Poor Polar BearsBlack Carbon, Arctic Sea Ice and Himalayan Glaciers

The Problem: Scientist have long found evidence that heat-trapping gases are causing an increase in the amount of sea ice that melts each year in the arctic. This increase in melting is causing many problems for local ecosystems (poor polar bears) and may have long term effects on other earth systems such as air temperature, weather patterns, ocean circulation and the water cycle. These changes directly impact us even though we are far from the arctic. Recently scientists have found evidence that black carbon is playing a major role in increasing the rate at which glacial and possibly sea ice melts. It is your job as a team to evaluate the effects of black carbon and to make recommendations as to how we can reduce the effects of black carbon on melting glacial and sea ice.

Your Task:Part 1 (DAY 1) – Become a black carbon expert. In order to solve this problem you will need to understand what black carbon (BC) is where it comes from and what it does. You will also need to understand something called albedo. Use the links provided as well as the materials in your folder to help you find answers to the questions below as well as any other questions you can think of. How you organize your team is up to you. Consider dividing the readings into sections, each of you read one section and summarize important details for the group. Remember, even though you are working as a team, it is your responsibility to make sure you understand everything. You may need to search for additional sources of information.

Resources: http://www.economist.com/node/21530079 Arctic sea ice is melting far faster than climate models predict.

Why? (HC = hard copy provided) https://www.windows2universe.org/earth/changing_planet/black_carbon_intro.html BC video http://www.nytimes.com/2009/04/16/science/earth/16degrees.html?_r=1 Third-World Stove Soot Is Target in

Climate Fight(HC)

http://www.giss.nasa.gov/research/news/20050323 simple explanation of the effects of BC http://www.nytimes.com/slideshow/2009/04/16/world/20090416INDIA_index.html photo’s of BC issues in poor

countries http://msdavisapes.wikispaces.com/In+class+resources power point introduction to BC and albedo http://www.arb.ca.gov/board/books/2012/052412/12-3-2-2pres.pdf presentation on black carbon http://csc.noaa.gov/psc/dataviewer/#view=aerosols animation showing black carbon and dust

Questions:1. How is black carbon (BC) emitted into the atmosphere? 2. What are the different sources of BC in the southern and northern hemisphere? 3. How does BC get to the arctic?4. In which pole does BC precipitate out in snow and Ice? From which hemisphere does this BC come from? 5. What is albedo? How does black carbon change the albedo of ice?6. What earth spheres are affected by this issue? Give examples of how changes in one sphere affect other spheres.

Part 2 (DAY 2)

1. Become an expert on albedo and heat transfer. Use the links below and the materials in your packet to build your understanding of albedo.

http://eo.ucar.edu/educators/ClimateDiscovery/ESS_lesson4_10.19.05.pdf Earth’s Energy Cycle: Albedo

(hard copy and materials provided) http://www.eoearth.org/article/Albedo?topic=54300 background on albedo with maps

http://blogs.nasa.gov/cm/blog/whatonearth/posts/post_1292991500275.html video and article showing sea ice change 1980-2010

A Dusty Situation – black carbon activity (materials included)

2. Understand how black carbon is studied in the atmosphere. http://hippo.ucar.edu/HIPPO/about-hippo background on the HIPPO project http://www.youtube.com/watch?v=NoHnY6a2dbs&feature=youtu.be hippo route animation http://hippo.ucar.edu/field-notes/hippo-ii-flights/hippo-flight-8-honiara-solomon-islands-to-kona-

hi#ii_rf08_flight_video video showing change in altitude of plane http://hippo.ucar.edu/HIPPO/videos/sampling-black-carbon-over-arctic-sea-ice-and-open-leads scientist explaining

why he studies black carbon over arctic sea ice http://hippo.ucar.edu/instruments/aerosols-cloud-physics#sp2 info about HIPPO instruments collecting BC data

3. Understand how ice cores provide data on the atmosphere http://www.pbs.org/wgbh/nova/warnings/stories/ explanation and visual of ice cores Stories in the Ice (HC) Complete the enclosed activity: Create Your Own Ice Core or A Dusty Situation (divide and conquer).

Part 3 (DAY 3) – Data Analysis1. Read these articles to build your background in how ice cores give us data on historical BC in the Himalayas:

http://www.giss.nasa.gov/research/briefs/hansen_14 best article on ice cores and BC in Himalayas http://newscenter.lbl.gov/feature-stories/2010/02/03/black-carbon-himalayan-glaciers/ (HC)

2. Go to: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/trop/everest/rongbuk2008bc.txt to view BC data from a Himalayan ice core taken from the East Rongbuk Glacier on Mt Everest. Make sure you scroll down to locate the black carbon data.

3. Work as a group to graph the black carbon found in the ice core over the 50 year time period.4. View the data in this power point: http://msdavisapes.wikispaces.com/In+class+resources 5. Work as a group to determine what the data tells you. You could start by considering the following questions:

o Is there a link between the amount of black carbon in the ice and rate or scale of glacial retreat in the Himalayas?

o When is black carbon most prevalent in the atmosphere of the northern hemisphere?o What is the source of this black carbon?o What has caused the increase in black carbon in the Himalayas?

Be sure you are asking yourselves more questions. These are just a start.

Part 4 (DAY 4) – RecommendationsNow that you have some evidence that black carbon increases the rate at which ice melts, what are you going to do about it? Time to save the polar bears. Make a list of recommendations for reducing the amount of black carbon that reaches the arctic. Use the information and data you have collected to create convincing options that the rest of us (and the world) can buy into.You will share your results in a brief presentation to the class. Create a Prezi or PowerPoint using the following guide:

Presentation length (8-10 minutes)o 2 minutes – backgroundo 2 minutes – what you learned from your data analysiso 4 minutes – your recommendations and why they would worko 2 minutes for questions

Each member of your group must participate in the presentation Be clear so others can get a good overview of your case study Write 2-3 clicker questions to be used both before and after your presentation to gauge the feelings and

opinions of your audience. This should provide you a measure of how your presentation informed you audience and changed their perceptions. These could be multiple choice, short answer, or likert scale.

Extracting ice cores in Greenland

Photo taken from: http://earthobservatory.nasa.gov/Features/Paleoclimatology_IceCores/

Photographs of East Rongbuk Glacier, 1921 (left) versus 2008. Images courtesy of Major E.O. Wheeler, Royal Geographic Society; David Breshears

Beating a retreat

Arctic sea ice is melting far faster than climate models predict. Why?Sep 24th 2011 | from the print edition

ON SEPTEMBER 9th, at the height of its summertime shrinkage, ice covered 4.33m square km, or 1.67m square miles, of the Arctic Ocean, according to America's National Snow and Ice Data Centre (NSIDC). That is not a record low—not quite. But the actual record, 4.17m square km in 2007, was the product of an unusual combination of sunny days, cloudless skies and warm currents flowing up from mid-latitudes. This year has seen no such opposite of a perfect storm, yet the summer sea-ice minimum is a mere 4% bigger than that record. Add in the fact that the thickness of the ice, which is much harder to measure, is estimated to have fallen by half since 1979, when satellite records began, and there is probably less ice floating on the Arctic Ocean now than at any time since a particularly warm period 8,000 years ago, soon after the last ice age.

That Arctic sea ice is disappearing has been known for decades. The underlying cause is believed by all but a handful of climatologists to be global warming brought about by greenhouse-gas emissions. Yet the rate the ice is vanishing confounds these climatologists' models. These predict that if the level of carbon dioxide, methane and so on in the atmosphere continues to rise, then the Arctic Ocean will be free of floating summer ice by the end of the century. At current rates of shrinkage, by contrast, this looks likely to happen some time between 2020 and 2050.

The reason is that Arctic air is warming twice as fast as the atmosphere as a whole. Some of the causes of this are understood, but some are not. The darkness of land and water compared with the reflectiveness of snow and ice means that when the latter melt to reveal the former, the area exposed absorbs more heat from the sun and

reflects less of it back into space. The result is a feedback loop that accelerates local warming. Such feedback, though, does not completely explain what is happening. Hence the search for other things that might assist the ice's rapid disappearance.

Forcing the issue

One is physical change in the ice itself. Formerly a solid mass that melted and refroze at its edges, it is now thinner, more fractured, and so more liable to melt. But that is (literally and figuratively) a marginal effect. Filling the gap between model and reality may need something besides this.

The latest candidates are “short-term climate forcings”. These are pollutants, particularly ozone and soot, that do not hang around in the atmosphere as carbon dioxide does, but have to be renewed continually if they are to have a lasting effect. If they are so renewed, though, their impact may be as big as CO2's.

