Reduction of Biosphere Life Span as a Consequence of Geodynamics <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" href="pik_neu.css" type="text/css"> </head> <body bgcolor="#FFFFFF" text="#000000" leftmargin="0" topmargin="0" marginwidth="0" marginheight="0" > <table width="101%" border="0" cellspacing="0" cellpadding="0" align="left" name="layout" > <tr> <td rowspan="3" align="left" valign="top"> <img src="images/spacer.gif" width="1" height="1"></td> <td align="left" valign="top" height="108"> <table width="521" border="0" cellpadding="0" cellspacing="0" name="header" height="108"> <tr> <td align="left" valign="top"><img src="images/spacer.gif" width="20" height="5"></td> <td align="left" valign="top"><img src="images/spacer.gif" width="85" height="5"></td> <td align="left" valign="top"><img src="images/spacer.gif" width="20" height="5"></td> <td align="left" valign="top"><img src="images/spacer.gif" width="313" height="5"></td> <td align="left" valign="top"> </td> </tr> <tr> <td align="left" valign="top"></td> <td align="left" valign="top" colspan="4"></td> </tr> <tr> <td align="left" valign="top"><img src="images/spacer.gif" width="20" height="10"></td> <td align="left" valign="bottom"> </td> <td align="left" valign="bottom"> </td> <td align="left" valign="bottom" class="singleline"> </td> <td align="left" valign="top" rowspan="3"><a href="http://www.pik-potsdam.de"><img src="images/logo.gif" width="82" height="82" border="0"></a></td> </tr> <tr> <td align="left" valign="top"><img src="images/spacer.gif" width="20" height="24"></td> <td align="left" valign="top" colspan="3"> </td> </tr> <tr> <td align="left" valign="top"><img src="images/spacer.gif" width="20" height="64"></td> <td colspan="3" align="left" valign="top"><a href="http://www.pik-potsdam.de/"><img src="images/titel.gif" width="418" height="40" border="0"></a></td> </tr> </table> </td> </tr> <tr> <td align="left" valign="top"> <table width="92%" border="0" cellpadding="0" cellspacing="0" name="content" > <tr valign="top"> <td align="left"><img src="images/spacer.gif" width="20" height="1"></td> <td align="left"><img src="images/spacer.gif" width="235" height="5"></td> <td align="left" width="100%"><img src="images/spacer.gif" width="135" height="5"></td> <td align="left"><img src="images/spacer.gif" width="40" height="20"></td> <td align="left"><img src="images/spacer.gif" width="180" height="1"></td> <td align="left"> </td> </tr> <tr> <td align="left" valign="top"> </td> <td align="left" valign="bottom" colspan="2"><span class="header_page">Werner von Bloh </span><br> <img src="images/orange.gif" width="100%" height="1"></td> <td align="left" valign="bottom"><img src="images/orange.gif" width="40" height="1"></td> <td align="left" valign="bottom"><img src="images/orange.gif" width="180" height="1"></td> </tr> <tr> <td align="left" valign="top"><img src="images/spacer.gif" width="20" height="44"></td> <td align="left" valign="bottom" colspan="2" height="3"> <span class="header"> Reduction of Biosphere Life Span as a Consequence of Geodynamics </span> </td> <td align="left" valign="top" rowspan="2"> </td> <td align="left" valign="top" rowspan="2" class="body"> <p><br><a href="../homepage/welcome.html">Werner von Bloh</a><img src="images/home2.gif" width="15" height="13"><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> <a href="../homepage/welcome.html#projects">Projects involved</a><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> <a href="../homepage/teaching">Teaching</a><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> <a href="welcome.html">Publications</a><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> <a href="../homepage/cv.html">Curriculum Vitae</a><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> <a href="../parallel.html">Parallel programming</a><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> <a href="../intranet">My intranet pages</a><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> <a href="../mpeg">Animations</a><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> <a href="../extern.html">External links</a><br> <img src="images/purple.gif" width="180" height="1" vspace="3"><br> </p></td> </tr> <tr align="left" valign="top"> <td> </td> <td colspan="2"><p><br>  <p class=body>S. Franck, A. Block, <A HREF="../homepage">W. von Bloh</A>, C. Bounama, <A HREF="/john">H.