Sedimentary records from three Canadian High Arctic ponds on Ellesmere Island, spanning the last several thousand years, show major shifts in pond communities within the last ∼200 years. These paleolimnological data indicate that aquatic insect (Diptera: Chironomidae) populations rapidly expanded and greatly increased in community diversity beginning in the 19th century. These invertebrate changes coincided with striking shift...

The transition from arid glacial to moist early Holocene conditions represented a profound change in northern lowland Neotropical climate. Here we report a detailed record of changes in moisture availability during the latter part of this transition (∼11 250 to 7500 cal. yr BP) inferred from sediment cores retrieved in Lake Petén Itzá, northern Guatemala. Pollen assemblages demonstrate that a mesic forest had been largely esta...