The ever-increasing issue of climate change poses numerous threats to our planet, particularly with its impact on our oceans. According to a research paper published in ‘Trends in Ecology and Evolution’, our warming climate is causing marine species to migrate from the equator towards the poles, a phenomenon known as tropicalisation. This article delves into the causes and potential consequences of climate change and ocean warming.
The Phenomenon of Tropicalisation
Tropicalisation is a process triggered by climate change where tropical marine species expand their habitats while temperate species retreat. This shift results from rising sea temperatures leading to intensifying competition for habitat and the arrival of new predators. This migration has been first observed in the Mediterranean Sea, which is considered a tropicalisation hotspot due to the significant increase in tropical species. Such global shifts not only disrupt ocean ecosystems and biodiversity but also pose significant risks to the global economy.
Impact of Climate Change on Species Dispersal
Climate change severely affects multiple physical factors that govern species dispersal, including ocean currents. Warm-water boundary currents are heating faster than the global seawater average, facilitating the movement of marine species towards the poles. These changes are forcing temperate species to retract their habitats. Marine species, such as tropical damselfishes and temperate reef fishes, adapt by modifying their feeding and social behaviors to accommodate cohabitation.
Evolutionary Changes Triggered by Climate Change
Changes in species interactions due to shifting habitats can lead to the evolution of new traits or behaviors. The profound connection between ecology and evolution makes marine species adapt rapidly to the changing environment.
Ocean Warming Defined
Oceans absorb most of the excess heat from greenhouse gas emissions, resulting in rising ocean temperatures. Human activities like burning fossil fuels, deforestation, and industrial processes release significant amounts of carbon dioxide, methane, and nitrous oxide into the atmosphere. These greenhouse gases trap heat leading to a warming effect on both the atmosphere and the oceans. While oceans act as a vast reservoir absorbing excess carbon dioxide, this process also contributes to ocean warming.
The Consequences of Ocean Warming
Ocean warming has several far-reaching impacts. Prolonged exposure to elevated temperatures can cause coral bleaching, where corals expel the symbiotic algae living in their tissues, leaving them susceptible to diseases. This phenomenon poses a substantial threat to coral reef ecosystems.
Rising ocean temperatures also contribute to the thermal expansion of seawater. This, coupled with the melting of polar ice caps and glaciers, causes sea level rise, which can lead to coastal erosion and increased vulnerability of coastal communities.
Changes in ocean temperatures can disrupt marine food webs by altering the distribution and abundance of marine species. Such changes can severely impact fisheries and the livelihoods of communities dependent on them. Moreover, the absorption of excess carbon dioxide by oceans leads to ocean acidification, which can harm marine organisms with calcium carbonate skeletons or shells, affecting the entire marine food chain.
The global shift of marine species due to climate-induced tropicalisation threatens biodiversity, coastal communities, and economies. Therefore, urgent climate change mitigation efforts are necessary to preserve ocean health.
Note: The questions mentioned at the end of the article are from the UPSC Civil Services Examination papers from 2017 and 2022. They assess the understanding and awareness of candidates regarding the impacts of global warming, specifically on coral life systems and India’s Himalayan and coastal regions. It also includes a question on control measures to reduce greenhouse gases in line with the Kyoto Protocol, 1997.