Feature Article

The effect of ocean acidification conditions has been investigated in cultures of the diatom Thalassiosira pseudonana CCMP1335. Expected end-of-the-century pCO2 (aq) concentrations of 760 µatm (equivalent to pH 7.8) were compared with present-day condition (380 µatm CO2, pH 8.1). Batch culture pH changed rapidly because of CO2 (aq) assimilation and pH targets of 7.8 and 8.1 could not be sustained. Long-term (~100 generation) pH-auxostat, continuous cultures could be maintained at target pH when cell density was kept low (

Chemical ozone destruction occurs over both polar regions in local winter–spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was—for the first time in the observational record—comparable to that in the Antarctic ozone hole.

The observation of unusually low ozone levels over the Arctic last winter provides reassuring evidence that our knowledge of stratospheric chemistry is robust. Whether such an episode will happen again is an open question.

Drought is the most pressing problem caused by climate change. It receives too little attention, says Joseph Romm.

The effects of global environmental change, including coastal flooding, reduced rainfall in drylands and water scarcity, will almost certainly alter patterns of human migration. Conventional narratives usually cast these displacements in a negative light, with many millions of people forced to move, and tension and conflict the result. Our study suggests that the picture is not so one-sided.

Experts question early release of incomplete trial data.

Uncertainties over contaminated groundwater in southern Asia highlight gaps in science.

Global data on Fukushima challenge Japanese estimates.

Results confirming climate change are welcome, even when released before peer review. (Editorial)

Germany must do more to encourage dialogue on animal experimentation. (Editorial)