Reviews & Analysis

Carbon dioxide uptake by the terrestrial biosphere has the potential to mitigate fossil fuel emissions. Comprehensive estimates of Europe's greenhouse-gas balance suggest that any uptake of carbon dioxide by the terrestrial biosphere is offset by methane and nitrous oxide emissions.

Efforts to control climate change require the stabilization of atmospheric carbon dioxide concentrations. An assessment of the trends in sources and sinks of atmospheric carbon dioxide suggests that the sinks are not keeping up with the increase in carbon dioxide emissions, but uncertainties are still large.

The rapid increase in anthropogenic emissions of greenhouse gases necessitates the consideration of mechanisms for capturing and storing carbon dioxide. Recent work suggests that fluid or gaseous carbon dioxide can be injected into the Earth's crust, and locked up as carbonate minerals to achieve near-permanent and secure sequestration.

Past interglacials can be thought of as a series of natural experiments in which boundary conditions varied considerably. Examination of the palaeoclimate record of the past 800,000 years reveals a large diversity among interglacials in terms of their intensity, duration and internal variability.

Many of the world's deltas are densely populated and intensively farmed. An assessment of recent publications indicates that the majority of these deltas have been subject to intense flooding over the past decade, and that this threat will grow as global sea-level rises and as the deltas subside.

Slab fluids drive mantle melting and return ocean water to the Earth's surface through arc volcanism. New ways of estimating the temperature of slab fluids indicate relatively hot conditions, and hint at a shallow and fast return path for ocean water.

Science and society are faced with two challenges that are inextricably linked: fossil-fuel energy dependence and rising levels of atmospheric carbon dioxide. Coupling of noble gas and carbon chemistry provides an innovative approach to understanding the deep terrestrial carbon cycle.

The Earth's mantle constitutes over 80% of the planet's volume and is a key reservoir in global geochemical cycling. An overview of the progress in understanding the generation of mid-ocean-ridge basalt from mantle melt shows that a variety of processes chemically alter mantle signals in the melt generated at depth before its eruption at the sea floor.

Marine dissolved oragnic matter contains roughly as much organic carbon as all living biota on land and in the oceans combined. New techniques in analytical chemistry show that a significant portion of this material has undergone thermal alteration, either on land or in sediments deep below the sea floor.