(Appendix 1) Crustal helium-4 abundance and flux data for ODP Hole 130-806B

The mass accumulation rates (MARs) of aeolian dust in the ocean basins provide an important record of climate in the continental source regions of atmospheric dust and of the prevailing wind patterns responsible for dust transport in the geologic past. The incorporation of other terrigenous components such as volcanic ashes in seafloor sediments, however, often obscures the aeolian dust record. We describe a new approach which uses the delivery rate of crustal 4He to seafloor sediments as a proxy for the mass accumulation rate of old continental dust which is unaffected by the addition of other terrigenous components. We have determined the flux of crustal 4He delivered to the seafloor of the Ontong Java Plateau (OJP) in the western equatorial Pacific over the last 1.9 Myrs. Crustal 4He fluxes vary between 7.7 and 30 ncc/cm**2/kyr and show excellent correlation with global climate as recorded by oxygen isotopes, with high crustal 4He fluxes associated with glacial periods over the entire interval studied. Furthermore, the onset of strong 100 kyr glacial-interglacial climate cycling is clearly seen in the 4He flux record about 700 kyrs ago. These data record variations in the supply of Asian dust in response to climate driven changes in the aridity of the Asian dust sources, consistent with earlier work on Asian dust flux to the northern Pacific Ocean. However, in contrast to previous studies of sites in the central and eastern equatorial Pacific Ocean, there is no evidence that the Inter Tropical Convergence Zone (an effective rainfall barrier to the southward transport of northern hemisphere dust across the equator in the central and eastern Pacific) has influenced the delivery of Asian dust to the OJP. The most likely carrier phase for crustal helium in these sediments is zircon, which can reasonably account for all the 4He observed in the samples. As a first order estimate, these results suggest that the mass accumulation rate of Asian dust on the OJP over the last 1.9 Myrs varied from about 4 to 15 mg/ cm**2/kyr. In contrast, previous studies show that over the same interval the total MAR of terrigenous dust (i.e. Asian dust plus local volcanics) on OJP varied between about 34 and 90 mg/ cm**2/kyr.

Osmium isotopic composition and platinum group element concentrations in sediments from ODP Hole 145-886C

Paired analyses of Os isotope composition and concentration of bulk sediment and leachable Os in a metalliferous pelagic clay sequence from the North Pacific, ODP Site 886C, are used to reconstruct the marine Os isotope record and the particulate meteoritic Os flux between 65.5 and 78 Ma. Measured 187Os/188Os of bulk sediments ranges from approximately 0.64 to 0.32 and those of leach analyses are very similar to bulk analyses. Hydrogenous Os dominates the sedimentary Os inventory throughout most of the studied interval. As a result the measured 187Os/188Os of leachable Os approximates that of contemporaneous seawater. The ODP 886C record shows rising 187Os/188Os in the deepest portion of the core, with a local maximum of 0.66 close to 74 Ma. The 67-72 Ma portion of the record is characterized by nearly constant 187Os/188Os ratios close to 0.6. The structure of the marine Os isotope record from ODP 886C differs markedly from the seawater 87Sr/86Sr curve, which rises monotonically throughout the time interval studied here. Calculated particulate meteoritic Os fluxes are between 0.5 and 2 pg/cm**2/kyr throughout most of the studied interval. Two discrete intervals of the core (one of which is within Cretaceous Tertiary, boundary KTB interval) are characterized by higher fluxes of meteoritic Os. Excluding these two intervals, the average background flux of particulate meteoritic Os is roughly half of that estimated from analyses of Cenozoic marine sediments. These are the first Os isotope data to provide evidence of resolvable temporal variations in the background flux of particulate meteoritic material to the Earth.

