Editorial
Declining Arctic Sea Ice: Has a "Tipping Point" Been Passed?: Is the Arctic - as we have known it throughout all of human history - truly on the eve of destruction?

Medieval Warm Period Record of the Week
This issue's Medieval Warm Period Record of the Week comes from the Cariaco Basin off the Venezuelan Coast.

Subject Index Summary
Urban CO2 Dome (Salt Lake City, UT, USA): What has been learned about it over the last few years?

Journal Reviews
New York City Hurricanes: There haven't been any for quite a while ... thanks, perhaps, to global warming.

A New History of Total Solar Irradiance Since AD 1700: How was it derived? ... and what does it look like?

The Photosynthetic and Transpiration Responses of Canola Siliquas to Elevated CO2 and UVB Radiation: What are they? And what do they imply about the future strength of the aerial fertilization and anti-transpiration effects of the ongoing rise in the air's CO2 content?

CO2 and Temperature Effects on Marine Picocyanobacteria: Isolates of two major groups of cyanobacteria exhibit radically different responses.

Cadmium Toxicity in a Green Microalga: How is it affected by atmospheric CO2 enrichment?