A new study has found that <a href="/earth/Atmosphere/airpollution_intro.html">pollution</a> from <a href="/earth/Atmosphere/particulates.html">fine particles</a> in the air - mainly the result of burning coal or <a href="/earth/interior/eruptions.html">volcanic eruptions</a> - can shade <a href="/earth/Life/cnidarian.html">corals</a> from sunlight and cool the surrounding water resulting in reduced growth rates.  Coral growth rates in the Caribbean were affected by volcanic aerosol emissions in the early 20th century and by aerosol emissions caused by humans in the later 20th century.  For more information, see the <a href="http://www.exeter.ac.uk/news/featurednews/title_278202_en.html">press release</a>.<p><small><em>Image courtesy of Toby Hudson (Wikimedia Commons)</em></small></p>The <a href="http://www.windows2universe.org/earth/Atmosphere/tornado/fujita.html">EF-5</a> <a href="http://www.windows2universe.org/earth/Atmosphere/tornado.html">tornado</a> that hit El Reno, Oklahoma on May 31st, 2013 was the widest ever recorded in the US, according to the National Weather Service in Norman Oklahoma. The tornado, which remained on the ground for 40 minutes and reached 2.6 miles across (4.2 km), took the lives of 18 people including storm chasers Tim Samaras, Paul Samaras and Carl Young.<p><small><em>Image courtesy of National Weather Service, Norman Oklahoma</em></small></p>As permafrost thaws, the land, atmosphere, water resources, ecosystems, and human communities are affected. Coastal areas and hillsides are vulnerable to erosion by thawing of permafrost.  Thawing permafrost also causes a positive feedback to global warming, as carbon trapped within the once-frozen soils is released as <a href="/physical_science/chemistry/methane.html">methane</a>, a powerful <a href="/earth/climate/cli_greengas.html">greenhouse gas</a>.
Watch the NBC Learn video - <a href="/earth/changing_planet/permafrost_methane_intro.html">Thawing Permafrost and Methane</a> to find out more.<p><small><em>Image courtesy of the    USGS</em></small></p>March 2012 marks the first anniversary of the 9.0 magnitude <a href="/earth/geology/quake_1.html">earthquake</a>, <a href="/earth/tsunami1.html">tsunami</a>, and resulting nuclear accident in Japan on <a href="/headline_universe/march112011earthquaketsunami.html">11 March 2011</a>.  The tsunami did massive damage, wiping out entire villages and killing ~16,000 people, and leading to one of the most serious nuclear accidents in history.  This image shows before and after photos of the area north of Sendai, where 10,000 people were lost.<p><small><em>Photos by <a href="http://www.nytimes.com/interactive/2011/03/13/world/asia/satellite-photos-japan-before-and-after-tsunami.html?hp">GeoEye/EyeQ</a>.</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>How did life evolve on <a href="/earth/earth.html">Earth</a> during the <a href="/earth/past/Archean.html">Archean</a>, when the <a href="/sun/sun.html">Sun</a> was about 25% weaker than today?  The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html">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">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html">carbon dioxide</a>.<p><small><em>Image courtesy of Manchester University</em></small></p>

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