The instrumental record of drought exists for 100 years or less for most of North America. This limited record is inadequate for assessing the rarity of major drought events of the 20th century, and may not be representative of long-term natural climate variability. Paleoclimatic records are critical for evaluating extreme drought events and drought variability in the 20th century in a broader temporal context.

In the last decade, a number of studies have produced reconstructions of drought from paleoclimatic records, primarily tree rings and lake sediments. One of these was the release of the first gridded continental-scale drought reconstruction from tree rings (Cook et al., 1999). This set of gridded tree-ring reconstructions of the Palmer Drought Severity Index (PDSI) for the conterminous United States from AD 1700-1978 provided the first opportunity both to assess nationwide patterns of pre-instrumental drought, and to have a dataset of pre-instrumental drought indices for all parts of the U.S. Further work has extended these reconstructions back in time, as well as extended them spatially to cover most of North America.

In 2002, The NOAA Paleoclimatology Program was realigned to become part of NOAA’s National Climatic Data Center. With that transition, collaborative efforts between the Climate Monitoring Branch and the Paleoclimatology Branch began the process of incorporating pre-instrumental perspectives on drought into the monthly and annual NCDC State of the Climate Reports. Each month regions that the Drought Monitor shows are particularly impacted by drought are chosen by authors of the State of the Climate Report to be discussed in its United States Drought section. In the past, this has been limited to instrumental data since 1900. Now, regions particularly hard hit are highlighted with paleoclimatic records, when possible, using either reconstructions from research specifically targeting the area of impact, or using the nearest gridpoint(s) from the gridded tree-ring reconstructed PDSI dataset. These data provide a multi-century record from which users can better assess the severity of ongoing droughts by understanding how they compare with droughts from previous centuries. Additionally, the gridded dataset allows NCDC or users to develop spatial reconstructions at regional to national levels.

The droughts that covered much of the U.S. in 2002 made the addition of paleoclimatic data to the State of the Climate Reports especially valuable. Unfortunately, paleoclimatic reconstructions are computed differently than their instrumental counterparts, and they almost never extend to the current year. Planning is underway to develop reconstructed drought records that better integrate with the instrumental record, and blended and “living” integrations of paleoclimatic and instrumental data will improve the way that these data products can be used together. Working with US and international partner organizations involved in the new North American Drought Monitor, scientists from NOAA/NCDC Paleoclimatology and universities hope to develop new tools that allow users to compare modern droughts to patterns in continental drought variability over the last several centuries.

This poster will provide examples of the use of paleoclimatic data in the NCDC Climate Reports and present plans for future pre-instrumental drought products. Input is sought on ways that paleoclimatic data can better serve users of the State of the Climate Report and the Drought Monitor.

The NCDC Climate Reports can be found at: http://lwf.ncdc.noaa.gov/oa/climate/research/monitoring.html. A variety of drought resources from NOAA Paleoclimatology can be found at: http://www.ncdc.noaa.gov/paleo/drought.html.