Volume 7 Issue 10, October 2014

The emerging scientific focus on cumulative carbon emissions may make climate negotiations harder. But, it serves to clarify the scale and scope of climate mitigation needed to meet potential temperature targets.

Jupiter's icy moon Europa is criss-crossed by extensional features. A tectonic reconstruction suggests that Europa's extension is balanced by subduction — if so, Earth may not be the only planetary body with a plate tectonic system.

Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

Upwelling within the highly productive Benguela current off the Namibian coast began in, and intensified throughout, the Neogene epoch. Model simulations indicate its development was intimately connected to evolving topography and mountain uplift in Africa.

Freshwater deficits and heavy rainfall have been projected to intensify in a warming climate. An analysis of hydrological data suggests that past changes in wet and dry extremes were more complex than a simple amplification of existing patterns.

Shorelines are vulnerable to the destructive waves and water levels of increasingly frequent extreme storm events. Wave tank experiments demonstrate that salt marsh vegetation dissipates wave energy and withstands extreme storm conditions.

Scientific confidence in climate change effects is much higher for aspects related to global patterns of surface temperature, than for circulation. Circulation will remain hard to predict, necessitating a risk-based approach to decision making.

In order to limit climate warming, CO₂ emissions must remain below fixed quota. An evaluation of past emissions suggests that at 2014 emissions rates, the total quota will probably be exhausted within the next 30 years.

Past continental dryness trends are difficult to assess. A comprehensive analysis of hundreds of combinations of data sets suggests that only 24.6% of the global land area have been exposed to robust dryness changes since 1948.

Plants may enhance sedimentation and help deltas to keep up with rising sea levels. Numerical simulations show that intermediate vegetation height and density are optimal, whereas too much vegetation inhibits sediment deposition in deltaic marshes.

Salt marshes protect coastlines against waves. Wave flume experiments show that marsh vegetation causes substantial wave dissipation and prevents erosion of the underlying surface, even during extreme storm surge conditions.

Melting of the Antarctic ice sheet and ice shelves reduces the salinity of the coastal seas. Satellite and model data suggest that the freshwater discharge has also caused coastal Antarctic sea level to rise by about 2 mm yr⁻¹ more than the regional mean.

Wrinkle structures in ancient sedimentary environments are enigmatic. Wave-tank experiments suggest that wrinkle structures are shaped by microbial mat fragments that are moved by waves over sandy-bed surfaces, and thus are morphological biosignatures.

The Benguela current cooled over the past 12 million years. Numerical modelling suggests that uplift of parts of Africa during this time enhanced coastal low level winds and promoted greater upwelling of cool subsurface waters.

A series of unusual, greenhouse-gas-induced warming events occurred in the Eocene. An isotope reconstruction of these hyperthermals indicates multiple events of a constant size and frequency, consistent with orbital forcing of the carbon cycle.

Precursor events to earthquakes are rarely reproduced. Measurement of groundwater chemistry in Iceland between 2008 and 2013 reveals distinct changes prior to two consecutive >M5 earthquakes.

Earthquakes on oceanic transform faults are often preceded by foreshock swarms. A theoretical model suggests that circulating hydrothermal fluids, which compress as the fault rocks expand and deform, cause this precursor seismic activity.

Despite widespread evidence for extension, there have been few signs of contraction on the icy surface of Jupiter’s Europa. Evidence for a subduction-like convergent boundary suggests that Europa may have active plate tectonics.

Stratospheric water vapour is a powerful greenhouse gas. Merging individual satellite data sets with a chemistry–climate model reveals that water vapour levels in the lower and mid-stratosphere have been decreasing since 1988.