In this study, we present a detailed investigation of the chemical composition of 12 specimens of very well preserved, 78-million-year-old oyster shells from southern Sweden. The chemical data show how the oysters grew, the environment in which they lived and how old they became and also provide valuable information about which chemical measurements we can use to learn more about ancient climate and environment from such shells. In turn, this can help improve climate reconstructions and models.

Modern climate change is causing expansions of low-oxygen zones, with detrimental impacts to marine life. To better predict future ocean oxygen change, we study past expansions and contractions of low-oxygen zones using microfossils of seafloor organisms. We find that, along the San Diego margin, the low-oxygen zone expanded into more shallow water in the last 400 years, but the conditions within and below the low-oxygen zone did not change significantly in the last 1500 years.

We conducted an extensive literature survey (meta-analysis) on how the C : N : P ratio varies with change in key environmental drivers. We found that the expected reduction in nutrients and warming under the future climate change scenario is likely to result in increased C : P and C : N of marine phytoplankton. Further, our findings highlight the greater stoichiometric plasticity of eukaryotes over prokaryotes, which provide us insights on how to understand and model plankton.

The cell size, degree of calcification and growth rates of coccolithophores impact their role in the carbon cycle and may also influence their adaptation to environmental change. Combining insights from culture experiments and the fossil record, we show that the selection for smaller cells over the past 15 Myr has been a common adaptive trait among different lineages. However, heavily calcified species maintained a more stable biogeochemical output than the ancestral lineage of E. huxleyi.

Four wheat cultivars were labeled with ¹³CO₂ to quantify the effect of rooting depth and root biomass on the belowground transfer of organic carbon. We found no clear relation between the time since cultivar development and the amount of carbon inputs to the soil. Therefore, the hypothesis that wheat cultivars with a larger root biomass and deeper roots promote carbon stabilization was rejected. The amount of root biomass that will be stabilized in the soil on the long term is, however, unknown.

The Zero Emissions Commitment (ZEC) is the change in global temperature expected to occur following the complete cessation of CO₂ emissions. Here we use 18 climate models to assess the value of ZEC. For our experiment we find that ZEC 50 years after emissions cease is between −0.36 to +0.29 °C. The most likely value of ZEC is assessed to be close to zero. However, substantial continued warming for decades or centuries following cessation of CO₂ emission cannot be ruled out.

Tropical forests play a crucial role in governing climate feedbacks, and are incredibly diverse ecosystems, yet most Earth system models do not take into account the diversity of plant traits in these forests and how this diversity may govern feedbacks. We present an approach to represent diverse competing plant types within Earth system models, test this approach at a tropical forest site, and explore how the representation of disturbance and competition governs traits of the forest community.