At the moment, most eyes are on soot (or “black carbon”, as jargon-loving researchers refer to it). In the Arctic, soot is a double whammy. First, when released into the air as a result of incomplete combustion (from sources as varied as badly serviced diesel engines and forest fires), soot particles absorb sunlight, and so warm up the atmosphere. Then, when snow or rain wash them onto an ice floe, they darken its surface and thus cause it to melt faster.

Reducing soot (and also ozone, an industrial pollutant that acts as a greenhouse gas) would not stop the summer sea ice disappearing, but it might delay the process by a decade or two. According to a recent report by the United Nations Environment Programme, reducing black carbon and ozone in the lower part of the atmosphere, especially in the Arctic countries of America, Canada, Russia and Scandinavia, could cut warming in the Arctic by two-thirds over the next three decades. Indeed, the report suggests, if such measures—preventing crop burning and forest fires, cleaning up diesel engines and wood stoves, and so on—were adopted everywhere they could halve the wider rate of warming by 2050.

Without corresponding measures to cut CO2 emissions, this would be but a temporary fix. Nonetheless, it is an attractive idea because it would have other benefits (soot is bad for people's lungs) and would not require the wholesale rejigging of energy production which reducing CO2 emissions implies. Not everyone agrees it would work, though. Gunnar Myhre of the Centre for International Climate and Environmental Research in Oslo, for example, notes that the amount of black carbon in the Arctic is small and has been falling in recent decades. He does not believe it is the missing factor in the models. Carbon dioxide, in his view, is the main culprit. Black carbon deposited on the Arctic snow and ice, he says, will have only a minimal effect on its reflectivity.

The rapid melting of the Arctic sea ice, then, illuminates the difficulty of modelling the climate—but not in a way that brings much comfort to those who hope that fears about the future climate might prove exaggerated. When reality is changing faster than theory suggests it should, a certain amount of nervousness is a reasonable response.

It's an ill wind…

The direct consequences of changes in the Arctic are mixed. They should not bring much rise in the sea level, since floating ice obeys Archimedes's principle and displaces its own mass of water. A darker—and so more heat-absorbent—Arctic, though, will surely accelerate global warming and may thus encourage melting of the land-bound Greenland ice sheet. That certainly would raise sea levels (though not as quickly as News Corporation's cartographers suggest in the latest edition of the best-selling “Times Atlas”, which claims that 15% of the Greenland sheet has melted in the past 12 years; the true figure is more like 0.05%). Wildlife will also suffer. Polar bears, which hunt for seals along the ice's edge, and walruses, which fish there, will both be hard-hit.

The effects on the wider climate are tricky to assess. Some meteorologists suspect unseasonal snow storms off the east coast of America in 2010 were partly caused by Arctic warming shifting wind patterns. One feedback loop that does seems certain, though, is that the melting Arctic will enable the extraction of more fossil fuel, with all that that implies for greenhouse-gas emissions.

The Arctic is reckoned to hold around 15% of the world's undiscovered oil reserves and 30% of those of natural gas. Hence a growing polar enthusiasm among energy companies—as witnessed last month in an Arctic tie-up between Exxon Mobil, of America, and Rosneft, Russia's state-controlled oil giant. Recent plankton blooms suggest a warmer Arctic will provide a boost to fisheries there, too. And the vanishing ice has begun to allow a trickle of shipping across the Arctic's generally frozen north-west and north-east passages, thus linking the Atlantic and Pacific oceans. In August a Russian supertanker, the Vladimir Tokohonov, aided by two nuclear icebreakers, became the first such vessel to cross the north-east route (or, as Russians refer to it, the northern sea route), hugging the Siberian coast.

So far, despite some posturing by Canada and Russia, there are few territorial disputes in the region and the Arctic Council, the club of Arctic nations, has functioned reasonably well. Whether the interests of these countries coincide with those of the wider world, though, is moot. A warming Arctic will bring local benefits to some. The rest of the world may pay the cost.

By Degrees

Third-World Stove Soot Is Target in Climate Fight

Adam Ferguson for The New York TimesCooking in Kohlua, India. Soot from tens of thousands of villages in developing countries is responsible for 18 percent of the planet’s warming, studies say.

By ELISABETH ROSENTHALPublished: April 15, 2009 KOHLUA, India — “It’s hard to believe that this is what’s melting the glaciers,” said Dr. Veerabhadran Ramanathan, one of the world’s leading climate scientists, as he weaved through a warren of mud brick huts, each containing a mud cookstove pouring soot into the atmosphere.

