Multiple Climate Tipping Points Metrics for Improved Sustainability Assessment of Products and Services

Mounting evidence indicates that climate tipping points can have
large, potentially irreversible, impacts on the earth system and human
societies. Yet, climate change metrics applied in current sustainability
assessment methods generally do not consider these tipping points,
with the use of arbitrarily determined time horizons and assumptions
that the climate impact of a product or service is independent of
emission timing. Here, we propose a new method for calculating climate
tipping characterization factors for greenhouse gases (carbon dioxide,
methane, and nitrous oxide) at midpoint. It covers 13 projected tipping
points, incorporates the effect that the crossing of a given tipping
point has on accelerating the crossing of other tipping points, and
addresses uncertainties in the temperature thresholds that trigger
the tipping points. To demonstrate the added value of the new metric,
we apply it to emissions stemming from end-of-life of plastic polymers
and compare them with commonly used metrics. This highlights the need
to consider climate tipping in sustainability assessment of products
and services.