A paper published January 21st in Quaternary Science Reviews reconstructs storm activity in Iceland over the past 1,200 years and finds storminess and extreme weather variability was far more common during the Little Ice Age in comparison to the Medieval Warm Period and the 20th century. The paper adds to many other peer-reviewed publications finding global warming decreases storm activity, the opposite of claims by climate alarmists.

The graph below shows storm activity shown in 2nd graph from top was much greater and more variable during the Little Ice Age in comparison to the Medieval Warm Period and the 20th century. Top graph shows one of Mann’s bogus hockey sticks in red, and another non-hockey-stick reconstruction in grey [Moberg et al 2005].

The paper:

Richard Streeter, Andrew Dugmore

Highlights

• Tephrochronology can be used to produce cross scale-analysis of land surface change.

• Grímsvötn tephras are dated to AD 1432 ± 5 and AD 1457 ± 5.

• High resolution 1200-year record of land surface change from Skaftártunga, south Iceland.

• Increasing spatial heterogeneity in sediment accumulation rates after AD ∼870.

• Relationship between climate, vegetation cover and land surface change contingent on past conditions.

Abstract

The chronological challenge of cross-scale analysis within coupled socio-ecological systems can be met with tephrochronology based on numerous well-dated tephra layers. We illustrate this with an enhanced chronology from Skaftártunga, south Iceland that is based on 200 stratigraphic profiles and 2635 individual tephra deposits from 23 different eruptions within the last 1140 years. We present new sediment-accumulation rate based dating of tephra layers from Grímsvötn in AD 1432 ± 5 and AD 1457 ± 5. These and other tephras underpin an analysis of land surface stability across multiple scales. The aggregate regional sediment accumulation records suggest a relatively slow rate of land surface change which can be explained by climate and land use change over the period of human occupation of the island (after AD ∼870), but the spatial patterning of change shows that it is more complex, with landscape scale hysteresis and path dependency making the relationship between climate and land surface instability contingent. An alternative steady state of much higher rates of sediment accumulation is seen in areas below 300 m asl after AD ∼870 despite large variations in climate, with two phases of increased erosion, one related to vegetation change (AD 870–1206) and another related to climate (AD 1597–1918). In areas above 300 m asl there is a short lived increase in erosion and related deposition after settlement (AD ∼870–935) and then relatively little additional change to present. Spatial correlation between rates of sediment accumulation at different profiles decreases rapidly after AD ∼935 from ∼4 km to less than 250 m as the landscape becomes more heterogeneous. These new insights are only possible using high-resolution tephrochronology applied spatially across a landscape, an approach that can be applied to the large areas of the Earth’s surface affected by the repeated fallout of cm-scale tephra layers.

This article was originally published on The Hockey Schtick, and presented here with some minor edits for format and clarity.

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