Climate change, variability and sea level change

• Warming the atmosphere - the greenhouse effect
• Climate change
• The danger in the Pacific
• Go to SPREP's Climate Change Portal

Warming the atmosphere - the greenhouse effect

Heat from the sun passes through the atmosphere and warms the surface of the Earth. Some of this heat is reflected back into outer space through the atmosphere and some is retained, just like in a greenhouse. It is this balance of absorption and reflection, known as the greenhouse effect, that has kept the Earth's temperature stable for eons. Over billions of years the Earth has developed a system that can absorb and recycle the gases produced by natural process like plant and animal respiration, volcanic eruptions and forest fires.

As oil and coal are burned the carbon they contain combines with oxygen in the air to give off heat and produce carbon dioxide, and other gases. As population increases and development spreads, more and more energy is being used and ever-increasing volumes of carbon dioxide are being generated. Since 1750, when written records were first kept, the global concentration of carbon dioxide has increased by about 30%. Emissions of methane and nitrous oxide, from fuel consumption, converting forest to farmland, cultivation and fertilization of soils, production of ruminant livestock and management of livestock manure, have increased by roughly 131% and 17% in 250 years. However, carbon dioxide is the main greenhouse gas.

The amounts of greenhouse gases that are being produced have exceeded the Earth's ability to absorb them and they are accumulating in the atmosphere. As they build up they trap more and more heat from the sun inside the atmosphere. It is generally accepted that this build up is one of the primary causes of an increase in the average temperature of the Earth, which will eventually cause significant changes in the Earth’s climate.

Climate change

One of the greatest challenges to sustainable development in the 21st century is climate change. Climate change is a change in the "average weather" that a region experiences. By increasing the amount of heat-trapping gases released, humankind has enhanced the warming capability of the natural greenhouse effect. It is the human-induced enhanced greenhouse effect that causes environmental concern.

The Intergovernmental Panel on Climate Change projects that unless drastic action is taken, global temperatures will continue to rise and extreme events will become more frequent and intense. Most governments in the world are making efforts to reduce the production of greenhouse gases, even though fossil fuels will remain the mainstay of energy production well into the 21st century and agriculture must produce more and more food. Governments are also looking for ways to remove the excess carbon dioxide that is already in the atmosphere, but the amounts are so huge this may not be practical. This has serious implications for the fragile and vulnerable islands of the Pacific, already witnessing the negative impacts of climate change as sea levels rise.

The danger in the Pacific

Many Pacific islands are extremely vulnerable to climate change, climate variability, and sea level rise and will be among the first to suffer the impacts of climate change and among the first to be forced to adapt or abandon or relocate from their environment. The islands are low lying or have coastal features and characteristics that make them particularly vulnerable to climate change, variability and sea level change. In addition to significant coastal impacts climate change will affect biodiversity, soils and the water supplies of small islands. Most small island states will find it extremely difficult to adaptation to these changing conditions. The impacts will be felt for many generations because of the small island states’ low adaptive capacity, high sensitivity to external shocks and high vulnerability to natural disasters.

Failure to adapt to climate change now could lead to high social and economic costs in the future. For the low lying atolls, the economic disruption could be catastrophic, even to the extent of requiring population relocation into other islands or increasing the number of people emigrating from the islands. Some areas of coral reefs, may be so enfeebled by overfishing that they may not be able to recover from bleaching events in the future. Public pressure is mounting for action on adaptation. There is growing community and government concern about the need to reduce the islands' vulnerability and manage the risks posed by extreme events and long-term change.

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