Estimates of methane emission during the last 125,000 years in Northern Eurasia

Stable carbon isotopes of invertebrate remains: do they reveal past methane release from lakes?

“…1400 years and that methane availability from this lake was larger during warmer periods than during cooler episodes. This is in line with models that suggest that during the previous glaciation Arctic wetlands produced more methane during the warmer interstadials than the cooler stadials (Velichko et al 1998;. If other high-latitude lakes responded similarly to past climatic changes as Lake S2 this would suggest that thermokarst lakes react dynamically in their methane output to environmental change.…”

Spatial distribution of Pleistocene/Holocene warming amplitudes in Northern Eurasia inferred from geothermal data

“…6 -blue area). According to another hypothesis of limited Pleistocene glaciation (Velichko, 2002) there was no continental Late Pleistocene glaciation in Western Siberia and Yakutia (Fig. 6 -brown areas).…”

“…However, the following question arises: if the influence of speculated Siberian glaciers can be so easily www.clim-past.net/3/559/2007/ (Hughes et al, 1977, Grosswald, 1996: Sc -Scandinavian, K -Kara's, ES -East Siberian. Brown areas -according to the limited Pleistocene glaciation hypothesis (Velichko, 2002). traced in today's temperature field, why is there no similar trace of the well-established Scandinavian Ice Sheet? The unexpectedly high geothermal estimates of PHW amplitudes for holes on the Kola peninsula (Kol, T =20 K, Glaznev et al, 2004), in Karelia (Krl, T =18 K, Kukkonen et al,1998), and in Poland (Udryn, T =17 K, Safanda et al, 2004) contain no indication of glacier-related warming.…”

“…Besides, several tens of thousands of years are needed to reach stationary conditions. At the same time, modern data show that the Kara's Ice Sheet was most developed during the Early and Middle Weichselian (90-60 thousand years before present), and its decay occurred at the peak of the last glaciation period (Karabanov et al, 1998;Saarnisto, 2001;Velichko, 2002). The "glacier hypothesis" is even less convincing at explaining the Late Pleistocene warming in the lower Lena River.…”

Atmospheric Methane: Trends and Impacts

“…However, results from several ice core studies support the hypothesis that increased emissions from low-latitude, followed by higher-latitude, wetlands in response to climate change were responsible for the majority of CH 4 increases (Chappellaz et al, 1993a, b;Thompson et al, 1993;Blunier et al, 1995;Brook et al, 1996). The importance of wetland emissions are emphasized by observations of a drop in CH 4 concentrations during the mid-Holocene, when tropical lakes may have dried (Blunier et al, 1995), and interactions between climatic influences and ecosystem dynamics would have reduced wetland emissions (Velichko et al, 1998). A high-resolution technique for sampling ice cores has shown that CH 4 increases at the end of the Younger Dryas cold period began somewhere between 0-30 years after an abrupt temperature increase.…”