Leveraging a Climate-neutral Society
Strategic Research Network

Hijioka Yasuaki, Lead Author of Chapter 3, IPCC Special Report on 1.5℃
Interview Date: 9 November 2018/ Location: National Institute for Environmental Studies

Kainuma: Please tell me what messages from the report you would like to deliver.

Hijioka: The message is that a difference of 0.5°C is more significant than I had thought. Previous studies have shown the difference in impact between 4℃ and 2℃. In this special report, we saw the difference in impact between 1.5℃ and 2℃. Before the review, I had expected that the impacts of 1.5℃ and 2℃ would not be substantially different, so I was surprised to see that the difference was more significant than I had thought.

Kainuma: In other words, does this mean that you focused on an area of research that had been relatively unexplored?

Hijioka: Although there have been some studies done on the impact of 1.5°C, these were extremely rare.
There are daily and monthly fluctuations in temperature. There are also variations in precipitation. These fluctuations are not linear, so I was expecting some differences in impact with respect to temperature change, but not in terms of changes in water resources.

Kainuma: In which areas can we see differences in the impacts?

Hijioka: We can see explicit differences between 1.5°C and 2°C in ecosystems.
It is projected that coral reefs will virtually disappear if there is a 2ºC temperature increase. On the other hand, if global temperatures increase by 1.5°C, 70-90% of coral reefs will be lost, but they will not become extinct. The difference between loss (even down to 10%) and extinction is significant. If warming is more gradual, coral may be able to move up north and survive.

Kainuma: Do you project that there will be impacts at the local level?

Hijioka: I was mainly focusing on water resources and was asked to evaluate impacts when considering how to create a global target. Therefore, I mainly focused on global impacts. I could not collate and evaluate papers on local impacts.

Kainuma: The report does mention how the Mediterranean would be impacted.

Hijioka: That’s right. Because the Mediterranean is dry to begin with and the region has a high degree of concern regarding this topic, we highlighted the impacts just in the Mediterranean. So you may ask, what about impacts in Asia? We did write about the region with regard to several topics, but I don’t think that the impacts in Asia have been adequately assessed. Further consideration would be prudent in the future.

Kainuma: Now, thinking about mitigation options, people are interested in how much investment is required to create a low-carbon society, but what about with respect to impacts and adaptation? Mitigation options are closely related to businesses. How about adaptation? Are there investments in adaptation as well?

Hijioka: For developing countries, there is a fund called the Green Climate Fund (GCF) under the UNFCCC. Half of GCF can be applied to mitigation, and the other half to adaptation.
It is becoming increasingly important to consider climate change risks when investing. In April 2015, the G20 Finance Ministers and Central Bank Governors Meeting requested the Financial Stability Board (FSB) to consider climate risks. In December 2015, the FSB launched the Task Force on Climate-related Financial Disclosures (TCFD) to develop recommendations on climate-related financial disclosures. The Task Force published its final recommendations in June 2017. Now, there is a push for companies to respond to climate change risks.

Kainuma: I think it’s difficult to distinguish what is considered “development” and what is considered “adaptation”. How can we distinguish between the two?

Hijioka: There is a fine line between development and adaptation. For example, even if there is no climate change, we might need to build flood banks (along rivers etc.) to protect residential areas (from flooding). It is very difficult to clarify how much is for natural disasters regardless of climate change and how much is to prepare for climate change risks. If a developing country proposes to construct (flood) banks under the premise of adapting to climate change risks and requests full coverage of construction costs, developed countries would have provide an immense amount of financial support. If we strictly distinguish the costs of development and adaptation, we may need to distinguish the “base” development part and the adaptation part of the project. Those who receive money say that it is for adaptation and those who support say that part of the funding goes beyond the purpose of adaptation. We need communication, but communication is sometimes difficult if we don’t have data. What is it like for mitigation?

