News + Media

Alli Gold Roberts
MIT Joint Program on the Science and Policy of Global Change

Policies to curb greenhouse gas emissions will come at a cost to energy producers, industry and consumers. Policymakers around the globe are working to determine the most effective and cost efficient way to reduce these emissions—from renewable energy subsidies and fuel efficiency standards to carbon taxes and cap-and-trade policies.

To tackle this challenge, Sergey Paltsev from MIT and Pantelis Capros from the National Technical University of Athens have come together to assess which methods and metrics are best for calculating the cost of climate policies. In their study, published this week in Climate Change Economics, they find that there is no one ideal metric for climate mitigation policies, but measuring changes in consumer welfare is one of the most appropriate techniques.  

“With many of these regulations, the total costs are often less visible to consumers because the true costs are not reflected in the price of energy, but distributed to other sectors of the economy,” says Paltsev, the assistant director for economic research at the MIT Joint Program on the Science and Policy of Global Change. “The true measure of the cost of a policy is reflected in the change in consumers’ behavior, something that economists call as ‘change in welfare,’ but it is hard to convey this measure to policy makers and general public.”

In the study, the researchers compare different concepts that are used to inform the public about the cost implications of climate change. They consider two major modeling types where costs are calculated, energy system models and macroeconomic models. Energy system models focus solely on the energy sector and treat the rest of the economy as a given.  Macroeconomic models represent the energy system as part of the entire economy and provide more detailed information on the various sectors. Within these approaches there are a variety of metrics used to calculate the cost of a climate mitigation policy.

After studying the cost metrics associated with each modeling approach, the researchers compared the metrics used by a team of international researchers to better understand the impacts of the current EU emissions targets (the EU Energy Modeling Forum 28 study). They find that there are large variations in cost estimates and most metrics are not directly comparable, which makes it difficult for policymakers to interpret the results of these studies.

Paltsev says there is no ideal metric for costs, but it’s clear that some approaches are more effective than others. For example, carbon prices and marginal abatement cost curves are unable to reflect the full impact of the policy on the economy. In addition, energy system models do not always take into account the full cost of a climate policy—particularly the economic impacts of policies interacting with one another. The authors recognize that depending on the objectives, other metrics and modeling techniques may be appropriate. They conclude that measuring changes in consumer welfare or consumption is an effective approach that should be used by policymakers to evaluate climate policies.

Oceans cover 97 percent of the Earth’s surface, and act as an important carbon sink. However, each part of the ocean works in different ways to take up carbon from the atmosphere and store it. Two new studies shed light on the nuances how these processes work in the Arctic Ocean and coastal zones.

The findings about the Arctic Ocean were published recently in the journal Global Biogeochemical Cycles. Stephanie Dutkiewicz, a research scientist at the Massachusetts Institute for Technology, worked with colleagues to figure out how decreasing sea ice in the summer is affecting the carbon cycle in that ocean basin from 1997-2006.

That period is in the middle a timeframe when the Arctic has been warming twice as fast as the rest of the globe, leading to major losses in sea ice, which hit a record low in 2012. Over that time, the Arctic Ocean has become a greater repository for carbon.

That’s because more open water provides more suitable habitat for phytoplankton, or algae, to grow and suck carbon dioxide out of the air. As days get shorter, the algae dies and sinks, sequestering the carbon at the bottom of the ocean.
With summer loss of sea ice and warming in the Arctic projected to continue, phytoplankton blooms are likely to be a more common occurance across the region. However, the warming trend encouraging algae growth could also have negative consequences on another ocean mechanism that removes carbon from the atmosphere.

Sunlight not only increases plant life but it also warms the surface waters of the Arctic. Dutkiewicz’s findings show that warming could eventually reduce the Arctic Ocean’s ability to absorb carbon dioxide because cold water dissolves it better than warm water.

Of course water is warming in a relative sense in the Arctic. Sea surface temperatures in the region have risen since 1965 but are still near freezing for most of the region during the summer. However, if the trend continues it could still reduce the region’s ability to take up carbon. Dutkiewicz also said the study’s findings have applications beyond the Arctic’s borders.

