Greenhouse Gases

The solar radiation that reaches the Earth's surface is either absorbed by the land, ocean and vegetation or is reflected back to the atmosphere as lower energy radiation with longer wavelengths. Greenhouse gases in the atmosphere such as carbon dioxide, water vapour, methane have physical structures suitable to absorb the long wavelength radiation and stopping it from escaping back to space. The result of this trapped radiation is a warmer atmosphere.

Carbon Cycle

The carbon cycle is the process of Carbon being recycled between Earth's atmosphere, oceans, soil and rocks. In the past 150 years, human activities such as burning coal (and other fossil fuels) increased the concentration of Carbon released into the atmosphere faster than the amount it can be absorbed back.

As the CO2 which is a greenhouse gas accumulates in the atmosphere, it stops the reflected sunlight from Earth's surface from going back to the space and the radiation that is trapped causes the temperature in the lower atmostphere to increase. This warming of the atmosphere causes a chain reaction, on land, on ocean, on climate with potentially irreversible damages.

Representative Concentration Pathways

In physical sciences, computers simulations are often used to model possible outcomes of a process given a set of initial conditions data.

In 2014 Intergovermental Panel on Climate Change used the RCPs do publish a set of representative future climate change scenarios combining the results of available climate models. The different scenarios result on different global warming estimates for 2100 based on the concentration of greenhouse gases. However, instead of being direct simulations with physical components, RCPs come from a combination of accepted possibilities in the literature and give us a range of likely scenarios.

Here is a great website to learn a lot more about the RCPs.