I

National Aeronautics and Space Administration

UNDERSTANDING EARTH

The Icy Arctic
In early July 2011, the Moderate Resolution 

Imaging Spectroradiometer (MODIS) onboard 

NASA’s Terra satellite captured this natural-color 

image of the Arctic. Relatively clear skies allow the 

smooth, white surface of sea ice to be seen near the 

center of the image. Greenland’s brilliant white 

ice sheet is also visible. 

The Icy Arctic 

UNDERSTANDING EARTH 
UNDERSTANDING EARTH:
 

The Icy Arctic
 

On the cover: Summer thaw was underway on the fringe of Eastern Greenland 

when the MODIS instrument on NASA’s 

Terra satellite captured this image on 

July 13, 2007. 

1 
WHAT IS THE ARCTIC?

The Arctic is one of the coldest regions on Earth. Scientifically defined as 

the region north of the Arctic Circle (located at 66° 33’ N latitude), the Arctic can be loosely defined by its icy waters largely bound by treeless land. 

The extent of sea ice atop the cool, nutrient rich Arctic Ocean expands 

and contracts in rhythm with the seasons, which oscillate between total 

darkness and total daylight, year after year. Cooler temperatures and frozen soil limit the number of trees and other shrubs that grow in the Arctic; 

in fact, our planet’s northernmost tree line currently hovers near the Arctic’s southern edge. 

Over the last few decades however, the average global temperature has 

been on the rise. Temperatures in the Arctic have risen at nearly twice 

the rate as temperatures elsewhere on the planet, and as warmer temperatures creep northward, so too might vegetation.

 ashington e, University of W edit: Kristin L. Laidr Photo cr

[Above] A polar bear walks 

across the pack ice—a large mass 

of sea ice—in Baffin Bay west 

of Greenland.

The image below shows the Arctic 

Circle, defined as 66° 33’ N 

latitude. The region north of the 

Arctic Circle is the Arctic. 

[Above] Each summer, Arctic sea ice melts considerably, usually reaching its 

minimum extent in September. From around September 22 to March 20, 

nighttime hours exceed daylight hours in the Northern Hemisphere, causing 

the Arctic to cool and the extent of sea ice to grow. Arctic sea ice usually 

reaches its maximum extent in March. This image pair shows Arctic sea ice 

concentrations for September 2010 and the following March. The yellow 

outline on each image shows the median sea ice extent observed by satellite 

sensors in September and March from 1979 to 2000. These images are made 

from a combination of observations from the Special Sensor Microwave/

Imagers (SSM/Is) flown on a series of Defense Meteorological Satellite 

Program missions and the Advanced Microwave Scanning Radiometer for 

EOS (AMSR-E), a Japanese-built sensor that flies on NASA’s Aqua satellite.

September 2010 March 2011

1000 km

Sea Ice Concentrations (percent)

0 50 100

2 The Icy Arctic

UNDERSTANDING EARTH
3

[Below] In May 2010, temperature records assembled by the NASA Goddard Institute for Space Studies (GISS) 

showed wide expanses of slightly above-normal temperatures (shades of red) and slightly below-normal temperatures 

(shades of blue) over most of the globe. Note the concentration of warming over the Arctic (darkest shades of red) 

where temperatures were close to 5 °C (9 °F) above average. The Arctic is very vulnerable to warming. Both sea 

ice retreat and snowmelt reduce Earth’s reflectivity, which can lead to increased warming and further melting that 

amplify the initial change. 

ICY FACT: Many species thrive in cooler ocean waters, which 

tend to be rich in nutrients and plant life. 

Norway

100 km

N

[Above] Each spring, the nutrient-rich waters of the Arctic are exposed 

to abundant sunshine and the region becomes a breeding ground for 

phytoplankton—microscopic plant organisms that form the foundation 

of the aquatic food web. Vibrant shades of blue and green reveal a large 

phytoplankton bloom in the Barents Sea in this natural-color image taken on 

August 14, 2011, by the MODIS instrument onboard NASA’s Aqua satellite.

This false-color image [below] made 

with data from the SeaWiFS, or Seaviewing Wide Field-of-View Sensor, 

shows chlorophyll concentrations—

indicating phytoplankton—during 

Northern Hemisphere summer. 

Over the oceans, red, yellow, and 

green show dense phytoplankton 

blooms while blue shades show where 

there is very little phytoplankton. 

