Perturbations in atmospheric CO₂ and in its isotopic composition, e.g., in response to carbon release from the land biosphere or from fossil fuel burning, evolve differently in time. We use an Earth system model of intermediate complexity to show that fluxes to and from the solid Earth play an important role in removing these perturbations from the atmosphere over thousands of years.

This study explores potential sources of bias on borehole-based temperature reconstruction from both methodological and physical factors using pseudo-proxy experiments that consider ensembles of simulations from the Community Earth System Model. The results indicate that both methodological and physical factors may have an impact on the estimation of the recent temperature trends at different spatial scales. Internal variability arises also as an important issue influencing pseudo-proxy results.

We reconstruct a detailed history of the East Asian summer monsoon (EASM) using stalagmite records in central China during the last millennium. We estimate responses of the EASM to anthropogenic global warming by comparing its relative intensity between the Current Warm Period and Medieval Climate Anomaly, two recent warm periods. We also study potential links of the EASM to the tropical Pacific and North Atlantic oceans. This work advances our understanding of EASM dynamics.

Paleoceanographic changes in Storfjorden during the Neoglacial (the last 4000 years) were reconstructed based on microfossil and ancient DNA records. Environmental changes were steered mainly by the interaction between the inflow of Atlantic Water (AW) and sea ice cover. Warming periods were associated with AW inflow and sea ice melting, stimulating primary production. The cold phases were characterized by densely packed sea ice, resulting in limited productivity.

We quantify how the greenhouse gas records of East Antarctic ice cores (which are the oldest ice cores) might differ from the actual atmosphere history. It is required to properly interpret ice core data. For this, we measured the methane of five new East Antarctic ice core sections using a high-resolution technique. We found that in these very old ice cores, one can retrieve concentration variations occurring in only a few centuries, allowing climatologists to study climate's fast dynamics.

The mid-Pliocene warm period (mPWP; 3.3–3.0 million years ago) is thought to be the last geological interval with similar atmospheric carbon dioxide concentrations as the present day. Further, the mPWP was 2–3 °C warmer than present, making it a good analogue for estimating the effects of future climate change. Here, we construct a new precise age model for the North Sea during the mPWP, and provide a detailed reconstruction of terrestrial and marine climate using a multi-proxy approach.

The Qinling mountains in China are biodiversity rich. We studied one of the high-latitude lakes on Mount Taibai with a view to looking at how aquatic diversity responded to long-term changes in climate over the past 3500 years. We specifically looked at a group of single-celled algae called diatoms, as they are very sensitive to the environment. We found that these algae changed gradually over time, but they showed abrupt change during the period known as the Little Ice Age, about 400 years ago.

Global cooling and a major expansion of ice over Antarctica occurred ~ 34 million years ago at the Eocene–Oligocene transition (EOT). A large secondary proxy dataset for high-latitude Southern Hemisphere temperature before, after and across the EOT is compiled and compared to simulations from two coupled climate models. Although there are inconsistencies between the models and data, the comparison shows amongst other things that changes in the Drake Passage were unlikely the cause of the EOT.

We investigate the changes in natural methane emissions between the Last Glacial Maximum and preindustrial periods with a methane-enabled version of MPI-ESM. We consider all natural sources of methane except for emissions from wild animals and geological sources. Changes are dominated by changes in tropical wetland emissions, high-latitude wetlands play a secondary role, and all other natural sources are of minor importance. We explain the changes in ice core methane by methane emissions only.

Tridacna, as the largest marine bivalves, can be used for high-resolution paleoclimate reconstruction in its carbonate skeleton. In this contribution, the modern δ¹⁸O shell is suggested to be a proxy for sea surface temperature in the Xisha Islands, South China Sea. Data from a fossil Tridacna (3673 ± 28 BP) indicate a warmer climate and intense ENSO-related variability but reduced ENSO frequency and more extreme El Niño winters compared to modern Tridacna.

