Fossil plankton assemblages have been widely used to reconstruct SST. In such approaches, full taxonomic resolution is often used. We assess whether this is required for reliable reconstructions as some species may not respond to SST. We find that only a few species are needed for low reconstruction errors but that species selection has a pronounced effect on reconstructions. We suggest that the sensitivity of a reconstruction to species pruning can be used as a measure of its robustness.

This study investigates the linear relationship between the water isotopes of three East Greenland ice cores and regional temperatures. By comparing the water isotopes with nearby instrumental temperature records and reanalysis data, this study demonstrates that it can be problematic to reconstruct temperatures through regression of water isotope data from coastal ice cores. We further show that the varying linear relationship could be connected with changes in sea ice near the drill site.

Atmospheric CO₂ was likely an important amplifier of global-scale orbitally-driven warming during the last deglaciation. However, the mechanisms responsible for the rise in CO₂, and the coherent rise in Antarctic isotopic temperature records, are under debate. Using a stochastic method, we detect variable lags between coherent changes in Antarctic temperature and CO₂. This implies that the climate mechanisms linking the two records changed or experienced modulations during the deglaciation.

We present a new high-resolution sea surface temperature (SST) reconstruction for the Holocene (last 11 700 years) in the westernmost Mediterranean Sea. We identify three sub-periods: the Early Holocene with warmest SST; the Middle Holocene with a cooling trend ending at 4200 years, which is identified as a double peak cooling event that marks the transition between the Middle and Late Holocene; and the Late Holocene with very different behaviour in both long- and short-term SST variability.

Fossil microorganisms from the last glacial found in marine sediments collected off southern Brazil suggest that more productive austral summer upwelling and more frequent austral winter incursions of nutrient-rich waters from the Plata River boosted regional productivity year-round. While upwelling was more productive due to the higher silicon content from the Southern Ocean, more frequent riverine incursions were modulated by stronger alongshore southwesterly winds.

The last glacial period was marked by the existence of of abrupt climatic changes; it is generally accepted that the presence of ice sheets played an important role in their occurrence. While an important effort has been made to investigate the dynamics and evolution of the Laurentide ice sheet during this period, the Eurasian ice sheet (EIS) has not received much attention. Here we investigate the response of the EIS to millennial-scale climate variability using a hybrid 3-D ice-sheet model.

Proxy records of glacial oxygen change provide constraints on the contribution of the biological pump to glacial CO₂ decrease. Here, we report our numerical simulation which successfully reproduces records of glacial oxygen changes and shows the significance of iron supply from glaciogenic dust. Our model simulations clarify that the enhanced efficiency of the biological pump is responsible for glacial CO₂ decline of more than 30 ppm and approximately half of deep-ocean deoxygenation.

This study discusses a simulation of the last 6000 years realized with a climate model in which the vegetation and carbon cycle are fully interactive. The long-term southward shift in Northern Hemisphere tree line and Afro-Asian monsoon rain are reproduced. The results show substantial change in tree composition with time over Eurasia and the role of trace gases in the recent past. They highlight the limitations due to model setup and multiple preindustrial vegetation states.

This is the first quantitative study of lignin biomarkers in stalagmites and cave drip water. Lignin is only produced by higher plants; therefore, its analysis can be used to reconstruct the vegetation of the past. We compared our lignin results with stable isotope and trace element records from the same samples and found correlations or similarities with P, Ba, U and Mg concentrations as well as δ¹³C values. These results can help to better interpret other vegetation proxies.

We simulate the Last Glacial Maximum atmospheric CO₂ decrease with a large ensemble of parameter sets to investigate the range of possible physical and biogeochemical Earth system changes accompanying the CO₂ decrease. Amongst the dominant ensemble changes is an increase in terrestrial carbon, which we attribute to a slower soil respiration rate, and the preservation of carbon by the LGM ice sheets. Further investigation into the role of terrestrial carbon is warranted.

The last time atmospheric CO₂ was similar to the present was 3–4 million years ago. The Arctic was warmer compared to the global average, and the causes are not fully known. To investigate this, we reconstructed summer temperature, forest fire and vegetation at a 3.9 Ma fen peat in Arctic Canada. The summer temperatures averaged 15.4 °C, and charcoal was abundant. Interactions between vegetation and climate were mediated by fire and may contribute to high Arctic temperatures during the Pliocene.

Multiproxy study of marine sediments off the Limpopo River mouth spanning the Late Pleistocene reveals the impact of atmospheric carbon dioxide on the development of the vegetation of southeast Africa and indicates changes in the interglacial vegetation before and after the Mid-Brunhes Event (430 ka).

A database of North American long-term ground surface temperatures, from approximately 1300 CE to 1700 CE, was assembled from geothermal data. These temperatures are useful for studying the future stability of permafrost, as well as for evaluating simulations of preindustrial climate that may help to improve estimates of climate models’ equilibrium climate sensitivity. The database will be made available to the climate science community.

We found that the tree-ring earlywood width (EWW) of Pinus tabuliformis from the eastern Qinling Mountains (central China) showed stronger response to May–July scPDSI than the tree-ring total width and latewood width. Therefore, variations in May–July scPDSI were reconstructed back to 1868 CE using the EWW chronology. The reconstruction exhibited a strong in-phase relationship with the East Asian summer monsoon intensity before the 1940s, which was different from that found in recent decades.

We present an equilibrium simulation of the climate of Marine Isotope Stage 3, with an IPCC-class model with a relatively high model resolution and a long integration. The simulated climate resembles a warm interstadial state, as indicated by reconstructions of Greenland temperature, sea ice extent, and AMOC. Sensitivity experiments to changes in atmospheric CO₂ levels and ice sheet size show that the model is in a relatively stable climate state without multiple equilibria.

Here we reconstruct vegetation and precipitation, in eastern South Africa, over the last 32 000 years, by measuring the stable carbon and hydrogen isotope composition of plant waxes from Mfabeni peat bog (KwaZulu-Natal). Our results indicate that the late Quaternary climate in eastern South Africa did not respond directly to orbital forcing or to changes in sea-surface temperatures. Our findings stress the influence of the Southern Hemisphere westerlies in driving climate change in the region.

By studying microfossils from sediments in Upernavik Fjord we investigate the role of ocean warming on the retreat of Upernavik Isstrøm during the past ~90 years. The reconstruction of Atlantic-derived waters shows a pattern similar to that of the Atlantic Multidecadal Oscillation, corroborating previous studies. The response of Upernavik Isstrøm to ocean forcing has been variable in the past, but the current retreat may be temporarily tempered by cooling bottom waters in the coming decade.