Expanded spatial extent of the <scp>M</scp>edieval <scp>C</scp>limate <scp>A</scp>nomaly revealed in lake‐sediment records across the boreal region in northwest <scp>O</scp>ntario

Laird, Kathleen R.; Haig, Heather A.; Ma, Susan; Kingsbury, Melanie V.; Brown, Thomas A.; Lewis, C F M; Oglesby, Robert J.; Cumming, Brian F.

doi:10.1111/j.1365-2486.2012.02740.x

Cited by 27 publications

(42 citation statements)

References 61 publications

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“…Variability in mFRI, fire cycles, and climate over the last millennia was examined during three main periods: MCA, Medieval Climate Anomaly (AD 900-1200); LIA, Little Ice Age (AD 1500-1850); AE, Anthropocene Era (AD 1950 to present; Waters et al 2016). The establishment of the three periods was justified based on the different climatologies that characterized those periods over central North America, particularly during the warm MCA (Laird et al 2012) and the cool LIA (Laird et al 2003).…”

Section: Discussionmentioning

confidence: 99%

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Recent fire activity in the boreal eastern interior of North America is below that of the past 2000 yr

et al. 2018

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Abstract. The North American boreal forest has been developing since the end of the last glaciation approximately 10,000 yr ago. With climate warming and human occupation, it is anticipated that fire danger, ignition, and activity will be increasing, compromising forests' benefits for generations to come. In this study, we show, however, that a century of rapid climate changes and human densification has had the opposite effect in the boreal eastern interior of the North American continent, reducing biomass burning to values below two millennia of historical levels. A multi-millennial fire history was reconstructed for eight forested landscapes from the Lake of the Woods Ecoregion (LWE) located at the boreal-prairie ecotone. Fire history was reconstructed using a combination of archival (period 1920-2010), tree-ring (stand initiations and fire scars: period 1690-2010), and lake sediment charcoal (2500 BP to present) records. The archival record revealed recent large fires (>200 ha) in 1948, 1980, and 1988. An additional 19 fires were identified by the fire-scar record. Fire events in 1805, 1840, 1863, and the 1890s were identified in numerous locations around multiple lakes suggesting that they were of large extents. In accordance with the tree-ring record, the charcoal accumulation rate (CHAR) peak record generally identified the major fires but tended to lag from the tree-ring records by several decades. Within LWE, the long-term charcoal record revealed that CHAR was higher for each lake in the earlier portion of the record including the warm Medieval Climate Anomaly (AD À900 to AD 1000), followed by a progressive decrease toward the cool Little Ice Age period. This decline was abruptly interrupted in the mid-to late 19th century with large synchronized fires, also reported over western and central North America, and resumed approximately four decades later. Fire disturbance level is today below the historical range, despite the accentuated climate warming. Aging of the forest landscape may create biodiversity loss notably in fire-adapted species while at the same time setting the tone for major fires in upcoming decades if no action is taken for managing fuels.

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Section: Discussionmentioning

confidence: 99%

“…The establishment of the three periods was justified based on the different climatologies that characterized those periods over central North America, particularly during the warm MCA (Laird et al. ) and the cool LIA (Laird et al. ).…”

Section: Methodsmentioning

confidence: 99%

Recent fire activity in the boreal eastern interior of North America is below that of the past 2000 yr

et al. 2018

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“…This time, 650 years bp (~ ad 1300), corresponds with one of the most significant climate changes in the Holocene, the transition from the Medieval Warm Period ( ad 800–1200) to the Little Ice Age ( ad 1300–1850) (Maasch et al ., ; Laird et al ., ). This transition produced polar cooling (Mayewski et al ., ), polar circulation reorganization (Maasch et al ., ), wetter and cooler weather in the Great Plains (Laird et al ., ) and northwest Ontario (Laird et al ., ), a sharp drop in the number of large floods in Arizona and Utah (Ely et al ., ), an abrupt change to cooler conditions in Greenland (O'Brien et al ., 1995), and of most significance to this study, decreased Atlantic tropical cyclone activity (Mann et al ., ). Fewer strong storms in the Great South Bay region (Scileppi & Donnelly, ; Mann et al ., ) likely reduced the frequency of breaching in the barrier island.…”

