The National Snow and Ice Data Center (NSIDC) supports research into the world’s frozen realms: the snow, ice, glacier, frozen ground, and climate interactions that make up Earth’s cryosphere.
- Sea Ice At Lowest Level In 800 Years Near Greenland
- Snowcap melts in Uganda as ice river grows in Argentina
- Researchers warn that a weak climate pact won’t slow climate change
- Mid-Pliocene Asian Monsoon Intensification and the onset of northern hemisphere glaciation
- Super-size Deposits of Frozen Carbon in Arctic Could Worsen Climate Change
- The mystery of Antarctica’s speeding glacier
- Increasing dust accelerates snowmelt
- National Snow and Ice Data Center
- Snow Optics Laboratory (SOL) The University of Utah
- Swiss Federal Institute for Forest, Snow and landscape Research
- Rock glacier working group Institute for Geology and Paleontology: University of Innsbruck
- University of Copenhagen: Climate Information Guide
- Geophysical Institute: University of Alaska Fairbanks
Are Global Temperatures Rising?
In 2007, in its Fourth Assessment Report, the Intergovernmental Panel on Climate Change reported that 11 of the 12 warmest years on in the instrumental record since 1850 fell between 1995 and 2006 (IPCC 2007). The updated 100-year trend, from 1996 to 2005 of 0.74°C ± 0.18°C, was greater than the 100-year warming trend at the time of the IPCC’s Third Assessment Report. The warming trend covered in the Third Assessment Report, from 1901 to 2000, was 0.6°C ± 0.2°C. Additional warm years after 2000 caused the higher warming trend reported in the Fourth Assessment Report. Temperature records supporting these findings have been assembled from thousands of land and ocean observation sites covering a large, representative portion of the Earth’s surface and carefully controlled for possible biases arising from station and instrument changes.
Temperatures vary from year to year, and also from decade to decade. These variations, however, are superimposed on a longer upward trend. The range of natural variability in global temperature seems to be about ± 0.2°C, so only after the late 1970s do global mean temperatures emerge from the noise of natural variability (Karl and Trenberth 2003). The northern high latitudes have experienced greater warming than the mid-latitudes or the southern high latitudes. This is apparent in the Temperature Anomalies graph.
In some northern regions, extreme warming has been detected. Locations in Alaska and northern Eurasia, for example, have warmed by nearly 6.0°C in the winter months since 1970 (Serreze et al. 2000). The warming is not universal; some cooling has occurred in the North Atlantic and central North Pacific and is known to be a consequence of changes in the atmospheric circulation.
In its fourth assessment report, the IPCC cited atmospheric concentrations of greenhouse gases as the causative agent in warming temperatures. The panel identified fossil fuel burning and changes in land use and the primary cause of increased carbon dioxide, and agriculture as the primary causes of increased methane and nitrous oxide. Atmospheric carbon dioxide concentrations in 2005 exceeded the natural range for this gas over the past 650,000 years. The IPCC attributed a “greater than 90 percent certainty” to scientists’ assertion that higher greenhouse gas concentrations have trapped more thermal radiation and consequently warmed the planet (IPCC 2007).
Is the Cryosphere Sending Signals About Climate Change?
The cryospheric regions, or regions where water is found in solid form, provide us with direct visual evidence of temperature changes. Unlike other substances found on Earth, ice and snow exist relatively close to their melting point and may frequently change phase from solid to liquid and back again. Consequently, consistent and prolonged warming trends should result in observable changes to Earth’s cryosphere. Water changing from solid to liquid and back often results in dramatic visual changes across the landscape as various snow and ice masses shrink or grow.
What are some examples of these snow and ice masses, how do we monitor their conditions, and what do the results show?
In State of the Cryosphere, snow cover, glaciers, permafrost, sea ice, ice shelves, and the related parameter sea level are discussed. In all cases, scientists attempt to monitor both the areal extent and mass of these snow and ice bodies. Areal extent is easier to determine than mass. Various forms of remote sensing, from both aircraft and satellite, allow us to look down on surfaces at varying spatial scales and over time to determine if the snow or ice covered area is expanding or contracting. Long-term monitoring includes looking at the areal extent of snow cover and sea ice, as well as changes in area and mass of mountain glaciers. In all cases shown here, regardless of parameter or measurement method, the amount of snow and ice has been decreasing over the past several decades.
Northern Hemisphere Snow
We all associate snowstorms with cold weather, but snow’s influence on the weather and climate continues long after the storm ends. Because snow is highly reflective, a vast amount of sunlight that hits the snow is reflected back into space instead of warming the planet. Without snow cover, the ground absorbs about four to six times more of the Sun’s energy. The presence or absence of snow controls patterns of heating and cooling over Earth’s land surface more than any other single land surface feature.
In many locations in recent decades, temperatures have risen while precipitation levels have remained largely the same. Satellite data have confirmed that average snow cover has decreased, especially in the spring and summer. Where snow cover is disappearing earlier in the spring, the large amounts of energy that would have melted the snow can now directly warm the soil.