Editorial
Effects of Atmospheric CO2 Enrichment on N2-Fixing Oceanic Cyanobacteria: How does atmospheric CO2 enrichment affect the abilities of these minute organisms to produce the nitrogen that is needed to support much of the world's oceanic productivity.

Medieval Warm Period Record of the Week
This issue's Medieval Warm Period Record of the Week comes from Effingham Inlet, West Coast of Vancouver Island, British Columbia, Canada.

Subject Index Summary
Weather Extremes (Hail): As the world has warmed and the air's CO2 content risen to values not seen for who knows how long, have hail storms changed in any substantial way?

Journal Reviews
Swiss Alps Glacier Lengths During the Holocene: How do they compare with the lengths they exhibited in the 1990s?

The Impact of Oceanic Ship Emissions on Marine Stratus Cloud Properties: What are they? ... and what is their impact on the shortwave radiative balance at the surface of the sea and the top of the atmosphere?

Atmospheric CO2 Enrichment Effects on Collembolan Communities in a Field Planted to Winter Wheat: What are they? ... and are they positive or negative?

The Role of Fungi in the Production of Biogenic Aerosols: How significant are they in the global scheme of things? What do they do for earth's climate? And how are they affected by rising air temperatures and CO2 concentrations?

The Photosynthetic Response of Pine Trees to Ultra-High CO2 Concentrations: Does it approach an asymptotic upper limit?