Climate change is already now altering biomes, adversely affecting terrestrial and marine ecosystems. Climate change represents long-term changes in temperature and average weather patterns. This leads to a substantial increase in both the frequency and the intensity of extreme weather events. As a region's climate changes, a change in its flora and fauna follows. 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.Parmesan, C., M.D. Morecroft, Y. Trisurat, R. Adrian, G.Z. Anshari, A. Arneth, Q. Gao, P. Gonzalez, R. Harris, J. Price, N. Stevens, and G.H. Talukdarr, 2022: Chapter 2: Terrestrial and Freshwater Ecosystems and Their Services. In Climate Change 2022: Impacts, Adaptation and Vulnerability [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 257-260 |doi=10.1017/9781009325844.004

Furthermore, climate change may cause ecological disruption among interacting species, via changes in behaviour and phenology, or via climate niche mismatch. For example, climate change can cause species to move in different directions, potentially disrupting their interactions with each other.

Examples of effects on some biome types are provided in the following. Research into desertification is complex, and there is no single metric which can define all aspects. However, more intense climate change is still expected to increase the current extent of drylands on the Earth's continents. Most of the expansion will be seen over regions such as "southwest North America, the northern fringe of Africa, southern Africa, and Australia".

Mountains cover approximately 25 percent of the Earth's surface and provide a home to more than one-tenth of the global human population. Changes in global climate pose a number of potential risks to mountain habitats.

Boreal forests, also known as taiga, are warming at a faster rate than the global average, leading to drier conditions in the Taiga, which leads to a whole host of subsequent impacts. Climate change has a direct impact on the productivity of the boreal forest, as well as its health and regeneration.

Almost no other ecosystem is as vulnerable to climate change as coral reefs. Updated 2022 estimates show that even at a global average increase of 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 warming and beyond.

Terminology and classification On Earth, biomes are the main constituent parts of the biosphere, defined by a distinctive biological community and a shared regional climate. A single biome would include multiple ecosystems and ecoregions. 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.Olson, D. M. & E. Dinerstein (1998). The Global 200: A representation approach to conserving the Earth's most biologically valuable ecoregions. Conservation Biol. 12:502–515, .Olson, D. M., Dinerstein, E., Wikramanayake, E. D., Burgess, N. D., Powell, G. V. N., Underwood, E. C., D'Amico, J. A., Itoua, I., Strand, H. E., Morrison, J. C., Loucks, C. J., Allnutt, T. F., Ricketts, T. H., Kura, Y., Lamoreux, J. F., Wettengel, W. W., Hedao, P., Kassem, K. R. (2001). Terrestrial ecoregions of the world: a new map of life on Earth. Bioscience 51(11):933–938, .Abell, R., M. Thieme, C. Revenga, M. Bryer, M. Kottelat, N. Bogutskaya, B. Coad, N. Mandrak, S. Contreras-Balderas, W. Bussing, M. L. J. Stiassny, P. Skelton, G. R. Allen, P. Unmack, A. Naseka, R. Ng, N. Sindorf, J. Robertson, E. Armijo, J. Higgins, T. J. Heibel, E. Wikramanayake, D. Olson, H. L. Lopez, R. E. d. Reis, J. G. Lundberg, M. H. Sabaj Perez, and P. Petry. (2008). Freshwater ecoregions of the world: A new map of biogeographic units for freshwater biodiversity conservation. BioScience 58:403–414, .Spalding, M. D. et al. (2007). Marine ecoregions of the world: a bioregionalization of coastal and shelf areas. BioScience 57: 573–583, .

General impacts The 2007 IPCC Fourth Assessment Report concluded that over the last three decades human-induced warming had likely had an influence on many biological systems. The Sixth Assessment Report found that half of all species with long-term data had shifted their ranges poleward (or upward for mountain species). Two-thirds have had their spring events occur earlier. Several European bird species' breeding seasons have been shifted to earlier periods, as indicated by the shifts in nestling ringing dates. The range of hundreds of North American birds has shifted northward at an average rate of 1.5 km/year over the past 55 years.

Furthermore, climate change may disrupt the ecology among interacting species, via changes on behaviour and phenology, or via climate niche mismatch. The disruption of species-species associations is a potential consequence of climate-driven movements of each individual species in opposite directions. These changes further complicate natural resource management, with shifting species distributions and ecosystem dynamics increasing the uncertainty of long-term planning. Consequently, management strategies must become more flexible and adaptive to address continuous environmental changes. Climate change may, thus, lead to another extinction, more silent and mostly overlooked: the extinction of species' interactions. 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.

Whole ecosystem disruptions will occur earlier under more intense climate change: under the high-emissions RCP8.5 scenario, ecosystems in the tropical oceans would be the first to experience abrupt disruption before 2030, with tropical forests and polar environments following by 2050. In total, 15% of ecological assemblages would have over 20% of their species abruptly disrupted if as warming eventually reaches ; in contrast, this would happen to fewer than 2% if the warming were to stay below .

Terrestrial biomes Deserts and drylands

Research into desertification is complex, and there is no single metric which can define all aspects. 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 21st century, under the "moderate" and high-warming Representative Concentration Pathways 4.5 and 8.5. Most of the expansion will be seen over regions such as "southwest North America, the northern fringe of Africa, southern Africa, and Australia".

Grasslands

Tundra Many of the species at risk are Arctic and Antarctic fauna such as polar bears Climate change is also leading to a mismatch between the snow camouflage of arctic animals such as snowshoe hares with the increasingly snow-free landscape.

Mountains Mountains cover approximately 25 percent of earth's surface and provide a home to more than one-tenth of global human population. Changes in global climate pose a number of potential risks to mountain habitats. Climate change can adversely affect both alpine tundra and montane grasslands and shrublands. It increases the number of extreme events such as the frequency and intensity of forest fires, 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. It also causes remarkable changes in phenology.

Studies suggest a warmer climate would cause lower-elevation habitats to expand into the higher alpine zone.The Potential Effects Of Global Climate Change On The United States Report to Congress Editors: Joel B. Smith and Dennis Tirpak US-EPA December 1989 Such a shift would encroach on rare alpine meadows and other high-altitude habitats. 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. Such uphill shifts of both ranges and abundances have been recorded for various groups of species across the world. In some mountain areas, such as the Himalayas, climate change appears to promote the appearance of various invasive species of shrubs, eventually converting them to shrublands. Changes in precipitation appear to be the most important driver.

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. Another study estimated that the rainforest would lose 69% of its plant species under the warming of .

Boreal forests

Boreal forests, also known as taiga, are warming at a faster rate than the global average. leading to drier conditions in the Taiga, which leads to a whole host of subsequent issues. Climate change has a direct impact on the productivity of the boreal forest, as well as health and regeneration. As a result of the rapidly changing climate, trees show declines in growth at the southern limit of their range, and are migrating to higher latitudes and altitudes (northward) to remain their climatic habitat, but some species may not be migrating fast enough. 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. The 10-year average of boreal forest burned in North America, after several decades of around 10,000 km2 (2.5 million acres), has increased steadily since 1970 to more than 28,000 km2 (7 million acres) annually.,US National Assessment of the Potential Consequences of Climate Variability and Change Regional Paper: Alaska and records in Canada show increases in wildfire from 1920 to 1999.

Early 2010s research confirmed that since the 1960s, western Canadian boreal forests, and particularly the western coniferous forests, had already suffered substantial tree losses due to drought, and some conifers were getting replaced with aspen. Similarly, the already dry forest areas in central Alaska and far eastern Russia are also experiencing greater drought, placing birch trees under particular stress, 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. At the same time, eastern Canadian forests have been much less affected; 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.