Nucleonic intensities investigated during the Atlantic Expedition IQSY 1965 of RV "Meteor" (Appendix)

The nucleonic component of the cosmic rays has been measured by the German research vessel "Meteor" during the Atlantic Expedition IQSY 1965. The pressure corrected intensities fit well the rigidity calculations of Kondo and Kodamo. In this way we confirm the earth's magnetic field model used by these authors. Two positions of the cosmic ray equator have been determined at 29,7 °W (6,5 ± 1) °N and at 19 °W (7 ± 1) °N. These positions agree with the calculated values of Kondo and Kodamo. The total latitude effect of the nucleonic component amounts to 1.74 and 1.76. The measurements were carried out at solar minima activity. Using the values of latitude measurements at maxima solar activity the degree of modulation of the primary cosmic rays was determined in the rigidity range 2 - 13 GV. For rigidity values above 6 GV the modulation remains constant to 20 %.

Model results of ocean physical field of the reference state and the targets in NetCDF format

In a feasibility study, the potential of proxy data for the temperature and salinity during the Last Glacial Maximum (LGM, about 19 000 to 23 000 years before present) in constraining the strength of the Atlantic meridional overturning circulation (AMOC) with a general ocean circulation model was explored. The proxy data were simulated by drawing data from four different model simulations at the ocean sediment core locations of the Multiproxy Approach for the Reconstruction of the Glacial Ocean surface (MARGO) project, and perturbing these data with realistic noise estimates. The results suggest that our method has the potential to provide estimates of the past strength of the AMOC even from sparse data, but in general, paleo-sea-surface temperature data without additional prior knowledge about the ocean state during the LGM is not adequate to constrain the model. On the one hand, additional data in the deep-ocean and salinity data are shown to be highly important in estimating the LGM circulation. On the other hand, increasing the amount of surface data alone does not appear to be enough for better estimates. Finally, better initial guesses to start the state estimation procedure would greatly improve the performance of the method. Indeed, with a sufficiently good first guess, just the sea-surface temperature data from the MARGO project promise to be sufficient for reliable estimates of the strength of the AMOC.

Model-based changes in global annual mean surface temperature change (Delta T_g) and radiative forcing due to land ice albedo changes (Delta R_[LI]) over the last 5 Myr, supplementary material

It is still an open question how equilibrium warming in response to increasing radiative forcing - the specific equilibrium climate sensitivity S - depends on background climate. We here present palaeodata-based evidence on the state dependency of S, by using CO2 proxy data together with a 3-D ice-sheet-model-based reconstruction of land ice albedo over the last 5 million years (Myr). We find that the land ice albedo forcing depends non-linearly on the background climate, while any non-linearity of CO2 radiative forcing depends on the CO2 data set used. This non-linearity has not, so far, been accounted for in similar approaches due to previously more simplistic approximations, in which land ice albedo radiative forcing was a linear function of sea level change. The latitudinal dependency of ice-sheet area changes is important for the non-linearity between land ice albedo and sea level. In our set-up, in which the radiative forcing of CO2 and of the land ice albedo (LI) is combined, we find a state dependence in the calculated specific equilibrium climate sensitivity, S[CO2,LI], for most of the Pleistocene (last 2.1 Myr). During Pleistocene intermediate glaciated climates and interglacial periods, S[CO2,LI] is on average ~ 45 % larger than during Pleistocene full glacial conditions. In the Pliocene part of our analysis (2.6-5 Myr BP) the CO2 data uncertainties prevent a well-supported calculation for S[CO2,LI], but our analysis suggests that during times without a large land ice area in the Northern Hemisphere (e.g. before 2.82 Myr BP), the specific equilibrium climate sensitivity, S[CO2,LI], was smaller than during interglacials of the Pleistocene. We thus find support for a previously proposed state change in the climate system with the widespread appearance of northern hemispheric ice sheets. This study points for the first time to a so far overlooked non-linearity in the land ice albedo radiative forcing, which is important for similar palaeodata-based approaches to calculate climate sensitivity. However, the implications of this study for a suggested warming under CO2 doubling are not yet entirely clear since the details of necessary corrections for other slow feedbacks are not fully known and the uncertainties that exist in the ice-sheet simulations and global temperature reconstructions are large.