Stanford scientists found that the global economy is likely to benefit from ambitious global warming limits agreed to in the United Nations Paris Agreement.

Failing to meet climate mitigation goals laid out in the U.N. Paris Agreement could cost the global economy tens of trillions of dollars over the next century, according to new Stanford research. The study, published in Nature, is one of the first to quantify the economic benefits of limiting global warming to levels set in the accord.

The agreement commits 195 countries to the goal of holding this century’s average temperature to 2 degrees Celsius above levels in the pre-industrial era. It also includes an aspirational goal of pursuing an even more stringent target of limiting temperature rise to 1.5 degrees. To date, the economic benefits of achieving these temperature targets have not been well understood.

 “Over the past century we have already experienced a 1-degree increase in global temperature, so achieving the ambitious targets laid out in the Paris Agreement will not be easy or cheap. We need a clear understanding of how much economic benefit we’re going to get from meeting these different targets,” said Marshall Burke, assistant professor of Earth system science in the School of Earth, Energy & Environmental Sciencesand lead author of the study.

To develop this understanding, a team of Stanford researchers studied how economic performance over the past half-century correlated with changes in temperature around the world. Then, using climate model projections of how temperatures could change in the future, they calculated how overall economic output is likely to change as temperatures warm to different levels.

The researchers found a large majority of countries – containing close to 90 percent of the world’s population – benefit economically from limiting global warming to 1.5 degrees instead of 2 degrees. This includes the United States, China and Japan – the three largest economies in the world. It is also true in some of the world’s poorest regions, where even small reductions in future warming generate a notable increase in per capita gross domestic product.

“The countries likely to benefit the most are already relatively hot today,” said Burke. “The historical record tells us that additional warming will be very harmful to these countries’ economies, and so even small reductions in future warming could have large benefits for most countries.”

The projected costs from higher temperatures come from factors such as increases in spending to deal with extreme events, lower agricultural productivity and worse health, the scientists said.

Previous research has shown that the actual climate commitments each country has made as part of the Paris Agreement add up to close to 3 degrees of global warming, instead of the 1.5–2 degrees warming goals.

Given this discrepancy, the researchers also calculated the economic consequences of countries meeting their individual Paris commitments, but failing to meet the overall global warming goals of 1.5–2 degrees. They found that failing to achieve the 1.5–2 degrees goals is likely to substantially reduce global economic growth.

Percentage gain in GDP per capita in 2100 from achieving 1.5 degrees Celsius global warming instead of 2 degrees.

Percentage gain in GDP per capita in 2100 from achieving 1.5 degrees Celsius global warming instead of 2 degrees. (Image credit: Marshall Burke)

“It is clear from our analysis that achieving the more ambitious Paris goals is highly likely to benefit most countries – and the global economy overall – by avoiding more severe economic damages,” said Noah Diffenbaugh, professor of Earth system science and paper co-author.

The authors note the study may underestimate the total costs of higher levels of global warming. That’s especially true if catastrophic changes such as rapid melting of the ice on Greenland or Antarctica come to pass, or if extreme weather events such as heatwaves and floods intensify well beyond the range seen in historical observations. A recent studyby Diffenbaugh and his colleagues showed that even with reduced levels of global warming, unprecedented extreme events are likely to become more prevalent.

The new research helps shed light on the overall economic value of the Paris Agreement, as well as on the Trump administration’s decision to withdraw the U.S. from the accord because of concerns that it is too costly to the U.S. economy. The researchers calculated that the overall global benefits of keeping future temperature increases to 1.5 degrees are likely in the tens of trillions of dollars, with substantial likely benefits in the U.S. as well. They note that these benefits are more than 30 times greater than the most recent estimates of what it will cost to achieve the more ambitious 1.5 degrees goal.

“For most countries in the world, including the U.S., we find strong evidence that the benefits of achieving the ambitious Paris targets are likely to vastly outweigh the costs,” said Burke.

