Ice ages are paced by astronomical parameters. On longer timescales, the astronomy also acts on climate, as evidenced by the 400 kyr signature observed in carbon isotopic records. In this paper, I present a conceptual model that links the astronomy to the dynamics of organic carbon in coastal areas. The model reproduces the carbon isotopic records and a two-step decrease in atmospheric CO₂ that would explain the Pleistocene (~ 2.8 Myr BP) and mid-Pleistocene (~ 0.8 Myr BP) transition.

Deep ocean temperatures are widely used as a proxy for global mean surface temperature in the past, but the underlying assumptions have not been tested. We use two unique sets of 109 climate model simulations for the last 545 million years to show that the relationship is valid for approximately the last 100 million years but breaks down for older time periods when the continents (and hence ocean circulation) are in very different positions.

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. 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.

Despite significant progress in modelling Quaternary climate dynamics, a comprehensive theory of glacial cycles is still lacking. Here, using the results of model simulations and data analysis, I present a framework of the generalized Milankovitch theory (GMT), which further advances the concept proposed by Milutin Milankovitch over a century ago. The theory explains a number of facts which were not known during Milankovitch time's, such as the 100 kyr periodicity of the late Quaternary.

We reconstruct changes in mean ocean temperature (ΔMOT) over the last 4.5 Myr. We find that the ratio of ΔMOT to changes in global mean sea surface temperature was around 0.5 before the Middle Pleistocene transition but was 1 thereafter. We subtract our ΔMOT reconstruction from the global δ¹⁸O record to derive the δ¹⁸O of seawater. Finally, we develop a theoretical understanding of why the ratio of ΔMOT / ΔGMSST changed over the Plio-Pleistocene.

We show that the analysis of δ¹⁸O and dust in the Greenland ice cores, and a critical study of their source variations, reconciles these records with those observed on the Eurasian continent. We demonstrate the link between European and Chinese loess sequences, dust records in Greenland, and variations in the North Atlantic sea ice extent. The sources of the emitted and transported dust material are variable and relate to different environments.

There is a lack of reconstructions from Antarctic ice cores of the temperature during the summer, a critical season in terms of solar energy received, preventing a good understanding of the link between Antarctic past climate and astronomically induced insolation changes. Here, the variations in total air content in an Antarctic ice core are found to be correlated to local summer temperatures simulated with a climate model. This tracer can be used to reconstruct past local summer temperatures.

Soil respiration is a critical but poorly constrained component of the global carbon cycle. We analyse the effect of changing soil respiration rates on the stable carbon isotope ratio of speleothems from northern Spain covering the last deglaciation. Using geochemical analysis and forward modelling we quantify the processes affecting speleothem stable carbon isotope ratios and extract a signature of increasing soil respiration synchronous with deglacial warming.

It is unclear how different components of the global atmospheric circulation, such as the El Niño effect, respond to large-scale climate change. We present a new ice core gas proxy, called krypton-86 excess, that reflects past storminess in Antarctica. We present data from 11 ice cores that suggest the new proxy works. We present a reconstruction of changes in West Antarctic storminess over the last 24 000 years and suggest these are caused by north–south movement of the tropical rain belt.

The first continuously measured transfer functions that quantify the age difference between the Greenland ice-core chronology 2005 (GICC05) and the U–Th timescale are presented. The transfer functions were generated using a novel probabilistic algorithm for the synchronization of proxy signals. The results greatly improve the accuracy and precision of previous synchronization estimates and reveal that the annual-layer counting error of GICC05 is less systematic than previously assumed.

We document Southern Ocean surface ocean conditions and changes therein during the Oligocene and Miocene (34–10 Myr ago). We infer profound long-term and short-term changes in ice-proximal oceanographic conditions: sea surface temperature, nutrient conditions and sea ice. Our results point to warm-temperate, oligotrophic, ice-proximal oceanographic conditions. These distinct oceanographic conditions may explain the high amplitude in inferred Oligocene–Miocene Antarctic ice volume changes.

Some 155 million years ago, sediments were deposited in a shallow subtropical sea. Coral reefs formed in a warm and arid climate during high sea level, and clays were washed into the ocean at low sea level and when it rained. Climate and sea level changes were induced by cyclical insolation changes. Analysing the sedimentary record, it appears that sea level rise today (as a result of global warming) is more than 10 times faster than the fastest rise reconstructed from the geologic past.

The Great Plains host the single most important climatic boundary in North America, separating the humid east from the semi-arid west. How this boundary will move as the world warms holds implications for the societies and ecosystems of the Plains. We study how this boundary changed in the past during a period of globally warmer temperatures. We find that this climatic boundary appears to be in the same location as today, suggesting that the Great Plains climate is resilient to global changes.

Our research explores climatic changes during the Early–Middle Pleistocene (1006–750 ka) on the southern Portuguese margin. We found that warm, subtropical-gyre-related conditions dominated. However, those conditions were occasionally interrupted by extreme cold events during the glacial periods. Our data show that these cold events, linked to changes in the North Atlantic's circulation, reached as far south as 36° N and significantly impacted marine ecosystems in the surface ocean.

Glacial cycle duration changed from 41 000 to 100 000 years during the Mid-Pleistocene Transition (MPT), but the cause is still under debate. We simulate the MPT with an ice sheet model forced by prescribed CO₂ and insolation and simple ice–climate interactions. Before the MPT, glacial cycles follow insolation. After the MPT, low CO₂ levels may compensate for warming at insolation maxima, increasing the length of glacial cycles until the North American ice sheet becomes large and thereby unstable.