Kawamiya et al. Progress in Earth and Planetary Science
https://doi.org/10.1186/s40645-021-00422-x(2021) 8:30

Progress in Earth andPlanetary Science

PREFACEOpen AccessPreface for “Projection and impact
assessment of global change”
Michio Kawamiya1* , Masayoshi Ishii2,3, Nobuhito Mori4, Eiichi Nakakita4, Izuru Takayabu2,3 andMasahiro Watanabe5

Keywords: Climate change, Climate model, Earth system model, Regional climate model, Hazard prediction, IPCC,
CMIP6
Scientists are now more confident than ever that climate
is changing due to greenhouse gas emissions from human activities, and that the impacts of the altered environment on society have already become apparent.
Numerical simulations based on the Coupled Model
Intercomparison Project Phase 6 (CMIP6) protocol, adesign for climate change projection with numericalmodels for global environment (Eyring et al. 2016), arebeing conducted by leading climate modeling centersworldwide, and the product data are being distributed
internationally. The Ministry of Education, Culture,
Sports, Science and Technology (MEXT) launched the
TOUGOU program in FY 2017 to develop numericalmodels to generate the CMIP6 projection data andutilize them to dynamical downscaling and impact assessment research (Fig. 1). This special issue consists
mainly of the studies conducted under the TOUGOU
program and also contains research papers related to theprogram. We hope that this special issue contributes tograsping the progress made by the TOUGOU programin the field of climate change projection research.
Oshima et al. (2020) measure the current radiative forcing in their model developed for CMIP6 and point out
the need for further research on the interaction between
aerosols and ice clouds. Such climate models are increasingly being used not only to make projections but
also to assess the contribution of human-induced
environmental change on the extreme events under thepresent climate—the approach called the event attribution.
* Correspondence: kawamiya@jamstec.go.jp
1
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
Full list of author information is available at the end of the article

For this approach, Hasegawa et al. (2020) introduce a new
method in which an atmosphere-ocean coupled model isdeployed instead of an atmosphere-only one.
Projection data generated by global climate models
such as the CMIP6 models can be applied, e.g., to evaluate the global geographic distribution of terrestrial precipitation change with uncertainty, as in the work of Itoet al. (2020b), and to elucidate the processes of sea levelchange associated with heat absorption and transport in
the North Pacific Ocean, as presented by Suzuki and
Tatebe (2020). Wang and Zhang (2020) utilize projection
data to estimate future changes in wetness over Asia,
which has a sub-continental spatial scale so that evenrelatively low-resolution data can be used as is. On theother hand, when focusing on local scale climate (e.g., aspecific country size) to conduct an assessment tounderpin adaptation measures, it is often necessary toapply a downscaling scheme to enhance the resolutionof the projection data, as Yamamoto et al. (2021) dowith a regional dynamical model when they assess theimpact of climate change on flood inundation inIndonesia. A global model with very high resolution canalso be used, as in the Mekong River flood projection by
Try et al. (2020).
When assessing risks based on future projections, it is
crucial to ensure a sufficient number of ensemble members and improve statistical reliability. The projection
dataset “Database for Policy Decision Making for Future
Climate Change” (d4PDF, Mizuta et al. 2017) has beendeveloped with this in mind. It includes subsets for 4 °C,
2 °C, and 1.5 °C temperature increases compared to preindustrial levels, as introduced by Nosaka et al. (2020),© The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License,
which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give
appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate ifchanges were made. The images or other third party material in this article are included in the article's Creative Commonslicence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commonslicence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain
permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Kawamiya et al. Progress in Earth and Planetary Science(2021) 8:30

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Fig. 1 Structure of the TOUGOU program. Titles are as of April 2017, when the TOUGOU program has launched. Modified from TOUGOU (2018)

who examine the scalability of temperature and precipitation changes among these subsets. Many impact assessment studies have utilized d4PDF, such as the one
on snowfall for mountain areas under a warmed climate
by Kawase et al. (2020). An extensive review on studies
using d4PDF was provided by Ishii and Mori (2020).
The alternations due to climate change in extreme
events such as typhoons are of great interest to society.
Nayak and Takemi (2020) have analyzed selected historicalextreme events having in mind the expected northward
shifts of affected areas in the future, and discuss the relationship between typhoon locations and extreme precipitations in northern Japan. Yamada et al. (2021) present a
study focusing on the survival rate of typhoon “seeds” until
they develop into typhoons using global data from HighResMIP (Haarsma et al. 2016), a collection of relatively
high-resolution models among the CMIP6 models. Takemi
and Ito (2020), on the other hand, perform a case study
using a regional model and show that in complex terrain,
improvements could be expected with higher resolutions
down to the level of several hundred meters.
High-resolution oceanographic data are essential for
elucidating the impacts on fisheries and changes instorm surge intensities. Nishikawa et al. (2021) describe
a model setup for creating an ocean projection datasetwith a resolution of up to 2 km in the seas around Japanand validate the output data. Based on the so-obtained
dataset named “Future Ocean Regional Projection”(FORP), Nishikawa et al. (2020) evaluate the frontal shiftof the Kuroshio and Oyashio under the warm climate,with a suggestion of an appropriate definition of fronts.
The Global Stocktake (GST) under the United Nations
Framework Convention on Climate Change (UNFCCC),
due for the first time in 2023, will discuss whether theemission reduction goals of each participating country
are consistent with the climate change mitigation targetsof 2 °C or 1.5 °C, including possible enhancements ofthe current reduction goals (UNFCCC 2015). Earth system models (ESMs), climate models with the carbon
cycle, and other biogeochemical processes as reviewed
by Kawamiya et al. (2020), play an essential role in yielding scientific knowledge as inputs to such an arena.
Hajima et al. (2020) analyze the instantaneous CO2
doubling experiment using two versions of an ESM andobtain some enlightening results, including visualizationof the differences in heat and carbon uptake processesby the ocean. The differences in heat and carbon behavior
are relevant to determining a quantity called transient
climate response to emission (TCRE), the proportionalityof the relationship between carbon emissions andtemperature rise (IPCC 2018). TCRE is the key to calculating the cumulative anthropogenic emission compatible
with meeting the mitigation targets. The dependence of
TCRE on emission scenarios, as shown by Tachiiri (2020),
is also a factor that should be considered when constructing emission reduction scenarios.
Taking advantage of the characteristics of ESM to deal
with forest dynamics, Ito and Hajima (2020) have shownKawamiya et al. Progress in Earth and Planetary Science(2021) 8:30