“The processes we’re looking at are happening everywhere,” Dutkiewicz said. “We need to be studying it (in the Arctic) and understanding the changes. That will help us understand what will happen in 20 or 50 years in other parts of other oceans.”
The other study, a review published in Nature, found that coastal oceans are also helping store carbon. Coastals oceans account for only 7 percent of the overall area of oceans, but the new study finds they play an outsize role when it comes to carbon storage.

Coastal zones weren’t always carbon sinks. Prior to the Industrial Revolution, oceans acted as net emitters of carbon. However, in the ensuing 50-100 years, a shift occurred and these areas now take up more carbon than they emit.

The new research estimates that in pre-industrial times, coastal areas emitted about 150 million metric tons of carbon a year. Presently they take up 250 million metric tons annually. That’s about equivalent to Turkey’s carbon emissions in 2008.
“Traditionally, most thinking has been that there’s a shift in biological production in recent decades, that the ocean has become more productive,” said Wei-Jun Cai, an oceanographer at the University of Delaware and author of the report. The reason, he said, is because increased runoff from agriculture finds it way down rivers and into the coastal zone, which in turn increases plant life.

However, Cai believes there’s another mechanism at play. Measurements in the open ocean of carbon dioxide in the water and the atmosphere tend to show the two stay pretty close to equilibrium. In other words, if there’s 400 parts per million of carbon dioxide in the atmosphere, a similar ratio is likely to exist in the ocean waters.

That relationship doesn’t exist in coastal areas, though. Cai recalled a trip to measure carbon dioxide in the water off the Georgia coast in 2005.

“It was very similar to what someone else measured in 1995,” he said about his measurements. “I was shocked as there was very little increase. The reason is the water doesn’t stay there for a long enough time so it doesn’t really accumulate the anthropogenic signal.”

Instead, water in coastal zones is constantly on the move thanks to the conveyor belt of ocean currents. Those currents eventually dive to the depth of the ocean, and could be storing the carbon down there according to Cai’s theory.

Both studies point to the need for better monitoring in both those regions. They offer tantalizing results that suggest revisiting our understanding of the globe’s carbon budget, but more data is needed to reinforce their results.

That data would not only inform a better understanding of the planet’s carbon budget, but also paint a clearer picture of how regions that have great economic and environmental importance are changing.

The Arctic Ocean has has long been known as a carbon sink, but a new study suggests that while the frigid waters do store large quantities of carbon, parts of the ocean also emit atmospheric carbon dioxide.

Researchers from MIT constructed a model to simulate the effect of sea ice loss in the Arctic, finding that as the region loses its ice, it is becoming more of a carbon sink, taking on about one additional megaton of carbon each year between 1996 and 2007. But while the Arctic is taking on more carbon, the researchers found, paradoxically, the regions where the water is warmest are actually able to store less carbon and are instead emitting carbon dioxide into the atmosphere.

While the Arctic region as a whole remains a large carbon sink, the realization that parts of the Arctic are carbon emitters paints a more complex picture of how the region is responding to global warming.

"People have suggested that the Arctic is having higher productivity, and therefore higher uptake of carbon," said Stephanie Dutkiewicz, an MIT research scientist. "What's nice about this study is, it says that's not the whole story. We've begun to pull apart the actual bits and pieces that are going on."

Dutkiewicz and her colleagues, including Mick Follows and Christopher Hill of MIT, Manfredi Manizza of the Scripps Institute of Oceanography and Dimitris Menemenlis of NASA's Jet Propulsion Laboratory, published their work in the journal Global Biogeochemical Cycles.

To model the Arctic's carbon cycle, the research team developed a model that traces the flow of carbon in the Arctic, looking for conditions that led to the ocean's storage or release of carbon. To accomplish this, the team incorporated three models, which MIT detailed in a news release:

"A physical model that integrates temperature and salinity data, along with the direction of currents in a region; a sea ice model that estimates ice growth and shrinkage from year to year; and a biogeochemistry model, which simulates the flow of nutrients and carbon, given the parameters of the other two models."

The model showed the Arctic taking on an average of 58 megatons of carbon each year, with an average increase of 1 megaton each year between 1996 and 2007. One megaton is 1 million tons.

The model confirms a long held theory: as sea ice melts, more organisms grow, leading to a larger carbon sink as the organisms store carbon.

