Boucher, Olivier; Bellassen, Valentin; Benveniste, Helene; Ciais,
Philippe; Criqui, Patrick; Guivarch, Celine et al. (2016): Opinion: In
the wake of Paris Agreement, scientists must embrace new directions for
climate change research. In Proceedings of the National Academy of
Sciences of the United States of America 113 (27), pp. 7287–7290. DOI
10.1073/pnas.1607739113.
http://www.pnas.org/content/113/27/7287
Opinion: In the wake of Paris Agreement, scientists must embrace new
directions for climate change research
At each Conference of Parties (COP), scientists hand over the climate
change problem to diplomats and policymakers. A COP also offers
scientists a chance to take stock of their research, confront emerging
policy questions, identify research gaps, and update their research
agendas. We, as an interdisciplinary group of academic experts who have
been providing independent insights to the COP21 French presidency and
negotiation team (1
<http://www.pnas.org/content/113/27/7287.full#ref-1>), have seen not
only the importance of science in policymaking but also its limitations
and sometimes its lack of alignment with the complex environmental and
societal issues addressed in the negotiations. Here we analyze research
gaps and identify new directions of research in relation to a number of
facets of the Paris Agreement, including the new 1.5 °C objective, the
articulation between near-term and long-term mitigation pathways,
negative emissions, verification, climate finance, non-Parties
stakeholders, and adaptation.
The Paris Agreement is an admirable first step, but scientists must come
to terms with its research and policy implications. Image courtesy of
Flickr/jmdigne.
The Paris Agreement has sealed several concrete achievements, in
particular the introduction of a five-year submission cycle for
nationally determined contributions (NDC), which spells out voluntary
short-term domestic climate policies and the generalization of a
measurement, verification, and monitoring (MRV) system to all parties.
Another objective is to increase finance flows “towards low greenhouse
gas emissions development” (2
<http://www.pnas.org/content/113/27/7287.full#ref-2>). These and other
measures aim to encourage “holding the increase in the global average
temperature to well below 2 °C” and call for “pursuing efforts to limit
the temperature increase to 1.5 °C above preindustrial levels” (2
<http://www.pnas.org/content/113/27/7287.full#ref-2>). Furthermore, the
agreement invites the Intergovernmental Panel on Climate Change (IPCC)
to provide a special report in 2018 on the impacts of a global
temperature rise of 1.5 °C above preindustrial levels and global
greenhouse gas emission pathways leading to this new objective.
A Controversial 1.5 °C Objective
However, the agreement has left in its wake numerous complex issues with
which scientists and policymakers must wrestle. For example, the 1.5 °C
objective offers contradictory perspectives that may be difficult to
reconcile, and hence may divide the scientific community. Diverging
short-term interests among signatory countries, socio-economic barriers
to changes, and technological lock-ins in energy systems question the
feasibility of such a goal. Furthermore, this 1.5 °C objective may
distract the community from focusing research efforts on the risks and
impacts of more severe warming scenarios between 2 °C and 4 °C. These
scenarios are more likely to happen than the 1.5 °C, and require
adaptation measures planned well in advance. Focusing on a 1.5 °C
scenario also constitutes, some argue, a form of hypocrisy, sustaining
false hope from the public and most vulnerable countries.
Although achieving a 1.5 °C objective may appear as a lost cause, it can
nevertheless be seen as a necessary baseline for climate negotiations (3
<http://www.pnas.org/content/113/27/7287.full#ref-3>). There is also an
ethical issue in play: it is certainly too early in climate negotiations
to accept the destruction of low-lying islands and other regions that
may not be capable of adapting to warmer conditions. Finally, we must
acknowledge that technological progress, together with efforts from all
stakeholders and widespread changes to individual behaviors, could bring
enough mitigation to effectively bridge the gap to the 2 °C—if not the
new 1.5 °C—objective.