Kainuma: For mitigation measures, I think that introducing new technologies through technological innovation is a major option.
There is an incentive towards technological development because companies will be left behind if they do not respond to new technologies. Recently, some companies have started recognizing the need to take climate actions and are promoting initiatives such as 100% renewables (RE100) and Science Based Target initiatives (SBTi).
Corporate reputation is also important. In the United States and Europe, it is becoming difficult to sell goods unless they are produced under RE100, which can serve as another incentive. Moreover, there is an increase in Environment, Society, Governance (ESG) investments.

Hijioka: In the case of adaptation, if we need flood banks, there are no substitutes. However, both building and strengthening flood banks are regarded as adaptation. In addition, evacuating from dangerous areas can also be one form of ‘soft’ adaptation.

Kainuma: When using models to estimate costs incurred to make the transition toward a low-carbon society, we often do not estimate the introduction of new technologies that may be required. In making a low-carbon society a reality, it is very important to prepare low-carbon infrastructure for transportation systems and the structure of the city. It is very expensive to develop low-carbon infrastructure, but, low-carbon or not, we need infrastructure, so we often do not factor in these costs.
In other words, whether or not to make a compact city is not a question of going low-carbon; it comes from the concept of people living comfortably even as they age. The “low-carbon” aspect becomes incorporated into the compact city when we power it with solar and wind instead of coal.
The International Energy Agency (IEA) has estimated costs to keep global warming to 2℃, considering investments in energy technologies, infrastructure, and transportation. Yet, among integrated assessment models, analyses that include infrastructural costs are uncommon.

Hijioka: To try to draw that line between development and adaptation, the preliminary building of the compact city would be considered urban ‘development,’ but building residential areas on elevated ground and preparing for disasters such as huge typhoons are classified as adaptation.
On the other hand, if we make a compact city and surround it with flood banks, could we say that the total cost to build the city falls under adaptation? If everything is considered ‘adaptation,’ the cost of adaptation becomes astronomical.

Kainuma: The Special Report on 1.5℃ mentions “strengthening the global response in the context of sustainable development”. What is necessary to link climate policies to sustainable development?

Hijioka: I think meeting the 1.5℃ target will be added to the Sustainable Development Goals (SDGs). The SDGs are the foundations of survival. If global warming progresses and severe impacts occur, there is likelihood that the SDGs may not be achieved. In such a case, it is important to prepare for impacts. If heavy rain causes floods, people may not have safe water. Adaptation is required to ensure that we will have safe water even in times of floods. If we put water purification plants on higher ground, we can eliminate water sanitation concerns and have safe drinking water, even when floods occur. Adaptation means preparing for the unexpected.

Kainuma: Do you have any comments that were not included in the Special Report.

Hijioka: Regional impacts and adaptation have not been fully studied. Impacts and adaptation methods are different region by region. In addition, because of the lack of quantification of impacts and adaptation, it is difficult to compare the costs of mitigation and the costs of adaptation. Furthermore, the impacts of climate change may still be felt, even after we implement mitigation and adaptation measures. We need to estimate the costs of mitigation, the costs of adaptation, and the costs of damage after mitigation and adaptation measures have been taken. These kind of studies are necessary.

Kainuma: That is a very important point. It is often said that mitigation measures are too costly to implement. However, the cost of climate change-related damage is not taken into account in most cases.
Although the Stern Review has shown some results, I think that more in-depth analysis is necessary. Some people may think that we do not have to worry about people’s lives in the future, as future incomes will be much higher. (If GDP increases 2% per year, in 2100, it will be about five times larger than that of 2018.) However, if we take impacts of climate change into account, it’s a different story. Even today, many people suffer from the impacts of climate change, and we need to consider those impacts more seriously.
It is very difficult to evaluate how much the impacts of climate change cost. For example, we cannot calculate how much coral reefs are monetarily worth. It is said that about 90 thousand species live in coral reefs, and fisheries will incur serious damage if coral reefs disappear. Some people argue that the GDP shares of agriculture, fisheries, and sightseeing are relatively low, hence they say that this would not seriously affect GDP. This, however, does not mean that they are not important. Food is indispensable, and Zero Hunger is one of the SDGs. Furthermore, the fact that climate change affects ecosystems means that we may not be able to avail of ecosystem services from the ocean in the future. This is not quantifiable, but nevertheless extremely problematic.

