New research finds that without climate change mitigation, even wealthy countries will see an economic downturn by 2100.

When thousands of scientists, economists and policymakers meet in Paris this December to negotiate an international climate treaty, one question will dominate conversations: what is the climate worth?

A new study published in the journal Nature shows that the global economy will take a harder hit from rising temperatures than previously thought, with incomes falling in most countries by the year 2100 if climate change continues unchecked. Rich countries may experience a brief economic uptick, but growth will drop off sharply after temperatures pass a critical heat threshold.

The study, co-led by Marshall Burke, a professor of Earth system science at Stanford's School of Earth, Energy & Environmental Sciences, provides a clear picture of how climate change will shape the global economy, which has been a critical missing piece for the international climate community leading up to the Paris talks. Understanding how much future climate change will cost in terms of global economic losses will help policymakers at the meetings decide how much to invest in emissions reductions today.

The work was co-authored by two researchers from the University of California, Berkeley: co-lead author Solomon Hsiang, the Chancellor's Associate Professor of Public Policy, and Edward Miguel, Oxfam Professor in Environmental and Resource Economics. 
 

Heat threshold

"The data tell us that there are particular temperatures where we humans are really good at producing stuff," said Burke, who is also Center Fellow at the Freeman Spogli Institute for International Studies and fellow, by courtesy, at the Stanford Woods Institute for the Environment. "In countries that are normally quite cold - mostly wealthy northern countries - higher temperatures are associated with faster economic growth, but only to a point. After that point, growth declines rapidly.

That point, it turns out, is an annual average temperature of about 55 degrees Fahrenheit.

As average temperatures move past that mark, wealthy countries will start to see a drop-off in economic output. Poorer countries, mostly in the tropics, will suffer even steeper losses because they are already past the temperature threshold. This has the potential to widen the global inequality gap, said Burke. 
 

A new approach

Looking at existing research, the team found a puzzling mismatch between micro-level studies, which show negative impacts of hot temperatures on output in specific sectors such as agriculture, and macro-level studies, which at least in rich countries show limited impacts on economic output.

"Many very careful studies show clearly that high temperatures are bad for things like agriculture and labor productivity, even in rich countries," Burke said. "While these relationships showed up again and again in the micro data – for example when looking at agricultural fields or manufacturing plants – they were not showing up in the existing macro-level studies, and we wanted to understand why."

The researchers suspected the problem was with the analysis, not the data, so they took a new approach.

Analyzing records from 166 countries over a 50-year period from 1960 to 2010, they compared each country's economic output in years of normal temperatures to that of unusually warm or unusually cool years. The data revealed a hill-shaped relationship between economic output and temperature, with output rising until the 55 F threshold and then falling faster and faster at higher temperatures. “Our macro-level results lined up nicely with the micro-level studies,” Hsiang said. 
 

Two possible future. Colors are 2100 temperatures under “business as usual” climate change (left) and aggressive climate policy (right). This image shows a simulation of future nightlights, as seen from space, since richer economies tend to glow brighter. A hotter world is a more unequal world, with the north benefitting and tropical economies declining. A cooler world leads to more equitable global growth, offering regions like Africa the chance to “catch up”. Courtesy of Marshall Burke.

Two possible future. Colors are 2100 temperatures under “business as usual” climate change (left) and aggressive climate policy (right). This image shows a simulation of future nightlights, as seen from space, since richer economies tend to glow brighter. A hotter world is a more unequal world, with the north benefitting and tropical economies declining. A cooler world leads to more equitable global growth, offering regions like Africa the chance to “catch up”. Source: Burke, Hsiang and Miguel. 
 

Higher temperatures, lower growth

The team then sought to understand what this historical pattern might mean for the future global economy as temperatures continue to warm. 

“Many other researchers have projected economic impacts under future climate change,” Hsiang said. “But we feel our results improve our ability to anticipate how societies in coming decades might respond to warming temperatures.”

Projecting future changes in economic output under climate change was challenging.

“Even without climate change, there are a lot of possible ways in which the future economy might evolve,” Burke said. “We start with a few different baseline scenarios and then we bring in our historical understanding of the relationship between temperature and economic output to better understand how these economic trajectories might change with warming temperatures."

The researchers’ findings were stark. 

In a scenario of unmitigated climate change, the team’s model shows that by 2100 the per-capita incomes of 77 percent of countries in the world would fall relative to current levels. By the team’s main estimate, global incomes could decline 23 percent by 2100, relative to a world without climate change. Other estimates are twice as high. The likelihood of global economic losses larger than 20 percent of current income is at least 40 percent, and much higher in some scenarios. 

These estimates are substantially larger than existing models indicate, a difference the research team attributes to their updated and data-driven understanding of how countries have historically responded to temperature increases.