The statistics and characteristics of cyclones over the North Atlantic and Europe are analysed for Last Glacial Maximum (LGM) climate conditions. LGM extreme cyclones were more frequent and characterised by less precipitation and stronger wind speeds than pre-industrial analogues. These results agree with the view of a colder and drier Europe during LGM, with little vegetation and affected by frequent dust storms, leading to the buildup of thick loess deposits in Europe.

The paper presents the main features of droughts in Poland in the period 996–2015 based on proxy data (documentary and dendrochronological) and instrumental measurements of precipitation. More than 100 droughts were found in documentary sources from the mid-15th century to the end of the 18th century with a maximum in the second halves of the 17th and, particularly, the 18th century. The long-term frequency of droughts in Poland has been stable for the last two or three centuries.

This paper aims to reconstruct high-resolution daily precipitation and temperature fields for Switzerland back to 1864 using a statistical approach called the analogue resampling method. Results suggest that the presented method is suitable for weather reconstruction. As illustrated with the example of the avalanche in winter 1887/88, these weather reconstructions have great potential for various analyses of past weather and climate impact modelling.

Here we describe the unique nature of droughts over semi-arid central Namibia (southern Africa) between 1850 and 1920. We establish temporal shifts in the influence and impact that historical droughts had on society and the environment during this period. The paper demonstrates and argues that human experience and the associated reporting of drought events depend strongly on social, environmental, spatial, and societal developmental situations and perspectives.

We present geographically explicit reconstructions of seasonal temperature and annual moisture variables at the Last Glacial Maximum (LGM), 21 000 years ago. The reconstructions use existing site-based estimates of climate, interpolated in space and time in a physically consistent way using climate model simulations. The reconstructions give a much better picture of the LGM climate and will provide a robust evaluation of how well state-of-the-art climate models simulate large climate changes.

New investigations of European loess records from MIS 6 reveal the occurrence of paleosols and horizon showing slight pedogenesis similar to those from the last climatic cycle. These units are correlated with interstadials described in various marine, continental, and ice Northern Hemisphere records. Therefore, these MIS 6 interstadials can confidently be interpreted as DO-like events of the penultimate climate cycle.

The PAGES2k multiproxy database offers a new and unique opportunity to study the lack of long-term cooling trends in tree-ring data, which can be expected in Northern Hemisphere summers, particularly in the high latitudes, due to orbitally driven changes in solar irradiance. Tests of different influencing factors reveal that preserving millennial-scale cooling trends related to orbital forcing is not feasible in most tree-ring datasets.

The El Niño–Southern Oscillation (ENSO) and Southern Annular Mode (SAM) are two important modes of climate variability, strongly influencing climate across the tropics and Southern Hemisphere mid- to high latitudes. This study sheds light on their relationship over the past millennium, combining evidence from palaeoclimate proxy archives and climate models. We show that their indices were mostly negatively correlated with fluctuations likely driven by internal variability in the climate system.

Comparison of Cretaceous OAE1a and OAE2 in two drill cores with unusually high sedimentation rates shows that long-lasting negative δ¹³C excursions precede the positive δ¹³C excursions and that the evolution of the marine δ¹³C positive excursions is similar during both OAEs, although the durations of individual phases differ substantially. Phosphorus speciation data across OAE2 and the Mid-Cenomanian Event suggest a positive feedback loop, enhancing marine productivity during OAEs.

This study provides the opportunity to extend climatic records to preindustrial periods in northern Pakistan. The reconstructed March–August PDSIs for the past 424 years, going back to 1593 CE, enable scientists to know how these areas were prone to climatic extremes in the past. The instrumental data are limited in Pakistan; however, the Cedrus deodara tree that preserves physical characteristics of past climatic variabilities can provide insight into the trend of climatic changes.

Long-term climate change impacts on fire, vegetation and permafrost in the Arctic are uncertain. Here, we show the high potential of organic compounds from low-temperature biomass burning to serve as proxies for surface fires in lake deposits. During warm periods of the last 430 000 years, surface fires are closely linked to the larch taiga forest with its moss–lichen ground vegetation that isolates the permafrost. They have reduced in warm–wet, spruce–dominated and cool–dry steppe environments.