Editorial
Optimizing Crop Yield Responses to Atmospheric CO2 Enrichment: Why is it needed? ... and what is the best and most cost-efficient way of doing it?

Medieval Warm Period Record of the Week
This issue's Medieval Warm Period Record of the Week comes from the Macal Chasm, Vaca Plateau, Cavo District, Belize.

Subject Index Summary
West Antarctic Ice Sheet (Sea Level): How might rising temperatures affect the ice sheet's impact on global sea level?

Journal Reviews
Earth's Atmospheric Methane Concentration: 2008 Update: How much has it risen over the past decade? Would you believe not at all?

Low-Flow Characteristics of Northern Eurasian Rivers: How have they varied over the last few decades?

The Future of Earth's Terrestrial Birds: What do projected climate and land-use trends suggest about the subject?

North American Birds in a Warming World: How did they adjust their northern and southern range boundaries over the last three decades of the 20th century?

Species Richness in a Central European Bird Community: How did it vary in response to the warming of the last two decades of the 20th century?