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Full Version: What is climate change? A really simple guide
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Scientists say global warming could have a catastrophic effect on the planet. Human activities have increased carbon-dioxide emissions, driving up temperatures.

What is climate change? The Earth's average temperature is about 15C but has been much higher and lower in the past. There are natural fluctuations in the climate but scientists say temperatures are now rising faster than at many other times. This is linked to the greenhouse effect, which describes how the Earth's atmosphere traps some of the Sun's energy. Solar energy radiating back to space from the Earth's surface is absorbed by greenhouse gases and re-emitted in all directions. This heats both the lower atmosphere and the surface of the planet. Without this effect, the Earth would be about 30C colder and hostile to life. Scientists believe we are adding to the natural greenhouse effect, with gases released from industry and agriculture trapping more energy and increasing the temperature.

What are greenhouse gases? The greenhouse gas with the greatest impact on warming is water vapour and it remains in the atmosphere for only a few days. Carbon dioxide, however, persists for much longer. It would take hundreds of years for a return to pre-industrial levels and only so much can be soaked up by natural reservoirs such as the oceans. Most man-made emissions of carbon dioxide come from burning fossil fuels. When carbon-absorbing forests are cut down and left to rot, or burned, that stored carbon is released, contributing to global warming.

Since the Industrial Revolution began in about 1750, carbon dioxide levels have risen more than 30%. Other greenhouse gases such as methane and nitrous oxide are also released through human activities but they are less abundant than carbon dioxide.

What is the evidence for warming? The world is about one degree Celsius warmer than before widespread industrialisation. The 20 warmest years on record all occurred in the past 22 years, with 2015-2018 making up the top four. Across the globe, the average sea level increased by 3.6mm per year between 2005 and 2015. Most of this change was because water increases in volume as it heats up. However, melting ice is now thought to be the main reason for rising sea levels. Most glaciers in temperate regions of the world are retreating. Satellite records show a dramatic decline in Arctic sea-ice since 1979. The Greenland Ice Sheet has experienced record melting in recent years. Satellite data also shows the West Antarctic Ice Sheet is losing mass. A recent study indicated East Antarctica may also have started to lose mass. The effects of a changing climate can also be seen in vegetation and land animals. These include earlier flowering and fruiting times for plants and changes in the territories of animals.

There is uncertainty about how great the impact of a changing climate will be. It could cause fresh water shortages, dramatically alter our ability to produce food, and increase the number of deaths from floods, storms and heatwaves. This is because climate change is expected to increase the frequency of extreme weather events. As the world warms, more water evaporates, leading to more moisture in the air. This means many areas will experience more intense rainfall - and in some places snowfall. The risk of drought in inland areas during hot summers will increase. More flooding is expected from storms and rising sea levels. Poorer countries, which are least equipped to deal with rapid change, could suffer the most.

Plant and animal extinctions are predicted as habitats change faster than species can adapt. As more carbon dioxide is released into the atmosphere, uptake of the gas by the oceans increases, causing the water to become more acidic. This could pose major problems for coral reefs. The World Health Organization has warned that the health of millions could be threatened by increases in malaria, water-borne disease and malnutrition. 

The UN is leading a political effort to stabilise greenhouse-gas emissions. China emits more carbon dioxide than any other country. It is followed by the US and the European Union member states. Even if we now cut greenhouse-gas emissions dramatically, scientists say the effects will continue. Large bodies of water and ice can take hundreds of years to respond to changes in temperature and it takes carbon dioxide decades to be removed from the atmosphere.
I think that more countries should be understanding the ‘bad’ that they have put into the environment and begin by following a simple act of change. I think even the smallest actions will help because eventually they will all add up and make a change and we can fight against climate change. I think we should try everything and anything that we can do, even if it seems like it won't change or do anything. We need to try to remove the carbon dioxide from the air now because it will be too late if we leave it all to the last minute.