New study suggests global warming decreases storm activity and extreme weather

Anthony Watts:

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].

Fig. 8. Multiple proxies of environmental change in Iceland AD 700–2000. (a) Two multi-proxy temperature reconstructions, North Atlantic sea surface temperatures (SST, Mann et al., 2009) and Moberg et al. (2005). (b) Shows GISP2 Na+ deviations from the mean, a proxy for storminess (Meeker and Mayewski, 2002). Cumulative deviations from the mean show a shift to stormier and windier conditions around AD 1425 (Dugmore et al., 2007). (c) Changes in total organic carbon at Lake Haukadalsvatn, west Iceland used as a proxy for aeolian erosion (Geirsdóttir et al., 2009). Bold horizontal bars show means over periods matching key tephra horizons in study (see Table 1). (d) Woodland cover is represented by Betulapollen percentages from a lake core near Lake Mývatn, north Iceland (Lawson et al., 2007) and charcoal pits present in south Iceland (Church et al., 2007) (e) Mean aggregate SeAR from Skaftártunga for period separated by dated tephra layers, with 1 standard deviation show by grey shading. Mean calculated where n = >10. (f) Mean aggregate SeAR at the scale of the landholding, from two small landholdings (Hrífunes and Flaga, see Fig. 1d). (g) Change in SeAR at the landscape scale, 2 stratigraphic sections which record the onset of increased erosion at AD 1597, but profile 38 shows stability through the entire settlement period prior to AD 1918. (h) Population trends in Iceland. Prior to the first census in AD 1703 estimates are based on medieval populations being similar to or even higher than the population in AD 1703 (90 and 43). Plague reductions of ∼40% in AD 1402–1404 and ∼30% in AD 1496 are shown (Karlsson, 1996).

The paper:

Late-Holocene land surface change in a coupled social–ecological system, southern Iceland: a cross-scale tephrochronology approach
Richard StreeterAndrew 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.

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