Section: Discussionmentioning

confidence: 99%

Response of mollusc assemblages to climate variability and anthropogenic activities: a 4000‐year record from a shallow bar‐built lagoon system

Cerrato

LoCicero

Goodbred

2013

Global Change Biology

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With their position at the interface between land and ocean and their fragile nature, lagoons are sensitive to environmental change, and it is reasonable to expect these changes would be recorded in well-preserved taxa such as molluscs. To test this, the 4000-year history of molluscs in Great South Bay, a bar-built lagoon, was reconstructed from 24 vibracores. Using x-radiography to identify shell layers, faunal counts, shell condition, organic content, and sediment type were measured in 325 samples. Sample age was estimated by interpolating 40 radiocarbon dates. K-means cluster analysis identified three molluscan assemblages, corresponding to sand-associated and mud-associated groups, and the third associated with inlet areas. Redundancy and regression tree analyses indicated that significant transitions from the sand-associated to mud-associated assemblage occurred over large portions of the bay about 650 and 294 years bp. The first date corresponds to the transition from the Medieval Warm Period to the Little Ice Age; this change in climate reduced the frequency of strong storms, likely leading to reduced barrier island breaching, greater bay enclosure, and fine-grained sediment accumulation. The second date marks the initiation of clear cutting by European settlers, an activity that would have increased runoff of fine-grained material. The occurrence of the inlet assemblage in the western and eastern ends of the bay is consistent with a history of inlets in these areas, even though prior to Hurricane Sandy in 2012, no inlet was present in the eastern bay in almost 200 years. The mud dominant, Mulinia lateralis, is a bivalve often associated with environmental disturbances. Its increased frequency over the past 300 years suggests that disturbances are more common in the bay than in the past. Management activities maintaining the current barrier island state may be contributing to the sand-mud transition and to the bay's susceptibility to disturbances.

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“…Laird and Cumming [2008] developed an approach to infer water depths in open-basin lakes from changes in diatom assemblages in sediment cores. They applied this approach to boreal forest lakes in northwestern Ontario, Canada to interpret the consequences of drought from A.D. 900-1400 [Laird et al, 2012]. A similar approach was also used with shallow lakes of Nebraska Sand Hills [Shinneman et al, 2010].…”

Section: Water Resources Researchmentioning

confidence: 99%

On modeling the paleohydrologic response of closed‐basin lakes to fluctuations in climate: Methods, applications, and implications

Liu

Schwartz

2014

Water Resources Research

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Climate reconstructions using tree rings and lake sediments have contributed significantly to the understanding of Holocene climates. Approaches focused specifically on reconstructing the temporal water-level response of lakes, however, are much less developed. This paper describes a statistical correlation approach based on time series with Palmer Drought Severity Index (PDSI) values derived from instrumental records or tree rings as a basis for reconstructing stage hydrographs for closed-basin lakes. We use a distributed lag correlation model to calculate a variable, x t that represents the water level of a lake at any time t as a result of integrated climatic forcing from preceding years. The method was validated using both synthetic and measured lake-stage data and the study found that a lake's ''memory'' of climate fades as time passes, following an exponential-decay function at rates determined by the correlation time lag. Calculated trends in x t for Moon Lake, Rice Lake, and Lake Mina from A.D. 1401 to 1860 compared well with the established chronologies (salinity, moisture, and Mg/Ca ratios) reconstructed from sediments. This method provides an independent approach for developing high-resolution information on lake behaviors in preinstrumental times and has been able to identify problems of climate signal deterioration in sediment-based climate reconstructions in lakes with a long time lag.

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Expanded spatial extent of the Medieval Climate Anomaly revealed in lake‐sediment records across the boreal region in northwest Ontario

Cited by 27 publications

References 61 publications

Recent fire activity in the boreal eastern interior of North America is below that of the past 2000 yr

Recent fire activity in the boreal eastern interior of North America is below that of the past 2000 yr

Response of mollusc assemblages to climate variability and anthropogenic activities: a 4000‐year record from a shallow bar‐built lagoon system

On modeling the paleohydrologic response of closed‐basin lakes to fluctuations in climate: Methods, applications, and implications

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