But there was the anomaly of 2005-2007 where portions of the Arctic released more carbon than they stored. These years saw significant sea ice shrinkage, yet in certain regions, more carbon was emitted than stored. The researchers accounted for the anomaly by factoring in water temperature along with the levels of sea ice loss.

"The Arctic is special in that it's certainly a place where we see changes happening faster than anywhere else," Dutkiewicz said. "Because of that, there are bigger changes in the sea ice and biology, and therefore possibly to the carbon sink."

Jennifer Chu, MIT News Office

For the past three decades, as the climate has warmed, the massive plates of sea ice in the Arctic Ocean have shrunk: In 2007, scientists observed nearly 50 percent less summer ice than had been seen in 1980.

Dramatic changes in ice cover have, in turn, altered the Arctic ecosystem — particularly in summer months, when ice recedes and sunlight penetrates surface waters, spurring life to grow. Satellite images have captured large blooms of phytoplankton in Arctic regions that were once relatively unproductive. When these organisms die, a small portion of their carbon sinks to the deep ocean, creating a sink, or reservoir, of carbon.

Now researchers at MIT have found that with the loss of sea ice, the Arctic Ocean is becoming more of a carbon sink. The team modeled changes in Arctic sea ice, temperatures, currents, and flow of carbon from 1996 to 2007, and found that the amount of carbon taken up by the Arctic increased by 1 megaton each year.

But the group also observed a somewhat paradoxical effect: A few Arctic regions where waters were warmest were actually less able to store carbon. Instead, these regions — such as the Barents Sea, near Greenland — were a carbon source, emitting carbon dioxide to the atmosphere. 

While the Arctic Ocean as a whole remains a carbon sink, MIT principal research scientist Stephanie Dutkiewicz says places like the Barents Sea paint a more complex picture of how the Arctic is changing with global warming.

“People have suggested that the Arctic is having higher productivity, and therefore higher uptake of carbon,” Dutkiewicz says. “What’s nice about this study is, it says that’s not the whole story. We’ve begun to pull apart the actual bits and pieces that are going on.”

A paper by Dutkiewicz and co-authors Mick Follows and Christopher Hill of MIT, Manfredi Manizza of the Scripps Institute of Oceanography, and Dimitris Menemenlis of NASA’s Jet Propulsion Laboratory is published in the journal Global Biogeochemical Cycles.

The ocean’s carbon cycle

The cycling of carbon in the oceans is relatively straightforward: As organisms like phytoplankton grow in surface waters, they absorb sunlight and carbon dioxide from the atmosphere. Through photosynthesis, carbon dioxide builds cell walls and other structures; when organisms die, some portion of the plankton sink as organic carbon to the deep ocean. Over time, bacteria eat away at the detritus, converting it back into carbon dioxide that, when stirred up by ocean currents, can escape into the atmosphere.

The MIT group developed a model to trace the flow of carbon in the Arctic, looking at conditions in which carbon was either stored or released from the ocean. To do this, the researchers combined three models: a physical model that integrates temperature and salinity data, along with the direction of currents in a region; a sea ice model that estimates ice growth and shrinkage from year to year; and a biogeochemistry model, which simulates the flow of nutrients and carbon, given the parameters of the other two models.

The researchers modeled the changing Arctic between 1996 and 2007 and found that the ocean stored, on average, about 58 megatons of carbon each year — a figure that increased by an average of 1 megaton annually over this time period.

These numbers, Dutkiewicz says, are not surprising, as the Arctic has long been known to be a carbon sink. The group’s results confirm a widely held theory: With less sea ice, more organisms grow, eventually creating a bigger carbon sink.

A new counterbalance

However, one finding from the group muddies this seemingly linear relationship. Manizza found a discrepancy between 2005 and 2007, the most severe periods of sea ice shrinkage. While the Arctic lost more ice cover in 2007 than in 2005, less carbon was taken up by the ocean in 2007 — an unexpected finding, in light of the theory that less sea ice leads to more carbon stored.

Manizza traced the discrepancy to the Greenland and Barents seas, regions of the Arctic Ocean that take in warmer waters from the Atlantic. (In warmer environments, carbon is less soluble in seawater.) Manizza observed this scenario in the Barents Sea in 2007, when warmer temperatures caused more carbon dioxide to be released than stored.

