Cooperative Institute for Research in Environmental Sciences

CIRES, NOAA researchers are part of global team urging better climate monitoring of high-elevation regions


 An international team of scientists is calling for urgent and rigorous monitoring of temperature patterns in mountain regions after compiling evidence that high elevations could be warming faster than previously thought.

Without substantially better information, people risk underestimating the severity of a number of already looming environmental challenges, including water shortages and the possible extinction of some alpine flora and fauna, according to the research team, which includes Henry Diaz and Imtiaz Rangwala from CIRES, the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. Both researchers are part of NOAA’s Earth System Research Laboratory.

 

The team’s report is published in the journal Nature Climate Change.

 

“There is growing evidence that high mountain regions are warming faster than lower elevations and such warming can accelerate many other environmental changes such as glacial melt and vegetation change,” said lead author, Nick Pepin of the University of Portsmouth. But scientists urgently need more and better data to confirm this, because there are so few observations from 11,000 feet or higher, he and his co-authors said.

 

Several reasons that mountain regions are at risk for faster rates of temperature increase:

  • Loss of snow and ice at high elevation means more exposed land surface, which can warm up faster in the sun; this effect disproportionately affects higher elevations which are more likely to contain snow and ice.
  • Dust and soot deposited on ice- or snow-covered the surfaces at high elevations causes more incoming sunlight to be converted to heat (dust deposition on snow is known to affect the timing of spring runoff in the Rocky Mountains, shifting it earlier by a week or more).
  • A warmer atmosphere holds more moisture, which can condense into clouds. That process releases heat, which can affect high-altitude regions that reach up toward the height of cloud formation;
  • Increases in the amount of atmospheric water vapor greatly increases the infrared heating of the land at high elevations relative to low elevation regions during winter.
  • At lower elevations, aerosol pollutants—haze, dust and smoke—reduce warming, increasing the difference in rates of warming between low and high elevations.

“It’s understandable. Mountains are difficult to study, they are remote and often inaccessible, and it is expensive and often challenging to find ways of effectively monitoring what is happening,” Pepin said. “Mountains are also very complicated landscapes, and have a wide variety of microclimates which makes it hard to see the overall picture.”

 

The most striking evidence that mountain regions are warming more rapidly than surrounding regions comes from the Tibetan plateau, according to the new paper. There, temperatures have risen steadily over the past 50 years and the rate of change is speeding up. But masked by this general climate warming are pronounced differences at different elevations. For example, over the past 20 years temperatures above 13,000 ft (4,000 m) have risen nearly 75 percent faster than temperatures in areas below 6,500 ft (2,000 m).  

 

The picture is more complicated in other regions. In the Rocky Mountains, for example, there are so few data that reach back more than a decade, researchers have not been able to make broad conclusions about warming trends at various altitudes, said CIRES’ Diaz, who works in the NOAA Earth System Research Laboratory.

 

However sparse, existing monitoring has been a huge help to scientists trying to understand how various physical processes act to change climate at high altitudes, said Rangwala, who works in NOAA’s Earth System Research Laboratory and also the Western Water Assessment (see sidebar).

 

Records of weather patterns at high altitudes are “extremely sparse,” the researchers found. The density of weather stations above 4,500 m is roughly one-tenth that in areas below that elevation. Long-term data, crucial for detecting patterns, doesn’t yet exist above 5,000 m anywhere in the world. The longest observations above this elevation are 10 years on the summit of Kilimanjaro.

 

The team of scientists came together as part of the Mountain Research Initiative, a mountain global change research effort funded by the Swiss National Foundation. The team includes scientists from the UK, United States, Switzerland, Canada, Ecuador, Pakistan, China, Italy, Austria and Kazakhstan. Between them, they have studied data on mountain temperatures worldwide collected over the past 60-70 years.

 

Improved observations, satellite-based remote sensing and climate model simulations are all needed to gain a true picture of warming in mountain regions, said Raymond Bradley, a climatologist at the University of Massachusetts and one of the report’s co-authors. “We are calling for special efforts to be made to extend scientific observations upwards to the highest summits to capture richer data on what is happening across the world’s mountains,” Bradley said. “We also need a strong effort to find, collate and evaluate observational data that already exists wherever it is in the world. This requires international collaboration.”

