How Glaciers affect Global Warming?
Bering glacier, Alaska:
The Bering glacier is the largest and longest in continental North America. In 1996 (left), its size reached a late 20th century peak. Since then, parts of its terminus have retreated more than three miles and thinned by more than 200ft. These images show the 1996-2005 retreat of the glacier.-Photograph: USGS
Barrow, Alaska:
Sea ice forms along the coast in the winter, and generally melts or breaks away by mid-July. Observations of sea ice positions reveal considerable year-to-year variability. The image on the left was taken in 2006, and that on the right in 2007-Photograph: USGS
We live in a time of increasing greenhouse gas concentrations with an attendant warming of the climate. Glaciers respond to slight but prolonged changes in climate. At least some aspects of these climate changes may be deduced from observations of glacier fluctuations. Understanding how glaciers of the world react is vital to better defining the regional pattern of climate change, and to project future changes in water resources.
Glacier mass balance (snow gain minus melt loss) from 1980 through 2011. Bars indicate positive (above the 0 line) and negative (below the 0 line) glacier mass balances each year, and the red line shows the cumulative annual balance. Only three years—1983, 1987, and 1989—experienced net gains. All other years had negative mass balances, with losses getting larger in more recent years. Graph adapted from Figure 2.9 in the 2012 BAMS State of the Climate report.
Scientists are also finding that glaciers reveal clues about global warming. How does human activity affect climate? Because glaciers are so sensitive to temperature fluctuations accompanying climate change, direct glacier observation may help answer these questions. Since the early twentieth century, with few exceptions, glaciers around the world have been retreating at unprecedented rates. Some scientists attribute this massive glacial retreat to the Industrial Revolution, which began around 1760. In fact, several ice caps, glaciers and ice shelves have disappeared altogether in this century. Many more are retreating so rapidly that they may vanish within a matter of decades.
Human activity has increased the amount of carbon dioxide in the atmosphere by 40 percent, and other gases, such as methane (natural gas) by a factor of 2 to 3 or more. These gases absorb heat being radiated from the surface of the earth, and by absorbing this heat the atmosphere slowly warms up. Heat-trapping gases, sometimes called “greenhouse gases,” are the cause of most of the climate warming and glacier retreat in the past 50 years. However, related causes, such as increased dust and soot from grazing, farming, and burning of fossil fuels and forests, are also causing glacier retreat.
Scientists now trying to piece together all of the data they are collecting, want to find out whether human-induced global warming is tipping the delicate balance of the world's glaciers.
According to recent studies, there are numerous evidences that prove the impact of melting glaciers on global warming. How can melting of glaciers affect global climate change, especially accelerating global warming?
Levels of carbon dioxide in the atmosphere have corresponded closely with temperature over the past 800,000 years. Although the temperature changes were touched off by variations in Earth’s orbit, the increased global temperatures released CO2 into the atmosphere, which in turn warmed the Earth. Antarctic ice-core data show the long-term correlation until about 1900. (Graphs by Robert Simmon, using data from Lüthi et al., 2008, and Jouzel et al., 2007.)