"The world is going to end in 12 years..." is a recent famous quote by a prominent Democrat. I'm surprised you haven't heard it.
Personally, I bought into the climate alarmism about 30 years ago, and my skepticism is based on seeing so many things I've heard and read (even from scientists) turn out to be exaggerated.
This isn't true, and you should probably cut whatever source told it to you out of your life. The world is going to end if we don't take action within 12 years, which is the gist of what the IPCC report says.
It doesn't matter.
"The world is going to end if we don't take action within 12 years" is also false, and not at all what the IPCC report says. When O'Rourke said something similar, the AP fact checked the claim:[2]
> THE FACTS: There is no scientific consensus, much less unanimity, that the planet only has 12 years to fix the problem.
> “This has been a persistent source of confusion,” agreed Kristie L. Ebi, director of the Center for Health and the Global Environment at the University of Washington in Seattle. “The report never said we only have 12 years left.”
And no, I'm not going to cut the AP and PBS out of my life just because some alarmists are delusional.
1: https://apnews.com/1c663bcb294c1752573f45fc5bf5e0f9/
2: https://www.pbs.org/newshour/politics/ap-fact-check-orourke-...
Of course the IPCC doesn't predict the world is going to end in 12 years. That's a strawman - I'm sure you can find someone who has predicted the world will end in 12 years, but that isn't the disaster people are concerned about.
Instead, they collect five key "reasons for concern" by "using the following specific criteria: large magnitude, high probability, or irreversibility of impacts; timing of impacts; persistent vulnerability or exposure contributing to risks; or limited potential to reduce risks through adaptation or mitigation." [2]
Some of the risks associated with these include:
Risk of death, injury, ill-health, or disrupted livelihoods in low-lying coastal zones and small island developing states and other smallislands, due to storm surges, coastal flooding, and sea level rise.
...
Risk of food insecurity and the breakdown of food systems linked to warming, drought, flooding, and precipitation variability and extremes,particularly for poorer populations in urban and rural settings.
[1] https://www.ipcc.ch/reports/ (click "Assessment Reports")
[2] Pg 12, https://www.ipcc.ch/site/assets/uploads/2018/02/ar5_wgII_spm...