-J. Schellnhuber</A>, and Y. M. Svirezhev<br><br> <I>Tellus 52B, no. 1, 94-107 (2000)</I> <P class=body> <A HREF="http://www.pik-potdsdam.de">Potsdam Institute for Climate Impact Research</A> (PIK), Telegrafenberg, P.O. Box 60 12 03, 14412 Potsdam, Germany. <p> <span class="header"><A NAME="part1">Abstract</A><br> <img src="images/purple.gif" width="100%" height="1"></span></p> <P class=body>The long-term co-evolution of the geosphere-biosphere complex from the Proterozoic up to 1.5 billion years into the planet's future is investigated using a conceptual Earth system model including the basic geodynamic processes. The model focusses on the global carbon cycle as mediated by life and driven by increasing solar luminosity and plate tectonics. The main CO<sub>2</sub> sink, the weathering of silicates, is calculated as a function of biologic activity, global run-off and continental growth. The main CO<sub>2</sub> source, tectonic processes dominated by sea-floor spreading, is determined using a novel semi-empirical scheme. Thus a geodynamic extension of previous geostatic approaches can be achieved.</P> <P class=body>As a major result of extensive numerical investigations, the "terrestrial life corridor", i.e. the biogeophysical domain supporting a photosynthesis-based ecosphere in the planetary past and in the future, can be identified. Our findings imply, in particular, that the remaining life span of the biosphere is considerably shorter (by a few hundred million years) than the value computed with geostatic models by Caldeira and Kasting (1992), and other groups. The "habitable-zone concept" is also revisited, revealing the band of orbital distances from the Sun warranting Earth-like conditions. It turns out that this habitable zone collapses completely in some 1.4 billion years from now as a consequence of geodynamics.</P> <P class=body>Full text of article incl. figures as a <A HREF="franck2000">HTML-document</A>.</P> <P align=center> <IMG SRC="franck99b.gif" width="349" height="229" alt="Figure"> </P> <P class=figure> Figure: Evolution of the habitable zone (HZ) for GSM-asymptotic (red line) and GDM-asymptotic (green line). Note that for GSM-asymptotic the HZ has a slightly increasing width and shifts outward from the Sun. The HZ for our favoured model, GDM-asymptotic, is both shifting and narrowing over geologic time, terminating life definitely at 1.4 Ga. The optimum position for an Earth-like planet would be at <I>R</I><sub>opt</sub>=1.08 AU. In this case the life span of the biosphere would realize the maximum life span, i.e. the above-mentioned 1.4 Ga. This figure is the main finding of our investigation. </P> </td> </tr> <tr align="left" valign="top"> <td> </td> <td class="body" colspan="2"> <p><br> </p></td> <td class="body"> </td> <td class="body"> </td> </tr> <tr align="left" valign="top"> <td> </td> <td class="body" colspan="2"> </td> <td class="body"> </td> <td class="body"> </td> </tr> </table> </td> </tr> <tr> <td align="left" valign="bottom"> <table width="500" border="0" cellspacing="0" cellpadding="0"> <tr align="left" valign="top"> <td><img src="images/spacer.gif" width="20" height="1"></td> <td><img src="images/spacer.gif" width="140" height="1"></td> <td> </td> <td><img src="images/spacer.gif" width="400" height="1"></td> </tr> <tr> <td> </td> <td class="body"><a href="http://www.pik-potsdam.de/impressum">Impressum © PIK 2006</a></td> <td> </td> <td class="body"> </td> </tr> </table> </td> </tr> </table> </body> </html>