Compared to pathways without overshoot, societies and ecosystems 
would be exposed to greater and more widespread changes in climatic 
impact-drivers, such as extreme heat and extreme precipitation, with 
increasing risks to infrastructure, low-lying coastal settlements, and 
associated livelihoods (high conﬁdence). Overshooting 1.5°C will result 
in irreversible adverse impacts on certain ecosystems with low resilience, 
such as polar, mountain, and coastal ecosystems, impacted by ice-sheet 
melt, glacier melt, or by accelerating and higher committed sea level 
rise (high conﬁdence). Overshoot increases the risks of severe impacts, 
such as increased wildﬁres, mass mortality of trees, drying of peatlands, 
thawing of permafrost and weakening natural land carbon sinks; such 
impacts could increase releases of GHGs making temperature reversal 
more challenging (medium conﬁdence). {WGI SPM C.2, WGI SPM C.2.1, 
WGI SPM C.2.3; WGII SPM B.6, WGII SPM B.6.1, WGII SPM B.6.2; SR1.5 3.6}
The larger the overshoot, the more net negative CO2 emissions needed 
to return to a given warming level (high conﬁdence). Reducing global 
temperature by removing CO2 would require net negative emissions of 
220 GtCO2 (best estimate, with a likely range of 160 to 370 GtCO2) 
for every tenth of a degree (medium conﬁdence).