This article finds that grain farming in historical Scania (ca. 1700–1900) was adapted to wet and cold summers, while being resilient to frost and climate variability in the spring and autumn. These relationships started to change in the late 19th century with the introduction of new grain varieties, particularly autumn grain varieties. Nonetheless, historical farmers faced a threat in common with contemporary farmers, namely summer droughts, like the summer drought of 2018.

In this study, we applied geochemical tools to well-preserved ∼180-million-year-old marine mollusc shells from polar and mid-latitude seas. These results indicate that polar shells grew at temperatures of 8–18°C, while mid-latitude shells grew at temperatures of 24–28°C. These results, together with previously published data, raise concerns about the ability of climate models to predict accurate polar temperatures under reasonably high atmospheric CO₂ levels.

We test a new method to reconstruct past atmospheric CO₂ levels based on the geochemistry of pelagic algal biominerals (coccoliths), which recent culture and numerical experiments have related to ambient CO₂ concentrations. By comparing the isotopic composition of fossil coccoliths to the inferred surface ocean CO₂ level at the time they calcified, we outline a transfer function and argue that coccolith vital effects can be used to reconstruct geological pCO₂ beyond the ice core record.

We provide new winter sea ice and summer sea surface temperature estimates for marine core TAN1302-96 (59° S, 157° E) in the Southern Ocean. We find that sea ice was not consolidated over the core site until ~65 ka and therefore believe that sea ice may not have been a major contributor to early glacial CO₂ drawdown. Sea ice does appear to have coincided with Antarctic Intermediate Water production and subduction, suggesting it may have influenced intermediate ocean circulation changes.

We employ acidity records from Greenland and Antarctic ice cores to estimate the emission strength, frequency and climatic forcing for large volcanic eruptions from the last half of the last glacial period. A total of 25 volcanic eruptions are found to be larger than any eruption in the last 2500 years, and we identify more eruptions than obtained from geological evidence. Towards the end of the glacial period, there is a notable increase in volcanic activity observed for Greenland.

We investigate the effects of a warmer climate from the Earth's paleoclimate (last interglacial) on the marine carbon cycle of the Southern Ocean using a carbon-cycle-enabled state-of-the-art climate model. We find a 150 % increase in CO₂ outgassing during this period, which results from competition between higher sea surface temperatures and weaker oceanic circulation. From this we unequivocally infer that the carbon uptake by the Southern Ocean will reduce under a future warming scenario.

Late Eocene to earliest Oligocene (37.97–33.06 Ma) climate and vegetation dynamics around the Tasmanian Gateway region reveal that changes in ocean circulation due to accelerated deepening of the Tasmanian Gateway may not have been solely responsible for the changes in terrestrial climate and vegetation; a series of regional and global events, including a change in stratification of water masses and changes in pCO₂, may have played significant roles.

Over the last 2.6 Myr, the Quaternary period has been marked by the alternation of extended and reduced Northern Hemisphere ice sheets, known as glacial-interglacial cycles. With a simple model, we are able to reproduce the main features of the ice volume evolution, like the switch of periodicity, from 41 kyr cycles to 100 kyr cycles, observed in the data after 1 Ma. The quality of the model-data agreement depending on the input insolation and period considered is discussed.

Earth experiences regular ice ages resulting in shifts between cooler and warmer climates. Around 1 million years ago, the ice age cycles grew longer and stronger. We used bacterial and plant lipids preserved in an Arctic lake to reconstruct temperature and vegetation during this climate transition. We find that Arctic land temperatures did not cool much compared to ocean records from this period, and that vegetation shifts correspond with a long-term drying previously reported in the region.

This paper synthesizes 66 records of glacier variations over the Holocene from lake archives across seven Arctic regions. We find that summers only moderately warmer than today drove major environmental change across the Arctic in the early Holocene, including the widespread loss of glaciers. In comparison, future projections of Arctic temperature change far exceed estimated early Holocene values in most locations, portending the eventual loss of most of the Arctic's small glaciers.

The Last Interglacial (129–116 ka) is characterised by an increased summer insolation over the Arctic region, which leads to a strong temperature rise. The aim of this study is to identify and quantify the main processes and feedback causing this Arctic warming. Using the IPSL-CM6A-LR model, we investigate changes in the energy budget relative to the pre-industrial period. We highlight the crucial role of Arctic sea ice cover, ocean and clouds on the Last Interglacial Arctic warming.

Carbon monoxide (CO) is a regulated pollutant and one of the key components determining the oxidizing capacity of the atmosphere. In this study, we analyzed five ice cores from Greenland at high resolution for CO concentrations by coupling laser spectrometry with continuous melting. By combining these new datasets, we produced an upper-bound estimate of past atmospheric CO abundance since preindustrial times for the Northern Hemisphere high latitudes, covering the period from 1700 to 1957 CE.

We report the discovery, examination and interpretation of a unique type of data source, i.e., the 19th century monthly water level observation of a reservoir named Lake Machang on the Grand Canal in China. The water level changes of the reservoir on monthly and annual scales were compared with relevant precipitation and hydrology chronologies. The relationship of the evolution of the reservoir with the flooding of the Yellow River and reclamation is discussed.