Used to refer to the rising temperatures on planet Earth, caused mostly be increases in greenhouse gases, especially the carbon-dioxide and other greenhouse gases caused by burning fossil fuels.
This is often used as a synonym for #climateChange, except it sounds worse. They are similar terms, and are closely related, but they do mean different things.
Climate change is actually more accurately portraying the full story, though, since some of the worst changes are things like the acidification of our oceans and the mass extinction of countless species. Some of these changes have more to do with directly introducing noxious chemicals into our environment and less to do with the actual rise in temperature. But many of these pollutants also contribute to the rising temperatures of Earth, which is referred to as Global Warming.
The process of global warming is an especially lethal aspect of climate change because it causes a feedback loop, where the rising temperatures affect other things in the environment which further contribute to rising temperatures. Without anything to slow down and even reverse these processes, we are nearing the tipping point of a runaway rise in temperature that could possibly result in the Earth becoming completely uninhabitable, and perhaps even the complete loss of our atmosphere, which would cause Earth to look a lot like Mars.
