Studies suggest that tropical cyclones are becoming more powerful with the most dramatic increase in the North Atlantic. The increase is correlated with an increase in ocean temperature. A debate concerns the nature of these increases with some studies attributing them to natural climate fluctuations, and others suggesting climate change related to anthropogenic increases in radiative forcing from greenhouse gases.

The summits of the neotropical Guayana Highlands in Venezuela have a unique biodiversity that is under serious threat because of habitat loss resulting from climate warming. Although conservation studies are urgently needed, these are blocked by official bodies that will not grant permits for fieldwork in the region. (Correspondence)

A unique drilling project in the western Ross Sea has revealed that Antarctica had a much more eventful climate history than previously assumed. A new sediment core hints that the western part of the now-frozen continent went through prolonged ice-free phases

Strong and new forces of change in the world food equation are transforming food consumption, production and markets. Unlike the pattern prevailing for the past few decades, today's global agricultural system is very much driven by the demand side. With income growth in emerging economies, globalisation and urbanisation, the demand for agricultural products will continue to grow and shift toward high-value commodities. Partly driven by the expansion of biofuels and demand for feed, strong global cereal consumption is likely to continue.

The anticipated impacts of climate change on grassland systems and appropriate management responses have been reviewed extensively, though the emphasis has been on European temperate and North American rangeland systems.

Tropospheric ozone contributes significantly to human-induced greenhouse warming. Calculations from satellite measurements of spectral radiance suggest that ozone in the upper troposphere caused an average reduction in clear-sky outgoing long-wave radiation over the oceans of 0.480.14 W m- 2 for the year 2006 between 45

Oxygen-poor waters occupy large volumes of the intermediate-depth eastern tropical oceans. Oxygen-poor conditions have far-reaching impacts on ecosystems because important mobile microorganisms avoid or cannot survive in hypoxic zones. Climate models predict declines in oceanic dissolved oxygen produced by global warming. The researchers constructed a 50-year time series of dissolved-oxygen concentration for select tropical oceanic regions by augmenting a historical database with recent measurements.

Subglacial water can significantly affect the velocity of ice streams and outlet glaciers of ice sheets. Depending on the geometry and capacity of the subglacial hydrologic system, increased surface melting in Greenland over the coming decades may influence the ice sheet's mass balance. Furthermore, subglacial lakes in Antarctica can modulate ice velocities and act as nucleation points for new fast-flowing ice streams.

Atmospheric carbon dioxide levels greatly influence the Earth's climate. Evidence from ice cores and marine sediments suggests that over timescales beyond the glacial cycles, carbon fluxes are finely balanced and act to stabilize temperatures.

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