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&edu=elem&dev=1">sea ice</a>, <a
  href="/earth/polar/polar_bears_jan07.html&edu=elem&dev=1">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&edu=elem&dev=1">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&edu=elem&dev=1">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>Many forms of air pollution are human-made. Industrial plants, power plants
and vehicles with internal combustion engines produce <a href="/earth/climate/nitrogen_airpollution.html&edu=elem&dev=1">nitrogen
oxides</a>,
<a href="/earth/Atmosphere/vocs.html&edu=elem&dev=1">VOCs</a>,
<a href="/physical_science/chemistry/carbon_monoxide.html&edu=elem&dev=1">carbon monoxide</a>,
<a href="/physical_science/chemistry/carbon_dioxide.html&edu=elem&dev=1">carbon dioxide</a>,
<a href="/physical_science/chemistry/sulfur_oxides.html&edu=elem&dev=1">sulfur dioxide</a> and
<a href="/earth/Atmosphere/particulates.html&edu=elem&dev=1">particulates</a>.
Some of these gases are <a href="/earth/climate/cli_greengas.html&edu=elem&dev=1">greenhouse
gases</a>,
meaning that they retain heat in the Earth's atmosphere, due to the Earth's
<a href="/earth/climate/earth_greenhouse.html&edu=elem&dev=1">greenhouse effect</a>.<p><small><em>Image copyright UCAR</em></small></p>Scientists at the University of Michigan have found that <a href="/earth/polar/cryosphere_permafrost1.html&edu=elem&dev=1">permafrost</a> in the <a href="/earth/polar/polar_north.html&edu=elem&dev=1">Arctic</a> is extremely sensitive to sunlight.  Exposure to sunlight releases carbon gases trapped in the permafrost, including <a href="/earth/climate/earth_greenhouse.html&edu=elem&dev=1">climate-warming</a> <a href="/physical_science/chemistry/carbon_dioxide.html&edu=elem&dev=1">carbon dioxide</a>, to the <a href="/earth/Atmosphere/overview.html&edu=elem&dev=1">atmosphere</a> much faster than previously thought.<p><small><em>George Kling, The University of Michigan</em></small></p>How did life evolve on <a href="/earth/earth.html&edu=elem&dev=1">Earth</a> during the <a href="/earth/past/Archean.html&edu=elem&dev=1">Archean</a>, when the <a href="/sun/sun.html&edu=elem&dev=1">Sun</a> was about 25% weaker than today?  The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html&edu=elem&dev=1">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html&edu=elem&dev=1">greenhouse</a> gas concentration was the same as today.  <a href="http://www.manchester.ac.uk/aboutus/news/display/?id=10798">Researchers</a> studying the <a href="/physical_science/physics/atom_particle/isotope.html&edu=elem&dev=1">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html&edu=elem&dev=1">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html&edu=elem&dev=1">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html&edu=elem&dev=1">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html&edu=elem&dev=1">carbon dioxide</a>.<p><small><em>Image courtesy of Manchester University</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&edu=elem&dev=1">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&edu=elem&dev=1">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><b><i>Looking for online resources about climate and climate change for your classroom?</i></b> Windows to the Universe is a free interlinked learning ecosystem to a wealth of resources on our site and elsewhere that support you on these topics, including <a href="/teacher_resources/climate_change_course.html&edu=elem&dev=1">course readings</a>,  <a href="/php/teacher_resources/activity.php#6">classroom activities and presentations</a>, and online interactives.  Our <a href="/teacher_resources/climate.html&edu=elem&dev=1">Climate Change Education Resources page</a> provides links to content you can use right away in the classroom!<p><small><em>   Ute Kaden/PolarTREC</em></small></p>

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