1.0Climate 411https://blogs.edf.org/climate411rich600338<blockquote class="wp-embedded-content" data-secret="ulXn5g2oFl"><a href="https://blogs.edf.org/climate411/2007/06/14/human_cause-1/">Part 1 of 5: A 175-year-old Puzzle</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://blogs.edf.org/climate411/2007/06/14/human_cause-1/embed/#?secret=ulXn5g2oFl" width="600" height="338" title="“Part 1 of 5: A 175-year-old Puzzle” — Climate 411" data-secret="ulXn5g2oFl" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script type="text/javascript"> /* <![CDATA[ */ /*! This file is auto-generated */ !function(d,l){"use strict";l.querySelector&&d.addEventListener&&"undefined"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-zA-Z0-9]/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),o=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),c=new RegExp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute("style"),"height"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new URL(s.getAttribute("src")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",function(){for(var e,t,s=l.querySelectorAll("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute("data-secret"))||(t=Math.random().toString(36).substring(2,12),e.src+="#?secret="+t,e.setAttribute("data-secret",t)),e.contentWindow.postMessage({message:"ready",secret:t},"*")},!1)))}(window,document); /* ]]> */ </script> This is the first installment of a five-part series by Bill Chameides on How We Know Humans Cause Global Warming. 1. A 175-year-old Puzzle 2. What Chemistry Tells Us 3. Causes of Past Climate Change 4. The Medieval Warming Period 5. The Only Explanation Left Most people these days accept that our planet is warming, ...