Causes of global warming
For a long time people on our Earth didn't think a lot about greenhouse gases. The situation changed when people started using more and more energy in the form of fossil fuels, like oil, gas and coal. We burn fossil fuels to power factories, run cars, produce electricity and heat houses. As fossil fuels burn they let carbon dioxide into the atmosphere.
During the last few decades people have also cut down many forests. Trees use carbon dioxide when they make their own food. Fewer trees mean that less carbon dioxide is taken out of the atmosphere.
Possible effects of global warming
Scientists have different opinions on how warm the Earth's surface will really get. The ...view middle of the document...
It works like an electric car but also has a small petrol engine.
Rising sea levels are the most common concern; taking place with a thermal expansion of the oceans—a result of water molecules expanding in warmer temperatures, increased precipitation, and the melting of mountain glaciers. Because all bodies of water have varying shapes and ocean water tends to “swell” differently depending on its starting temperature, the change in sea level is not uniform over the surface of the Earth. In the 20th century alone, sea levels rose 0.17 meters predictions for the next century range anywhere from 0.18 to 0.59 meters. While smaller projections would likely have only relatively modest impacts, the higher projections could have dramatic effects on low-lying coastal communities.
Currently, the Arctic summer sea ice is about half as thick as it was in 1950. Just like an ice cube melting in a glass of water, the melting Arctic sea ice does not contribute to sea-level rise, except for the expansion of seawater with increasing heat. However, melting Arctic sea ice may lead to global changes in ocean circulation. Water from melted ice forms a layer at the sea surface that is less dense than the underlying water since it is less salty, potentially preventing the pattern of deep ocean currents from rising to the surface. Additionally, melting sea ice speeds up the warming of the Arctic since water absorbs 80% of sunlight, about the same amount that the cover of sea ice used to reflect.
While the idea of swimming in a warmer ocean is pleasant to most human beings, increasing ocean temperatures could cause serious ecological damage. Approximately one quarter of the world’s coral reefs have died over the last few decades, many of them affected by coral bleaching—a process directly tied to warming waters which weakens the coral animals.
An increase in global temperature will likely enhance the ability for severe weather, which could mean stronger and more frequent storms. Warmer temperatures cause more evaporation of water, which, as part of the water cycle eventually leads to increased precipitation and further increasing the potential for flooding. While some parts of the world are projected to experience increased precipitation, others may experience higher levels of drought as places that are typically dry—such as the centers of continents—experience even more evaporation as global temperatures climb....