We analyzed GDGT-based proxy temperatures in the polar oceans. In the eastern Fram Strait (79° N), the nutrient distribution may determine the depth habit of Thaumarchaeota and thus the proxy temperature. In the Antarctic Polar Front (50° S), the contribution of Euryarchaeota or the nonlinear correlation between the proxy values and temperatures may cause the warm biases of the proxy temperatures relative to SSTs.

We estimate heterotrophic respiration (R_h) – the respiration from microbes in the soil – using satellite estimates of the net carbon flux and other quantities. R_h is an important carbon flux but is rarely studied by itself. Our method is the first to estimate how R_h varies in both space and time. The resulting new estimate of R_h is compared to the best currently available alternative, which is based on interpolating field measurements globally. The two estimates disagree and are both uncertain.

Unique and spectacular under water speleothems termed as Hells Bells were recently reported from sinkholes (cenotes) of the Yucatán Peninsula, Mexico. However, the mystery of their formation remained unresolved. Here, we present detailed geochemical analyses and delineate that the growth of Hells Bells results from a combination of biogeochemical processes and variable hydraulic conditions within the cenote.

We investigated air–sea gas exchange in oceanic upwelling regions for the case of nitrous oxide off Peru. In this region, routine concentration measurements from ships at 5 m or 10 m depth prove to overestimate surface (bulk) concentration. Thus, standard estimates of gas exchange will show systematic error. This is due to very shallow stratified layers that inhibit exchange between surface water and waters below and can exist for several days. Maximum bias occurs in moderate wind conditions.

To elucidate the potential effects of crushed nodule particle deposition on abyssal meiobenthos, we covered abyssal soft sediment in the Peru Basin (4200 m depth) with approximately 2 cm of this nodule material for 11 d. About half of the meiobenthos migrated from the sediment into the added material, and nematode feeding type proportions in that added layer were altered. These results considerably contribute to our understanding of the short-term responses of deep-sea meiobenthos to burial.

A budget of anthropogenic carbon in the Arctic Ocean, the main driver of open-ocean acidification, was constructed for the first time using a high-resolution ocean model. The budget reveals that anthropogenic carbon enters the Arctic Ocean mainly by lateral transport; the air–sea flux plays a minor role. Coarser-resolution versions of the same model, typical of earth system models, store less anthropogenic carbon in the Arctic Ocean and thus underestimate ocean acidification in the Arctic Ocean.

Human activities strongly interfere in the land–atmosphere interactions through changes in land use and land cover changes and land management. The objectives of this review are to synthesize the existing experimental and modelling works that investigate physical, chemical, and biogeochemical interactions between land surface and the atmosphere. Greater consideration of atmospheric chemistry, through land–atmosphere interactions, as a decision parameter for land management is essential.

We studied methane emitted as episodic bubble release (ebullition) from water and bare peat surfaces of a boreal bog over three years. There was more ebullition from water than from bare peat surfaces, and it was controlled by peat temperature, water level, atmospheric pressure and the weekly temperature sum. However, the contribution of methane bubbles to the total ecosystem methane emission was small. This new information can be used to improve process models of peatland methane dynamics.