Scientists believe that humanity is adding to the natural greenhouse effect, with the gases released from industries and agriculture, trapping more energy and increasing the temperature.

This is known as climate change or global warming.

Many man made emissions of CO2 come from burning fossil fuels. When carbon-absorbing forests are cut down and left to rot, or burned, that stored CO2 is released, adding to global warming.

Other greenhouse gases such as methane and nitrous oxide are also released through human activities but they are less abundant than carbon dioxide.

Across the globe, the average sea level increased by 3.6mm per year between 2005 and 2015. Most of this change due to the increases in volume of water as it heats up.

However, melting ice is now the main reason for rising sea levels. As most glaciers in temperate regions of the world are withdrawing. Satellite records show a dramatic decline in Arctic sea-ice since 1979. The Greenland Ice Sheet has experienced record melting in recent years.

The effects of a changing climate can also be seen in vegetation and animals. These include earlier flowering and fruiting times for plants and changes in the territories and habitats of animals.

An Intergovernmental Panel on Climate Change (IPCC) has reported in 2018, has suggested that keeping to the 1.5C target would require "rapid, far-reaching and unprecedented changes in all aspects of society".

The UN is a leading political effort to help stabilise greenhouse-gas emissions. China emits more CO2 than any other country. It is followed by the US and the European Union member states, but has stated that emissions per person, are much greater.

But even if we now cut down greenhouse-gas emissions dramatically, scientists say the effects will still continue. Large bodies of water and ice can take hundreds of years to respond to changes in temperature. And it takes CO2 decades to be removed from the atmosphere by natural means.

More flooding is expected from storms and rising sea levels, but there are likely to be very strong variations in these patterns. Poorer countries are least equipped to deal with rapid change and could suffer the most. Plant and animal extinctions are also predicted as habitats change faster than species can adapt. And the World Health Organization (WHO) has warned that the health of millions of people’s lives could be threatened by the increases in disease and malnutrition. 

When large amounts of CO2 is released into the atmosphere, the uptake of the gas by the oceans increases. This can cause the water to become more acidic and harm coral reefs. Global warming will cause further heating which includes the release of large quantities of methane will become permafrost which is frozen soil found mainly at high latitudes will melt. Responding to climate change is one of the biggest challenges we face this century.