Effects of climate change on biomes

[7] For instance, out of 4000 species analyzed by the IPCC Sixth Assessment Report, half were found to have shifted their distribution to higher latitudes or elevations in response to climate change.

Updated 2022 estimates show that even at a global average increase of 1.5 °C (2.7 °F) over pre-industrial temperatures, only 0.2% of the world's coral reefs would still be able to withstand marine heatwaves, as opposed to 84% being able to do so now, with the figure dropping to 0% at 2 °C (3.6 °F) warming and beyond.

[16][17] On Earth, biomes are the main constituent parts of the biosphere, defined by a distinctive biological community and a shared regional climate.

According to the World Wildlife Fund classification, terrestrial, marine and freshwater environments each consist of hundreds of ecoregions, around a dozen biome types, and a single-digit number of biogeographic regions.

As a consequence of the spatial decoupling of species-species associations, ecosystem services derived from biotic interactions are also at risk from climate niche mismatch.

However, more intense climate change is still expected to increase the current extent of drylands on the Earth's continents: from 38% in late 20th century to 50% or 56% by the end of the[which?]

It increases the number of extreme events such as the frequency and intensity of forest fires,[47] and accelerates snowmelt, which makes more water available earlier in the year and reduces availability later in the year, while the reduction in snow cover insulation can paradoxically increase cold damage from springtime frost events.

High-elevation plants and animals have limited space available for new habitat as they move higher on the mountains in order to adapt to long-term changes in regional climate.

[55][56] It's been estimated that by 2050, climate change alone could reduce species richness of trees in the Amazon Rainforest by 31–37%, while deforestation alone could be responsible for 19–36%, and the combined effect might reach 58%.

The paper's worst-case scenario for both stressors had only 53% of the original rainforest area surviving as a continuous ecosystem by 2050, with the rest reduced to a severely fragmented block.

[60][61][62] The number of days with extremely cold temperatures (e.g., −20 to −40 °C (−4 to −40 °F) has decreased irregularly but systematically in nearly all the boreal region, allowing better survival for tree-damaging insects.

[15] Similarly, the already dry forest areas in central Alaska and far eastern Russia are also experiencing greater drought,[67] placing birch trees under particular stress,[68] while Siberia's needle-shedding larches are replaced with evergreen conifers - a change which also affects the area's albedo (evergreen trees absorb more heat than the snow-covered ground) and acts as a small, yet detectable climate change feedback.

[69] At the same time, eastern Canadian forests have been much less affected;[70][71] yet some research suggests it would also reach a tipping point around 2080, under the RCP 8.5 scenario which represents the largest potential increase in anthropogenic emissions.

Since 1998, the lack of severe winters in British Columbia had enabled a devastating pine beetle infestation, which had killed 33 million acres or 135,000 km2 by 2008;[82][83] a level an order of magnitude larger than any previously recorded outbreak.

This size allows it to produce around half of its own rainfall by recycling moisture through evaporation and transpiration as air moves across the forest;[90] tree losses interfere with that capability, to the point where if enough is lost, much of the rest will likely die off and transform into a dry savanna landscape.

[93][94] Research suggests that slow-growing trees are only stimulated in growth for a short period under higher CO2 levels, while faster growing plants like liana benefit in the long term.

In general, but especially in rainforests, this means that liana become the prevalent species; and because they decompose much faster than trees their carbon content is more quickly returned to the atmosphere.

[95] Warmer-than-ideal conditions result in higher metabolism and consequent reductions in body size despite increased foraging, which in turn elevates the risk of predation.

It found that if their water temperature increases by 4 °C (7.2 °F) in July (said to occur under approximately the same amount of global warming), then cold-water fish species like cisco would disappear from 167 lakes, which represents 61% of their habitat in Minnesota.

Ocean krill, a cornerstone species, prefer cold water and are the primary food source for aquatic mammals such as the blue whale.

[99] Species of fish living in cold or cool water can see a reduction in population of up to 50% in the majority of U.S. freshwater streams, according to most climate change models.

[100] The increase in metabolic demands due to higher water temperatures, in combination with decreasing amounts of food will be the main contributors to their decline.

[100] To add to this, rising seas will begin to flood coastal river systems, converting them from fresh water habitats to saline environments where indigenous species will likely perish.

[100] This rise in sea level not only contaminates streams and rivers with saline water, but also the reservoirs they are connected to, where species such as sockeye salmon live.

[100] In the Arctic, the waters of Hudson Bay are ice-free for three weeks longer than they were thirty years ago, affecting polar bears, which prefer to hunt on sea ice.