Rich countries not immune

A common assumption among researchers has been that wealth and technology protect rich countries from the economic impacts of climate change, because they use these resources to adapt to higher temperatures.

"Under this hypothesis, the impacts of future warming should lessen over time as more countries become richer," Burke said. "But we find limited evidence that this is the case."

Burke's team found that, historically, rich countries did not appear to respond any differently to temperature change than poor countries. 

“The data definitely don’t provide strong evidence that rich countries are immune from the effects of hot temperatures,” said Hsiang.  “Many rich countries just happen to have cooler average temperatures to start with, meaning that future warming will overall be less harmful than in poorer, hotter countries.”

Paris climate talks

From Nov. 30 to Dec. 11, France will host the 21st Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21/CMP11).

More than 40,000 delegates from national governments, private companies and civil society will meet in Paris to hash out an international agreement aimed at keeping global emissions low enough to prevent warming of more than two degrees Celsius.

On the table are three key issues: climate adaptation, mitigation and financing.

"We don't want to rule out that we could see unprecedented adaptation to hotter temperatures in the future, and we certainly hope we do see it," Burke said. "The historical evidence, though, suggests that this is not something we should count on."

The team says that mitigation, and how to pay for it, should be at the forefront of discussions in Paris.

"Our research is important for COP21 because it suggest that these economic damages could be much larger than current estimates indicate," said Burke. "What that means for policy is that we should be willing to spend a lot more on mitigation than we would otherwise. The benefits of action on mitigation are much greater than we thought, because the costs of inaction are much greater than we thought."

Note for reporters: The research team has created a website about their research results and methodology, including an interactive map showing country-by-country GDP projections through 2100 under a scenario of unmitigated climate change.

Stanford students worked together to pitch marketing ideas to a major Japanese airline at an event last Tuesday. The event, called an “ideathon,” is part of a series of events seeking to strengthen the U.S.-Japan relationship through exchange of ideas.

The ideathon was the first of its kind at the Shorenstein Asia-Pacific Research Center, led by the Japan Program under the rubric of the Stanford Silicon Valley-New Japan Project (SV-NJ). The project is supported in part by All Nippon Airways (ANA), the Japanese airline featured at the event.

Nineteen students participated, from both undergraduate and graduate levels and across disciplines – including students from the Graduate School of Business, and other majors including economics, mathematics, computer science, philosophy and East Asian studies.

Placed on a team with others they had just met, students were encouraged to assemble quickly and generate solutions to the challenge: how can ANA strengthen its brand awareness in the United States?

ANA is seeking to double in size in the next three years, yet it faces a few obstacles in this endeavor, including a customer base that is mostly in Japan and low brand visibility internationally, according to a senior employee that presented at the event.

“Who had heard of ANA before this event?” asked Hiroyuki Miyagawa, a marketing executive at ANA. Few hands raised in the audience.

Organized into four teams, each student team was joined by an ANA employee who listened in and offered guidance and a chance to learn from a longtime practitioner.

One and a half hours later, with Post-it notes and scribbled diagrams sprinkled across tables, each team emerged ready to present their 3-minute pitch to a panel of judges. The panel included executives from ANA, the World Innovation Lab (WiL), a venture capital firm in Palo Alto, and bTrax, a San Francisco based design firm.

Below are a few pictures from the event.

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Team Three acts out a skit.  |  They proposed that ANA establish lounges for the general public to gather in and purchase goods from Uniqlo and Muji, two Japanese lifestyle retailers. The lounges would offer a place to reinforce ANA's brand outside of the airport, they said.

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Team Four puts their heads together to generate ideas.  |  In their pitch, the team noted that baseball is a popular sport among Americans and Japanese. They recommended baseball be a focus of the marketing campaign, and said television and social media would best reach the target audience.

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Team Five explains their marketing approach.  |  Flying can lead to some unpleasant experiences, and a way ANA can set itself apart is to make those experiences manageable, and even enjoyable, they said. Their proposal was to bring new amenities to the in-flight experience such as a care package for people who sit in the middle seat.

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Team One poses for a picture after their presentation.  |  In their pitch, they recommended using ANA’s association with Japan to differentiate from other global airlines. Their approach included creating a film that features an American celebrity traveling on ANA.

The winning team was Team One whose concept was to use a celebrity figure – Ellen DeGeneres – in their advertising. They said that the target audience could relate to DeGeneres, and her already-established following would be an advantage.

The judges commended Team One for the creativity of their idea and its level of feasibility. Team One consisted of students Yaqian Fan, Michael Hong, Sam Ide, Lu Li and Adelbert Tan.

Kenji Kushida, a Stanford alumnus and project leader of SV-NJ, said:

“When I was a student, I craved for an opportunity to brainstorm solutions to real-world challenges and to do it in an environment that provided instant feedback,” he said, “We were able to make that happen here with the support of ANA and WiL, and are thrilled with the outcome."