Indeed, the Paris Agreement does not specify a date for the long-term
goal, opening the possibility for overshoot scenarios, whereby global
warming would "What synergies and trade-offs exist with other policy
goals (including development, poverty alleviation, air quality, energy
security, and employment)? Such analyses are necessary to understand how
ambitious climate policies can strive to be."exceed 1.5 °C or 2 °C
before being driven down via negative-emission technologies. In this
view, there is a real risk that such technologies will meet constraints
that strongly limit their large-scale deployment (4
<http://www.pnas.org/content/113/27/7287.full#ref-4>, 5
<http://www.pnas.org/content/113/27/7287.full#ref-5>); as a result, they
would not deliver the hypothesized greenhouse gas mitigation in the
second half of the century. The continued development and effective
deployment of these technologies cannot occur without a strong political
drive, as well as sustained research and development efforts.
To gain credibility, scenarios compatible with the 1.5 °C or 2 °C
objectives will have to identify all potential innovations—whether
incremental or disruptive, social or technical—and consider the many
barriers involved in curbing emissions. Achieving such pathways will
require transformational changes in human behavior and economic
production, arguably carrying profound geopolitical implications. A
massive reliance on bioenergy, for example, could have important
consequences on water resources and food security. Such pathways will
have to be considered in a systemic way, beyond the usual model
assumptions of rapid and optimal deployment of solutions for greenhouse
gas emissions reductions.
In any case, the research effort to reduce uncertainties on the
magnitude of the response of the climate system to greenhouse gases
should not be diminished, as possible 21st century greenhouse gas
emissions pathways depend strongly on it.
<http://www.pnas.org/content/113/27/7287.full#sec-3>
Reconciling Short- and Long-Term Visions
A number of analyses, including that of the United Nations Framework
Convention on Climate Change secretariat (6
<http://www.pnas.org/content/113/27/7287.full#ref-6>) and the United
Nations Environment Programme Gap Report (7
<http://www.pnas.org/content/113/27/7287.full#ref-7>), have estimated
that current intended NDCs will place 2030 global emissions well above
emissions trajectories compatible with the 2 °C objective. This estimate
is acknowledged in the COP decision, which notes “with concern” that
“much greater emission efforts will be required than those associated
with the intended NDCs in order to hold the increase in global
temperature to below 2 °C” (2
<http://www.pnas.org/content/113/27/7287.full#ref-2>). There is,
therefore, a pressing need to reconcile the long-term global 2 °C
objective with the short-term national objectives. The Paris Agreement
therefore calls for a dual articulation of efforts across the space and
time dimensions.
Research should focus on both the short-term effects of planned policies
centered on greenhouse gases emissions abatement, as well as their
long-term implications. Emissions reductions imply socio-economic
transformations that need to be made explicit (8
<http://www.pnas.org/content/113/27/7287.full#ref-8>): What might be the
role of different mitigation wedges, including those that have been
understudied such as improved urban planning or behavioral changes? What
socio-technical challenges will come about because of the high rate of
changes (e.g., on stranded assets in the energy sector) and how can they
be addressed? How should the needed policies and measures be financed
and by whom?
Managing terrestrial carbon sinks, as put forward in the intended NDC of
some countries, is another way to achieve mitigation. The rate of carbon
uptake by vegetation and soils varies between regions, fluctuates over
years in response to climate variations, and may have slightly weakened
over the last 50 years (9
<http://www.pnas.org/content/113/27/7287.full#ref-9>). The short- to
long-term potential for carbon sequestration in (natural and managed)
ecosystems remains uncertain, and models currently fail to produce a
consistent story about the future efficiency of carbon sinks as climate
change proceeds (10
<http://www.pnas.org/content/113/27/7287.full#ref-10>). This calls for a
better description of land-use management in Earth system models and
further improvement in their explanatory and predictive capability of
the carbon cycle.
From Global to Local and Back
Research efforts must decipher to what extent national scenarios build
on plausible future international contexts and whether global scenarios
are integrating realistic national priorities (11
<http://www.pnas.org/content/113/27/7287.full#ref-11>). Hence, national
and global models and scenarios have to be made consistent with one
another. Doing so would allow policymakers to check the consistency of
NDCs, understand their interlinkages (through explicit dependencies in
national or regional policies, such as emission trading schemes,
technology transfers, trade, and capital flows), and potentially
identify levers to raise their collective ambition. This analysis is
particularly important for energy-exporting nations in the context of a
transition to a low-carbon world economy.
