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

Roz Naylor, Director of the Center on Food Security and the Environment talks how technology will help meet the growing demand for food and water in the developing world and why tech companies should invest in Africa.

Walter Falcon, the Helen Farnsworth Professor of International Agricultural Policy in Economics (emeritus), writes from an unusual perspective. During the academic year he serves as a senior fellow with the Freeman Spogli Institute for International Studies and the Stanford Woods Institute for the Environment. He spends the summers on his family farm near Marion, Iowa. He returns to campus each year with reflections on the challenges and rewards of faming life in his "Almanac Report." Falcon is former deputy director of the Center on Food Security and the Environment. 

It is now the end of summer for what has been a milestone year for my wife and me. This essay, itself a mini-milestone, is the fifth annual report from our farm. As readers of prior Almanac postings will know, my day job is as professor of international agricultural policy at Stanford University; however, we also own a medium-sized farm in east central Iowa that produces corn, soybeans, alfalfa and beef from a cow-calf herd. Our friends laughingly refer to our operation as a corn-California crop rotation. 

The 2016 crop year has been nothing short of phenomenal. Planting was early, the weather was warm – sometimes downright hot – and the rains were ideal. On average, our county receives nine inches of rain during the critical growing months of June and July. This year we received more than 12 inches, quite unlike the two inches I wrote about in 2012.

Both corn and soybeans are about two weeks ahead of their maturity schedules for what promises to be record production. Corn yields of 225 bushels per acre on our farm look probable. Soybeans are more uncertain; they are loaded with pods, but all of the rain has left them susceptible to a fungal disease known as sudden-death syndrome (SDS). This fungus, present in many Iowa soils, enters the roots and emits a toxin. Plants looking healthy one day can suddenly wither a few days later. The exact amount of bean loss is mainly a function of how close the plants are to being ripe. We are almost past that maturity barrier now, so even if SDS strikes, it should not lower our yields very much. Unfortunately, record yields do not equate to record incomes, an important point that I return to later.

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The perfect summer and record crops were complemented by two milestone events of a more personal nature. In June, my wife and I celebrated our 60^th wedding anniversary. Then in September, we both celebrated our 80^th birthdays. There has never been a day when I have not known my wife. We grew up on nearby farms and are fourth-generation caretakers of land that was settled in the late 1850’s. And, we have both seen the most extraordinary changes over our eight decades. Even with a 50-year hiatus while at Harvard and Stanford universities, Iowa has always been home. 

Anniversaries are the time for reminiscing and looking at old pictures. Not surprisingly, a major topic of conversation at our gathering was the change in farming practices. As the younger son in our family, I remember a long list of chores, even when I was small – gathering eggs, filling the watering tanks for pigs and “going after” the cows in the evening. But I really took notice of agriculture when I was about 10.

It was shortly after Word War II, and at that time we used a four-year crop rotation: corn, corn, oats, clover. We were in the transition from horses to tractors, with the corn still being planted with a two-row horse-drawn planter. This was a task reserved for my father (a.k.a. Buck), for no one else could get the rows sufficiently straight to suit him. On a really long day, when the horses were in good condition, father could plant 15 acres. He used 42-inch rows, wide enough for the horses, and planted about 18,000 kernels of seed per acre. The seed was “checked”, which meant that cornfields could be cultivated for weeds both via the length of the field and across it. 

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The contrast between then and now is stark. An 18-row planter, dispensing 36,000 seeds per acre in 20-inch rows, can now plant 40 acres per hour – almost three times what my father could do in an entire day. Unlike horses, the tractors do not get tired. And they have lights. Steering the tractor is no longer a problem, since the fields and tractors are now synchronized with global positioning systems. For the most part, farmers are just along for the ride, and to keep awake on mile-long rows, several have become Sudoku fanatics! The planting system is wonderful except for one large problem – a new 24-row planter costs upwards of $225,000, not including the tractor.

When I was 12 my father decided that he needed more help and that I was his newly designated “hired man.” To reinforce the point, he decided that I needed my own tractor. He purchased a new Farmall “C” for me, including a two-row cultivator for attacking weeds. The grand total cost of this equipment was $1600! (Perhaps what I remember most is driving myself around the block in my hometown on the day we took delivery.)

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For the next 10 years, I spent most of my summers on that damned tractor fighting morning glories (that would tangle and often require dismounting every 100 yards), thistles, button weeds and all manner of other species. Now, herbicides, Roundup-ready seeds and no-tillage farming are the norm. What took a summer for me to do is now completed easily in a day or two with a high-clearance sprayer with long booms that cover 48 rows at a time.  

What the future will bring is an interesting question. For 20 years or more, farmers have used and overused highly effective herbicides such as Roundup.  And predictably, there is increasing weed resistance to these herbicides. In our county, there has been a devastating spread of Palmer amaranth—a tall spiky plant that produces thousands of seeds. It is highly resistant to commonly used herbicides, and whether its control lies in yet another new herbicide remains to be seen. For the moment, however, it is a menace.

