Feature Article

he stable isotope ratios of atmospheric CO2 (18O/16O and 13C/12C) have been monitored since 1977 to improve our understanding of the global carbon cycle, because biosphere–atmosphere exchange fluxes affect the different atomic masses in a measurable way. Interpreting the 18O/16O variability has proved difficult, however, because oxygen isotopes in CO2 are influenced by both the carbon cycle and the water cycle.

The global uptake of carbon by land plants may be greater than previously thought, according to observations based on the enigmatic Keeling curve of rising atmospheric carbon dioxide.

There are many challenges involved in understanding climate variations in the tropics, and how the Pacific climate might change with global warming. One study offers a surprising perspective on the mechanisms involved.

Clinical trials are crumbling under modern economic and scientific pressures. Nature looks at ways they might be saved.