A first pan‐Arctic assessment of the influence of glaciation, permafrost, topography and peatlands on northern hemisphere lake distribution

The locations of ∼200 000 large northern hemisphere lakes (sized 0.1 to 50 km2, northwards of ∼45°N latitude) are intersected with new global databases on topography, permafrost, peatlands and LGM glaciation to identify some first‐order controls on lake abundance and land area fraction at the pan‐Arctic scale. Of the variables examined here, glaciation history and the presence of some form of permafrost appear most important to the existence of lakes. Lake densities and area fractions average ∼300–350% greater in glaciated (versus unglaciated) terrain, and ∼100–170% greater in permafrost‐ influenced (versus permafrost‐free) terrain. The presence of peatlands is associated with additional ∼40–80% increases in lake density and ∼10–50% increases in area fraction. On average, lakes are most abundant in glaciated, permafrost peatlands (∼14.4 lakes/1000 km2) and least abundant in unglaciated, permafrost‐free terrain (∼1.2 lakes/1000 km2). Lake statistics are surprisingly similar across continuous, discontinuous and sporadic permafrost zones, decrease modestly in isolated permafrost, and drop sharply in the absence of permafrost. A simple calculation based on ‘space‐for‐time’ substitution for all glaciated/lowland terrain (∼2.7 × 107 km2, of which ∼48% is currently in some state of permafrost) suggests that in a ‘permafrost‐free’ Arctic, the number of lakes could be reduced from ∼192 000 to 103 000 (−46%) and their total inundation area reduced from ∼560 000 to 325 000 km2 (−42%). A more realistic scenario of thawed discontinuous, sporadic and isolated permafrost only, with a +10% lake increase in continuous permafrost and no change in permafrost‐free areas suggests reductions to ∼155 000 lakes (−15%) and ∼476 000 km2 (−15%), respectively. Copyright © 2007 John Wiley & Sons, Ltd.