In the first part of this post we presented the big apparent differences between the carbon budgets (CB)
reported by the IPCC SR1.5 in 2018 and the ones formerly reported in the IPCC AR5 in
2014. Indeed, in terms of the 2019 CBs the difference, especially for the
budgets associated to lower global warming goals, are huge (see Figure-1 where
the ratio between SR1.5 and AR5 CBs is presented).
Still, in any case, as we
documented in the first part of this post the situation is extremely tight, with just a bit more than one decade (SR1.5
optimistic vision) or very few years (AR5 vision) to completely transition
towards a zero carbon emissions economy if the worst impacts of climate change
are to be avoided. Moreover, if uncertainties in CBs are considered, we showed
that CBs could in fact already be exhausted.
Figure-1: Ratio between the 2019 carbon budgets as reported
by IPCC SR1.5 in 2018 and the IPCC SR AR5 in 2014.
But let’s delve a bit deeper into the origin of the mismatch
between the CBs reported by IPCC in SR1.5 and AR5.
As shown in Figure-2 (taken from chapter-2 of
the IPCC SR1.5), the origin of the modification in CBs estimates comes from the
displacement of the relationship between global warming and cumulative
emissions, occasioned by a discrepancy between measured and modeled historic
CO2 emissions. The origin of this discrepancy is better explained by
Carbon Brief ,
with Figure-3 clearly identifying the origin of this CB discrepancy in the difference
between observed and modeled historical CO2 emissions, specifically
around 1940. The Carbon Brief’s post makes clear mention to the uncertainties associated to historic CO2
emissions observations, which seem to be specially accentuated around the 1940
period. Therefore, this being the origin of the discrepancies between SR1.5 and
AR5 CBs, calls for a note of caution when interpreting the apparent increase in
available CBs as reported by the IPCC SR1.5 as a licence to emit more carbon.
Figure-2: Functional relationships between global warming
and cumulative emissions, from where the CBs estimates are derived. The figure
comes from chapter-2 of the IPCC SR1.5 and
presents two versions of this functional relationship (and their uncertainty
bands). The functional relationship from the top comes from the climate models
used to derive the IPCC AR5 reported CBs. The functional relationship at the
bottom is the one used for the IPCC SR1.5 and incorporates a displacement of
the curve following the historic observed emissions, and then using the AR5
slopes to extrapolate the functional dependency between global warming and
cumulative emissions from 2017 onward.
Figure-3: Origin of the discrepancy between SR1.5 and AR5
IPCC reported CBs, as provided by Carbon Brief .
The origin of the discrepancy lies in the difference between observed and
modeled emissions around 1940.
In fact the evidence is growing around the fact that we
could well have overestimated CBs up till now, like the findings reported by
this recent paper, reporting a documented higher than previously thought build-up
of heat in the oceans: ‘Startling new research finds large buildup of heat inthe oceans, suggesting a faster rate of global warming’.
In fact the evidence is growing around the fact that we
could well have overestimated CBs up till now, like the findings reported by
this recent paper, reporting a documented higher than previously thought build-up
of heat in the oceans: ‘Startling new research finds large buildup of heat inthe oceans, suggesting a faster rate of global warming’.
Evidence is also building up regarding the increase of
climate impacts that we are already observing in 2018 as a result of climate
change:
- ‘Extreme global weather is 'the face of climate change' says leading scientist’
- ‘Extreme weather events in the summer of 2018 in Europe’
- ‘Yes, You Can Blame Bad Storms on Climate Change’
- ‘California’s Underwater Forests Are Being Eaten by the ‘Cockroaches of the Ocean’’
- ‘A hurricane in Spain? Leslie is headed that way’
And so many more…
Clearly corporations and
institutions have been unable to properly tackle climate change up till now, which
has left us as a legacy the extremely tight and critical situation we are
currently facing. Only a deep social change and evolution could bring us into an
appropriate transition pathway. And although already very tight, signs are
showing up of ongoing social changes that bring hope for humanity, from school
kids to poets taking the lead, and clearly illustrating the deep social nature of
tackling climate change:
- The Swedish 15-year-old who's cutting class to fight the climate crisis
- Australian students plan school strikes to protest against climate inaction
- U.S. children suing government over climate change, Australian students planning nationwide school strike
- Protesters Arrested Outside Parliament In'Extinction Rebellion' Against Climate Inaction
- Indigenous poets read urgent climate message on a melting glacier
So let’s joint efforts and between all, each maximizing its individual
and collective contributions, buildup momentum for an effective social steering
of the transition, avoiding the delays, misalignment and additional challenges
that would stem from allowing a partial and biased transition approach, like
those only focusing on the energy system, or even the economic system, as if
they were self-contained systems, and hence missing its embedded nature into society
and Earth (Figure-4), as well as missing the fundamental requirement for an overall and
integrated transition that properly addresses the structural elements that have
led to us to the brim of collapse and that prevent appropriate alternative
pathways to be followed.
Figure-4:
Acknowledging the embedded nature of the energy system and the economy into
society and Earth is the starting point for a successful transition.
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