As women in ragged saris of a thousand hues bake bread and stew lentils in the early evening over fires fueled by twigs and dung, children cough from the dense smoke that fills their homes. Black grime coats the undersides of thatched roofs. At dawn, a brown cloud stretches over the landscape like a diaphanous dirty blanket.

In Kohlua, in central India, with no cars and little electricity, emissions of carbon dioxide, the main heat-trapping gas linked to global warming, are near zero. But soot — also known as black carbon — from tens of thousands of villages like this one in developing countries is emerging as a major and previously unappreciated source of global climate change.

While carbon dioxide may be the No. 1 contributor to rising global temperatures, scientists say, black carbon has emerged as an important No. 2, with recent studies estimating that it is responsible for 18 percent of the planet’s warming, compared with 40 percent for carbon dioxide. Decreasing black carbon emissions would be a relatively cheap way to significantly rein in global warming — especially in the short term, climate experts say.

Replacing primitive cooking stoves with modern versions that emit far less soot could provide a much-needed stopgap, while nations struggle with the more difficult task of enacting programs and developing technologies to curb carbon dioxide emissions from fossil fuels.

In fact, reducing black carbon is one of a number of relatively quick and simple climate fixes using existing technologies — often called “low hanging fruit” — that scientists say should be plucked immediately to avert the worst projected consequences of global warming. “It is clear to any person who cares about climate change that this will have a huge impact on the global environment,” said Dr. Ramanathan, a professor of climate science at the Scripps Institute of Oceanography, who is working with the Energy and Resources Institute in New Delhi on a project to help poor families acquire new stoves.

“In terms of climate change we’re driving fast toward a cliff, and this could buy us time,” said Dr. Ramanathan, who left India 40 years ago but returned to his native land for the project.

Better still, decreasing soot could have a rapid effect. Unlike carbon dioxide, which lingers in the atmosphere for years, soot stays there for a few weeks. Converting to low-soot cookstoves would remove the warming effects of black carbon quickly, while shutting a coal plant takes years to substantially reduce global CO2 concentrations.

But the awareness of black carbon’s role in climate change has come so recently that it was not even mentioned as a warming agent in the 2007 summary report by the Intergovernmental Panel on Climate Change that pronounced the evidence for global warming to be “unequivocal.” Mark Z. Jacobson, professor of environmental engineering at Stanford, said that the fact that black carbon was not included in international climate efforts was “bizarre,” but “partly reflects how new the idea is.” The United Nations is trying to figure out how to include black carbon in climate change programs, as is the federal government.

In Asia and Africa, cookstoves produce the bulk of black carbon, although it also emanates from diesel engines and coal plants there. In the United States and Europe, black carbon emissions have already been reduced significantly by filters and scrubbers.

Like tiny heat-absorbing black sweaters, soot particles warm the air and melt the ice by absorbing the sun’s heat when they settle on glaciers. One recent study estimated that black carbon might account for as much as half of Arctic warming. While the particles tend to settle over time and do not have the global reach of greenhouse gases, they do travel, scientists now realize. Soot from India has been found in the Maldive Islands and on the Tibetan Plateau; from the United States, it travels to the Arctic. The environmental and geopolitical implications of soot emissions are enormous. Himalayan glaciers are expected to lose 75 percent of their ice by 2020, according to Prof. Syed Iqbal Hasnain, a glacier specialist from the Indian state of Sikkim.

These glaciers are the source of most of the major rivers in Asia. The short-term result of glacial melt is severe flooding in mountain communities. The number of floods from glacial lakes is already rising sharply, Professor Hasnain said. Once the glaciers shrink, Asia’s big rivers will run low or dry for part of the year, and desperate battles over water are certain to ensue in a region already rife with conflict.

Doctors have long railed against black carbon for its devastating health effects in poor countries. The combination of health and environmental benefits means that reducing soot provides a “very big bang for your buck,” said Erika Rosenthal, a senior lawyer at Earth Justice, a Washington organization. “Now it’s in everybody’s self-interest to deal with things like cookstoves — not just because hundreds of thousands of women and children far away are dying prematurely.”

In the United States, black carbon emissions are indirectly monitored and minimized through federal and state programs that limit small particulate emissions, a category of particles damaging to human health that includes black carbon. But in March, a bill was introduced in Congress that would require the Environmental Protection

Agency to specifically regulate black carbon and direct aid to black carbon reduction projects abroad, including introducing cookstoves in 20 million homes. The new stoves cost about $20 and use solar power or are more efficient. Soot is reduced by more than 90 percent. The solar stoves do not use wood or dung. Other new stoves simply burn fuel more cleanly, generally by pulverizing the fuel first and adding a small fan that improves combustion.

