Here we reconstruct atmospheric CO₂ values across major climate transitions over the past 16 million years (Myr) from two sites in the West Pacific Warm Pool using a pH proxy on surface-dwelling foraminifera. We are able to reproduce pCO₂ data from ice cores; therefore we apply the same framework to older samples to create a long-term pH and pCO₂ reconstruction. We give quantitative constraints on pH and pCO₂ changes over the main climate transitions of the last 16 Myr.

New pollen and spore data from the Antarctic Peninsula region reveal temperate rainforests that changed and adapted in response to Eocene climatic cooling, roughly 35.5 Myr ago, and glacially related disturbance in the early Oligocene, approximately 33.5 Myr ago. The timing of these events indicates that the opening of ocean gateways alone did not trigger Antarctic glaciation, although ocean gateways may have played a role in climate cooling.

Here we study the elemental signatures of plant wax compounds as well as molecules from algae and bacteria to understand how water sources changed over the last 11 000 years in the northeastern part of Europe surrounding the Baltic Sea. Our results show diversity in plant and aquatic microorganisms following the melting of the large ice sheet that covered northern Europe as the regional climate continued to warm. A shift in water source from ice melt to rain also occurred around the same time.

The study of abrupt climate changes is a relatively new field of research that addresses paleoclimate variations that occur in intervals of tens to hundreds of years. Such timescales are much shorter than the tens to hundreds of thousands of years that the astronomical theory of climate addresses. We revisit several high-resolution proxy records of the past 3.2 Myr and show that the abrupt climate changes are nevertheless affected by the orbitally induced insolation changes.

The role of land–sea fluxes during deglacial flooding in ocean biogeochemistry and CO₂ exchange remains poorly constrained due to the lack of climate models that consider such fluxes. We implement the terrestrial organic matter fluxes into the ocean at a transiently changing land–sea interface in MPI-ESM and investigate their effect during the last deglaciation. Most of the terrestrial carbon goes to the ocean during flooding events of Meltwater Pulse 1a, which leads to regional CO₂ outgassing.

Glaciers in the northern Rocky Mountains began retreating 17 000 to 18 000 years ago, after the end of the most recent global ice volume maxima. Climate in the region during this time was likely 10 to 8.5° colder than modern with less than or equal to present amounts of precipitation. Glaciers across the Rockies began retreating at different times but eventually exhibited similar patterns of retreat, suggesting a common mechanism influencing deglaciation.

It is still a challenge to simulate the so–called Green Sahara (GS), which was a wet and vegetative Sahara region in the mid–Holocene, using current climate models. Our analysis shows that Holocene greening is simulated better if the amount of soil nitrogen and soil texture is properly modified for the humid and vegetative GS period. Future climate simulation needs to consider consequent changes in soil nitrogen and texture with changes in vegetation cover for proper climate simulations.

The East Asian winter monsoon causes orographic snowfall over the windward side of the Japanese islands (facing the Sea of Japan and the northwesterly winter monsoon flow) and negative temperature anomalies around Japan. In this study, we reconstruct the outbreak of the winter monsoon around Japan for the winter from the 1840s to the early 1850s by using daily weather information recorded in old Japanese diaries and early daily instrumental temperature data.

Temperature seasonality is an important climate parameter for biodiversity. Fossil plants describe its middle Eocene to early Oligocene increase in the Northern Hemisphere, but underlying mechanisms have not been studied in detail yet. Using climate simulations, we map global seasonality changes and show that major contemporary forcing – atmospheric CO₂ lowering, Antarctic ice-sheet expansion and particularly related sea level drop – participated in this phenomenon and its spatial distribution.

We investigated the diversity of algae called diatoms in Lake Baikal, the oldest and deepest lake in the world, because algae sit at the base of aquatic foodwebs and provide energy (in the form of primary production) for other organisms to use. Diatom diversity and primary production have been influenced by both long-term and abrupt climate change over the past 16 000 years. The shape of these responses appears to be time-period specific.

Sea ice is important for our climate system and for the unique ecosystems it supports. We present a novel way to understand past Antarctic sea-ice ecosystems: using the regurgitated stomach contents of snow petrels, which nest above the ice sheet but feed in the sea ice. During a time when sea ice was more extensive than today (24 000–30 000 years ago), we show that snow petrel diet had varying contributions of fish and krill, which we interpret to show changing sea-ice distribution.