Despite substantial changes in climate, sea-ice and glacier extent, and vegetation in much of the Arctic, the area near Toolik Lake, Alaska has experienced no significant trends of increasing temperature, altered precipitation, or increasing active-layer thaw depth. There has been, however, a near doubling of alkalinity in Toolik Lake since 1975 and increases in alkalinity in many lakes of all depths and sizes in the surrounding area. Lake monitoring indicates that in-lake processes such as sulfate or nitrate reduction cannot account for these alkalinity increases. Measurements of strontium isotopes and trace element concentrations indicate that increased weathering in the sediments beneath lakes and streams explains the dramatic geochemical changes over 30 years in Toolik Lake. Similar geochemical alterations may be occurring in unmonitored areas of the Arctic, even if soil thaw depth remains unchanged. In addition to these geochemical trends, terrestrial responses to climate change have recently resulted in dramatic land-surface disturbances in the form of thermokarst failures and tundra fires – such disturbances have the potential for alteration of aquatic geochemistry and may result in larger and more rapid transformations than will the steady trends in climate change.