergence of animal life. Lithium (Li) isotopes in calcium carbonates can be used as a proxy to understand changes in the palaeo-environment. We conducted experiments that allow us to use Li isotopes in dolostones to extend our understanding of palaeo-environmental changes deeper into the geological record, where other calcium carbonates archives are not present.

The climate of Granada (southern Spain) during the first third of the 18th century is reconstructed. Results suggest that climatic conditions were similar to those of the first decades of the 20th century, when the global warming signal was of less importance than today. In addition, the paper presents the instrumental data taken in Granada in 1729, probably the first instrumental meteorological data recorded in Spain. Some extreme events, such as the cold wave of winter 1729, are studied.

Antarctic temperature changes over the past millennia have been reconstructed from isotope records in ice cores in several studies. However, the link between both variables is complex. Here, we investigate the extent to which this affects the robustness of temperature reconstructions using pseudoproxy and data assimilation experiments. We show that the reconstruction skill is limited, especially at the regional scale, due to a weak and nonstationary covariance between δ¹⁸O and temperature.

We present a unique dataset of multiple tree-ring and stable isotope parameters, representing temperature-sensitive Siberian ecotones, to assess climatic impacts after six large stratospheric volcanic eruptions at 535, 540, 1257, 1640, 1815, and 1991 CE. Besides the well-documented effects of temperature derived from tree-ring width and latewood density, stable carbon and oxygen isotopes in tree-ring cellulose provide information about moisture and sunshine duration changes after the events.

This study evaluates the impact of enhanced seasonality characteristic of the Marine Isotope Stage 31 (MIS31) on the El Niño–Southern Oscillation (ENSO). Based upon coupled climate simulations driven by present-day (CTR) and MIS31 boundary conditions, we demonstrate that MIS31 does show a strong power spectrum at interannual timescales but the absence of decadal periodicity. The implementation of the MIS31 conditions results in a distinct global monsoon system and its link to the ENSO.

We present a 2700-year timescale and snow accumulation history for an ice core from Roosevelt Island, Ross Ice Shelf, Antarctica. We observe a long-term slightly decreasing trend in accumulation during most of the period but a rapid decline since the mid-1960s. The latter is linked to a recent strengthening of the Amundsen Sea Low and the expansion of regional sea ice. The year 1965 CE may thus mark the onset of significant increases in sea-ice extent in the eastern Ross Sea.

We present a reconstruction of winter climate around 4.2 ka cal BP in Europe, west Asia, and northern Africa that shows generally low temperatures and heterogeneously distributed precipitation. We hypothesize that in the extratropical Northern Hemisphere the 4.2 ka BP event was caused by the strengthening and expansion of the Siberian High, which effectively blocked the moisture-carrying westerlies from reaching west Asia and also resulted in outbreaks of northerly cold and dry winds.

Plant-based proxies for estimating atmospheric CO₂ in the geologic past are becoming more popular. Here we test the reliability of a method based on leaf gas-exchange principles in a wide range of living plants. Overall, the average error rate (~28 %) is broadly similar to other paleo-CO₂ proxies. Our results should increase confidence in using this recently developed method.

The cause of the rapid warming events documented in proxy records across the Northern Hemisphere during the last glacial has been a long-standing puzzle in paleo-climate research. Here, we use high-resolution ice-core data from to cores in Greenland to investigate the progression during the onset of these events on multi-annual timescales to test their plausible triggers. We show that atmospheric circulation changes preceded the warming in Greenland and the collapse of the sea ice by a decade.

To reveal sources of variability imprinted in central European drought records, regression and wavelet analysis were applied to 5 centuries of reconstructed data characterizing Czech climate. Mid- to long-term changes in temperature in the North Atlantic and North Pacific were identified as one of the potential sources of drought variations; transient colder and wetter episodes were linked to the effects of large volcanic eruptions.

A long-standing question in climate science is concerned with what processes contributed to the increase in atmospheric CO₂ after the last ice age. From the range of possible processes we try to constrain the change in carbon storage in the land biosphere. By combining ice core and marine sediment data in a modeling framework we show that the carbon storage in the land biosphere increased largely after the last ice age. This will help to further understand processes at work in the Earth system.