The Role of Climate Change in Interpreting Historical Variability

Abstract

Significant climate anomalies have characterized the last 1000 yr in the Sierra Nevada, California, USA. Two warm, dry periods of 150-and 200-yr duration occurred during AD 900-1350, which were followed by anomalously cold climates, known as the Little Ice Age, that lasted from AD 1400 to 1900. Climate in the last century has been significantly warmer. Regional biotic and physical response to these climatic periods occurred. Climate variability presents challenges when interpreting historical variability, including the need to accommodate climate effects when comparing current ecosystems to historical conditions, especially if comparisons are done to evaluate causes (e.g., human impacts) of differences, or to develop models for restoration of current ecosystems. Many historical studies focus on ''presettlement'' periods, which usually fall within the Little Ice Age. Thus, it should be assumed that ecosystems inferred for these historical periods responded to different climates than those at present, and management implications should be adjusted accordingly. The warmer centuries before the Little Ice Age may be a more appropriate analogue to the present, although no historic period is likely to be better as a model than an understanding of what conditions would be at present without intervention. Understanding the climate context of historical reconstruction studies, and adjusting implications to the present, should strengthen the value of historical variability research to management.

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

“…years ). Period I, characterized by contemporaneous wet phases in all three cores, and associated with significantly lower values of percentage melt (BY-LowC, BY-HighC and BY-a) and δ 18 O (BY-a), is broadly coeval with a period of climatic cooling well documented from sites in the North Atlantic region (Lamb 1965;Williams & Wigley 1983;Millar & Woolfenden 1999) including the Arctic (Williams & Wigley 1983;Gajewski & Atkinson 2003): i.e. the Little Ice Age (LIA).…”

Climate Change and Forests of the Future: Managing in the Face of Uncertainty

“…In this case, management seeks to bring processes of the disturbed landscape into the range of current or expected future environments (Halpin 1997). The Mono Basin case in California exemplifies this approach, where water balance models were used to determine appropriate lake levels buffered for current and expected future climate variability (Millar and Woolfenden 1999).…”

Strengths and Weaknesses of Quantitative Climate Reconstructions Based on Late-Quaternary Biological Proxies

“…Similarly the understanding of historical 'ecological legacies' (Flessa & Jackson 2005aWillis & Birks 2006) in present-day ecosystems requires records of past climate or land-use changes (Millar & Woolfenden 1999;Swetnam et al 1999;Foster et al 2003). For example, Heiri et al (2006) elegantly illustrate the use of a chironomid-based quantitative climate reconstruction as a driver in a vegetation dynamics model to simulate tree-line fluctuations during the Holocene and to test hypotheses about the causes of tree-line changes.…”