We used palaeoecological records from peatlands in southern Siberia. We showed that warmer climate conditions have lowered the water level and increased the fuel amount and flammability, consequently also increasing the frequency and severity of fires as well as the composition of tree types.

In layer counted proxy records each measurement is accompanied by a timestamp typically measured by counting periodic layers. Knowledge of the uncertainty of this timestamp is important for a rigorous propagation to further analyses. By assuming a Bayesian regression model to the layer increments we express the dating uncertainty by the posterior distribution, from which chronologies can be sampled efficiently. We apply our framework to dating abrupt warming transitions during the last glacial.

Previous studies of Paleogene greenhouse climates identified short-lived global warming events, termed hyperthermals, that provide insights into global warming scenarios. Within the same time period, we have identified a short-lived cooling event in the late Paleocene, which we term a hypothermal, that has potential to provide novel insights into the feedback mechanisms at work in a greenhouse climate.

The geochemistry preserved in polar ice can provide detailed histories of Earth’s climate over millennia. Here we use the stable isotope ratios of ice from many Antarctic ice cores to reconstruct temperature variability of Antarctica and the midlatitude Southern Hemisphere over tens of thousands of years. We improve upon existing methods to estimate temperature from the geochemical measurements and investigate the patterns of climate change in the past.

Terrestrial materials in marine environments record source information and help us understand how climate and ocean impact sediment compositions. Here, we use evidence on the Ninetyeast Ridge to analyze the relationship between terrestrial material supplementation and climatic change. We find that the ITCZ controlled the rainfall in the Burman source area and that closer connections occurred between the Northern–Southern Hemisphere in the eastern Indian Ocean during the late LGM.

The mid-Pliocene (MP; ∼3.0 Ma) had CO₂ levels similar to today and average temperatures ∼3°C warmer. At terrestrial high latitudes, MP temperatures from climate models are much lower than those reconstructed from data. This mismatch occurs in the winter but not the summer. The winter model–data mismatch likely has multiple causes. One novel cause is that the MP climate may be outside the modern sample, and errors could occur when using information from the modern era to reconstruct climate.

This comprehensive inventory of quantitative documentary evidence related to climate extending back to 1400 CE promotes the first ever global perspective on documentary climate records. It lays the foundation for incorporating documentary evidence from archives of societies into global-scale climate reconstructions, complementing (early) instrumental measurements and natural climate proxies. Documentary records are particularly relevant in seasons and regions poorly covered by natural proxies.

Termination V (TV, ~ 404–433 kyr BP) marks a transition in the climate system towards amplified glacial–interglacial cycles. While the associated atmospheric CO₂ changes are mostly attributed to the Southern Ocean, little is known about the terrestrial biosphere contribution to the carbon cycle. This study provides the first (model- and pollen-based) reconstruction of global forests highlighting the potential role of temperate and boreal forests in atmospheric CO₂ sequestration during TV.

Salinity is an important and integrative measure of changes to the water cycle steered by changes to the balance between rainfall and evaporation and by vertical and horizontal movements of water parcels by ocean currents. However, salinity measurements in our oceans are extremely sparse. To fill this gap, we have developed a 334-year coral record of seawater oxygen isotopes that reflects salinity changes in the globally important Agulhas Current system and reveals its main oceanic drivers.

We assess the climatic and societal impact of the 852/3 CE Alaska Mount Churchill eruption using environmental reconstructions, historical records and climate simulations. The eruption is associated with significant Northern Hemisphere summer cooling, despite having only a moderate sulfate-based climate forcing potential; however, evidence of a widespread societal response is lacking. We discuss the difficulties of confirming volcanic impacts of a single eruption even when it is precisely dated.

The Southern Annular Mode (SAM) is a major mode of climate variability. Proxy-based SAM reconstructions show changes that last millennium climate simulations do not reproduce. We test the SAM's sensitivity to solar forcing using simulations with a range of solar values and transient last millennium simulations with large-amplitude solar variations. We find that solar forcing can alter the SAM and that strong solar forcing transient simulations better match proxy-based reconstructions.