PALEOCLIMATE: The Amazon Reveals Its Secrets--Partly

The role of the tropics in global climate change during glacial cycles is hotly debated in paleoclimate cycles today. Records from South America have not provided a clear picture of tropical climate change. In his Perspective, Betancourt highlights the study by Maslin and Burns, who have deduced the outflow of the Amazon over the past 14,000 years. This may serve as a proxy that integrates hydrology over the entire South American tropics, although the record must be interpreted cautiously because factors other than rainfall may contribute to the variability in outflow.     

Agriculture. Genetically modified crops and farmland biodiversity

The debate about genetically modified crops that are resistant to herbicides and their effects on the environment rages on. In their Perspective, Firbank and Forcella discuss a new model (Watkinson et al.) that seeks to calculate the impact of genetically modified herbicide-resistant sugar beet on growth of the weed Chenopodium album and on the skylark, which feeds on the seeds of this weed.