The results point to a subtle balance: An ocean’s carbon flow depends on both water temperature and biological activity. In warmer waters, carbon is more likely to be expelled into the atmosphere; in waters with more biological growth — for example, due to less sea ice — carbon is more likely to be stored in ocean organisms.

In short, while the Arctic Ocean as a whole seems to be storing more carbon than in previous years, the increase in the carbon sink may not be as large as scientists had previously thought.

“The Arctic is special in that it’s certainly a place where we see changes happening faster than anywhere else,” Dutkiewicz says. “Because of that, there are bigger changes in the sea ice and biology, and therefore possibly to the carbon sink.”

Manizza adds that while the remoteness of the Arctic makes it difficult for scientists to obtain accurate measurements, more data from this region “can both inform us about the change 
in the polar area and make our models highly reliable
for policymaking decisions.”

This research was supported by the National Science Foundation and the National Oceanic and Atmospheric Administration.

Vicki Ekstrom
MIT Joint Program on the Science and Policy of Global Change

As countries try to protect their domestic air carriers from a European Union proposal that would put a price on the emissions they release over European airspace, the global aviation industry is working to curb those emissions. Industry-wide, air carriers set a goal to be carbon neutral by 2020 and cut their emissions in half by 2050. One way they’ll meet this goal is through the use of biofuels.

“Biofuels release significantly fewer emissions than conventional fuel, and could reduce fuel price volatility for airlines,” says Niven Winchester, an economist at the Joint Program on the Science and Policy of Global Change and the lead author of a study looking at the costs and efficiency of making the switch.

To meet the global targets, the U.S. Federal Aviation Administration has set its own goal to use one billion gallons of renewable biofuels each year starting in 2018. Because the goal includes U.S. Air Force and Navy carriers, which consume the vast majority of fuel, commercial airlines are responsible for just 35 percent of the target (350 million gallons). In studying this target, Winchester and his co-authors find that while a carbon tax or cap-and-trade system – as the Europeans have employed – would be the most efficient way to reduce emissions, there are ways to cut the costs of using biofuels.  The study was published in the December issue of Transportation Research.

“The cost of abating emissions in the aviation sector is higher than in other sectors, so a broad cap-and-trade or carbon price policy that covers a variety of sectors would spread out those costs and allow for improvements in technology and infrastructure,” Winchester says. “But because employing a carbon tax or cap-and-trade appears to be politically infeasible at this time in the U.S., we looked for other ways to reduce emissions.”

The researchers find that growing biofuel crops in rotation with food crops, as research from the U.S. Department of Agriculture suggests, can reduce the cost of biofuels. Pennycress, for example, is a winter annual crop that could potentially be grown in the Midwest in rotation with summer corn and spring soybean crops.

The researchers found that without any policy to constrain emissions, airlines will spend $3.41 per gallon of fuel in 2020, or about $71 billion for the year. Using biofuels that are not grown in rotation with food crops would cost $6.08 per gallon – almost double the cost of conventional fuel. But because the biofuel target for commercial aviation represents only 1.7 percent of total fuel purchased by the industry, the average fuel costs for commercial carriers would increase by only $0.04 per gallon. While a seemingly small change, airlines would spend $830 million more per year on fuel. That price tag becomes significantly smaller when biofuels are grown as rotation crops. In this scenario, the average fuel costs could increase by as little as less than one cent per gallon – raising total annual fuel costs by about $125 million.

Using rotation crops is not only a cheaper way of reaching the renewable target, it also delivers greater bang for the buck in terms of reducing emissions – costing just $50 per ton of COâ‚‚ abated versus $400 per ton without their use. But again, it’s far from the most efficient option: a broad carbon tax or cap-and-trade system. Under the European Union’s Emissions Trading System, COâ‚‚ cost $5 per ton in mid-2013, and is predicted to cost $7 per ton in 2018.

“Because biofuels would account for such a small portion of the total fuel used by commercial aviation, meeting the goal would have only a minor impact on the price of jet fuel. But it would also have a minor impact on emissions,” Winchester says.  “A broad cap-and-trade policy or a carbon offsetting scheme, as is currently being promoted by the International Air Transport Association, would reduce emissions at a lower cost by allowing aviation to tap into low-cost abatement options in other industries.”

