Biosphere

In terrestrial ecosystems, the earlier timing of spring events, as well as poleward and upward shifts in plant and animal ranges, have been linked with high confidence to recent warming.^[150] It is expected that most ecosystems will be affected by higher atmospheric CO₂ levels and higher global temperatures.^[151] Global warming has contributed to the expansion of drier climatic zones, such as, probably, the expansion of deserts in the subtropics.^[152] Without substantial actions to reduce the rate of global warming, land-based ecosystems risk major shifts in their composition and structure.^[153] Overall, it is expected that climate change will result in the extinction of many species and reduced diversity of ecosystems.^[154] Rising temperatures push bees to their physiological limits, and could cause the extinction of bee populations.^[155]

The ocean has heated more slowly than the land, but plants and animals in the ocean have migrated towards the colder poles as fast as or faster than species on land.^[156] Just as on land, heat waves in the ocean occur more due to climate change, with harmful effects found on a wide range of organisms such as corals, kelp, and seabirds.^[157] Ocean acidification threatens damage to coral reefs, fisheries, protected species, and other natural resources of value to society.^[158] Higher oceanic CO₂ may affect the brain and central nervous system of certain fish species, which reduces their ability to hear, smell, and evade predators.^[159]