To understand the warm climate during the late Pliocene (~3.205 Ma), modeling experiments with the new boundary conditions are launched and analyzed based on the Institut Pierre Simon Laplace (IPSL) atmosphere–ocean coupled general circulation model (AOGCM). Our results show that the warming in mid- to high latitudes enhanced due to the modifications of the land–sea mask and land–ice configuration. The pCO2 uncertainties within the records can produce asymmetrical warming patterns.

The oxygen isotopic ratio of water in fluid inclusions in speleothems is an important proxy for the changes in past hydroclimate and temperatures. This isotopic ratio, however, may be affected by isotopic exchange between the water and the host calcite. Here we evaluate this exchange reaction based on a laboratory experiment. We demonstrated that the exchange was detectable but not significant for temperature reconstruction, likely because the reaction occurred only with a thin calcite layer.

Abrupt climate change during the last ice age can be used to provide important insights into the timescales on which the climate is capable of changing and the mechanisms that drive those changes. In this study, we construct climate records for the period 60 to 120 ka using stalagmites that formed in caves along the northern rim of the European Alps and find good agreement with the timing of climate changes in Greenland and the Asian monsoon.

Using available information from historical documents, the maximum storm surge and storm tide at Hong Kong during the passage of a typhoon in 1874 were determined by reconstructing the possible typhoon track and found to be higher than all existing records since the 1883 establishment of the Hong Kong Observatory. This reveals that a more detailed frequency analysis of extreme sea levels taking the 1874 typhoon into account is essential for realistic storm surge risk assessments in Hong Kong.

Past climate conditions are reconstructed using indirect and incomplete geological, biological, and geochemical proxy data. We propose that such reconstructions are best obtained by statistical inversion of hierarchical models that represent how multi–proxy observations and calibration data are produced by variation of environmental conditions in time and/or space. These methods extract new information from traditional proxies and provide robust, comprehensive estimates of uncertainty.

The South Pacific Subtropical High (SPSH) is a main feature of the South American (SA) climate. We analyzed its behavior during two extreme temperature events based on paleoclimate records and climate models. The SPSH expands (contracts) in warm (cold) periods. The changes affect other elements of the SA climate like the strength of the southerly winds and the position of the westerly wind belt. Projections indicate that this expansion and its consequences will continue during the 21st century.

Using reconstructed extreme drought/flood chronologies and grain harvest series derived from historical documents, it is found that the frequency of reporting of extreme droughts in any subregion of eastern China was significantly associated with lower reconstructed harvests during 801–1910. The association was weak during the warm epoch of 920–1300 but strong during the cold epoch of 1310–1880, which indicates that a warm climate might weaken the impact of extreme drought on poor harvests.

We analyse the end of the African humid period (AHP) in a transient Holocene simulation performed with the comprehensive Earth system model MPI-ESM1.2. The model reproduces the time-transgressive end of the AHP evident in proxy data and indicates that changes in moisture can be attributed to the retreat of the summer monsoon and to changes in the extratropical troughs. The spatially varying impact of these systems imposes regionally different responses to the Holocene insolation change.

We measured the chemical composition (trace-element concentrations and stable-isotope ratios) of a Belgian speleothem that deposited annual layers. Our sub-annual resolution dataset allows us to investigate how the chemistry of this speleothem recorded changes in the environment and climate in northwestern Europe. We then use this information to reconstruct climate change during the 16th and 17th century on the seasonal scale and demonstrate that environmental change drives speleothem chemistry.

All major mountain ranges were uplifted during Earth's history. Previous work showed that African uplift might have influenced upper-ocean cooling in the Benguela region. But the surface ocean cooled also in other upwelling regions during the last 10 million years. We performed a set of model experiments altering topography in major mountain regions to explore the effects on atmosphere and ocean. The simulations show that mountain uplift is important for upper-ocean temperature evolution.

Here we report the PlioMIP2 simulations by two versions of the Norwegian Earth System Model (NorESM) with updated boundary conditions derived from Pliocene Research, Interpretation and Synoptic Mapping version 4. The two NorESM versions both produce warmer and wetter Pliocene climate with deeper and stronger Atlantic meridional overturning circulation. Compared to PlioMIP1, PlioMIP2 simulates lower Pliocene warming with NorESM-L, likely due to the closure of seaways at northern high latitudes.

The paper shows, using climate simulations, that the Pacific–North American (PNA) teleconnection was distorted or completely broken at the Last Glacial Maximum (LGM). The results suggest that ENSO would have little direct impact on North American climates at the LGM.

