{"id":2877,"date":"2015-04-29T07:46:23","date_gmt":"2015-04-29T11:46:23","guid":{"rendered":"http:\/\/site.extension.uga.edu\/climate\/?p=2877"},"modified":"2015-04-29T07:46:23","modified_gmt":"2015-04-29T11:46:23","slug":"the-thin-blue-line","status":"publish","type":"post","link":"https:\/\/site.extension.uga.edu\/climate\/2015\/04\/the-thin-blue-line\/","title":{"rendered":"The thin blue line"},"content":{"rendered":"

On Facebook last week a friend posted a picture of the Earth\u2019s atmosphere, taken at sunrise from the International Space Station.\u00a0 In the photo, the atmosphere is shown as a thin blue line separating the sphere of the planet from the blackness of space.<\/p>\n

\"Source:<\/a>
Source: NASA<\/figcaption><\/figure>\n

The image reminded me of how thin the atmosphere is compared to the size of our planet.\u00a0 I\u2019ve heard it said that if the Earth was the size of a basketball, the thickness of the atmosphere would be like a latex balloon stretched over it.\u00a0 A thin skin to be sure!<\/p>\n

How can such an insubstantial wisp of gas be so important to us on Earth?\u00a0 The key lies in the chemical properties of the gases that make up the atmosphere.\u00a0 Each type of gas reacts to a different wavelength of light either entering or leaving the Earth\u2019s system.\u00a0 Most of the gases don\u2019t react to the short wavelengths of incoming solar light, allowing us on the surface to see the full visible spectrum of light that is displayed in a rainbow.\u00a0 Ozone is the major gas that absorbs incoming solar light; that protects us from the harmful ultraviolet rays.\u00a0 That\u2019s why the development of the \u201cozone hole\u201d was such a cause for concern, since the high-energy incoming solar light can cause all sorts of medical havoc like cancers and cataracts.<\/p>\n

Once sunlight hits the surface of the Earth, it warms it up and allows the Earth to send energy back to space in the form of long wavelength radiation to maintain the Earth\u2019s energy balance.\u00a0 This longer-wavelength, lower energy light is absorbed by different gases in the atmosphere that we call \u201cgreenhouse gases\u201d, including carbon dioxide, methane and several other gases.\u00a0 Without these gases, the Earth would be much colder than it is now, making it difficult for life on Earth to exist.\u00a0 But recent observations have shown that carbon dioxide is now at a greater concentration than it has been for the last 800,000 years, based on measurements from ice cores and ocean sediments.\u00a0 The graph below shows what is known as the \u201cKeeling Curve\u201d describing concentrations of carbon dioxide in the atmosphere.<\/p>\n

\"Source:<\/a>
Source: Scripps\/The Keeling Curve<\/figcaption><\/figure>\n

Carbon dioxide is a very small portion of the gas in the atmosphere.\u00a0 You\u2019d think it would not be very important for controlling the Earth\u2019s temperature.\u00a0 But because of the shape of the CO2 molecule, it vibrates at the same frequency as the light that is emitted from Earth back to space.\u00a0 That makes it a very good absorber of this light.\u00a0 A little bit goes a long way!\u00a0 You could compare this to putting a bit of arsenic in a stew\u2014it does not take much to poison the pot.\u00a0 Carbon dioxide and other trace greenhouse gases have a huge effect on Earth\u2019s temperature because they keep the terrestrial light from leaving the Earth, trapping the energy near the surface and helping to heat it up.\u00a0 As greenhouse gases are increasing, more and more energy is being trapped in the ocean-earth-atmosphere system, warming it up.<\/p>\n

Where has the excess carbon in the atmosphere come from?\u00a0 We can use radiocarbon dating methods to determine that the extra carbon is from sources that are millions of years old.\u00a0 The only sources that provide such old carbon are fossil fuels like oil and coal, which were created millions of years ago when carbon-bearing plants were buried far underground and compressed into the fuels we use today.<\/p>\n

That “thin blue line” is indeed thin, but critical to life as we know it.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

On Facebook last week a friend posted a picture of the Earth\u2019s atmosphere, taken at sunrise from the International Space Station.\u00a0 In the photo, the atmosphere is shown as a thin blue line separating the sphere of the planet from the blackness of space. The image reminded me of how thin the atmosphere is compared […]<\/p>\n","protected":false},"author":58,"featured_media":2878,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-2877","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-climate-science"],"_links":{"self":[{"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/posts\/2877","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/users\/58"}],"replies":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/comments?post=2877"}],"version-history":[{"count":1,"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/posts\/2877\/revisions"}],"predecessor-version":[{"id":2879,"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/posts\/2877\/revisions\/2879"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/media\/2878"}],"wp:attachment":[{"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/media?parent=2877"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/categories?post=2877"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/site.extension.uga.edu\/climate\/wp-json\/wp\/v2\/tags?post=2877"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}