 

The world’s highest mountain, Mt Everest, stands at 8,848 m (29,029 feet). More than 250 other mountains, including Mt Elbrus in Russia, Mt Denali in Alaska, Mt Aconcagua in Argentina and Mt Kilimanjaro in Africa also all top the 5,000-m (16,000-feet) mark.

 

CIRES is a partnership of NOAA and CU Boulder.

 

Download a high-resolution image of Mount Cook from CIRES Flickr. 


This news story is adapted from the University of Portsmouth.

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Henry Diaz
Imtiaz Rangwala

Several reasons that mountain regions are at risk for faster rates of temperature increase:

  • Loss of snow and ice at high elevation means more exposed land surface, which can warm up faster in the sun; this effect disproportionately affects higher elevations which are more likely to contain snow and ice.
  • Dust and soot deposited on ice- or snow-covered the surfaces at high elevations causes more incoming sunlight to be converted to heat (dust deposition on snow is known to affect the timing of spring runoff in the Rocky Mountains, shifting it earlier by a week or more).
  • A warmer atmosphere holds more moisture, which can condense into clouds. That process releases heat, which can affect high-altitude regions that reach up toward the height of cloud formation;
  • Increases in the amount of atmospheric water vapor greatly increases the infrared heating of the land at high elevations relative to low elevation regions during winter.
  • At lower elevations, aerosol pollutants—haze, dust and smoke—reduce warming, increasing the difference in rates of warming between low and high elevations.

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Ethanol fuel refineries could be releasing much larger amounts of some ozone-forming compounds into the atmosphere than current assessments suggest, according to a new study that found emissions of these chemicals at a major ethanol fuel refinery are many times higher than government estimates.

New airborne measurements downwind from an ethanol fuel refinery in Decatur, Illinois, show that ethanol emissions are 30 times higher than government estimates. The measurements also show emissions of all volatile organic compounds (VOCs), which include ethanol, were five times higher than government numbers, which estimate emissions based on manufacturing information. VOCs and nitrogen oxides react with sunlight to form ground-level ozone, the main component of smog.

If emissions at the more than 200 fuel other ethanol refineries in the U.S. are also being underestimated, these plants could be a higher source of VOC emissions than currently thought, according to the new findings accepted for publication in the Journal of Geophysical Research: Atmospheres, a publication of the American Geophysical Union.

Ethanol, a renewable transportation fuel made from corn, constitutes approximately 10 percent of the fuel used in gasoline vehicles in the U.S., according to the new study. The renewable fuel standard mandating the use of ethanol and other renewable fuels aims to reduce greenhouse gas emissions and petroleum imports, while encouraging development and expansion of the U.S. renewable fuels sector, according to the U.S. Environmental Protection Agency.

The new study is one of the first and most detailed investigations of emissions from ethanol fuel refining, according to its lead author Joost de Gouw, a scientist at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder and NOAA’s Earth System Research Laboratory in Boulder, Colorado. Information about the refining process is one piece of examining the entire lifecycle of ethanol fuel emissions, from growing the corn used to make the fuel to the effect of emissions on urban air quality, he said.

“Over the past decade, because of the renewable fuel mandate, we have added 10 percent of ethanol to all the gasoline that is sold in the U.S. and so the question is: what does that do to the environment,” de Gouw said. “That is a very complicated question and it has many different aspects. One of the aspects is the air-quality implications and, to get at them, we have to know what are the emissions associated with producing ethanol and using ethanol. That is where this study fits in.”

To make the measurements they report, de Gouw and his colleagues flew an airplane downwind of an Archer Daniels Midland ethanol refinery, the third largest producer of fuel ethanol in the U.S., and took air-quality readings at three different distances from the plant. The researchers used those to calculate emissions of various gases, including VOCs, nitrogen oxides and sulfur dioxide.

They then compared their findings with government emissions estimates from 2011. Emissions of sulfur dioxide and nitrogen oxides – compounds generated by the coal-burning plant – were in-line with government estimates, but emissions of VOCs, including ethanol, were higher than government estimates. De Gouw said the VOC emissions are likely generated by the refining process, not the coal-burning that powers it.

The researchers also used government estimates and ethanol production numbers from the Renewable Fuels Association to analyze emissions from all fuel ethanol refineries in the U.S. and compare those to emissions from burning ethanol in motor vehicles.