that land use change due to human activities has a considerable impact on the runoff of soil moisture to rivers
and vegetation biomass. Land use change deserves attention as a process that excites the interaction between human society and climate change. Tachiiri et al. (2021)
surveyed the media that can form a feedback loop between the socio-economy and the global environment,
citing the temperature dependence of labor productivity
in addition to land use change.
While ESMs have the benefit of incorporating various
biogeochemical processes and representing their interactions with climate change, many processes have been
identified as desirable but have not yet been implemented in most ESMs. An example is the dynamics ofpermafrost, for which Saito et al. (2020) use a newly developed model to determine the distribution of soil carbon and ground ice under the present climate. Yokohata
et al. (2020b) have shown that improved modeling ofphysical properties of soil in polar regions can significantly modify future permafrost area projections. Furthermore, Yokohata et al. (2020a) assess greenhouse gas
emissions from permafrost by combining the distributions obtained by Saito et al. (2020) with the projection
by Yokohata et al. (2020b).
Other major processes lacking in current ESMs include
the various transport processes that link the ocean andland material cycles. Ito et al. (2020a) present improved
modeling and results of iron supply to the ocean via aerosols generated by forest fires. Hatono and Yoshimura(2020) introduce a sediment dynamics model that can reproduce the transport of suspended sediment from land
to the ocean through rivers. Their model has been implemented in the Integrated Land Simulator (ILS) frameworkdescribed by Nitta et al. (2020), which accommodates
component models of land surface processes developed
mainly in Japan. ILS is expected to be introduced into
several ESMs in the future.
Models that simulate the global environment are increasingly embedding processes functioning on the real planet.
This special issue will provide a glimpse into the evolutionof the tool that is becoming indispensable to humanity’s
stewardship of the changing global environment.
Abbreviations
CMIP6: Coupled model intercomparison project phase 6; d4PDF: Databasefor policy decision making for future climate change; ESMs: Earth systemmodels; FORP: Future ocean regional projection; GST: Global stocktake;
ILS: Integrated land simulator; HighResMIP: High resolution modelintercomparison project; MEXT: Ministry of education, culture, sports, scienceand technology; TCRE: Transient climate response to emission;TOUGOU: Integrated research program for advancing climate models (theabbreviation is from the Japanese word for “integration”); UNFCCC: United
Nations framework convention on climate change
Acknowledgements
This work is supported by TOUGOU, the “Integrated Research Program for
Advancing Climate Models” of the Ministry of Education, Culture, Sports,
Science and Technology of Japan (Grant Number JPMXD0717935715). The

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authors are grateful to associate editors of this special issue (SPEPS11), Drs.
Tatsuo Suzuki, Kenji Tanaka, and Roy Rasmussen for their devoted work.
Thanks are extended to all the participants of the TOUGOU program andcontributors to SPEPS11. The TOUGOU program has always beenencouraged by Dr. Akimasa Sumi, the program director, Drs. Masahide
Kimoto and Hideo Harasawa, the program officers.
Authors’ contributions
MK leads theme B of the TOUGOU program and composed the main text.
MW, IT, and EN are the leaders of themes A, C, and D respectively andexamined the corresponding parts of the text. MI and NM manage andpromote researches of themes C and D, respectively, and checked the text
regarding the papers from the themes they are responsible for. All authors
read and approved the final manuscript.
Funding
This work is supported by TOUGOU, the “Integrated Research Program for
Advancing Climate Models” of the Ministry of Education, Culture, Sports,
Science and Technology of Japan (Grant Number JPMXD0717935715).

Declarations
Competing interests
The authors declare that they have no competing interests.
Author details
1
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan.
2
Meteorological Research Institute, Japan Meteorological Agency, Tsukuba,
Japan. 3Japan Meteorological Business Support Center, Tokyo, Japan.
4
Disaster Prevention Research Institute, Kyoto University, Uji, Japan.
5
Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa,
Japan.

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