Fjords line mountainous continental margins where icesheets and glaciers once stood. A two-dimensional model simulation suggests that fjords can be eroded within one million years, primarily in response to topographic ice steering and erosion from ice discharge. Subsequent glaciers that form on these landscapes are smaller and exhibit greater responses to climate change.

The termination of the Marinoan glaciation 635 million years ago is one of the most spectacular climate change events ever recorded. Methane release from equatorial permafrost might have triggered this global meltdown.

An index that both climate scientists and policy makers anxiously keep track of is national emission rates of carbon dioxide, particularly for China, which has quickly been catching up with the US, hitherto the world's largest emitter of carbon dioxide. Despite all eff orts to the contrary, the rates for both China and the world are rapidly going up, rather than down.

The recently published 800,000-year greenhouse-gas records from Dome C, Antarctica, show that old ice still bears surprises. As long as the records challenge our understanding, we should go back for more. (Editorial)

Anyone clinging to the notion that we can wipe the slate clean of all our climate mistakes by deflecting the sun's rays with space mirrors is in for a disappointment. Dan Lunt of the University of Bristol, UK, and colleagues carried out the most detailed climate-modelling study to date on the impact of a sunshade.