Climate change is occurring but oceans can act to ease this change

2010-07-09 13:39

What is climate change?

Climate change is the long term change that you can see happening in the weather patterns. Examples include changes in the wind, temperature, rainfall, ice cover and ocean currents.

Although there are natural variations in the climate such as the changes you see when the seasons change, modern society’s use of oil and coal for energy and transport is causing an increasing amount of noticable change in the earth’s climate system.

According to the Intergovernmental Panel on Climate Change (IPCC), the earth is already warming (global warming). The truth is that even if society put a stop to all their harmful activities today, changes in the climate would be experienced for a long time into the future.

The major cause of global warming is the increasing concentrations of greenhouse gases (GHGs) in the atmosphere. These gases enhance what is called the greenhouse effect, by absorbing and trapping most of the energy from the sun that bounces off the land and the ocean.

The natural greenhouse effect makes earth a place where human beings and other creatures are able to live. With¬out the natural greenhouse effect the average temperature on earth would be about -19°C. But with the extra greenhouse gases coming from modern society’s industrial activities, the global temperatures are going to rise to unacceptable levels.

Climate change in the oceans

Oceans are a key part of the climate system because of their ability to absorb, store and release large amounts of heat and carbon dioxide that comes from the atmosphere.

Oceans are both affected by climate change and have the ability to ease climate change. Ways in which oceans are affected by climate change include:

•    warming and acidification of the surface waters;
•    the strength and distribution of winds and currents; and
•    the ocean’s level of productivity.

The oceans are able to ease climate change by removing heat and carbon dioxide from the atmosphere.

All over the globe, the temperatures of the surfaces of the sea have risen and the increase of carbon has led to the ocean becoming more acidic.

Oceans surrounding South Africa clearly show regions where consistent and significant warming of the sea surface and the acidification of seawater has taken place.

Ocean fertilisation

The change taking place in the ocean environment because of an increase in carbon dioxide is a concern for people throughout the world, and it demands urgent attention.

Recently, scientists have suggested a process called ocean fertilisation as another way that carbon dioxide can be removed from the atmosphere. Ocean fertilisation works by changing the chemistry of the surface seawater in the ocean.

During this process, iron is added to the sea surface water to increase the production of phytoplankton. More phytoplankton means enhanced photosynthesis. Photosynthesis is the process whereby phytoplankton uses CO2 to create food in the presence of light.

Depending on the amount of phytoplankton in the surface waters, carbon dioxide is extracted from the atmosphere and into the sea surface water where it will be used by phytoplankton as they grow.

When one of the required nutrients is used up, phytoplankton will die and sink.

Scientists think (but aren’t sure) that when the phytoplankton sink they remove carbon dioxide from the surface waters. It is not known if ocean fertilisation is a long term solution to the problem or just temporary relief from it.

But, human beings can make a big difference by doing their bit to limit acidifica-tion by reducing their carbon footprint.

Ocean acidification

The continuous release of CO2 into the atmosphere will mean an increase of CO2 in the oceans.

This in turn means a change in the chemical composition of the seawater.

Carbonic acid is formed when seawater and CO2 combine, and the process is known as ocean acidification.

Ocean acidification can negatively affect most marine life.

Acidic seawater (seawater with a low pH level) dissolves calcium carbonates. Calcium carbonates are the basic chemical building blocks needed by some marine ¬creatures such as shell-fish to survive.

Coral reefs use calcium carbonate to produce their skeletal structure. The decrease in the available calcium carbonate because of the decline in the pH level of the seawater is a very big threat to the survival of coral reefs.

The more acidic the ocean is, the more disruptive it is to the ocean’s ecosystem. Species could be endangered, and this would impact negatively on the fishing and tourism industries.

The pH level in the surface water around South Africa is about 8.13. Lower and more acidic waters of about 7.95 are found in tropical waters as nearby as Angola.

As more and more carbon is burned, the carbon dioxide in the atmosphere is expected to increase, and the oceans will gradually become more acidic.
 

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