An innovative feature of the Paris Agreement is that it recognizes the
crucial role of “non-Parties stakeholders,” including the private sector
and subnational authorities. This feature drastically widens the scope
of relevant research for social and economic sciences. First, studies on
development strategies could analyze the macroeconomic implications (in
terms of, for example, growth and employment) of a “New Climate Economy”
that achieves prosperity while also addressing climate change (12
<http://www.pnas.org/content/113/27/7287.full#ref-12>). Second, research
on the role of low-carbon technologies could help identify new
innovation strategies for companies of all sizes (13
<http://www.pnas.org/content/113/27/7287.full#ref-13>).
Furthermore, the role of local, state, and regional governments should
be taken into consideration. In many cases, managing low-carbon
solutions depends on local authorities’ abilities to design appropriate
systemic solutions, such as in urban planning and public transportation.
Mitigation actions at the local level may also trigger important
cobenefits in terms of adaptation, as well as specific capacities to
limit climate risks and other social and environmental risks.
Transparency and Verification
Comparing the intended NDCs from countries to emission inventories and
pathways available in academic studies leads to more questions than
answers regarding data sources, quality, and accounting methods.
Extending to non-Annex 1 countries the obligation to submit appropriate
national greenhouse gas inventories in line with IPCC guidelines will
generate a more transparent and accurate emission dataset at the
national scale. However, transparency should not be seen merely as a
technical issue, but also as a full-fledged research topic both in
natural and social sciences.
In the social sciences, the cost/benefit of an increased effort to
strengthen MRV needs to be carefully assessed: higher MRV stringency can
be detrimental if they hamper possible mitigation actions (14
<http://www.pnas.org/content/113/27/7287.full#ref-14>). In practice, MRV
rules adopted in actual climate-mitigation mechanisms strongly influence
the cost efficiency of MRV (15
<http://www.pnas.org/content/113/27/7287.full#ref-15>). Designing rules
that optimize resource allocation in MRV is therefore paramount.
In the natural sciences, reducing uncertainties in greenhouse gases
sources and sinks—especially for non-CO_2 gases and soil carbon in the
sector of agriculture, forestry and other land use (16
<http://www.pnas.org/content/113/27/7287.full#ref-16>)—should be a high
priority. In particular, estimates of soil carbon content and its
variations are very uncertain. New and future CO_2 measurements offer
opportunities for source and sink inversion methods combining bottom-up
(statistical data) and top-down (atmospheric) approaches (17
<http://www.pnas.org/content/113/27/7287.full#ref-17>).
Beyond Emissions
Reduction in greenhouse gas emissions is the final outcome of a
mitigation policy, which takes time to achieve. The urgency of climate
action calls for verification procedures to be broadened to structural
changes and other early indicators of climate policies (such as
investment and financing). This verification would allow checking that
the Paris Agreement measures, with regard to finance flows, effectively
contribute toward low greenhouse gas emissions development. More regular
and intercomparable ex post assessments of climate policies will be
needed to provide critical information on which policy is more
effective, so that countries can learn from each other on how to best
implement and monitor their climate policies.
Finally, the Paris Agreement underscores the importance of climate
change adaptation policies with substantial funding mechanisms.
Approving and prioritizing such adaptation undertakings will require
robust climate science on regional climate change and impact assessment,
with improved global climate simulations and downscaling techniques.
This will involve a better understanding of regional climate
variability, and disentangling the role of climate change and other
drivers for changes. It also requires assessing synergies between
adaptation to climate change and increased resilience to natural climate
variability and other stresses.
In conclusion, the Paris Agreement not only calls for further
disciplinary research but also for an increased capacity of the
scientific community for interdisciplinary work on multiple scales. The
need to better estimate the magnitude of the climate response to
greenhouse gases, and its regional aspects in relation to adaptation
strategies, cannot be overstated. Research in social and economic
sciences rely on three paradigms: the use of Integrated Assessment
Models, the development of national de-carbonization scenarios, and the
production of sectoral or community level “innovation-for-transition”
studies that are applied jointly to climate governance at international,
regional, national, and subnational levels. Finally, the need for
transparency and verification will require research to improve
regulatory design.
The Paris Agreement is an admirable first step. But in order for the
deal to have a long-term impact, scientists must come to terms with its
research and policy implications, and pursue all aspects of this massive
challenge.
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