1. Habitat Loss and Alteration
Climate change can lead to the loss and alteration of habitats, making them unsuitable for many species:
- Temperature Changes: Rising temperatures can alter the geographic range of habitats, forcing species to move to cooler areas, such as higher altitudes or latitudes.
- Sea Level Rise: Rising sea levels can inundate coastal habitats, such as mangroves, salt marshes, and coral reefs, leading to habitat loss for many marine and coastal species.
- Changes in Precipitation: Altered precipitation patterns can lead to droughts, reducing water availability in freshwater habitats and affecting species that depend on these ecosystems.
2. Shifts in Species Distributions
Climate change can cause species to shift their geographic ranges in response to changing environmental conditions:
- Poleward and Upward Movements: Many species are moving toward the poles or to higher elevations in search of suitable climates, leading to changes in species composition and community structure.
- Range Contractions and Expansions: Some species may experience range contractions if they cannot move to suitable habitats, while others may expand their ranges into new areas, potentially leading to new competitive interactions and ecological imbalances.
3. Altered Phenology
Phenology refers to the timing of biological events, such as flowering, migration, and breeding. Climate change can disrupt these events:
- Earlier Spring Events: Warmer temperatures can cause earlier onset of spring events, such as flowering and migration, which can lead to mismatches between species and their food sources or pollinators.
- Shifts in Breeding Seasons: Changes in temperature and precipitation patterns can alter the timing of breeding seasons, affecting reproductive success and survival rates.
4. Changes in Species Interactions
Climate change can disrupt interactions between species, such as predation, competition, and symbiosis:
- Altered Food Webs: Shifts in species distributions and phenology can affect food webs, leading to changes in predator-prey relationships and availability of food resources.
- New Competitive Interactions: As species move into new areas, they may encounter new competitors, leading to changes in community dynamics and potential declines in native species.
- Disruption of Symbiotic Relationships: Climate change can disrupt mutualistic relationships, such as those between plants and their pollinators or coral and their symbiotic algae, leading to declines in affected species.
5. Increased Risk of Extinction
Many species face an increased risk of extinction due to the combined effects of habitat loss, range shifts, altered phenology, and disrupted interactions:
- Species with Limited Dispersal Ability: Species that cannot move quickly or far enough to find suitable habitats are at higher risk of extinction.
- Specialist Species: Species with specialized habitat or dietary requirements may struggle to adapt to changing conditions and face higher extinction risks.
- Small and Fragmented Populations: Species with small, isolated populations are more vulnerable to extinction due to reduced genetic diversity and limited ability to recolonize suitable habitats.
6. Coral Bleaching
Coral reefs are particularly vulnerable to climate change, especially rising sea temperatures:
- Coral Bleaching: Higher sea temperatures cause corals to expel their symbiotic algae (zooxanthellae), leading to bleaching and increased mortality. Bleached corals are more susceptible to disease and have reduced growth and reproductive rates.
7. Ocean Acidification
Increased CO2 absorption by oceans leads to acidification, which affects marine biodiversity:
- Impact on Calcifying Organisms: Ocean acidification reduces the availability of carbonate ions needed for shell and skeleton formation, affecting organisms such as corals, mollusks, and some plankton species.
- Disruption of Marine Ecosystems: Changes in the abundance and distribution of calcifying organisms can have cascading effects on marine food webs and ecosystems.
