Recent  

In this study, we use climate modeling to investigate the relative impact of CO₂ and orbit on Early Eocene (~55 million years ago) climate, as well as compare our modeled results to fossil records to determine the context for the Paleocene-Eocene Thermal Maximum, the most extreme hyperthermal in the Cenozoic. Our conclusions consider limitations and illustrate the importance of climate models when interpreting paleoclimate records in times of extreme warmth.

The Mt. Samalas eruption had global-scale impacts on climate and has been linked to historical events throughout later half of the 13th Century. Using model simulations and proxy data we constrain the year and season of the eruption to Summer 1257 and investigate the regional-scale variability in surface cooling following the eruption. We also re-evaluate evidence from ice core records, including their limitations when applied to historical eruptions such as Mt. Samalas.

A new federative chronology for five deep polar ice cores retrieves 800 000 years of past climate variations with an improved accuracy. Precise ice core timescales are key to study the mechanisms linking changes in the Earth’s orbit to the diverse climatic responses (temperature and atmospheric greenhouse gas concentrations). To consruct the chronology, new measurements from the oldest continuous ice core as well as glaciological modeling estimates were combined in a statistical model.

Water isotopes correlate with the salt content of the sea. In this study we reconstruct the water isotope signal of the sea surface during the last deglaciation by analyzing the hydrogen isotopes of alkenones, an organic compound preserved in sediment. We compare it to oxygen isotopes analyzed on calcite shells produced in the bottom water. Our results suggest that the surface water experienced more freshening during the last 20.000 years then the bottom waters.

We present an ice-free season temperature based on brGDGTs over the last 15 ka on the eastern TP. The result shows that Holocene Thermal Maximum occurred during 8–3.5 ka, which lags behind pollen-based July temperature recorded in same sediment core, indicating a significant seasonal bias between different proxies. We also investigated previously published brGDGTs-based temperatures on TP to determine the pattern of Holocene temperature changes and possible reasons for the diverse records.

This work introduces the possibility and consequences of monsoons on Antarctica in the warm Eocene climate. We suggest that such a monsoonal climate can be important to understand conditions on Antarctica prior to large-scale glaciation. We can explain seemingly contradictory indications of ice and vegetation on the continent through regional variability. In addition, we provide a new mechanism through which most of Antarctica remained ice-free through a wide range of global climatic changes.

The Middle Eocene Climatic Optimum (MECO) is an enigmatic global warming event with scarce terrestrial records. To contribute to this issue, this study documents a new comprehensive geochemical record of the MECO in the fluvial Escanilla Formation, Spain. Results demonstrate continental sedimentary successions as key archives of past climate and stable isotopes as a powerful tool to correlate difficult to date fluvial successions.

The ability of climate models to faithfully reproduce past warming episodes is a valuable test considering potentially large future warming. We develop a new method to compare simulations of the last deglaciation with temperature reconstructions. We find that reconstructions differ more between regions than simulations, potentially due to deficiencies in the simulation design, models, or reconstructions. Our work is a promising step towards benchmarking simulations of past climate transitions.

The Oligocene and Early Miocene periods featured dynamic glacial cycles on Antarctica. In this paper, we use Sr isotopes in marine carbonate sediments to document a change in the location and intensity of continental weathering during short periods of very intense Antartic glaciation. Potentially, the weathering intensity of old continental rocks on Antarctica was reduced during glaciation. We also show improved age models for correlation of Southern ocean and North Atlantic sediments.

Wind and wave metrics were derived from historical naval logs of multiple ships dispersed by a powerful hurricane off Nova Scotia in 1757. Midlatitude Little Ice Age (LIA) storms appeared to be more intense than today, and reconstructed wind field and coastal surge show it was a major hurricane and more powerful than any since modern records began in 1851. Understanding the climatology of such intense LIA midlatitude storms is warranted given hurricane projections under future ocean warming.

Are phenomenological dynamical paleoclimate models physically similar to Nature? We demonstrated that though they may be very accurate in reproducing empirical time series this is not sufficient to claim physical similarity with Nature until similarity parameters are considered. We suggest that the diagnostics of physical similarity should become a standard procedure before a phenomenological model can be utilized for interpretations of historical records or for future predictions.

