Rising/Sinking: Greenland's Melting Ice Sheet

RISING//SINKING a look at the effects of Greenland’s melting ice sheet

Northwestern Glacier, Alaska, 1940

THE SEA IS RISING

Northwestern Glacier, Alaska, 2005

it’s already risen more than

380 feet in the last 18,000 years

causes Over the past century, the burning of fossil fuels and other human and natural activities has released enormous amounts of heat-trapping gases into the atmosphere. These emissions have caused the Earth’s surface temperature to rise, and the oceans absorb about 80 percent of this additional heat.

The rise in sea levels is linked to three primary factors, all induced by this ongoing global climate change: Toboggan Glacier, Alaska, 1909

Toboggan Glacier, Alaska, 2000

Thermal expansion: When water heats up, it expands. About half of the past century’s rise in sea level is attributable to warmer oceans simply occupying more space.

Melting of glaciers and polar ice caps: Large ice formations, like glaciers and the polar ice caps, naturally melt back a bit each summer. But in the winter, snows, made primarily from evaporated seawater, are generally sufficient to balance out the melting.

Recently, though, persistently higher temperatures caused by global warming have led to greater-than-average summer melting as well as diminished snowfall due to later winters and earlier springs.

Ice loss from Greenland and West Antarctica: As with glaciers and the ice caps, increased heat is causing the massive ice sheets that cover Greenland and Antarctica to melt at an accelerated pace. Scientists also believe meltwater from above and seawater from below is seeping beneath Greenland’s and West Antarctica’s ice sheets, effectively lubricating ice streams and causing them to move more quickly into the sea. Moreover, higher sea temperatures are causing the massive ice shelves that extend out from Antarctica to melt from below, weaken, and break off.

greenland’s ice sheet The Greenland Ice Sheet blankets 81% of Greenland Island. This monstrous ice slab stretches 2,480 kilometers (1,540 miles) long and up to 750 kilometers (465 miles) wide. The ice sheet is so big it would stretch from Key West, Florida, to 100 miles beyond Portland, Maine, covering a swath as wide as from Washington, D.C., to Indianapolis, Indiana. It’s 80 percent as big as the entire United States east of the Mississippi River.

Greenland Mexico Greenland’s Ice Sheet France Germany Italy 0.0

0.5

Area, in million km2

1.0

1.5

2.0

2.5

30.1% Ground Water

1.2% Surface/Other Freshwater

WHERE IS EARTH’S FRESH WATER LOCATED?

60.7% Glaciers and Ice Caps

The Greenland Ice Sheet contains roughly 8% of the Earth’s fresh water supply

After Antarctica, Greenland's ice cap contains the second largest mass of frozen freshwater in the world

June 26, 2010

August 13, 2010

PETERMANN GLACIER

greenland

An iceberg more than four times the size of Manhattan broke off the Petermann Glacier along the northwestern coast of Greenland.

Warmer water below the floating ice and at the sea’s surface were probably responsible for the break.

land ice melt 1800 gt

greenland

May 2002 1485.6 gt

July 2003 1200 gt

600 gt

0

1324.7 gt

Along the margin of the Greenland Ice Sheet, outlet glaciers flow as icy rivers through fjords and out to sea. These pictures show a fjord in which Helheim Glacier (on the left) is crumbling into large and small icebergs (light blue, on the right). The glacier outlet (“calving front�) held steady from the 1970s until about 2001, then began to retreat towards its source about 7.5 kilometers (4.7 miles) between 2001 and 2005.

Data from NASA’s Grace satellites show that the land ice sheet in Greenland is losing mass at a rate of

June 2005 1026.6 gt

287 BILLION METRIC TONS PER YEAR that’s equivalent to about 45,000 times the weight of the Great Pyramid of Giza

"EVEN IF WE COULD JUST STOP GLOBAL EMISSIONS TOMORROW ON A DIME, FORT LAUDERDALE, MIAMI GARDENS, HOBOKEN, NEW JERSEY WILL BE UNDER SEA LEVEL" Benjamin Strauss, Vice President for Sea Level and Climate Impacts, Climate Central

Muir Glacier, Alaska, 2005 and 1882

cities below seas united states

If global carbon emissions continue to increase at the current rate, it could lead to an increase in sea levels of up to 23 feet by the end of this century, submerging more than 1,400 cities and towns in the U.S., including Miami, Vivrginia Beach, Sacramento and Jacksonville.

According to the study, published Monday in the Proceedings of the National Academy of Sciences, the amount of carbon pollution on the planet so far has “locked in” or assured a rise in sea levels of more than 4 feet from today’s levels, which is enough to sink more than half of the population in 316 coastal cities in the lower 48 states in the U.S.

Projected Population Effected in 2100 State Population as of 2010 census

FL

NY

CA

LA

NJ

VA

MA

TX

SC

NC

MD

GA

MS

CT

NUMBER OF CITIZENS AT RISK low

high

2100

NEW YORK

9,142,669

citizens at risk

projection of US states with highest populations at risk of submersion

CALIFORNIA

3,128,332

citizens at risk

FLORIDA

10,211,938

citizens at risk

INFORMATION SOURCES climate.nasa.gov/vital-signs/land-ice/ climate.nasa.gov/vital-signs/sea-level/ earthobservatory.nasa.gov ibtimes.com ocean.nationalgeographic.com/ocean/critical-issues-sea-level-rise http://water.usgs.gov/edu/earthwherewater.html

IMAGE SOURCES climate.nasa.gov/state_of_flux

Book Design by Emily Duncan Word & Image II Washington University in St. Louis Sam Fox School of Design & Visual Arts Fall 2015 Text set in United Serif