Current Research Topics

Annual Cycle of Surface Temperature

The vast majority of the variability observed in the instrumental surface temperature record is at annual frequencies. Systematic changes have occurred in the amplitude and phase of the annual cycle of surface temperature over the past half century, which appear to be related to seasonal changes in atmospheric circulation over the same period. I am interested in understanding natural and anthropogenic influences on variability in seasonality, and how we can distinguish them from one another.

Tree Rings

Because tree-ring growth is correlated with temperature at many locations, long tree-ring records have been used to infer the temperature history of the Earth before the advent of the thermometer. However, in later part of the 20th century many of these tree rings ceased to track temperature, suggesting a large-scale change in the way the terrestrial biosphere responds to climate. This recent behavior, known as the "tree-ring divergence problem," represents not only a problem for climate reconstructions -- it is an important ecological problem in its own right. I am interested in understanding the effects of climate upon tree growth, and on how the multiple influences on tree growth effect our ability to interpret tree rings as a record of past climates.

Links

• Some datasets I have found useful
• Non-climate related resources