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.

Earth's global average surface <a href="/earth/climate/ipcc_feb2007.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">warming</a> relative to the 1980-1999 average over the past 100 years is shown in the black line. Predictions of the amount of warming in the future are shown by the red, green, and purple lines. These predictions, developed with <a href="/earth/climate/cli_models.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">computer models</a>, make different assumptions about how many <a href="/earth/climate/cli_greengas.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">greenhouse gases</a> we release into the atmosphere in the future.<p><small><em> A Windows to the Universe image based on a graph from the IPCC 4th Assessment Report</em></small></p>Roaming across Arctic <a href="/earth/polar/sea_ice.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">sea ice</a>, <a href="/earth/polar/polar_bears_jan07.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">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=high&dev=1/k=/teacher_resources/moons/Sun">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=high&dev=1/k=/teacher_resources/moons/Sun">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&edu=high&dev=1/k=/teacher_resources/moons/Sun">Permafrost</a> is ground that is below the freezing point of water (0C or 32F) for two or more years. Permafrost is found at high latitudes like the <a href="/earth/polar/polar_north.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">Arctic</a> and <a href="/earth/polar/polar_south.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">Antarctic</a>. It is also common at high altitudes - like mountainous areas wherever the <a href="/earth/climate/cli_define.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">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&edu=high&dev=1/k=/teacher_resources/moons/Sun">global warming</a>.<p><small><em>Image courtesy of the USGS</em></small></p>How did life evolve on <a href="/earth/earth.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">Earth</a> during the <a href="/earth/past/Archean.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">Archean</a>, when the <a href="/sun/sun.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">Sun</a> was about 25% weaker than today? The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">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=high&dev=1/k=/teacher_resources/moons/Sun">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">carbon dioxide</a>.<p><small><em>Image courtesy of Manchester University</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&edu=high&dev=1/k=/teacher_resources/moons/Sun">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&edu=high&dev=1/k=/teacher_resources/moons/Sun">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>As temperatures rise and soil moisture decreases, plants are stressed, which can lead to <a href="/earth/climate/crops_withering.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">crop withering</a>. <a href="/teacher_resources/online_courses/health/events_health.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">Droughts</a> accompanied by increased temperatures can lead to famine, social and political disruptions. Scientists are helping with early identification of drought that might trigger food shortages. Watch the NBC Learn video - <a href="/earth/changing_planet/withering_crops_intro.html&edu=high&dev=1/k=/teacher_resources/moons/Sun">Changing Planet: Withering Crops</a> to find out more.<p><small><em>Image taken by Tomas Castelazo, Creative Commons <a href=&quot;http://creativecommons.org/licenses/by/3.0/deed.en&quot;>Attribution 3.0 Unported</a> license.</em></small></p>

Explore Climate and Global Change

What Is Climate?

Climate in your place on the globe is called regional climate. It is the average weather pattern ...Read more

What Controls the Climate System?

A factor that has an affect on climate is called a “forcing.” Some forcings, like volcanic ...Read more

Climates of the Past (Paleoclimates)

Climate change has affected the Earth throughout its 4.6 billion year history. The Earth has ...Read more

Our Changing Planet

Our planet is changing rapidly. Check out videos and lesson plans for key climate change indicators ...Read more

Effects of Climate Change Today

The world's surface air temperature increased an average of 0.6° Celsius (1.1°F) during the ...Read more

Climate Change in Polar Regions

The effects of climate change are not felt with the same intensity in all parts of the world. ...Read more

El Nino and Other Climate Events

Sometimes there is a disruption in Earth’s climate system that might last a few weeks or a ...Read more

The Role of Clouds in Climate

Clouds are an important part of Earth's weather and climate. Scientists use computer models ...Read more

Energy Choices and Climate Change

The choices we make about the sources of the energy we use and the amount of energy we use affect ...Read more

The Intergovernmental Panel on Climate Change

The IPCC is a group of hundreds of experts from more than 100 countries ...Read more

Tackling the Global Warming Challenge

Earth’s climate is warming quickly and human activities are mostly to blame.  By releasing ...Read more

More about Climate and Global Change

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Earth and Space Science Concept of the Day

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Seismogenic
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Research Highlights

Scientists Study "Glaciovolcanoes," Mountains of Fire and Ice, in Iceland, British Columbia, U.S.

Glaciovolcanoes, they're called, these rumbling mountains where the orange-red fire of magma meets the frozen blue of glaciers. Iceland's Eyjafjallajökull volcano, which erupted recently, is but one of...Read more


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