Ocean Currents and Global Warming

In News

• According to a recent study, cold ocean currents have sheltered the Galápagos Islands from global warming.

Key Findings of Study

• Overcoming Global Warming:
  • The islands are protected from an otherwise warming Pacific Ocean by a cold, eastward equatorial ocean current and this current has been gaining strength for decades.
  • The temperatures in waters along the west coast of the Galápagos have dropped by 0.5 degrees Celsius since the early 1990s.
  • There’s a tug of war between global warming and the cold ocean current. Right now, the ocean current is winning — it’s getting cooler year after year.
• Importance of Phenomenon:
  • This phenomenon is a cause for cautious optimism for the Galápagos Islands.
  • Flora and fauna of the Galápagos could assist reseed failing ecosystems and maintain the region’s fisheries.
  • Corals do not bleach and die in these waters off the west coast of Ecuador. So, the marine food chain does not suffer, unlike in the warm waters nearby.
  • As the Galápagos so far has been relatively unaffected by climate change, it’s worth looking at the Galápagos as a potential site to really try to put some climate change mitigation efforts into.

Significance of Ocean Current

• Nutrient-rich Water: The equatorial undercurrent in the Pacific Ocean is bound to the equator by the force of the planet’s rotation. 
  • Under the ocean’s surface, a swift circulation of cold, nutrient-rich water flows from west to east.
  • Some of this water is forced to the surface when it reaches the Galápagos Islands. 
  • The nutrient-rich water triggers photosynthesis and leads to an explosion of food for a wide variety of animals.
• Stability for Coral Reefs: The cold ocean current creates a cooler, more stable environment for coral reefs and marine life and birds that often live much closer to the poles. 
• Position from Equator: From space, the Galápagos may appear to be a collection of minuscule specks in the eastern Pacific Ocean. However, it is their precise position on the equator that makes them significant.

Image Courtesy: Ces.Fau

Challenges

• Future of Current: The worry is if in the future there are changes in this current, it could be really devastating for the ecosystem.
• Regulation of Overfishing: The island group is certainly in need of greater protection from overfishing as well as the pressures of growing eco-tourism.
• Human Pressures: The human pressures on this area and the mechanism that keeps it alive are at odds. It’s a major resource that should be protected.
• Adverse Impact of El Niño: El Niño poses a threat to the island group. It shuts down the cold current every couple of years, causing penguin populations to collapse. El Niño is a climate pattern that causes unusual warming of surface waters in the eastern tropical Pacific Ocean.

Impact of Climate Change on Ocean Currents

• Influx of Warm Freshwater: Climate change leading to increases in ocean temperatures, evaporation of seawater, and glacial and sea ice melting could create an influx of warm freshwater onto the ocean surface. 
• Blocking Ice Formation: This would further block the formation of sea ice and disrupt the sinking of denser cold, salty water. 
• Excess Heat in Atmosphere: The shallow, speedy currents could ultimately limit how much heat the ocean can absorb, causing more of that excess heat to remain in the atmosphere. 
• Altering Global Temperatures: These events could slow or even stop the ocean conveyor belt, which would result in global climate changes that could include drastic decreases in Europe’s temperatures due to a disruption of the Gulf Stream.
• Affecting Marine Biodiversity: Marine microbes and wildlife could be subjected to shallower, hotter, and faster surface waters.

Conclusion

• Ocean currents can regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth’s surface. 
• Without currents in the ocean, regional temperatures would be more extreme — super hot at the equator and frigid toward the poles — and much less of Earth’s land would be habitable.

Source: DTE