Phytoplankton thrive along coastlines 

where runoff from rivers provides 

an abundance of nutrients. Data 

from SeaWiFS help scientists 

understand the spatial distribution of 

phytoplankton in the Arctic.
4 The Icy Arctic

UNDERSTANDING EARTH

CHANGES IN THE ARCTIC

For the past several decades, Earth-observing satellites have enabled continuous global observations of our home planet, and have played an especially important role in revealing the magnitude of change in remote, difficult 

to access locations like the Arctic. Over the last decade, satellite data—

often combined with data from other sources—have revealed that the Arctic is changing at rates faster than anywhere else on Earth. These changes 

include dramatic reductions in minimum sea-ice extent; alterations of landscape resulting from thawing of frozen soil, or permafrost; increases in phytoplankton productivity; changes in the extent and types of vegetation found 

in the Arctic; and changes in the intensity of storms impacting Arctic coasts. 

As temperatures rise in the Arctic, the extent of sea ice declines. Sea ice is 

highly reflective of the Sun’s energy; therefore, reductions in sea ice impact 

Earth’s radiation budget. Rather than reflecting most of the Sun’s energy, 

ice-free areas absorb sunlight causing subsequent warming of the ocean. 

Warmer ocean temperatures in turn impact Arctic coastlines, which can 

cause permafrost to thaw and rates of erosion to accelerate. The warming 

can also change global ocean and atmosphere circulations that subsequently affect weather patterns. Changes in the Arctic environment are 

interrelated and have both long- and short-term effects on Earth’s land 

surfaces, oceans, and atmosphere, ultimately impacting the Earth’s climate system.

[Above] In September 2011, sea ice covering the Arctic Ocean declined 

to the second-lowest extent on record. This image depicts the average sea 

ice extent in September 2011 as observed by the AMSR-E instrument 

onboard NASA’s Aqua satellite. The purple area shows the median extent 

for 1979–2000.

500 km

Russia

Greenland

median extent —

Canada

Alaska

Sea Ice Concentrations (percent)

0 50 100

ICY FACT: Since 1979, the 

five lowest Arctic sea ice extents 

have all occurred between 

2007 and 2011. 

November 1, 1979 - January 31, 1980

November 1, 2011 - January 31, 2012

edit: NASA Image cr

The images above show Arctic sea ice 

coverage for November 1 to January 31 

from 1979 to 1980 [top] and 2011 

to 2012 [bottom] as observed by passive microwave sensors on NASA’s 

Nimbus-7 satellite and by the 

Special Sensor Microwave Imager/

Sounder (SSMIS) from the Defense 

Meteorological Satellite Program 

(DMSP). Multi-year sea ice—i.e., 

ice that has survived two or more 

melt seasons—is shown in bright 

white, while average sea ice cover is 

shown in milky white. Multi-year 

sea ice has been vanishing at a rate 

of -15.1% per decade. The disappearance of multiyear ice makes 

Arctic sea ice more vulnerable to 

further decline in the summer.
5

Pinzon.

d Epstein et al. edit: Howar Image cr

[Above] The Arctic is becoming greener and greener. In fact, scientists 

have discovered that vegetation in the Arctic—i.e., Arctic biomass—has 

increased nearly 20% from 1982 to 2010. Shades of green indicate areas 

where vegetation increased while orange indicates areas where vegetation 

decreased. The data used to create this image are from a 30-year Advanced 

Very High Resolution Radiometer Normalized Difference Vegetation Index 

dataset produce at NASA’s Goddard Space Flight Center by Jorge 

Change of

Ice Thickness

Since 2003 - , Cal

ahr

[Right] This image, created with data from the Gravity 0

, J. W

Recovery and Climate Experiment, or GRACE satellites, 

er

-20

shows dramatic changes in Greenland’s ice mass from -40

. Lander, F

2003 to 2011. The darkest shades of blue indicate areas -60

-80

opulsion Laboratory

that lost the most ice mass—i.e., areas where the most -100

echnology

net melting occurred. Greenland has been losing large -120

amounts of water into the ocean as surface ice melts and -140

edit: NASA/Jet Pr

glaciers discharge more ice into the sea. centimeters water

equivalent height

Image cr

nia Institute of T ifor

11/18/2011

Change in

Phytomass

1982–2010

Decrease

Increase

no change

non-Arctic

Ocean

[Left] Lakes near 

a riverbank in 

alker and Molly McGraw

Arctic Alaska are 

being drained 

because of permafrost thawing 

and ice-wedge 

edit: Jess W

melting. 

Photo cr

edit: U.S. Geological Society Photo cr

[Above] In the Arctic, permafrost—

ground that remains at or near 0 °C 

(32 °F) for at least two years at a 

time—is beginning to warm and thaw, 

particularly along coastlines, and shifting inward. Ocean waves—especially 

in ice-free areas—undercut permafrost 

cliffs, which can cause large chunks of 

land to erode away. This image shows 

coastal erosion of mud-rich permafrost 

along the Beaufort Sea coastline.

ICY FACT: Warming temperatures and subsequent melting of 

mountain glaciers, ice caps, and 

the Greenland ice sheet contributes to global sea level rise. 
6 The Icy Arctic

UNDERSTANDING EARTH

ICESat and ICESat-2 

Launched in 

2003, NASA’s Ice, 

Cloud, and land 

Elevation Satellite 

(ICESat) mission 

was designed 

to measure icesheet elevations, 

changes in elevation through time, 

height profiles of 

clouds and aerosols, land elevations and vegetation cover, and approximate sea ice thickness. 

ICESat’s sole instrument—the Geoscience Laser Altimeter System 

(GLAS)—measured the vertical distance from orbit to the Earth’s 

surface 40 times per second with a pulse of energy from a laser. 

When each pulse was fired, ICESat collected data for calculating exactly where it was in space using global positioning system 

(GPS) receivers. These data were used to calculate the elevation

and position of each point measurement on Earth to determine

the net amount of ice lost or gained each year for Greenland and 

Antarctica. The mission collected data until 2009, when the final 

laser within GLAS failed.

The second generation ICESat, or ICESat-2, is scheduled to 

launch in 2016. Until then, NASA’s IceBridge mission will collect 

ice-sheet elevation and other data—see Filling in the Ice-Cap 

Gap on the next page. 

edit: NASA/Kathryn Hansen Photo cr

[Above] As ice melts, the liquid 

water collects in depressions on the 

surface, forming melt ponds like 

the ones shown here. ICESCAPE 

science teams collected water samples 

from the ponds to examine water 

chemistry and to observe the colonies 

of plankton growing in the water 

and on the surfaces of the ice.

[Above] NASA’s ICESCAPE mission, or Impacts of Climate change 

on the Eco-Systems and Chemistry 

of the Arctic Pacific Environment, was a NASA shipborne 

project aimed to study the impacts 

of climate change on ecosystems 

and chemistry in the Chukchi and 

Beaufort Seas along Alaska’s western 

and northern coasts during summer 

months in 2010 and 2011. This is 

an image of the U.S. Coast Guard 

Cutter Healy, the official platform 

used during ICESCAPE. 

MONITORING THE ARCTIC

To understand the changes taking place in the Arctic, the scientific community must view the Arctic and the rest of the world as one large, interactive, coupled system. 

To better understand the Arctic environment, scientists at NASA are 

working in collaboration with various experts from other federal agencies, universities, private companies, and not-for-profit organizations. 

From shipborne and airborne campaigns to decadal satellite missions, 

NASA keeps a close eye on the changes taking place in the Arctic. 

Future missions such as ICESat-2 and GRACE Follow-On will continue 

to provide data that will help quantify changes in sea ice thickness and 

ice-sheet mass, identify the mechanisms that drive those changes, and 

determine the impacts of these changes on future global sea level. 

edit: NASA/Kathryn Hansen Photo cr
7

ICY FACT: Satellite instruments such 

as the Advanced Microwave Scanning Radiometer for the Earth 

Observing System 

(AMSR-E) aboard the 

Aqua spacecraft, have 

provided a continuous, nearly complete 

record of Arctic sea ice 

extent since 1979.

edit: NASA/Eric Fraim Image Cr

[Above] A variety of different types of sea ice are visible in this image taken on April 2, 2012 by the Digital 

Mapping System on NASA’s P-3 aircraft during the fourth annual IceBridge campaign. The image depicts an 

area approximately 3083 feet (940 meters) across, and 672 feet (205 meters) wide. 

Filling in the Ice-Cap Gap 

NASA’s IceBridge mission is the world’s 

largest airborne survey of polar ice. 

Through IceBridge, scientists are able to 

track changes in the extent and thickness 

of polar ice, important for understanding 

ice dynamics. The mission began in March 

2009 as a means to fill the gap in polar 

observations between the loss of NASA’s ICESat satellite—in 2009—and the 

future ICESat-2 mission planned for 2016. IceBridge is critical for ensuring a 

continuous series of observations.

The mission yields an unprecedented three-dimensional view of Arctic and Antarctic ice sheets, ice shelves, and sea ice. In the spring, IceBridge pilots conduct flights over the Arctic. The flights provide a yearly, multi-instrument look at 

the behavior of the rapidly changing features occurring in the world’s icy Arctic. 

[Left] On May 12, 2011, IceBridge 

surveyed Barnes Ice Cap, which covers 

about 2300 square miles (6000 

square kilometers) of Baffin Island in 

edit: NASA/Michael Studinger

the Canadian territory of Nunavut. 

In addition to mapping its surface 

elevation, instruments also measured the 

bedrock topography, which will allow 

scientists to better model ice dynamics 

and estimate when the Barnes Ice Cap 

will be completely melted.

Image cr

Image credit: U.S. Navy
8 The Icy Arctic

UNDERSTANDING EARTH

THE ARCTIC AND YOU

The impacts of warming in the Arctic will be felt far beyond the local ecosystems and people who live in the region. Consider the recent decline in 

Arctic sea ice cover; it is likely that Arctic-shipping routes will become more 

popular if sea ice continues to decline. From international trade, to weather 

patterns, shipping routes, natural resource use, and more, there will be 

impacts on human life. Adaptation and mitigation strategies can be used to 

help lessen the impacts of warming in the Arctic on human life.

Image credit: NASA Goddard’s Scientific Visualization Studio

[Above] In 2011, Arctic sea ice declined to the second-lowest extent on 

record. This image shows the 2011 minimum reached on September 9 as 

observed by the AMSR-E instrument onboard NASA’s Aqua satellite. On 

this date, sea ice declined to a level far smaller than the 30-year average 

(yellow line) and opened up the Northwest Passage shipping lanes (in red).

edit: USGS/Benjamin Jones Photo cr

[Above] According to the Arctic Council, nearly four million people live in 

the Arctic. Unfortunately, coastal erosion and thawing permafrost have damaged foundations of homes, buildings, and other man-made infrastructures. 

This photograph shows a cabin along the Arctic Alaska coastline that was recently washed into the ocean because the land it was sitting on eroded away.

[Above] Children stand clothed in 

traditional Greenlandic costume 

signifying their Inuit heritage. The 

Inuit—meaning “the people”—are 

indigenous peoples who inhabit the 

Arctic. Typically, children wear the 

traditional costume on the first day 

of school. 

eenland edit: Ilovegr Photo cr

ICY FACT: Sea ice in the 

Arctic is one of the main controls

on weather for the entire planet. 

Changes in temperature and 

precipitation trends in North 

America for example, could impact agriculture and water supply

in the United States.
Scientists working in the Arctic [top image] are investigating 

bromine explosions—a cascade of chemical reactions that 

abruptly increases bromine monoxide (BrO) in the lower 

atmosphere. BrO depletes ground-level ozone and deposits 

toxic mercury on sea ice, snow, and land. Humans can ingest 

mercury that has been passed up the food chain from marine 

organisms that live in these areas. The bottom image shows 

BrO in the atmosphere observed by the European Space 

Agency’s GOME-2 satellite on March 11, 2012, across the 

Alaskan North Slope looking south toward the Brooks Range 

at the horizon, which blocked the bromine from going further 

south into the Alaskan interior. The presence of BrO in the air 

is shown in a semi-transparent layer in shades of red-orange 

across the North Slope landscape where lakes are visible on 

the land surface. The BrO was originated from offshore sea ice 

and spread onto land along with the moving air mass.

opulsion Laboratory-Caltech/University of Bremen edit: NASA/Jet Pr Image cr opulsion Laboratory-Caltech/University of Bremen edit: NASA/Jet Pr Image cr

REDUCE YOUR

CARBON FOOTPRINT

Take action and go greener with 

these quick tips adopted from the 

Environmental Protection Agency’s 

Global Climate Change website: 

1. Reduce waste. Reduce, reuse, 

recycle, and choose products made 

from recycled materials whenever 

you can.

2. Power down. Conserve energy 

by unplugging cell phone chargers, 

laptops, video game consoles, etc. 

when not in use.

3. Travel green. When possible, 

walk, bike, skateboard, rollerblade,

or take a bus.

4. Be water-wise. For example, turn 

off the water while brushing your 

teeth, and try taking shorter showers.

5. Consider buying local. The 

further your food travels, the more 

greenhouse gas emissions are produced in transporting the food from 

the farm to your plate. 

These tips and more can be found 

online at www.epa.gov/climate

change/kids/solutions/actions.

NASA Resources:

ice.nasa.gov 

earthobservatory.nasa.gov

eos.nasa.gov 

espo.nasa.gov/icescape 

giss.nasa.gov

nasa.gov/grace

nasa.gov/icebridge

oceancolor.gsfc.nasa.gov/SeaWiFS 

terra.nasa.gov 

visibleearth.nasa.gov
National Aeronautics and Space Administration

Goddard Space Flight Center

Greenbelt, Maryland

www.nasa.gov

NP-2012-3-327-GSFC