Hijioka: There are many things that we still don’t know about the impacts of climate change on human society. For mitigation, we can quantify the cost of technologies and how much CO2 could be reduced. On the other hand, we cannot take a similar end-use approach in adaptation research. Even if we know there are co-benefits to protecting coral reefs (such as protecting species depending on them), it is difficult to show it in terms of money. In theory, it is possible to show that there are higher impacts if we use lower discount rates, but the problem is that we do not have enough data to estimate impacts in the first place.
Research on extreme events is also inadequate. Impacts of climate change cannot be estimated by the annual average temperature alone. If you cannot accurately estimate the trends in extreme events when the global average temperatures will increase by 1.5℃ or 2℃, it is difficult to estimate their impacts.

Kainuma: In Japan, summer this year (2018) was very hot. I think many people were able to ‘perceive’ global warming due to the hot summer weather this year. Sometimes I feel that Japan’s climate has become tropical. The spring and fall periods have become shorter. In the summer, it is hot, even at night. Rainfall in the rainy season is very heavy, even though historically, the rainy season had been characterized by light rain that persisted the whole day.

Hijioka: There were many fatalities due to heatwaves in Europe in 2003. One reason was that people were not accustomed to hot weather. At that time, air conditioners were not popular in Europe. Some people went down to the basements of cemeteries for some cool air. It is difficult to adapt to a new set of environmental conditions never seen before. People in the city are used to hot weather, so even if there is a 1℃ increase, they may only perceive it as “a little warmer.” However, for those who are not used to it, the results can be deadly.

Kainuma: I have visited the International Institute for Applied Systems Analysis (IIASA) in Vienna annually since 1993. When I first visited, most hotels and cafes had no air conditioning. A few years later, I began noticing posters saying, “We have air conditioning” on the entrance doors. Now almost all hotels and cafes have air conditioners.

Hijioka: During past summers, I was able to recover at night when it became cool, but recently, it is hot around the clock and I get physically tired.

Kainuma: In the Paris Agreement, the term “until 2100” is not written explicitly. However, the report considers the possibility of limiting the global temperature increase to 1.5℃ by 2100. What do you think about the target year?

Hijioka: When we are talking about adaptation, we are not considering tens of thousands of years from now. We are considering how the present society will be. It is very difficult to imagine what society will be like beyond the year 2100 and we cannot make assumptions about technologies. It’s not our task to predict the world in 500 years time. I think the year 2100 is the upper limit when thinking about countermeasures. Even in the sense of handing over a sustainable world to generations after 2100, I think it is better to think about the world up to 2100. It is important to keep the temperature increase below 1.5℃ by 2100.

Kainuma: What kind of research do you think is necessary for that?

Hijioka: There were time constraints in preparing the Special Report on 1.5℃, so we focused on the global impacts. I think it is important for the IPCC to assess the global impacts when we discuss global climate goals. Indeed, you can read about some of the regional impacts in the report, such as in Asia and the Mediterranean. But we generally assessed the global impacts this time.
The report showed that there are differences in impact between 1.5℃ and 2℃, but it is necessary to assess the regional impacts in more detail.
With respect to water stress, changes in population and GDP are more significant factors than the differences between 1.5℃ and 2℃. Decreasing the global population and reducing water use have greater impacts on water stress than whether we limit global warming to 2℃ or 1.5℃. We need more studies about the impacts on water stress, which depend on how future societies look.
I expect that the 6th Assessment Report will assess how much investment will increase and how much the impact of global warming will be reduced.

Kainuma: Thank you very much for taking time out of your busy schedule.