Abstract
“Climate tipping elements” often refer to large-scale earth systems
with the potential to respond nonlinearly to anthropogenic climate
change by transitioning towards substantially different long-term states
upon passing key thresholds, frequently referred to as “tipping
points.” In some but not all cases, such changes could produce
additional greenhouse gas emissions or radiative forcing that could
compound global warming. Improving understanding of tipping elements is
important for predicting future climate risks. Here we review
mechanisms, predictions, impacts, and knowledge gaps associated with ten
notable earth systems proposed to be climate tipping elements. We
evaluate which tipping elements are more imminent and whether shifts
will likely manifest rapidly or over longer timescales. Some tipping
elements are significant to future global climate and will likely affect
major ecosystems, climate patterns, and/or carbon cycling within the
21st century. However, assessments under different emissions scenarios
indicate a strong potential to reduce or avoid impacts associated with
many tipping elements through climate change mitigation. Most tipping
elements do not possess the potential for abrupt future change within
years, and some proposed tipping elements may not exhibit tipping
behavior, rather responding more predictably and directly to the
magnitude of forcing. Nevertheless, significant uncertainties remain
associated with many tipping elements, highlighting an acute need for
further research and modeling to better constrain risks.