Man made climate change has far reaching impact including impact on oceans.
The effect if Climate Change on Oceans is as follows –
1) Increase in surface sea level –
According to Intergovernmental Panel on Climate Change Assessment Report 5, 28 – 98 cm rise in Sea Surface Level by 2011
a. Due to melting of glaciers
b. Due to steric expansion which is the expansion of seawater due to temperature
2) Increase in Sea Surface Temperature which is affecting the climate pattern of the world including frequent El-Nino
3) On ocean currents – According to Intergovernmental Panel on Climate Change Assessment Report 5, Global Warming would lead to weakening of Atlantic Gyre by 12-54%.
If Atlantic Gyre weakens
a. Area around Newfoundland would be affected having an impact on fisheries
b. Will lead to freezing of ports in Norway affecting its economy in which North Atlantic drift plays a major role
c. Also currents play an important role in movement of ships, which would get affected due to weakening of ocean currents
d. Thermohaline circulation would weaken which would have an impact on SST thereby affecting global climate
4) On corals – Increasing Sea Surface Temperature has led to bleaching of corals. 2015 saw the third mass coral bleaching event. Corals are supposed to be the Tropical Rain Forest of the ocean and support ocean biodiversity in a large way. Bleaching of corals thus has an effect on ocean biodiversity as well
5) Effect on Biodiversity
a. Fish Migration – Increased ocean temperature has led to migration of fishes towards the poles which has affected the fishing zones of the world, thereby having an impact on livelihood of people in coastal areas
b. Increasing Ocean acidification due to greater absorption of CO2 as blue carbon leading to deoxygenation of oceans. This impacts biodiversity including coral formation. It leads to increasing levels of Lysocline ie the line above which corals can not exist thereby impacting coral ecosystem. Increasing acidification has impacted the Sulfur cycle ie the flow of Sulfur from the oceans back into the atmosphere. This reduces reflection of solar radiation back into space, resulting in even more warming.
6) Drowning Wetlands – Wetlands are critical ecosystems having immense benefits and rising sea level has led to inundation of wetlands. Normally wetlands have the capability of vertical expansion to match up with rising sea levels, however the pace of increase of SSL has led to inundation of wetlands