Thenardite deposits from the lower Miocene unit of the Tajo basin, Spain, result from a mirabilite diagenetic transformation salt that forms under cool climatic conditions. The time of the mirabilite formation correlates with a Mi cooling event coincident with mammal assemblages related to a relatively cool and arid climate in other basins of the Iberian Peninsula. This diagenetic transformation can be used as an analog with deposits from extreme conditions such as Antarctica or Mars.

New diatom isotope records are presented alongside existing geochemical and isotope records to document changes in the photic zone, including nutrient supply and the efficiency of the soft-tissue biological pump, between MIS 4 and MIS 5e in the subarctic north-west Pacific Ocean. The results provide evidence for temporal changes in the strength and efficiency of the regional soft-tissue biological pump, altering the ratio of regenerated to preformed nutrients in the water.

By using a statistical tool termed emulator, we study the sensitivity of the Indian monsoon during the the Pleistocene. The originality of the present work is to consider, as inputs, several elements of the climate forcing that have varied in the past, and then use the emulator as a method to quantify the link between forcing variability and climate variability. The methodology described here may naturally be applied to other regions of interest.

We compare an off-line and an on-line ensemble-based data assimilation method, for the climate of the 17th century. Both schemes perform better than the simulations without DA, and similar skill on the continental and hemispheric scales is found. This indicates either a lack of control of the slow components in our setup or a lack of skill in the information propagation on decadal timescales. The temporal consistency of the analysis in the on-line method makes it generally more preferable.

The Paleocene-to-Eocene thermal maximum was a period of extreme global warming caused by perturbation to the global carbon cycle 56Mya. Evidence from marine sediment cores has been used to suggest that the onset of the event was very rapid, over just 11 years of annually resolved sedimentation. However, we argue that the supposed annual layers are an artifact caused by drilling disturbance, and that the microfossil content of the cores shows the onset took in the order of thousands of years.

Ice core acidities agree with historical volcanic eruptions and tree ring effects in recent centuries, but in the 1st millennium, ice acid dates appear offset from tree ring evidence. This offset appears real between AD 1000 and 50 BC. If correct, then current identification of Vesuvius tephra at AD 79 is erroneous, and geophysicists are working with a false volcanic record especially regarding multiple eruptions in AD 536 and 540-541, highlighting a major global hazard in proximate eruptions.