The study was funded by the U.S. Federal Aviation Administration.

By Alli Gold Roberts
MIT Joint Program on the Science and Policy of Global Change

The MIT-Tsinghua China Energy and Climate Project and Emory University held a workshop on Thursday November 21^st with researchers and government officials to discuss new research analyzing the impacts of China’s vehicle emissions policies. Researchers worked with policymakers to develop policy scenarios for a new integrated model that will analyze the emissions, air quality, economic, and public health impacts of policy proposals.

A joint team of researchers from Emory University, MIT, and Tsinghua University is carrying out the study. The project is supported by a grant from the Energy Foundation, which provides resources to institutions that most effectively leverage change in transitioning to a sustainable energy future. The Institute for Energy, Environment, and Economy at Tsinghua University hosted the workshop on their Tsinghua campus.  At the meeting, policymakers, researchers, and other stakeholders engaged in a detailed, candid discussion of policy developments and scenario designs. The first meeting to launch this effort was held in March of 2013.

“This study will help policymakers understand the implications of taking more aggressive steps to control transportation emissions, particularly emissions from road vehicles, which have been outlined in the country’s new air pollution action plan,” says Dr. Valerie Karplus, who leads the MIT-Tsinghua China Energy and Climate Project. “Our framework allows us to quantify the costs and benefits of these measures within a single integrated framework.”

The meeting included representatives from the Chinese Ministry of Finance, Integrated Energy and Climate Policy Bureaus of the National Development and Reform Commission, Ministry of Industry and Information Technology, National Vehicle Emissions Control Center of the Ministry of Environment, and the Beijing Environmental Protection Bureau. The MIT, Tsinghua and Emory researchers used this workshop to communicate their results to policymakers and receive their input in designing policy scenarios for their model.

Using the China Regional Energy Model (C-REM), the group will model the impacts of China’s current and future transportation policies on the national economy and in the individual 30 provinces. The C-REM model was developed as part of the MIT-Tsinghua China Energy and Climate Project over the past two years. Recent modeling efforts include adding detail on the transportation sector and connecting the energy and economic data with a comprehensive inventory of China’s provincial emissions. The team used an atmospheric chemistry model to simulate air quality, including concentrations of ozone and particulate matter. Population-weighted concentrations are then used to simulate impacts on human health and economic activity.

The group plans to test three policy scenarios that will meet the needs of decision makers working on transport policy in China. They currently plan to test a no policy “business as usual” case for comparison, a current policies scenario, and an accelerated scenario that implements a more aggressive transport-focused pollution policy. The aggressive policy scenario focuses mainly on the role of tighter standards for fuel quality and vehicle tailpipe emissions. 

“China’s leaders are placing ever greater emphasis on improving air quality and the environment,” says Eri Saikawa, assistant professor at Emory University and principal investigator on the project. “Policymakers are eager to identify specific measures that will help to achieve these goals.”     

While building the transportation section of the model, researchers found that freight transport dominates energy use and emissions in most provinces, except the more urbanized regions. In addition, private vehicle ownership is rising rapidly and will have major implications for future emissions.  

“China’s leaders have an opportunity to manage this growth by accelerating the adoption of low emissions vehicles nationwide,” says Karplus.

Over the coming months, the group will continue to improve the modeling framework and simulate the three policy scenarios.  The final results will be shared with policymakers by the end of 2014.

The next meeting is planned for March of 2014.

Update 7:30pm, Saturday, November 23
Decisions have been adopted on the three major elements of COP19: Durban Platform, Loss and Damage, and institutional mechanisms for finance.

Update 4:11pm, Saturday, November 23
The decision of the Durban Platform was adopted and the plenary to finalize other COP decisions on finance and loss and damage will commence soon.
 
Two weeks at the UN climate negotiations in Warsaw (COP19) have passed, and talks continued well into Saturday. As I wrote earlier this week, this conference was an important step on the way to Paris in 2015, when an international treaty for action on climate change post-2020 will be sought. Much reporting has focused on the acrimony between developed and developing countries, largely based on outstanding issues of development assistance and compensation for climate damages that were held by some as preconditions for success.  Into the late hours, unmet expectations from some developing countries pushed discussion on the prospective structure and timeline for the 2015 agreement into Saturday afternoon.