Prevailing estimates had indicated that refining ethanol fuel and burning it in cars and trucks generate equivalent amount of VOCs, including ethanol. But, the new emissions measurements from the Decatur plant show that ethanol emissions from production of one kilogram of ethanol at the refinery are 170 times higher than what comes out of a vehicle burning the same amount of ethanol, de Gouw said.  If the Decatur refinery is like most other refineries in the U.S., he added, “the higher emissions of ethanol and VOCs that we calculated from our data would make the refining process a larger source of these gases than burning the ethanol fuel in your car.”

“Obviously, this was just one refinery that we looked at, so we’d like to do more and see if these findings are more universal or if this plant was just exceptional,” de Gouw added.

The new study points to the need for more measurements of emissions coming from ethanol fuel refineries, said Dylan Millet, an associate professor of atmospheric chemistry at the University of Minnesota in St. Paul. He was not involved with the new research. Additional observational data will help scientists better understand the emissions and their impact on air quality, he said.

“If we are going to accurately assess the air-quality implications of our fuel choices, then these are important emissions to know,” Millet said.

CIRES is a partnership of NOAA and the University of Colorado Boulder.

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CIRES is a partnership of NOAA and CU Boulder.


This is a joint release of the Cooperative Institute for Research in Environmental Sciences (CIRES), the American Geophysical Union (AGU), NASA and the Chemical Sciences Division of NOAA’s Earth System Research Laboratory.

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The Know Your AQcurriculum engages students to learn about key air quality issues impacting Colorado's Front Range through the use of real-world data from the DISCOVER-AQ and FRAPPE air monitoring campaign. This standards-aligned, four-module curriculum investigates how particulate matter, ground level ozone, nitrogen

nitrogen deposition, and carbon gas emissions relate to the region's air quality.


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Findings will help experts forecast bad ozone days over the U.S. West


New research reveals a strong connection between high ozone days in the U.S. West during late spring, the stratosphere, and La Niña, an ocean-atmosphere phenomenon that affects global weather patterns.

Following a La Nina winter, ozone-rich air is more likely to descend from the stratosphere and reach the surface in western U.S. communities at higher elevations, according to the new study led by Meiyun Lin (of NOAA’s Geophysical Fluid Dynamics Laboratory and NOAA’s cooperative institute at Princeton University). Co-authors of the study, published May 12 in Nature Communications, include Andy Langford of NOAA’s Earth System Research Laboratory (ESRL) in Boulder, Colorado and CIRES’s Samuel Oltmans, who also works at ESRL.

Recognizing this link offers an opportunity to forecast high surface ozone pollution several months in advance, which could improve public education to reduce health effects. It could also help western U.S. air quality managers prepare to track these events, which can have implications for attaining the national standard for ozone, a regulated pollutant that has harmful effects on human health, crops and ecosystems.   

“Ozone in the stratosphere, located 6 to 30 miles (10 to 48 kilometers) above the ground, typically stays in the stratosphere,” said Lin. “But not on some days in late spring following a strong La Niña winter. That’s when the polar jet stream meanders southward over the western United States and facilitates intrusions of stratospheric ozone to ground level where people live.”

During the last two decades, there have been three La Niña events: 1998-1999, 2007-2008 and 2010-2011. After these events, scientists saw spikes in ground level ozone for periods of two to three days at a time during late spring in high-altitude locations of the U.S. West, including the Denver-Boulder area.

It’s more common to hear about high ozone levels on muggy summer days when pollution from cars and power plants fuels the formation of regional ozone pollution. But in springtime in high-altitude regions of the U.S. West, the stratosphere—which contains 90 percent of the ozone in Earth’s atmosphere—can be a source of the ozone at ground level. High-elevation areas are more vulnerable to the intrusions of air from above, owing to their closer proximity to the stratosphere.

Lin and her colleagues found that these deep intrusions of stratospheric ozone could add 20 to 40 parts per billion of ozone to the ground-level ozone concentration, which can push the ozone levels closer to, or even over, the standard set by the Environmental Protection Agency (EPA). The EPA has proposed tightening that standard currently set at 75 parts per billion for an eight-hour average to between 65 and 70 parts per billion.

Under the Clean Air Act, these deep stratospheric ozone intrusions can be classified as “exceptional events” that are not counted towards EPA attainment determinations. If our national ozone standard becomes more stringent, the relative importance of these stratospheric intrusions grows, leaving less room for human-caused emissions to add to the surface ozone levels without triggering an exceedance of the standard set by the  EPA.  

