Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass.

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Pollinators are critical for food and nutritional security and face multiple stresses including climate change. Climate change research has mostly overlooked managed pollinators (honey bees) – in spite of them playing an outsized role in providing pollination services for agriculture – and focused on feral pollinator species range shifts and altered plant-pollinator interactions that affect forage availability. Impacts of warmer autumn temperatures have also received limited focus, even though they can have subtle but important effects on plants and animals. We highlight that warmer autumns and winters in higher latitudes result in expanded geographic areas with conditions conducive for late-season honey bee flight. Utilizing honey bee colony population dynamics model simulations, we demonstrate that this late-season flight alters the overwintering colony age structure, skews the population towards older bees, leading to greater risks of colony failure. Management interventions such as overwintering colonies in cold storage facilities will likely become a critical tool to reduce honey bee colony losses. There are critical gaps in our current understanding of winter management strategies to improve the survival of overwintering colonies, and it is imperative that we bridge this gap to sustain honey bees and the beekeeping industry and ensure food and nutritional security.