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Climate and Global Change

Warm near the equator and cold at the poles, our planet is able to support a variety of living things because of its diverse regional climates. The average of all these regions makes up Earth's global climate. Climate has cooled and warmed throughout Earth history for various reasons. Rapid warming like we see today is unusual in the history of our planet. The scientific consensus is that climate is warming as a result of the addition of heat-trapping greenhouse gases which are increasing dramatically in the atmosphere as a result of human activities.

Roaming across Arctic <a
  href="/earth/polar/sea_ice.html">sea ice</a>, <a
  href="/earth/polar/polar_bears_jan07.html">polar
  bears</a> peer through cracks in the ice to look for ringed seals, their
  favorite food, in the water below. Almost all of a polar bear's food comes
  from the sea. The <a
  href="/earth/polar/sea_ice.html">floating sea
  ice</a> is a perfect vantage point for the bears as they hunt for food.
  Unfortunately, the amount of sea ice floating in the <a
  href="/earth/polar/polar_north.html">Arctic
  region</a> is shrinking each year, and getting farther apart.<p><small><em>Image courtesy of Ansgar Walk.  Creative Commons Attribution-Share Alike 2.5 Generic license.</em></small></p><a href="/earth/polar/cryosphere_permafrost1.html">Permafrost</a> is
ground that is below the freezing point of water (0°C or 32°F) for two
or more years. Permafrost is found at high latitudes like the
<a href="/earth/polar/polar_north.html">Arctic</a> and
<a href="/earth/polar/polar_south.html">Antarctic</a>.
It is also common at high altitudes - like mountainous areas wherever the
<a href="/earth/climate/cli_define.html">climate</a> is
cold. 
Permafrost has been thawing relatively quickly in recent years. Scientists
have found that the rate of permafrost thaw has increased because of <a href="/earth/climate/cli_effects.html">global
warming</a>.<p><small><em>Image courtesy of the    USGS</em></small></p>Although we humans have never experienced fast <a href="/earth/climate/climate.html">global
warming</a>, our
planet has. And our planet keeps records of what happened. The oldest
records that the
<a href="/earth/earth.html">Earth</a> keeps
are in its
<a href="/earth/geology/sed_intro.html">rocks</a>.
In this image, <a href="/headline_universe/olpa/methane_28may08.html">geologists Chris von der Borch and Dave
Mrofka</a> collect
sediment samples in South Australia. These rocks hold clues to help
explain why climate changed abruptly 635 million years ago.<p><small><em>                    Courtesy of Martin Kennedy, UCR</em></small></p><a href="/earth/climate/cli_define.html">Regional climate</a> is
the average weather pattern in a place over more than thirty years,
including the variations in
<a href="/earth/climate/cli_seasons.html">seasons</a>.
The climate of a region depends on many factors including sunlight,
altitude, topography, and proximity to oceans. Since the equatorial regions
receive more sunlight than the poles, climate varies with
<a href="/earth/climate/cli_latitude.html">latitude</a>.
This image shows how sea surface temperatures change at different latitudes.<p><small><em>Image courtesy of NOAA.  Public domain.</em></small></p><b><i>Looking for online resources to use in support of climate change education?</i></b>  Our <a href="/teacher_resources/climate.html">Climate Change Educator Resources page</a> provides links to online content, classroom activities, interactives, and videos as well as resources provided by other leading organizations and agencies on this topic.  Our <a href="/teacher_resources/climate_change_course.html">Climate Change Course Content page</a> provides links to online content for a range of climate change associated topics.<p><small><em>Image courtesy of   Mila Zinkova, Creative Commons Attribution ShareAlike license</em></small></p>Scientists are concerned that melting Arctic sea ice will increase the amount of fresh water in the <a href="/earth/polar/arctic_currents.html">Beaufort Gyre</a>, which could spill out into the Atlantic and cause major climate shifts in North America and Western Europe. Watch the <a href="/earth/changing_planet/freshwater_arctic.html">Changing Planet: Fresh Water in the Arctic video</a>.<p><small><em> Courtesy of Jack Cook, WHOI (<a href="http://www.whoi.edu">Woods Hole Oceanographic Institute</a>)</em></small></p>

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF