Earth’s climate system is characterized by complicated and fascinating interactions between physical, chemical, and biological processes. My current research ambitions lie in understanding processes that govern cryosphere–climate interaction and feedback. Such processes include radiative transfer in the atmosphere and cryosphere, transport and processing of aerosols, large-scale energy transport, snow–vegetation interaction, and growth of algae on snow and ice. We strive to study these interactions using a combination of numerical modeling, remote sensing, and experimental studies.

The Snow, Ice, and Aerosol Radiative (SNICAR) model version 3 is available at http://snow.engin.umich.edu/

Students interested in researching these and related topics are welcome to contact me about potential graduate studies.

Group News

April, 2024 — Chloe publishes a paper in JGR describing the implementation into an Earth System Model of a new radiative transfer scheme for simulating the albedo of glacier ice, particularly on the Greenland Ice Sheet. The new scheme is informed by ice optical properties retrieved from MODIS and marks a significant improvement over the original constant-albedo technique used in the model. This new model allows for explicit representation of ice bubbles and light-absorbing constituents like algae, dust, and black carbon. Way to go, Chloe!

December, 2023 — Chloe Whicker-Clark successfully defends for her Ph.D! Her dissertation is titled “The Physical Representation of Bare Ice Albedo in Radiative Transfer Models and the Implications on Greenland Ice Sheet Albedo and Surface Mass Balance.” She will soon start as a project scientist at UC–Irvine. Congratulations, Chloe!

September, 2023 — Mark appears in a BBC video about ice albedo feedback.

October, 2022 — Mark co-authors a paper in Nature Communications with members of an AMAP expert group exploring how changes in the emissions of short-lived pollutants affect Arctic climate and air quality.  Some of the key takeaways are: 

  • Reductions in sulfur emissions (which cool climate) that will likely occur under existing clean air policies will unmask additional Arctic warming of 0.4–0.8°C by 2050
  • Ambitious efforts that further target black carbon and methane (which warm climate), however, could reduce Arctic warming by 0.5°C by 2050. This is similar to the Arctic climate benefit that could be achieved in 2050 through aggressive mitigation of global carbon dioxide emissions.
  • Maximum feasible emissions reductions could reduce mortality from particulate matter (PM2.5) by more than a million global deaths per year in 2050, and by roughly 100,000 deaths per year in Arctic Council countries.
Graphs of different molecules

September, 2022 — Zach Fair publishes a paper in the Cryosphere on his Ph.D. work exploring how retrievals of snow grain size exploiting the 1.03 μm ice absorption feature can be influenced by dust loading in the snow and uncertainty about ice particle shape.

Model grain radius graphs

April, 2022 — Ph.D. student Chloe Whicker publishes a lead-author paper in The Cryosphere describing adaptations to the SNICAR model for representing the spectral albedo of glacier ice. The new model accounts for Fresnel reflectance, scattering from air bubbles and surface snow on ice, and light absorption by pigmented ice algae. We hope this model can ultimately be used to improve the simulation of ice sheet processes in climate models. Way to go, Chloe!

Diagrams of different layers

December, 2021 — Comprehensive documentation of the SNICAR-ADv3 snow spectral albedo model is published in Geoscientific Model Development. Numerous improvements and updates have been incorporated into the model. Try running it online at: http://snow.engin.umich.edu/!


May, 2021 — The AMAP expert group co-chaired by Mark releases its Summary for Policymakers, coinciding with the Arctic Council Ministerial Meeting. One key message from the SPM is that reduced sulfate pollution has “unmasked” a substantial amount of Arctic warming in recent decades. Moving forward, it is therefore important to simultaneously reduce emissions of short-lived warming agents like black carbon, as noted by Secretary of State Blinken in his comments at the meeting. To limit long-term warming globally and in the Arctic, however, it is imperative to reduce carbon dioxide emissions.

Graphic about climate

May, 2021 — Zach Fair successfully defends for his Ph.D with his dissertation titled “Application of lidar altimetry and hyperspectral imaging to ice sheet and snow monitoring”. Zach will move on to a post-doc position at the NASA Goddard Space Flight Center. Congratulations, Zach!

April, 2021 — Mark is quoted in a New York Times article describing how reduced soot pollution in South Asia associated with COVID-19 lockdowns led to cleaner snow and later snowmelt in the Indus River Basin, likely helping water supplies last longer into the year.

November, 2020 — Graduate student Zach Fair’s paper on the detection of supraglacial lake depth from ICESat-2 is published in The Cryosphere. Zach’s work shows that the bottoms of melt ponds up to 7 meters deep can be “seen” with the space-borne laser altimeter.


November, 2020 — Jamie’s new paper on Greenland atmospheric blocking is published in the Journal of Geophysical Research. It has long been known that Greenland blocks decrease cloud cover over Greenland. Jamie’s paper deepens our understanding by showing that northern blocks are more effective than southern blocks at decreasing summer cloud cover, which increases solar heating of the ice sheet but decreases cloud longwave warming of the surface.


June, 2020 — Congratulations to doctoral student Jamie Ward for successfuly defending for her Ph.D! Jamie’s dissertation explored the effects of light-absorbing aerosols, atmospheric blocking, and clouds on Greenland’s surface energy budget. Her online defense was attended by more than 40 people. Dr. Ward will continue as a postdoctoral scholar with Professor Ashley Payne.

March, 2020 — Ph.D. student Chloe Whicker earns a prestigious NSF Graduate Research Fellowship for her proposal to incorporate snow and ice algae into Earth System Models. Congratulations, Chloe!

February, 2020 — Greenland expedition participant and U-M graduate student Chelsea Snide leads a piece published in Eos entitled “Seeing the Greenland Ice Sheet Through Students’ Eyes”

September, 2019 — Mark gives a seminar at Harvard University in the Atmospheric & Environmental Chemistry Seminar Series on the topic of light-absorbing impurities in snow.

September, 2019 — Mark is a contributing author to the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate, released in September. The Summary for Policymakers, Technical Summary, and full technical report can be found at the link above. Mark contributed text to Chapter 3 (Polar Regions) on the energy impacts of reduced snow cover.

June, 2019 — Mark co-leads an undergraduate expedition to Greenland with students from the University of Michigan, SUNY-Albany, and Virginia Tech. Students conducted surface energy flux and stream volume measurements, launched rawindsondes and pilot balloons to measure vertical properties of the atmosphere, flew drones over the ice, visited Summit Station via an LC-130 flight, and embarked on a long hike to the historic Mt. Evans site, where a U-M team made some of the first-ever vertical wind measurements over Greenland in the 1920’s. It was an inspiring trip for both students and faculty!

Group photo at the Summit Station
People working on machine

June, 2019 — Graduate student Adam Schneider’s paper describing the Near-Infrared Emitting and Reflectance-Monitoring Dome (NERD) instrument that he designed and built to infer snow optical grain size is published in The Cryosphere. This study also applies NERD measurements to explore how black carbon and dust affect the metamorphic rate of snow.

NERD Dome diagram

November, 2018 — Postdoctoral fellow Yang Li publishes a new paper in Atmospheric Chemistry and Physics. The paper describes the analysis of a huge number of model simulations she conducted to characterize how black carbon deposition on the Greenland Ice Sheet affects melt runoff, which ultimately raises sea level.

May, 2018 — Graduate student Jamie Ward’s paper on aerosol forcing over the Greenland Ice Sheet is accepted for publication in Journal of Geophysical Research Atmospheres. This study finds that light-absorbing aerosols deposited on the snow are more effective at warming the surface than aerosols in the overlying atmosphere, which have offsetting impacts of warming the troposphere and “dimming” the surface.

April, 2018 — Congratulations to Dr. Adam Schneider on a successful Ph.D. defense! His defense was lively and well-attended by his family.

February, 2018 — Graduate student Adam Schneider’s paper on temporal variability in global albedo feedback is accepted for publication in Geophysical Research Letters. This paper shows that positive albedo feedback is unlikely to weaken in the 21st century, even as the mean extent of snow and sea-ice diminishes.

February, 2018 — Mark’s paper on greenhouse gas forcing during polar winter is accepted for publication in Geophysical Research Letters. This paper explores the unique situation where increased greenhouse gas concentrations within polar temperature inversion layers can actually exert negative radiative forcing and cool the troposphere, opposite of the canonical global greenhouse effect. Despite the oddities of this situation, polar surface temperatures warm as a result of high stability and increased downwelling longwave flux.

May, 2017 — Accolades role in for Jamie Ward, who earns a prestigious NASA Earth and Space Science Fellowship (NESSF)! Jamie is one of six CLaSP graduate students to earn this fellowship, which was awarded to only 18% of applicants in the Earth Science division. Her fellowship application is entitled: “Quantifying the Relative Contributions of Aerosols, Blocking Events, and Low Level Liquid Clouds to Greenland Snow Melt”.

April, 2017 — Congratulations to graduate student Jamie Ward, who earned a second place award for her presentation at the Michigan Geophysical Union Student Research Symposium! Jamie’s poster was titled: “Modeled Response of Greenland Snowmelt to the Presence of Biomass Burning-Based Absorbing Aerosols in the Atmosphere and Snow”.

January, 2017 — During his sabbatical stay at The Institute of Environmental Geosciences in Grenoble France, Mark works with collaborators at Col du Lautaret to measure snow spectral optical properties and understand the impacts on snow evolution of light-absorbing impurities, including soot from forest fires and Saharan dust.

People placing stakes in the snow

October, 2016 — Graduate student Deepak Singh’s paper on the spectral albedo of carbon dioxide snow has been published in the Journal of Geophysical Research Planets. This study applies to Mars, where snow and ice consisting of different mixtures of H2O, CO2, and dust are present on the surface.

July, 2016 — Congratulations to Deepak Singh for a successful Ph.D. defense! Deepak presented his research on the spectral reflectance of carbon dioxide ice and the incorporation of an improved representation of cryosphere reflectance into the LMD Mars Global Climate Model.

April, 2016 — Chaoyi Jiao’s paper on changing Arctic aerosol transport is accepted in the Journal of Geophysical Research Atmospheres. In this paper we assess the relative impacts of changing circulation, precipitation, and emissions on aerosol transport to the Arctic during the 21st century under a scenario with continued growth in greenhouse gas emissions. One interesting finding is that changes in the structure of the winter polar dome (shown below) tend to favor poleward transport of pollutant emissions from East Asia.

Graph of wind patterns

We also welcome Dr. Jiao’s continued involvement in our group as a postdoctoral fellow! Below: Chaoyi and Mark at the U-M spring commencement ceremony

Two people graduating

January, 2016 — Congratulations to Deepak Singh for earning an Outstanding Student Paper Award for his presentation at the AGU Fall meeting! Deepak presented work on the impact of dust on the albedo of the Martian polar ice caps, which consist of both carbon dioxide and water ice.

Deepak also produced this neat video about water on Mars:

December, 2015 — Congratulations to Chaoyi Jiao for successfully defending his Ph.D! Chaoyi’s thesis is titled: “Sources of Variability in Transport and Deposition of Arctic Aerosols in Changing Climates.” Two chapters of his work were communicated in separate presentations at the AGU 2015 Fall meeting.

December, 2015 — Mark is co-author of a report published by The Arctic Monitoring and Assessment Programme (AMAP) on the effects of black carbon and tropospheric ozone on Arctic climate. The full 128 page report is available here, and an accompanying press release from AMAP is available here.

AMAP Assessment 2015 cover

November, 2015 — Graduate student Deepak Singh publishes a paper in The Cryospherequantifying the land cryosphere radiative effect during the MODIS era. This study estimates that land-based snow and ice decrease the amount of solar power that Earth absorbs by about 2.6 W/m2.

Annual Mean CrRE

July, 2015 — Congratulations to Justin Perket for a successful Ph.D. defense! Dr. Perket will start a new postdoctoral position at the National Center for Atmospheric Research (NCAR) in September, as part of the CUAHSI hydrological research project.

May, 2015 — Mark ventures onto the Arctic sea-ice near Barrow Alaska, as part of an NSF-funded workshop that brought together modelers and measurement experts who study snow on sea-ice.

People working in the snow

April, 2015 — The Arctic Monitoring and Assessment Programme (AMAP) releases a Summary for Policy Makers on the impacts of short-lived climate forcers (including black carbon, methane and ozone) on Arctic climate. Mark is one of the authors of the assessment underlying this summary.

Summary for Policy-makers cover

April, 2015 — Congratulations to graduate student Chaoyi Jiao for earning first place at the Michigan Geophysical Union Student Research Symposium! Chaoyi’s poster presentation explored how aerosol transport to the Arctic will change from present to future climate.

August, 2014 — Mark’s paper on aerosol radiative forcing from the 2010 volcanic eruptions of Eyjafjallajökull (Iceland) is published in JGR–Atmospheres. This study found that cooling from sulfate was largely offset by warming from ash, which darkened snow surfaces and absorbed infrared energy in the atmosphere.


July, 2014 — Mark lectures at the 2014 Connaught Summer Institute in Arctic Science, held in Alliston, Ontario and organized by the University of Toronto. The theme of this year’s institute was: “Atmosphere, Cryosphere, and Climate”.

March, 2014 — Graduate student Adam Schneider constructs a prototype of a new instrument to measure snow optical grain size, and introduces it at a snow workshop in Davos, Switzerland. The Near-infrared Emitting and Reflectance Monitoring Dome (NERD) uses LEDs and photodiodes to measure snow reflectance at wavelengths that are sensitive to grain size.

Machine on the ice
Machine hooked up to computer on ice

January, 2014 — Graduate student Chaoyi Jiao’s paper, describing a multi-model assessment of black carbon deposition to Arctic snow and sea-ice, is accepted for publication in Atmospheric Chemistry and Physics.

Carbon deposit graph

January, 2014 — Graduate student Justin Perket’s paper, describing a new model diagnostic of the cryosphere radiative effect and its 21st century evolution, is accepted for publication in JGR–Atmospheres.

New model diagnostic of cryosphere radiative effect

November, 2013 — Graduate student Deepak Singh co-chairs the Engineering Graduate Symposium.

August, 2013 — Mark discusses interactions between fires and climate in this short MichEpedia MconneX video: 

May, 2013 — Mark is awarded a Faculty Early Career Development (CAREER) grant from the National Science Foundation, Division of Polar Programs. The project, titled “Linking cryospheric processes across scales to model non-linear albedo feedback” is described on the NSF award page

May, 2013 — Former post-doc Alex Gardner publishes an article in Science concluding that melting glaciers accounted for 30% of the sea-level rise between 2003 and 2009. The work was featured on the NBC Nightly News.

January, 2013 — Mark is one of 31 co-authors of a 4-year international study bounding the role of black carbon in climate. The study, published in JGR, concludes that black carbon exerts a substantially stronger warming effect on climate than quantified in the IPCC (2007) report. Media coverage:

June, 2012 — Mark lectures on aerosol-cryosphere-climate interactions at the Alpine Summer School in Valsavarenche, Italy. Lecture slides are available through the website.

June, 2012 — Alex accepts a professorship in the Geography Department at Clark University, starting September 2012.

February 16, 2012 — On invitation from Secretary of State Hillary Clinton, Mark visits the State Department to attend the announcement of the new U.S.-led Climate and Clean Air Coalition (CCAC), targeted at reducing short-lived pollutants that adversely affect both climate and health. New York Times coverage of initiative.

January, 2012 — Graduate students Chaoyi Jiao and Justin Perket visit Joe McConnell’s Trace Chemistry Laboratory at the Desert Research Institute to assist with the analysis of an Arctic ice core

Fall 2011 — Mark is a lead author on two reports published about climate effects of black carbon:

  • Integrated Assessment of Black Carbon and Tropospheric Ozone (2011), published by the United Nations Environmental Programme and the World Meteorological Organization. See the Summary for Decision Makers or the Full Report
  • The Impact of Black Carbon on Arctic Climate (2011), published by the Arctic Monitoring and Assessment Programme (AMAP).  Full report
Integrated Assessment of Black Carbon and Tropospheric Ozone cover
The Impact of Black Carbon on Arctic Climate cover

May, 2011 — Alex’s Nature article on the mass balance of Canadian Arctic glaciers is featured on the cover of the May 19 issue:

Nature cover

March, 2011 — Mark’s Nature Geoscience article on cryosphere radiative forcing and albedo feedback is featured on the cover of the March issue:

Nature Geoscience cover