That remote rural villages like Kohlua could play an integral role in tackling the warming crisis is hard to imagine. There are no cars — the village chief’s ancient white Jeep sits highly polished but unused in front of his house, a museum piece. There is no running water and only intermittent electricity, which powers a few light bulbs.

The 1,500 residents here grow wheat, mustard and potatoes and work as day laborers in Agra, home of the Taj Majal, about two hours away by bus.

They earn about $2 a day and, for the most part, have not heard about climate change. But they have noticed frequent droughts in recent years that scientists say may be linked to global warming. Crops ripen earlier and rot more frequently than they did 10 years ago. The villagers are aware, too, that black carbon can corrode. In Agra, cookstoves and diesel engines are forbidden in the area around the Taj Majal, because soot damages the precious facade.

Still, replacing hundreds of millions of cookstoves — the source of heat, food and sterile water — is not a simple matter. “I’m sure they’d look nice, but I’d have to see them, to try them,” said Chetram Jatrav, as she squatted by her cookstove making tea and a flatbread called roti. Her three children were coughing.

She would like a stove that “made less smoke and used less fuel” but cannot afford one, she said, pushing a dung cake bought for one rupee into the fire. She had just bought her first rolling pin so her flatbread could come out “nice and round,” as her children had seen in elementary school. Equally important, the open fires of cookstoves give some of the traditional foods their taste. Urging these villagers to make roti in a solar cooker meets the same mix of rational and irrational resistance as telling an Italian that risotto tastes just fine if cooked in the microwave.

In March, the cookstove project, called Surya, began “market testing” six alternative cookers in villages, in part to quantify their benefits. Already, the researchers fret that the new stoves look like scientific instruments and are fragile; one broke when a villager pushed twigs in too hard.

But if black carbon is ever to be addressed on a large scale, acceptance of the new stoves is crucial. “I’m not going to go to the villagers and say CO2 is rising, and in 50 years you might have floods,” said Dr. Ibrahim Rehman, Dr. Ramanathan’s collaborator at the Energy and Resources Institute. “I’ll tell her about the lungs and her kids and I know it will help with climate change as well.”

Stories in the Iceby Peter TysonOnline Producer, NOVA

Nature's Time MachineHow would you like to have a time machine that could take you back anywhere over the past 300,000 years? You could see what the world was like when ice sheets a thousand feet thick blanketed Canada and northern Europe, or when the Indonesian volcano Toba blew its top in the largest volcanic eruption of the last half million years.

Well, scientists have such a time machine. It's called an ice core. Scientists collect ice cores by driving a hollow tube deep into the miles-thick ice sheets of Antarctica and Greenland (and in glaciers elsewhere). The long cylinders of ancient ice that they retrieve provide a dazzlingly detailed record of what was happening in the world over the past several ice ages. That's because each layer of ice in a core corresponds to a single year—or sometimes even a single season—and most everything that fell in the snow that year remains behind, including wind-blown dust, ash, atmospheric gases, even radioactivity.

Indeed, fallout from the Chernobyl nuclear accident has turned up in ice cores, as has dust from violent desert storms countless millennia ago. Collectively, these frozen archives give scientists unprecedented views of global climate over the eons. More important, the records allow researchers to predict the impact of significant events—from volcanic eruptions to global warming—that could strike us today.

The Ice Core Timeline requires JavaScript support in your browser. If your browser doesn't support JavaScript, please try the non-JavaScript version.

Ice Core Timeline (see website)

Special thanks to Mark Twickler, University of New HampshireTaken from: http://www.pbs.org/wgbh/nova/warnings/stories/

Black Carbon A Significant Factor in the Melting of Himalayan Glaciers Berkley LabsFebruary 03, 2010

Julie Chao 510-486-6491 JHChao@lbl.gov

Feature

The fact that glaciers in the Himalayan mountains are thinning is not disputed. However, few researchers have attempted to rigorously examine and quantify the causes. Lawrence Berkeley National Laboratory scientist Surabi Menon set out to isolate the impacts of the most commonly blamed culprit—greenhouse gases, such as carbon dioxide—from other particles in the air that may be causing the melting. Menon and her collaborators found that airborne black carbon aerosols, or soot, from India is a major contributor to the decline in snow and ice cover on the glaciers.

