When talking about climate change, you will often hear the markers of 1.5 C and 2 C.
As the UN`s Intergovernmental Panel on Climate Change (IPCC) recently reported, just half a degree more in global temperatures rising since pre-industrial times could mean the difference between life and death for a large portion of the planet.
Right now, the Earth is around 1 C hotter since pre-industrial times.
In 2015, nations agreed to limit warming to 2 C as part of the Paris Agreement, which many consider the upper threshold before irreversible and catastrophic damage is done to the planet. A more ambitious, but non-binding goal, of 1.5 C was set as well, at the urging of more vulnerable countries that called 2 C warming a death sentence.
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At 1.5 C warming, the world can keep “a semblance” of the ecosystems we have now, according to IPCC.
Global warming is likely to reach 1.5 C between 2030 and 2052, according to the IPCC.
The difference between half a degree warming from now and a full degree of warming is stark.
According to IPCC’s report, with 2 C warming since pre-industrial times, sea levels would rise 0.1 metres more, there would be more heat waves, droughts and downpours, and will run the risk of the West Antarctic ice sheet irreversibly melting.
As well, there is a chance to save the coral reefs with 1.5 C warming, as opposed to no chance at 2 C, according to the report.
Half a degree more may sound small, but the number is an average of temperatures around the globe, meaning some places will become significantly hotter. The Arctic, for example, is likely to be several degrees warmer, increasing the amount of ice that will melt and how high sea levels will rise.
As well, around the Mediterranean, freshwater availability will drop almost twice as much at 2 C compared to 1.5 C warming — down 17 per cent versus nine per cent, according to the report.
The report also shows that extreme heat would be much more common, with 37 per cent of the world population exposed to extreme heat at 2 C rather than 14 per cent at 1.5 C, with the tropics experiencing the biggest increase in “highly unusual” hot days.
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Sea levels would be at least 10 centimetres higher by the end of the century at 2 C warming than they would at 1.5 C, causing mass migration from areas that may be flooded, warns the UN report.
Unfortunately, humans are well on track to passing 2 C and to limit warming to 1.5 C would require immediate, draconian cuts to emissions, which the UN sees little chance of happening.
Even worse, if we remain at our current levels of emissions, we are on a path to warming 4 C above pre-industrial levels by 2100, which if reached would trigger a chain of cataclysmic changes that include extreme heatwaves, declining global food stocks, substantial species extinctions and sea-level rising that would affect hundreds of millions of people, according to the report.