- The world oceans, global climate drivers
- > The oceans cover around 70 per cent of the Earth’s surface. They thus play an important role in the Earth’s climate and in global warming. One important function of the oceans is to transport heat from the tropics to higher latitudes. They respond very slowly to changes in the atmosphere. Beside heat, they take up large amounts of the carbon dioxide emitted by humankind.
Earth’s climate system – a complex framework
The great ocean currents – the climate engine
Time to actClimate change will affect the oceans in many ways, and these will not be limited to just altering the currents or heat budget. Increasing carbon dioxide concentrations in the atmosphere are accompanied by higher concentrations in the oceans. This leads to increased carbonic acid levels, which acidifies the water. At present the consequences for marine animals cannot be predicted. Similarly, very little is known about how the weakening of thermohaline circulation or the Gulf Stream will affect biological communities, such as crab or fish larvae which are normally transported by currents through the oceans. The dangers associated with rising sea level were again stressed during the climate conference in Copenhagen in 2009. Specialists today largely agree that sea level will rise by around one metre by the end of this century if the worldwide emission of greenhouse gases by humans continues to increase as rapidly as it has in recent decades. This will be fatal for island nations like the Maldives, which inundation could render uninhabitable within a few decades. The fact that scientists cannot yet predict with complete certainty what the future effects of climate change will be is not a valid argument for inaction. The danger is real. Human society needs to do everything in its power to bring the climate-change experiment to an end as soon as possible. The climate system reacts slowly to changes caused by human intervention, so there is a strong possibility that some changes are already irreversible. This risk should provide sufficient motivation for forward-looking action to significantly reduce the emission of climate-relevant gases. There is no time to lose in implementing climate protection measures. There are many indications that the most severe consequences of climate change can still be avoided if investment is made today in low-carbon technology. It is time to act.