To quantify the sensitivity of the earth system to orbital-scale forcings we conducted an unprecedented quasi-continuous coupled general climate model simulation with the Community Earth System Model, which covers the climatic history of the past 3 million years ago. This study could stimulate future transient paleo-climate model simulations and perspectives to further highlight and document the effect of anthropogenic CO₂ emissions in the broader paleo-climatic context.

We present the first attempt to constrain the climatic impact of volcanic eruptions with return periods of hundreds of years by the oxygen isotope records of Greenland and Antarctic ice cores covering the last glacial period. A clear multi-annual volcanic cooling signal is seen, but its absolute magnitude is subject to the unknown glacial sensitivity of the proxy. Different proxy signals after eruptions during cooler versus warmer glacial stages may reflect a state-dependent climate response.

We reconstructed changes in 4 climate variables using fossil pollen samples from the eastern Mediterranean. The reconstructions were expressed as time series that were compared with transient climate model simulations to explore possible causes. The early Holocene was colder-drier than the present, but these conditions improved between 10.3 and 9.3 ka. Changes in winter temperature are consistent with insolation changes, while summer temperature was likely influenced by the relict of polar caps.

Upwelling regions have great ecological, social, and economic importance, but predicting the effects of future climate change on upwelling systems is extremely difficult. One of the best tools we have is to look into the past and study their response to climate events. However, good proxies are hard to find due to different reasons. Here we show how using fossil coccolithophores, unicellular algae with calcified scales, is a promising tool, by using size variation to infer upwelling intensity.

We reconstructed the monthly mean scPDSI for May–July in the Upper Heilongjiang (Amur) Basin since 1796. Our analysis suggests that the dry/wet variability in the Upper Heilongjiang (Amur) River Basin is related to several large-scale climate stresses and atmospheric circulation patterns (the ENSO and Silk Road models). the cause of drought is primarily a reduction in advective water vapor transport, rather than precipitation circulation processes.

Sea-level rise and global climate change caused by ice melt in Antarctica is a puzzle of feedbacks between the climate, ocean and ice sheets, over tens to thousands of years. Antarctic Ice Sheet melting is caused mainly by warm deep water from the Southern Ocean. Here, we analyse close relationships between deep water temperatures and global climate in the last 800,000 years. This knowledge can help us to better understanding how climate and sea-level are likely to change in the future.

Analyzing simulations of Antarctic ice sheet variability during the early and mid-Miocene (23 to 14 million years ago), we find that the ice sheet area responds faster and more strongly than volume to climate change on quasi-orbital timescales. Considering the recent discovery that ice area, rather than volume, influences deep ocean temperatures, this implies that the Miocene Antarctic ice sheet affects deep ocean temperatures more than its volume suggests.

The study examines the relationship between temperature values and precipitation rates as explanatory variables and the probability of death due to waterborne, airborne, and other diseases in historical urban space. So far, the literature has not been focused on epidemiology of 19th -century Polish urban areas in climatological context. We used individual data on mortality from Poznań parish death registers for 1850–1900. We studied the relationship between weather conditions and mortality.

Drivers for dinocyst assemblage compositions differ regionally and through time. Shifts in the assemblages can sometimes only be interpreted robustly by locally, sometimes by globally calibrated transfer functions, questioning the reliability of environmental reconstructions. We suggest the necessity of a thorough evaluation of transfer function performances and significances for downcore applications to disclose the drivers for present and fossil dinocyst assemblages in a studied core location.

Atmospheric levels of molecular hydrogen (H₂) can impact climate and air quality. Constraining past changes to atmospheric H₂ is useful for understanding how H₂ cycles through the Earth system and predicting the impacts of increasing anthropogenic emissions under the "Hydrogen Economy." Here, we use the aging air found in the polar snowpack to reconstruct H₂ levels over the past 100 years. We find that H₂ levels increased by 30 % over Greenland and 60 % over Antarctica during the 20^th century.

This study analyzed ancient climate patterns using plant fossils called palynomorphs. We identified 69 different palynomorphs from different plant groups (e.g., ferns, gymnosperms, angiosperms), and used statistical methods to support our findings. We found a trend towards increased humidity, likely influenced by a weather phenomenon called the Intertropical Convergence Zone.

