According to a report by IPCC, the globe is expected to experience a 1.5-degree temperature rise by 2040, relative to the pre-industrial period. Given that the global temperature is currently 1-degree warmer than the pre-industrial level, this 0.5-degree increase might seem like a small difference. However, temperature increases at different speeds in different places.
For example, if Earth experiences a 1.5-degree temperature increase, the Arctic will likely to be several degrees warmer than average. This will cause ice to melt and the sea level to rise. In addition, heat waves, severe droughts, crop shrinkage and coral bleaching will occur in many parts of the world.
If the globe reaches 2 degrees of warming, the effects will be even more devastating in terms of their frequency, length and damage. In particular, almost all coral reefs will be at risk of complete destruction, which would significantly disrupt the marine ecosystem.