More...
 

By Vicki Ekstrom

Read the 2013 Energy and Climate Outlook

As international negotiators discuss global efforts to confront climate change at the 19^th United Nation’s Conference of Parties (COP19), a group of MIT researchers suggest that the current regional efforts may not be enough to avoid the dangerous consequences of rising emissions.

“As our global population swells to more than 10 billion by the end of this century, climate change is one of the forces of global change that will shape how the world feeds, shelters, transports, and otherwise attends to this growing mass of people,” says John Reilly, co-director of the Joint Program on the Science and Policy of Global Change and an author of the 2013 Energy and Climate Outlook. “Our latest Outlook is a window into the future as we view it in 2013, but it is still in our power to change what we see by taking action.”

While much of the Outlook’s projections remain the same as in their 2012 Outlook – highlighting that large or developing countries will play a greater role in shaping our global challenges over time – shifting trends and new and updated data have led to subtle changes.  One such trend is the growing use of natural gas and, to a lesser extent, renewable energy. Policies such as the European Union’s Emissions Trading System (and assuming Europe continues on its announced post 2020 policies)helped bring about some of these changes; cutting Europe’s coal generation in 2050 by almost half compared to the last Outlook. The U.S. is also expected to generate 35 percent more renewable energy and 15 percent more natural gas by 2050 compared to the 2012 Outlook.

Taking into account these resource and policy changes, the researchers project global natural gas consumption by 2050 to be 8 percent higher than their 2012 estimates, with China’s consumption alone more than tripling. They also project global consumption of renewable sources by 2050 to be 13 percent higher, while coal and oil usage will sink slightly (3 percent).

Changes in the global energy mix are partly responsible for a 12 percent dip in the projected CO₂ emissions by the end of the century. Yet, these emissions are still projected to be 95 percent higher than in 2010. Even with cumulative emissions sinking slightly, the Outlook projects the world will warm by 3 to 6°C by 2100 compared to 2000, with the median forecast at 3.8°C.

“With natural gas becoming more and more important to the global energy mix each year, and recent policy efforts spurring an increased use of renewables, we do believe there will be slightly fewer emissions than we originally forecasted,” says Sergey Paltsev, an author of the study and the assistant director for economic research at the Joint Program on Global Change. “But, while growing at a slightly lesser rate, emissions are still increasing, and if they continue to grow we might experience very harmful consequences.”

Building on the models used for their 2012 Outlook, the researchers identify the hottest and coldest regions and the range of uncertainty. They find that generally the polar areas display the most warming, with Northern Canada and Siberia warming between 6 and 12°C by 2100. Meanwhile, North America, Europe and Asia can expect temperatures to warm by as much as 4 to 8°C, and Africa, Australia and South America can expect temperature increases between 3 and 7°C. The researchers also warn there could be very damaging consequences from an increase in extreme precipitation events, such as floods.  Their analysis shows most land areas will become wetter, while over the ocean and Tropics a few regions could become drier.  

“Taking into account the vast uncertainty in climate projections, even in our most optimistic scenario we see that these changes will surely impact food and water resources, among other changes,” says Erwan Monier, an author of the study and a scientist at the Joint Program on Global Change.

As in the 2012 Outlook, the researchers emphasize that further cuts in developed countries would be useful. But only 13 percent of emissions are expected to come from these countries by 2100, meaning their efforts will have less of an impact over time as the share of emissions from other nations increases. Emissions from countries outside the developed world could grow by almost 150 percent by the end of the century.

Reilly, Paltsev and nine others based their projections on the United Nations' estimate that the world's population will grow to more than 10 billion by 2100. Using their computer modeling system to project how this growth would affect our energy and climate, they then incorporated pledges made by G20 nations at international meetings in Copenhagen in 2009 and Cancun in 2010 to cap emissions by 2020.

“As difficult as the progress made in Copenhagen and Cancun was to achieve, far more effort is needed to limit greenhouse gas concentrations to levels that avoid dangerous climatic consequences,” the authors write, stressing the importance of the ongoing international talks.