Burke is also a fellow at the Center on Food Security and the Environment, the Stanford Woods Institute for the Environmentand the Freeman Spogli Institute for International Studies. Diffenbaugh is also the Kara J Foundation Professor, the Kimmelman Family Senior Fellow in the Stanford Woods Institute for the Environment and an affiliate of the Precourt Institute for Energy. Additional co-authors include W. Matt Davis, a former researcher at the Center on Food Security and the Environment. The research was supported by the Erol Foundation.

Media Contacts

Marshall Burke, School of Earth, Energy & Environmental Sciences: mburke@stanford.edu, (650) 721-2203
Noah Diffenbaugh, School of Earth, Energy & Environmental Sciences: diffenbaugh@stanford.edu, (650) 223-9425
Michelle Horton, Center on Food Security and the Environment: mjhorton@stanford.edu, (650) 498-4129

On May 14 and 15, 2018, many of the CISAC fellows were lucky enough to visit the United States Strategic Command (USSTRATCOM) at Offutt Air Force Base near Omaha, Nebraska. USSTRATCOM oversees strategic deterrence on multiple fronts, including nuclear weapons, missile defense, and, until recently, cyber-attacks. This trip was only the latest iteration of a longstanding relationship between CISAC and USSTRATCOM to foster research and debate on deterrence, assurance, and nuclear security

Our visit involved several highlights. General John Hyten, Commander of USSTRATCOM, took time out of his schedule to speak with us during breakfast on the first day. We were briefed on the global mission and history of USSTRATCOM, strategic planning, laws of armed conflict, nuclear modernization, and cybersecurity. The fellows were also able to visit the Global Operations Center and Battle Deck, where many of USSTRATCOM’s most important day-to-day functions take place. Several CISAC fellows (including me) had the opportunity to brief both military and civilian members of USSTRATCOM on a range of issues spanning from nuclear terrorism to the proliferation of offensive cyber capabilities to the domestic politics of American citizens’ growing perception (now at a historic high) of national decline.

I walked away from the experience with three strong impressions.

First, USSTRATCOM is populated with thoughtful individuals who have deeply sober attitudes about the devastating impact of using nuclear weapons. Each person we met was committed to ensuring the nation’s security but emphasized how seriously they took the notion of nuclear conflict and how they all sought never to prevent conflicts from reaching that point.

Second, I was struck by how everyone at USSTRATCOM was open to discussing new or provocative ideas. During our breakfast, General Hyten called upon one of the fellows working on Russian nuclear doctrine. It was clear that he was aware of the fellow’s work and disputed its conclusion. The two conversed about their differing views for several minutes before agreeing to disagree. Another one of our fellow’s briefings focused on the origins of the recent United Nations treaty on the prohibition of nuclear weapons. Her talk drew some skepticism, but also many questions and generated a very civil discussion. USSTRATCOM invited us to speak, took our arguments seriously, and sought to understand any viewpoint that they felt could be valuable.

Third, and lastly, there is enormous need and potential to continue building connections between the military (or government more broadly) and the academic community. Visiting USSTRATCOM highlighted how scholars who study security may not fully grasp the realities behind how to effect and maintain it. This might lead to academic work that tends to be unrealistic or too reductive. Conversely, both military and civilian members of USSTRATCOM may be so engrossed in addressing specific problems that they sometimes miss the forest for the trees or overlook fallacies in their strategic logic. This could result in policies that have unintended and, given USSTRATCOM’s purview, severe consequences. Collaboration between these two worlds is perhaps the best tool we have for solving both problems simultaneously. The potential ramifications are too important not to do so.

Eric Min is a Zukerman Postdoctoral Fellow in Social Sciences at the Center for International Security and Cooperation at Stanford University, where he also obtained his Ph.D. in Political Science. His research focuses on the application of text analysis, machine learning, and statistical methods to analyze the dynamics of conflict and diplomacy. Starting in the fall of 2018, he will be an Assistant Professor in Political Science at the University of California, Los Angeles. He can also be found on Twitter. 

