In this study, we train machine learning models on tree rings, speleothems, and instrumental rainfall to estimate seasonal monsoon rainfall over India over the last 500 years. Our models highlight multidecadal droughts in the mid-17th and 19th centuries, and we link these to historical famines. Using techniques from explainable AI (artificial intelligence), we show that our models use known relationships between local hydroclimate and the monsoon circulation.

To improve the simulation of surface mass balance (SMB) that influences the advance–retreat of ice sheets, we run a snow model, the BErgen Snow SImulator (BESSI), with transient climate forcing obtained from an Earth system model, iLOVECLIM, over Greenland and Antarctica during the Last Interglacial (LIG; 130–116 ka). Compared to the simple existing SMB scheme of iLOVECLIM, BESSI gives more details about SMB processes with higher physics constraints while maintaining a low computational cost.

In this study, we compute glacial–interglacial sea-level changes across the mid-Pliocene Warm Period (MPWP; 3.264–3.025 Ma) resulting from ice mass loss from different ice sheets. Our results quantify the relationship between changes in local sea level and global mean sea level (GMSL) and highlight the level of consistency in this mapping across different ice melt scenarios. These predictions can help guide site selection in efforts to constrain the sources and magnitude of MPWP GMSL change.

The upper and lower atmospheres interact. The polar regions, with high-speed, cyclonically rotating winds, provide a window through which upper winds affect surface weather and climate variability. By analysing climate model results, we found that ice sheets induced anomalous upward wave propagation and stretched the rotating winds towards North America, increasing the likelihood of cold-air outbreaks at the mid-latitudes. This accounts for the enhanced winter cooling at these latitudes.

Based on dinoflagellate cyst assemblages and sea surface temperature records west of offshore Tasmania, we find a northward migration and freshening of the subtropical front, not at the M2 glacial maximum but at its deglaciation phase. This oceanographic change aligns well with trends in pCO₂. We propose that iceberg discharge from the M2 deglaciation freshened the subtropical front, which together with the other oceanographic changes affected atmosphere–ocean CO₂ exchange in the Southern Ocean.

Late Eocene summers, 34 million years ago, were hot on Antarctica, with temperatures up to 30 °C. We also know that during this period the first Antarctic ice sheet formed. Since climate models do not show the transition from this warm climate to ice sheet formation accurately, we imposed regional ice sheets onto the continent in a realistic climate and show that these ice sheets do not melt away. This suggests that the initiation of ice sheet growth might have happened during warmer periods.

We introduce a new model that simulates Dansgaard–Oeschger events, dramatic and irregular climate shifts within past ice ages. The model consists of simplified equations inspired by ocean current dynamics. We fine-tune this model to capture the Dansgaard–Oeschger events with unprecedented accuracy, providing deeper insights into past climate patterns. This helps us understand and predict complex climate changes, aiding future climate change resilience efforts.

In general, it is not easy to examine unseasonable weather years that have affected human history using a single proxy. In this study, we propose a new method to quantitatively extract drought/long-rainfall events over the past 400 years by integrating tree-ring cellulose oxygen isotope ratios and historical documentary records. The results can be utilized to investigate the relationship between climate and long human history.

We constructed a geologic record of East Antarctic Ice Sheet thickness from deposits at Otway Massif to directly assess how Earth's largest ice sheet responds to warmer-than-present climate. Our record confirms the long-term dominance of a cold polar climate but lacks a clear ice sheet response to the mid-Pliocene Warm Period, a common analogue for the future. Instead, an absence of moraines from the late Miocene–early Pliocene suggests the ice sheet was less extensive than present at that time.

Large volcanic eruptions have caused temperature deviations over the past 1000 years; however, climate model results and reconstructions of surface cooling using tree rings do not match. We explore this mismatch using the latest models and find a better match to tree-ring reconstructions for some eruptions. Our results show that the way in which eruptions are simulated in models matters for the comparison to tree-rings, particularly regarding the spatial spread of volcanic aerosol.

We study the climate effects on mortality, using annual mortality records and meteorological data, in Sweden between 1749 and 1859. It is found that colder winter and spring temperatures increased mortality, while no statistically significant associations were observed between summer or autumn temperatures and mortality, and only weak associations existed with hydroclimate. Further research is needed about which specific diseases caused the mortality increase following cold winters and springs.

A coral reconstruction of past climate shows changes in the seasonal cycle of sea surface temperature in the south-eastern tropical Indian Ocean. An enhanced seasonal cycle suggests that the tropical rainfall belt shifted northwards between 1856–1918. We explain this with greater warming in the north-eastern Indian Ocean relative to the south-east, which strengthens surface winds and coastal upwelling in the eastern Indian Ocean, leading to greater cooling south of the Equator.

We used cGENIE, a climate model, to explore how changes in continental configuration, CO₂ levels, and orbital configuration affected ocean oxygen levels during the Devonian period (419–359 million years ago). Key factors contributing to ocean anoxia were identified, highlighting the influence of continental configurations, atmospheric conditions, and orbital changes. Our findings offer new insights into the causes and prolonged durations of Devonian ocean anoxic events.

Reconstructions of past glaciations tell us about how ice sheets grow and retreat. In this study, we use speleothems (cave deposits, e.g. stalagmites) in the British Isles to help constrain the extent of past glaciations in both time and space. Speleothems require liquid water to grow, and therefore their presence indicates the absence of ice above the cave. By dating these speleothems, we can improve existing reconstructions of past ice sheets.

We reconstruct sea surface temperatures (SSTs) of the past 43 kyr in the Gulf of Oman. We find SST variations of up to 7 °C with lower SSTs during Heinrich events (HEs), especially HE4, and higher SSTs during Dansgaard–Oeschger events. Our record shows no profound cooling during the Last Glacial Maximum but abrupt variations during the Holocene. We surmise that SST variations are influenced by the southwest (northeast) monsoon during warmer (colder) periods.

Using a multiproxy approach, we analyzed biomarkers and diatom assemblages from a marine sediment core from the Powell Basin, Weddell Sea. The results reveal the first continuous coastal Antarctic sea ice record since the Last Penultimate Glacial. Our findings contribute valuable insights into past glacial–interglacial sea ice responses to a changing climate and enhance our understanding of ocean–sea ice–ice shelf interactions and dynamics.