Global warming is exactly what it sounds like, the temperatures around the Earth increasing. The Earth has a regular cycle of temperatures, from warm periods, to cold ones, like the ice age, and this is known as climate oscillation. However, what is different now to the cycles ever experienced before, is that the period of warming we are currently in seems to have been made worse by the effects of humans.
Many of the changes to the average temperature around the globe have occurred since humans have started releasing more greenhouse gases and chemicals into the atmosphere.
As the temperatures around the globe increase, it leads to more ice and glaciers melting, and following that increases in the sea levels around the world. However, not only this but the weather can become more unpredictable and although, as expected, some areas will become much warmer, others will become colder. This includes the United Kingdom where, as sea levels rise, the warming effect of what is known as the Gulf Stream will lessen making temperatures colder.
Such big changes to the environment on Earth will have dramatic effects for all life, some species will likely become extinct and some countries completely disappear under water. As such people from around the world are working hard to try and reverse some of these changes, or at least stop them getting any worse.
Things we can all do to help can be very simple, like not wasting electricity and trying to move to sustainable energy sources, like solar and wind power, rather than burning fossil fuels, like gas and coal, which make the problem worse. We can make sure we use energy-saving light bulbs in our houses, and maybe turn our thermostats down by a degree. Small changes can help, but we need countries to work together on big schemes to really make a difference.