For years, our entire crop rotation was constrained by labor availability at harvest. The picking of ear corn by hand was time-consuming, and typically a cold, miserable task. I can still hear my father saying, “the mark of a man is whether he can pick 100 bushels of ear corn, and then shovel them into a crib before nightfall.

Several things happened almost simultaneously, however, that fundamentally changed rural Iowa life: the switch from horses to tractors; the availability of cheap commercial nitrogen fertilizer; and the large-scale introduction of soybeans.  The departure of the horses was a joyful occasion in itself – tractors neither kick nor need their sheds cleaned.

Moreover, much less land was now needed to provide hay, oats and straw for the horses. A new crop rotation evolved that took the form of corn, soybeans, corn, soybeans. Commercial nitrogen helped maintain the soil fertility; hybrid corn seeds offered new genetic potential as yields on our farm went from 70 bushels per acre in 1946 to more than 200 bushels per acre currently; herbicides more or less controlled the weeds; and perhaps most of all, the mechanical corn picker broke the critical labor bottleneck at harvest.

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To the extent that my family ever celebrated, we partied the night our first new Case corn picker was delivered in 1948. (Father may have even had one of his carefully hidden beers that evening!) It was a one-row snapper that was simple beyond belief – just rollers that stripped the corn ears from the stock and elevated them into a trailing wagon.

It was the start of a new era, however, and the one-row pull machine quickly gave way to two-row pickers that mounted directly on a tractor, which in turn gave way to self-propelled picker-combines that used multiple “heads” for harvesting either corn or soybeans.  These machines are huge – and are extraordinarily costly. A new 12-row combine fitted for corn harvest costs on the order of $600,000. Unlike picking by hand, when 100 bushels per day was the norm, the new behemoths can harvest 10 acres per hour – some 20,000 bushels per day – provided that the farmer has enough trucks and collector wagons to move the grain from the combine to market or to on-farm storage units. Many are the farm spouses who now drive massive grain trucks during the harvest season!

The coffee crowd is delighted that the traffic from presidential politicians across Iowa is down substantially from last summer, but the two remaining candidates seemingly have yet to say anything meaningful to my neighbors. Farmers are feeling economically trapped and politically abandoned. “None of the above” would certainly win the election if it were held today. While Iowa shows as a dead heat in the presidential polls, it is the most unenthusiastic 50/50 that I have ever seen on both sides.

Most farmers truly enjoy their work and lifestyle, but they are now hurting. It is easy to understand how the hurt arises. In the last 36 months, corn, soybean and fed-cattle prices have dropped about 50 percent, 33 percent and 25 percent, respectively. The $600,000 machines that (perhaps!) were feasible economically with $7 per bushel corn now look like a mechanical albatross with corn at $3.50 or less per bushel.

Even with low interest rates, many farmers find themselves overcapitalized and with heavy debt burdens. During the prior period of high prices, many borrowed against the equity they had in land, only to see local land prices go from about $9,200 to roughly $7,800 per acre. Solvency has become a serious question for some. Interestingly, the younger, most modern, and most aggressive young farmers seem in the most trouble, whereas some of the older, more conservative farmers using rebuilt machinery are coping better.

The morning coffee conversations are also punctuated by several environmental topics, especially nitrogen and water runoffs.  The state of Iowa is pressing hard for voluntary conservation approaches. But farmers are truly puzzled and worried about what they should do. For 100 years they have been urged to improve their land by tiling, that is, to lay clay or perforated plastic pipe three to four feet underground such that wet portions of fields could be drained to facilitate greater yields. Often these tiles have outlets into creeks or ditches.

But now there is a dilemma. The EPA is asserting that water from tiles is running water, and therefore subject to EPA regulation under the Clean Water Act. Given uncertainty about the regulations, farmers fear the worst. Moreover, much of the nitrogen runoff from cornfields is via drainage into those same tiles. While better placement and timing of fertilizer applications can help, it is hard to envisage major curtailment of nutrient runoff without also taking up the tile issue. 

Tiles are virtually in all fields, and the implications of potential new regulations are enormous. As a consequence, groups like the Farm Bureau are pushing new voluntary conservation measures very strongly. They are also going after EPA’s attempt to regulate farm waters in an all-out war. In the meantime, farmers wait uneasily and hope for the best.

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My final comment for the summer is not a “cock and bull” story, although it borders on one. (Definition: “an absurd, improbable story presented as the truth.”) It was partly motivated by “Desperado,” the 2,972-pound Angus bull that won the “Super Bull” contest at the Iowa State Fair. (Lest I be accused of being gender insensitive, I should also report that the life-sized cow, sculpted in butter, is still doing well and now stands beside a sculpturefrom “Star Trek”, also in butter.  Do not ask me why!)

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