The World Meteorological Organisation announced last month that there is a 50/50 of average global temperatures exceeding 1.5°C in the next 5 years. 
Why is average global temperature increasing by 1.5°C a big deal?
Firstly, the increase of 1.5°C is measured against a baseline from mid-to-late nineteenth century. And secondly, it’s important to remember that when we talk about global average temperatures increasing, this is the Earth’s average temperature – some places around the world have already crossed this line. And in some places, temperatures could rise significantly past 1.5°C.
The IPCC projects that going from 1.5 degrees of global warming to 2 degrees could mean:
•    1.7 billion more people experience severe heatwaves at least once every five years.
•    Seas rise – on average – another 10 centimetres 
•    Up to several hundred million more people become exposed to climate-related risks and poverty.
•    The coral reefs that support marine environments around the world could decline as much as 99 percent.
•    Global fishery catches could decline by another 1.5 million tonnes.