Stanford scholars debate whether the Iran nuclear deal can withstand U.S. withdrawal, if a revitalized nuclear program is possible and what a new deal would look like.

Following the announcement of the U.S. withdrawal from the Iran deal, three Stanford scholars consider what it means for American foreign policy and diplomacy.

Stanford scholars debate how the Trump administration’s decision on Iran will affect foreign relations. (Image credit: ruskpp / Getty Images)

In 2015, the Joint Comprehensive Plan of Action – known as the Iran nuclear deal, or JCPOA – was agreed between Iran and the U.S., United Kingdom, France, Germany, China and Russia. The international agreement limited Iran’s nuclear activities in exchange for a reprieve from international sanctions.

What happens next remains unclear. What does withdrawal signal about American foreign policy? What would a new agreement look like – and is it even possible? To answer some of these questions, Stanford News Service talked to three scholars about the issues:

• Siegfried Hecker is a top nuclear security scholar, former Los Alamos National Laboratory director and senior fellow at the Center for International Security and Cooperation. Hecker’s research interests include plutonium science, nuclear weapons policy and international security, nuclear security (including nonproliferation and counter terrorism) and cooperative nuclear threat reduction.
• Abbas Milani is the Hamid and Christina Moghadam Director of Iranian Studiesand affiliate at FSI’s Center on Democracy Development and the Rule of Law. He has been one of the founding co-directors of the Iran Democracy Project and a research fellow at the Hoover Institution. In 2016, he launched the Iran2040 Project that produces research on the future of the Iranian economy, population, energy, water, agriculture and the financial system.
• Allen Weiner is a senior lecturer of law, director of the Stanford Program in International and Comparative Law and co-director of the Stanford Center on International Conflict and Negotiation. His scholarship focuses on international law and the response to the contemporary security threats of international terrorism, the proliferation of weapons of mass destruction and situations of widespread humanitarian atrocities.

What does withdrawal from the Iran deal signal about American foreign policy?

Milani: It signifies that U.S. foreign policy is dependent on the views, even whims, of one person – the president – and the rhetoric he used during the campaign. Views of U.S. government experts or allies has I think never counted for less.

Weiner: The withdrawal from the JCPOA signals a departure from the notion that the U.S. places high value on the benefits of stability, predictability and consistency in its foreign relations. It also reflects the Trump administration’s belief that the U.S. has the ability to persuade other countries to accommodate American interests through coercive mechanisms.

How will withdrawal from the Iran nuclear deal be viewed from inside Iran?

Milani: Iran is a country divided. The people, suffering from a profound – even existential – economic crisis, are worried about their future. Bickering political factions in the regime are playing the blame game: first blame the U.S., and then opposing factions.

Can the Iran nuclear deal withstand U.S. withdrawal? What options are available – both politically and legally?

Hecker: I don’t see Iran making a mad dash for nuclear weapons to respond to the U.S. withdrawal. The country has too much to lose. Tehran could decide to keep the essence of the deal with the other countries and isolate the U.S. It may find that it will get adequate sanctions relief from the other countries in spite of U.S. pressure. That may be sufficient for Iran to continue to honor its nuclear deal commitments for now.

Milani: I would be surprised if the deal does not survive. It was never a U.S. deal.  The U.S. was simply a key player. Europe, U.K., China, Russia, the UN, and International Atomic Energy Agency (IAEA) want it to continue – Iran, too.

Weiner: In a sense, yes. Iran is free to continue to comply with the restraints on its nuclear activities negotiated in the JCPOA and to accept IAEA inspections. The other signatories to the JCPOA are free not to re-impose on Iran the sanctions that were lifted under the JCPOA. Because of the reach of U.S. sanctions, however, European companies in particular will face significant risks in doing business in Iran, which means Iran will be deprived of many of the commercial benefits it sought in negotiating the JCPOA. It is far from clear that the remaining, much more limited benefits available under the JCPOA will be appealing enough for Iran to continue to suspend those aspects of its nuclear program that are covered by the JCPOA.

What are reasons to oppose the Iran nuclear deal?

Hecker: The deal was able to get more Iranian nuclear concessions than I had ever thought possible. Apparently, the Trump administration objected primarily that the deal did not include Iran’s other activities, such as missile tests and Iran’s role in the region that it views as unacceptable. However, some of President Trump’s claims about the nuclear deal were simply incorrect.

Milani: The deal surely had flaws. It did not address such critical issues as Iran’s missile program, the regime’s role in places like Syria and Iraq, and human right abuses at home. It surely was not the worst deal in history. It was the least bad option at the time.

Weiner: The key objection voiced by many critics of the JCPOA concerns the “sunset provisions” in the deal, under which many key restrictions in the JCPOA on Iranian nuclear activities last only for 10 or 15 years (depending on the particular restriction). This potentially allows Iran to benefit from sanctions relief now and to merely postpone its pursuit of a nuclear weapon. Other objections concern the failure of the JCPOA adequately to address Iran’s missile development programs or its destabilizing regional activities more generally.

What nuclear facilities remain in place in Iran, and how easily might they be repurposed to create weapons?

Hecker: Iran has dramatically reduced its inventories of enriched uranium in compliance with the deal. It has enrichment facilities that could be restarted rather easily to enrich uranium to weapons grade, but not without withdrawing from the deal. It could also begin construction of a new plutonium-producing reactor, but that would be rather costly since it made the one under construction inoperative in compliance with the deal. The bottom line is that it would take quite some time to get back to the material inventories and facilities Iran had before the deal went into effect.

Milani: Iran’s enrichment facilities remain but much of their capacity has been mothballed. Ninety-eight percent of the country’s low enrichment uranium has been shipped out of the country. The Arak heavy water reactor has been virtually dismantled. All known facilities are under constant surveillance by the IAEA. The regime’s missile program has, however, continued.

What effect could withdrawal have on anticipated talks with North Korea?

Hecker: That’s quite uncertain. North Korea may still want a deal, but it would likely ask for greater assurances from the U.S. about potential withdrawal, just as the U.S. is pressing North Korea about its past history of compliance.

Weiner: Commentators have observed that withdrawal from the JCPOA raises questions about U.S. credibility and its willingness to keep its word. Some suggest that this will make North Korea less likely to move actively in the direction of complete, verifiable, irreversible nuclear disarmament for fear that once it has given up its nuclear program, the U.S. might simply re-impose sanctions or pursue other hostile policies towards it. On the other hand, President Trump has emphasized that he would keep any commitments he makes in negotiations with North Korea; it was only the commitments of the prior U.S. administration that he did not feel obliged to honor. Whether this would provide enough confidence to the North Koreans to trust the United States is, of course, far from clear.

What would a new deal look like?

Hecker: I don’t see a new deal involving this administration as a possibility.

Milani: I think the U.S. could have had more impact on a possible revamped deal had it stayed in the agreement. It remains to be seen whether Europeans will continue to try to coordinate with the U.S. and will try to forge a different agreement with the regime.

Weiner: A new agreement, to be acceptable to the U.S., would have to eliminate (or at least significantly extend) the sunset clauses and address Iran’s missile program. From Iran’s side, a revised deal would have to involve more than just lifting sanctions against Iran. It would also have to more emphatically embrace the prospect of American companies doing business in Iran. With respect to commercial relations, Iran argues that even though the United States formally lifted sanctions against Iran after the JCPOA took effect, the ongoing threat that U.S. sanctions would be re-imposed has effectively dissuaded many businesses in both the U.S. and Europe from pursuing long-term business arrangements in Iran.

In his article for the The Bulletin of Atomic Scientists, Abbas Milani writes that "the much-rumored and long-expected announcement by President Trump that he will order the United States to withdraw from the Iran nuclear deal—officially known as the Joint Comprehensive Plan of Action, or JCPOA­—is arguably the worst policy option for addressing problems in what was the least-bad possible deal when it was signed." Read the full article here.