“Our simulations showed greenhouse gases alone are not nearly enough to be responsible for the snow melt,” says Menon, a physicist and staff scientist in Berkeley Lab’s Environmental Energy Technologies Division. “Most of the change in snow and ice cover—about 90 percent—is from aerosols. Black carbon alone contributes at least 30 percent of this sum.”

Menon and her collaborators used two sets of aerosol inventories by Indian researchers to run their simulations; their results were published online in the journal Atmospheric Chemistry and Physics.

The actual contribution of black carbon, emitted largely as a result of burning fossil fuels and biomass, may be even higher than 30 percent because the inventories report less black carbon than what has been measured by observations at several stations in India. (However, these observations are too incomplete to be used in climate models.) “We may be underestimating the amount of black carbon by as much as a factor of four,” she says.

The findings are significant because they point to a simple way to make a swift impact on the snow melt. “Carbon dioxide stays in the atmosphere for 100 years, but black carbon doesn’t stay in the atmosphere for more than a few weeks, so the effects of controlling black carbon are much faster,” Menon says. “If you control black carbon now, you’re going to see an immediate effect.”

The Himalayan glaciers are often referred to as the third polar ice cap because of the large amount of ice mass they hold. The glacial melt feeds rivers in China and throughout the Indian subcontinent and provide fresh water to more than one billion people.

Atmospheric aerosols are tiny particles containing nitrates, sulfates, carbon and other matter, and can influence the climate. Unlike other aerosols, black carbon absorbs sunlight, similar to greenhouse gases. But unlike greenhouse gases, black carbon does not heat up the surface; it warms only the atmosphere.

This warming is one of two ways in which black carbon melts snow and ice. The second effect results from the deposition of the black carbon on a white surface, which produces an albedo effect that accelerates melting. Put another way, dirty snow absorbs far more sunlight—and gets warmer faster—than pure white snow.

Previous studies have shown that black carbon can have a powerful effect on local atmospheric temperature. “Black carbon can be very strong,” Menon says. “A small amount of black carbon tends to be more potent than the same mass of sulfate or other aerosols.”

Black carbon, which is caused by incomplete combustion, is especially prevalent in India and China; satellite images clearly show that its levels there have climbed dramatically in the last few decades. The main reason for the increase is the accelerated economic activity in India and China over the last 20 years; top sources of black carbon include shipping, vehicle emissions, coal burning and inefficient stoves. According to Menon’s data, black carbon emitted in India increased by 46 percent from 1990 to 2000 and by another 51 percent from 2000 to 2010.

This map of the change in annual linear snow cover from 1990 to 2001 shows a thick band (blue) across the Himalayas with decreases of at least 16 percent while a few smaller patches (red) saw increases. The data was collected by the National Snow and Ice Data Center.

However, black carbon’s effect on snow is not linear. Menon’s simulations show that snow and ice cover over the Himalayas declined an average of about one percent from 1990 to 2000 due to aerosols that originated from India. Her study did not include particles that may have originated from China, also known to be a large source of black carbon. (See “Black soot and the survival of the Tibetan glaciers,” by James Hansen, et al., published last year in the Proceedings of the National Academy of Sciences.) Also the figure is an average for the entire region, which saw increases and decreases in snow cover. As seen in the figure, while a large swath of the Himalayas saw snow cover decrease by at least 16 percent over this period, as reported by the National Snow and Ice Data Center, a few smaller patches saw increases.

Menon’s study also found that black carbon affects precipitation and is a major factor in triggering extreme weather in eastern India and Bangladesh, where cyclones, hurricanes and flooding are common. It also contributes to the decrease in rainfall over central India. Because black carbon heats the atmosphere, it changes the local heating profile, which increases convection, one of the primary causes of precipitation. While this results in more intense rainfall in some regions, it leads to less in other regions. The pattern is very similar to a study Menon led in 2002, which found that black carbon led to droughts in northern China and extreme floods in southern China.

“The black carbon from India is contributing to the melting of the glaciers, it’s contributing to extreme precipitation, and if black carbon can be controlled more easily than greenhouse gases like CO2, then it makes sense for India to regulate black carbon emissions,” says Menon.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research for DOE’s Office of Science and is managed by the University of California. Visit our Website at www.lbl.gov/

Additional information: Read the paper, “Black carbon aerosols and the third polar ice cap” (see online)