Radiocarbon is best known as a dating tool, but it also allows us to track CO₂ exchange between the ocean and atmosphere. Using decades of data and novel mapping methods, we have charted the ocean’s average radiocarbon 'age' since the last Ice Age. Combined with climate model simulations, these data quantify the ocean’s role in atmospheric CO₂ rise since the last ice Age, while also revealing that Earth likely received far more cosmic radiation during the last Ice Age than hitherto believed.

Receding Arctic ice caps reveal moss killed by earlier ice expansions. 186 moss kill-dates from 71 ice caps cluster at 250–450, 850–1000 & 1240–1500 CE, and continued expanding 1500–1880 CE, as recorded by regions of sparse vegetation cover, when Ice caps covered > 11,000 km², but < 100 km² at present. The 1880 CE state approached conditions expected during the inception of an ice age; climate models suggest this was only reversed by anthropogenic alterations to the planetary energy balance.

Analyses of reconstructed data suggest that the precipitation and availability of water has evolved in a similar way during the Last Millennium in different regions of the world, including areas of North America, Europe, the Middle East, Southern Asia, northern South America, East Africa and the Indo-Pacific. To confirm this link between distant regions and to understand the reasons behind it, the information from different reconstructed and simulated products has been compiled and analysed.

The climatic factors sustaining vegetation in the Sahara during the African Humid Period (AHP) are still not fully understood. Using biomarkers in a marine sediment core from the Eastern Mediterranean, we infer variations in Mediterranean (winter) and monsoonal (summer) rainfall in the Nile River watershed around the AHP. We find that winter and summer rain enhanced during the AHP suggesting that Mediterranean moisture supported the monsoon in sustaining the “Green Sahara”.

We combine [CO] measurements from ice core and firn air collected in Antarctica to produce the first continuous record of atmospheric carbon monoxide mixing ratio ([CO]) for Southern Hemisphere high latitudes over the past three millennia. Our Antarctic [CO] record is relatively stable from −835 to 1500 CE, exhibits a minimum during the Little Ice Age, and then reaches a maximum by ~1985 CE. This record will provide a useful benchmark for future atmospheric chemistry modeling studies.

Available data suggests that Alaska was not as cold as much of the high latitude areas of the northern hemisphere during the Last Ice Age. These results come from isolated climate records, climate models, and data synthesis projects. We used the extents of mountain glaciers during the Last Ice Age and Little Ice Age to show precipitation gradients across Alaska and provide temperature data from across the whole state. Our findings support a relatively warm Alaska during the Last Ice Age.

In the context of understanding current global warming, the middle Pliocene (3.3–3.0 million years ago) is an important interval in Earth's history because atmospheric carbon dioxide concentrations were similar to levels today. We have reconstructed deep sea temperatures at two different locations for this time, and find that a very different mode of ocean circulation or mixing existed, with important implications for how heat was transported in the deep ocean.

This study provides an analysis of the response of climate (temperature, precipitation, wind and atmospheric circulation) over the Australian region in climate model simulations of the Last Glacial Maximum (21,000 years before present). Model results are evaluated and compared with available paleoclimate proxy records. Analysis of the moisture balance (precipitation minus evaporation) demonstrates that the Australian climate may not have been uniformly drier during the glacial period.

In southern Europe, Holocene climate variability is characterised by a strong heterogeneity whose patterns are still poorly understood. Here, a multi-proxy approach (pollen and biomarkers) is applied to the Canroute sequence to reconstruct the climatic variation over the last 15,000 years in southern Massif Central, France. Results reveal that reconstructions of regional climate trends notably differ depending on proxies and sites, notably concerning the presence of a Holocene thermal maximum.

We present the weather diaries of the Kirch family, 1677–1774, containing weather observations made in Leipzig and Guben and, from 1701 onward, instrumental observations made in Berlin. We publish the imaged diaries (10445 images) and the digitised measurements (from 1720 onward). This is one of the oldest and longest meteorological record from Germany. The digitised pressure data show good agreement with neighbouring stations, highlighting their potential for weather reconstruction.