Reviews & Analysis

Naturally produced hydrocarbons such as isoprene influence air quality and climate. Accounting for circadian control of isoprene emissions helps to bring model simulations of ground-level ozone into closer agreement with observations.

Atmospheric aerosols strongly influence Earth's climate, but how they form has remained a mystery. According to cloud chamber experiments, a mixture of vapours, as well as ions formed by galactic cosmic rays, contribute to the particle formation recipe.

During the last interglacial period, summer temperatures were warmer and the Greenland ice sheet smaller than today. Modelling suggests that the low ice-sheet volume was not simply a consequence of high ambient temperatures.

The quantity of heat generated by radioactive decay in Earth's interior is controversial. Measurements of geoneutrinos emitted from the mantle during this decay indicate that this source contributes only about half of Earth's total outgoing heat flux.

Analysis of the first Apollo samples suggested that Earth's only satellite was bone dry. Spacecraft data and improved analysis techniques now indicate that the Moon is more volatile-rich and complex than previously thought.

River systems have changed through time; the sinuous, stable channels common today developed relatively late in Earth's history. The rock record suggests that a specific type of fixed-channel river system arose after the expansion of arborescence.

An exotic arrow-shaped cloud was discovered in the atmosphere of Saturn's moon Titan last year. Numerical modelling shows how a large-scale atmospheric wave can naturally shape tropical clouds to such an arrow.

Hydroelectric energy is renewable, but reservoirs contribute to climate change by releasing carbon dioxide and methane to the atmosphere. A global estimate suggests that young reservoirs in low latitudes produce the largest emissions.

Whether interannual variability in the Pacific Ocean was a feature of the warm Pliocene climate is debated. Variance in reconstructed eastern tropical Pacific surface temperatures provides strong support for persistent El Niño activity at this time.

Forests affect climate not only by taking up carbon, but also by absorbing solar radiation and enhancing evaporation. In the tropics, the climate benefit of afforestation may be nearly double that expected from carbon budgets alone.

Volcanic deposits on the Moon are almost entirely composed of basaltic lava flows that make up the dark and extensive mare plains. High-resolution images and compositional data now reveal rare, non-mare volcanism on the Moon's farside.

Ice sheets, and in particular the West Antarctic ice sheet, are expected to shrink in size as the world warms, which in turn will raise sea level. A Review of the literature suggests that much of this ice sheet will survive beyond this century, but confident estimates of the likelihood of future collapse require further work.

Dynamic motions in Earth's mantle can be expressed at the surface. Rocks and landscapes beneath the North Atlantic Ocean record surface uplift driven by pulses of hot material upwelling in a mantle plume beneath Iceland.

Large earthquakes can build mountains, but they can also trigger landslides that wear landscapes away. An analysis from the 2008 Wenchuan earthquake shows that landslides destroyed more topography than was created by uplift.

The southern San Andreas fault is due for a large earthquake. Seismic images of sediments deposited in an ancient lake overlying the southern end of the fault indicate that episodic flooding may have triggered earthquakes in the past.

Oxygen isotope variations in Chinese cave deposits have been interpreted as proxies for the East Asian summer monsoon. Numerical simulations suggest the deposits may instead record remote climate changes over India and the Indian Ocean.

The relationship between soil moisture and rainfall has proved tricky to pin down. An analysis of close to 4,000 Sahelian storms suggests that certain soil-moisture patterns enhance the likelihood of rainfall.