1. Many changes to our planet are accelerating, unprecedented and irreversible
Climate change is affecting every inhabited region across the globe, and some of the impacts are accelerating.
For example, the rate of sea level rise was twice as fast between 2006 and 2018 than it was between 1971 to 2006, and three times as fast as between 1901 and 1971. We are also seeing a faster increase in the amount of rain falling over land areas in recent decades compared to earlier.
The scale of several changes are also unprecedented over centuries and even millenia. Current levels of carbon dioxide in the atmosphere are the highest in at least 2 million years and the last time the ocean warmed this quickly was when the last Ice Age ended.
And many of these changes across the climate system are irreversible over human timescales, such as changes to our oceans, ice sheets and sea level.
2. Human influence on the climate system are the main driver of changes
There is strong confidence that human influence on the climate system is the main driver of retreating glaciers worldwide, the shrinking extent of Arctic sea ice, the declining springtime snow cover in the Northern Hemisphere and a rising sea level.
Further, human-caused climate change has been linked to occurrences of extreme heat, heavy downpours (including hurricanes) and drought conditions. And compound extreme events, such as concurrent heatwaves and droughts, are also found to have been made more likely due to human influence.
3. We may cross the 1.5C threshold earlier than expected
It is likely that we will pass the average 1.5C temperature rise level by 2040, which is about a decade earlier than predicted in the 2018 IPCC report. The difference is in part because we have better estimates of global temperature between 1850 and 1900 (the baseline period for temperature increase), which resulted in scientists determining that the planet has warmed more since this time period than previously thought.
Compared to today, a warming of 1.5C will likely result in intensifying and more frequent heat waves, heavier rainfall and flooding, more severe droughts and more powerful storms.