Letters in 2007

Increasing levels of atmospheric carbon dioxide leads to ocean acidification, causing significant reductions in the growth of crustose coralline algae.

The speed of a glacier is affected most by sudden jumps in the water supply to the glacier, but it goes back to previous levels if high water inputs are sustained because the glacier's plumbing system adjusts.

The isotopic composition of oceanic basalts suggests that they are composed of true recycled oceanic crust and sediments, which are mixed with the depleted mantle.

The Great Ordovician Biodiversification Event coincides ~470 million years ago with the break-up of a large asteroid and the resultant frequent bombardment of Earth with asteroid fragments.

Sea level during the last interglacial stood at least 4 m higher than at present, with evidence of short-term fluctuations of up to 10 m. A new continuous sea level record from the Red Sea and coral ages suggest that during these fluctuations, sea level changes were on the order of 1.6 m per century.

Clustering of earthquakes at various spatial scales is the result of a heterogeneous distribution of stresses, and – at least for intermediate-magnitude earthquakes – areas that are quiet at present are likely to remain so in the future.

Carbon isotopes of fossil plants and model simulations suggest that atmospheric carbon dioxide levels were variable during the period 200 to 60 million years ago. The large decreases in the partial pressure of CO₂ coincide with glaciations, providing evidence against climate–CO₂ decoupling during the Mesozoic.

Multibeam mapping of the northwestern Indian Ocean seafloor provides clear evidence of dextral strike-slip motion along the Owen fracture zone and helps constrain the nature of deformation as well as the rate of slip along this little-studied plate boundary.