Few studies have paid attention to the important effect of nonsummer monsoon (NSM) precipitation on the speleothem δ¹⁸O in SE China. We find the summer monsoon precipitation is equivalent to NSM precipitation amount in the area of spring persistent rain in SE China, and we discuss the relationships between seasonal precipitation amount, moisture source, δ¹⁸O, and ENSO. Characterizing the spatial differences in seasonal precipitation is key to interpreting the speleothem δ¹⁸O record.

A geochemical study of a continental section reveals a rapid global warming event (hyperthermal U), occurring ca. 50 Myr ago, only described until now in marine sediment cores. Documenting how the Earth system responded to rapid climatic shifts provides fundamental information to constrain climatic models. Our results suggest that continental deposits can be high-resolution recorders of these warmings. They also give an insight on the climatic conditions occurring during at the time.

In this paper we identify warming thresholds, rates, and forcing mechanisms from a novel alpine temperature record of the southern Iberian Peninsula during the Common Era in order to contextualize the modern warming and its potential impact on these vulnerable alpine ecosystems. To do so, we have developed and applied the first lacustrine temperature calibration in alpine lakes for algal compounds, called long-chain alkyl diols, which is a significant advance in biomarker paleothermometry.

Here, mid-ocean seasonality is resolved through time, using differences in the oxygen isotope composition between individual shells of the commonly used (sub)polar planktonic foraminifera species in ocean-climate reconstruction, N. pachyderma and G. bulloides. Single-specimen isotope measurements during the deglacial period revealed a surprising bimodality, the cause of which was investigated.

High-resolution multiproxy analysis of sediment core from a high-elevation lake on Corsica allows us to reconstruct past African dust inputs to the western Mediterranean area over the last 3 millennia. Millennial variations of Saharan dust input have been correlated with the long-term southward migration of the Intertropical Convergence Zone, while short-term variations were associated with the North Atlantic Oscillation and total solar irradiance after and before 1070 cal BP, respectively.

In this paper, we present new climate reconstructions in SW Alaska from recovered marine sediments in the Gulf of Alaska. We find that glaciers reached the Gulf of Alaska during a cooling climate 2.9 million years ago, and after that the Cordilleran Ice Sheet continued growing during a global drop in atmospheric CO₂ levels. Cordilleran Ice Sheet growth could have been supported by an increase in heat supply to the SW Alaska and warm ocean evaporation–mountain precipitation mechanisms.

The East Asian summer monsoon and winter monsoon are anticorrelated on a centennial timescale during 16–1 ka. The centennial monsoon variability is connected to changes of both solar activity and North Atlantic cooling events during the Early Holocene. Then, North Atlantic cooling became the major forcing of events during the Late Holocene. This work presents the great challenge and potential to understand the response of the monsoon system to global climate changes in the past and the future.

Usefully combining models and data to learn about past climates relies in part on translating observed paleoclimate quantities into the discrete time and space of climate models. This work addresses errors that can arise in translation when time offsets, smoothing, or averaging is different in data and models. These errors depend on sampling timescales, which are important to report in proxy metadata, and can be large relative to the climate signals of interest.

One can use the similarity between sparse indirect observations of past climates and full fields of simulated climates to learn more about past climates. Here, we detail how one can compute uncertainty estimates for such reconstructions of past climates. This highlights the ambiguity of the reconstruction. We further show that such a reconstruction for European summer temperature agrees well with a more common approach.

Northeastern Siberia is currently known for its harsh cold climate, but remarkably it did not experience large-scale glaciation during the last ice age. We show that the region is also exceptional in climate models. As a result of subtle changes in model setup, climate models show a strong divergence in simulated glacial summer temperatures that is ultimately driven by changes in the circumpolar atmospheric stationary wave pattern and associated northward heat transport to northeastern Siberia.

Large-scale reorganization of global ocean circulation has been documented in a variety of marine archives, including the enhanced North Pacific Intermediate Water NPIW. Our data support both the model- and data-based ideas that the enhanced NPIW mainly developed during cold spells, while an expansion of oxygen-poor zones occurred at warming intervals (Bölling-Alleröd).

The radiocarbon (¹⁴C) levels of a stalagmite (grown 27–11 kyr before today) from Socotra Island (Arabian Sea) show drastic changes across the last termination. Our study highlights the influence of a warming climate with increasing precipitation towards the ending glacial on stalagmite ¹⁴C. High-resolution measurements suggest ¹⁴C is linked to a denser vegetation coverage on the island. Therefore, stalagmite ¹⁴C can be used as a climate tracer on millennial to sub-centennial timescales.