“Regardless of whether these events count towards non-attainment, people are living in these regions and the possibility of predicting a high-ozone season might allow for public education to minimize adverse health effects,” said Arlene Fiore, an atmospheric scientist at Columbia University and a co-author of the research.

Though stratospheric intrusions have been recognized and studied for many years, the link to La Niña is a new finding that opens up the possibility of longer-term predictions of the intrusions. Predicting where and when stratospheric ozone intrusions may occur would also provide time to deploy air sensors to obtain evidence as to how much of ground-level ozone can be attributed to these naturally occurring intrusions and how much is due to human-caused emissions.

The study involved collaboration across two NOAA laboratories, NOAA’s cooperative institutes at Princeton and the University of Colorado Boulder, and scientists at partner institutions in the United States, Canada and Austria.

“This study brings together observations and chemistry-climate modeling to help understand the processes that contribute to springtime high-ozone events in the western U.S.,” said Langford, an atmospheric scientist who measures ozone concentrations using lidars.

“You’ve heard about good ozone, the kind found high in the stratosphere that protects the earth from harmful ultraviolet radiation,” said Langford. “And you’ve heard about bad ozone at ground level. This study looks at the factors that cause good ozone to go bad.”

Lin, Fiore, and Langford conducted the research with Larry Horowitz of GFDL; Samuel Oltmans of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, who works in NOAA's Earth System Research Laboratory; David Tarasick of Environment Canada; and Harald Rieder of the University of Graz in Austria. 

CIRES is a partnership of NOAA and the University of Colorado Boulder

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The Larsen C Ice Shelf—whose neighbours Larsen A and B, collapsed in 1995 and 2002—is thinning from both its surface and beneath, according to an international study published in the journal The Cryosphere, a journal of the European Geophysical Union.

For years scientists were unable to determine whether warming air temperatures or warmer ocean currents are causing the Antarctic Peninsula’s floating ice shelves to lose volume and become more vulnerable to collapse. This new study takes an important step forward in assessing Antarctica’s likely contribution to future sea level rise.

The research team combined satellite data and eight radar surveys captured during a 15-year period from 1998-2012. They found that Larsen C Ice Shelf lost an average of 4 meters of ice, and had lowered by an average of one meter at the surface.

“What’s exciting about this study is we now know that two different processes are causing Larsen C to thin and become less stable. Air is being lost from the top layer of snow (called the firn), which is becoming more compacted, probably because of increased melting by a warmer atmosphere. We know also that Larsen C is losing ice, probably from warmer ocean currents or changing ice flow,” said lead author Paul Holland from the British Antarctic Survey (BAS).

“If this vast ice shelf—which is over two and a half times the size of Wales and 10 times bigger than Larsen B—was to collapse, it would allow the tributary glaciers behind it to flow faster into the sea,” Holland said. “This would then contribute to sea-level rise.”

The Antarctic Peninsula is one of the fastest warming regions on Earth, with a temperature rise of 2.5˚C over the last 50 years.

The team, which continues to monitor the ice shelf closely, predicts that a collapse could occur within a century, possibly sooner and with little warning. A crack is forming in the ice which could cause it to retreat back further than previously observed. The ice shelf appears also to be detaching from a small island called Bawden Ice Rise at its northern edge.

“When Larsen A and B were lost, the glaciers behind them accelerated and they are now contributing a significant fraction of the sea-level rise from the whole of Antarctica. Larsen C is bigger and if it were to be lost in the next few decades then it would actually add to the projections of sea-level rise by 2100," said David Vaughan, a glaciologist and Director of Science at BAS.

“Ice shelves strongly regulate the flow of glaciers into the ocean and when they weaken or collapse, this flow increases, often substantially," said CIRES researcher Dan McGrath, a co-author on the new study. "Quantifying the changes occurring to Larsen C and other ice shelves around the continent is essential for informed predictions of sea-level rise.”

The study was carried out by scientists from British Antarctic Survey, the United States Geological Survey, the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, University of Kansas and the Scripps Institution of Oceanography.

It was funded by the Natural Environment Research Council in the UK, the National Science Foundation in the US and a range of international funding bodies around the world.

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