Jekyll plugin that shows climate change trends
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Jekyll CO₂

Written by William Denton.

This is a plugin for the static web site generator Jekyll to show the change in atmospheric CO₂ at the Mauna Loa observatory in Hawaii. It was inspired by CO2Now. The data comes from the NOAA's Earth System Research Laboratory.

It shows the CO₂ concentrations for the latest known month (usually last month, but sometimes the month before that) over the last 15 years in a text sparkline that looks something like this: ▁▁▂▂▂▂▃▃▃▄▄▄▅▅▅▅▆▆▆▇▇.

In a browser it looks like this:


How to install

Download co2.rb and put it in your _plugins directory. That's all!

How to use

The plugin creates an include file: _includes/co2.html. Include it in a web page like this:

{% include co2.html %}

When the page is rendered, the tag will be replaced by a short block of HTML like this:

<div id="co2">
<span class="sparkline"><span title="355.63">▁</span>[13 years]<span title="395.28">▇</span></span>
<p><span class="co2_title">Atmospheric CO₂ at Mauna Loa (ppm) in September over the last 20 years</span> </p>
<span class="co2_source">(<a href="">Source</a>)</span>

You could style it with CSS like this:

#co2 {
  border: thin solid green;
  padding: 5px;

#co2 .co2_title {

#co2 .sparkline {
    font-size: smaller;

#co2 .co2_source {
  font-size: smaller;