{"id":17765,"date":"2014-12-08T05:38:20","date_gmt":"2014-12-08T10:38:20","guid":{"rendered":"http:\/\/www.realclimate.org\/?p=17765"},"modified":"2014-12-08T13:26:24","modified_gmt":"2014-12-08T18:26:24","slug":"the-most-popular-deceptive-climate-graph","status":"publish","type":"post","link":"https:\/\/www.realclimate.org\/index.php\/archives\/2014\/12\/the-most-popular-deceptive-climate-graph\/","title":{"rendered":"The most popular deceptive climate graph"},"content":{"rendered":"
\n

The “World Climate Widget” from Tony Watts’ blog is probably the most popular deceptive image among climate \u201cskeptics\u201d. \u00a0We’ll take it under the microscope and show what it would look like when done properly.<\/strong><\/p>\n

So called “climate skeptics” deploy an arsenal of misleading graphics, with which the human influence on the climate can be down played (here are\u00a0two<\/a>\u00a0other \u00a0examples<\/a>\u00a0deconstructed at Realclimate). \u00a0The image below is especially widespread. \u00a0It is displayed on many \u201cclimate skeptic\u201d websites and is regularly updated.<\/p>\n

\"Watts_world_climate_widget\"<\/a><\/p>\n

The\u00a0“World Climate Widget”\u00a0of US “climate skeptic” Anthony Watts with our explanations added. \u00a0The original can be found on\u00a0Watts’ blog<\/a><\/em><\/p>\n

What would a more honest display of temperature, CO2<\/sub>\u00a0and sunspots look like?<\/strong><\/p>\n

    \n
  1. \u00a0It is better to plot the surface air temperature<\/strong>. \u00a0That is what is relevant for us humans: we do not live up in the troposphere, nor do natural ecosystems, nor do we grow our food up there. By the way, the satellite-based tropospheric temperatures shown by Watts show almost the same climatic warming trend as those measured by weather stations near ground level (in both cases 0.16 C per decade over the last 30 years<\/a>). \u00a0However, variability in the tropospheric data is considerably larger, especially because of higher sensitivity to El\u00a0Ni\u00f1o (as happened in 1998) and the solar cycle (we showed that in\u00a0Foster and Rahmstorf ERL 2011 – <\/a>when corrected for those factors the surface and troposphere data agree closely<\/a>). \u00a0Because of increased noise, the trend is less obvious to the eye, especially if one shows monthly values which adds yet more noise. \u00a0Let us thus use the GISTEMP global annual temperature record from NASA’s Goddard Institute for Space Science (all surface data sets agree to better than 0.1 \u00b0C, see comparison graph<\/a>).<\/li>\n<\/ol>\n
      \n
    1. \u00a0One needs to\u00a0scale the CO<\/strong>2<\/sub> <\/strong>data correctly<\/strong> for an honest comparison with temperature, so that it can actually be used to evaluate climate scientists’ predictions of the CO2<\/sub>\u00a0effect. \u00a0You can calculate this with a complicated climate model, but one can also use a back-of-envelope estimate. \u00a0A CO2<\/sub>\u00a0increase from 280 to 400 ppm (equivalent to 2 Watts\/meter2<\/sup>\u00a0radiative forcing) produces about 1 \u00b0C of global warming (at the time when 400 ppm is reached – some further warming will follow with delay). Thus, an increase of 100 ppm CO2<\/sub>\u00a0on the right hand side of the graph corresponds to a temperature increase of 0.8\u00b0C on the left hand side.\u00a0That matches the IPCC’s estimate of the “transient climate response (TCR)” of ~2\u00b0C at the time of CO2<\/sub>\u00a0doubling (see Technical Summary of the IPCC WG1 report, p. 84).\u00a0The TCR is smaller than the equilibrium climate sensitivity (about 3\u00b0C for doubled CO2<\/sub>) because it takes time to warm the oceans. The full equilibrium warming is thus only reached after a time delay. We are going to use the annual values from the\u00a0famous CO2<\/sub>\u00a0measurements<\/a>\u00a0which began in 1958 on Mauna Loa in Hawaii.<\/li>\n<\/ol>\n
        \n
      1. \u00a0And last but not least one should show honest\u00a0sunspot data (annual time series)<\/strong>, not just a snapshot of the number of spots on the sun today (which is completely uninformative for climate purposes \u2013 it\u2019s apparently been added to the widget simply to insinuate an important role of the sun).\u00a0Here also there is a question of the proper scaling (which is actually not that important because solar activity is cyclical and shows no significant trend over the period of the graph)<\/em>. \u00a0We will chose the scaling from the\u00a0correlation analysis of Lean and Rind (2008)<\/a>\u00a0from which one can find a measurable effect on global temperature with an amplitude of 0.05\u00b0C.<\/li>\n<\/ol>\n

        When done this way the graph looks like this:<\/p>\n

        \"climate_widget_2013\"<\/a><\/p>\n

        One of the readers of our German sister blog KlimaLounge<\/a>, Bernd Herd, has programmed a\u00a0widget for this graph\u00a0<\/a>so it can be added to any website at a size you like, automatically updated annually.<\/p>\n

        The trends in the CO2<\/sub>\u00a0and temperature anomaly curves agree very well with each other. \u00a0This is surprising at first because CO2<\/sub>\u00a0is of course not the only factor that influences global temperature. There are two reasons for this agreement:<\/p>\n

        (1) \u00a0Of the other anthropogenic factors, some have a warming effect (other greenhouse gases such as methane) while others have a cooling effect (air pollution). These roughly balance in global average. The IPCC AR4 report found a\u00a0radiative forcing of 1.7\u00a0W\/m2<\/sup>\u00a0from the CO2<\/sub> increase alone, while the total from all anthropogenic factors amounted to 1.6\u00a0W\/m2<\/sup><\/a>.<\/p>\n

        (2) \u00a0Natural factors (volcanoes, solar cycle) influencing the trend are very small in comparison to anthropogenic CO2<\/sub>\u00a0(as e.g. standard correlation analyses show, see for example\u00a0Lean and Rind 2008<\/a>,\u00a0Foster and Rahmstorf 2011<\/a>). The IPCC AR5 found their contribution to global temperature change since 1951 to be in the range of \u22120.1\u00b0C to 0.1\u00b0C.<\/p>\n

        It requires quite some skill to produce a misleading graph like Watts\u2019 global climate widget, which hides the actual connections between global temperature, CO2<\/sub> and the sunspot cycle. Watts’ widget is quite a useful indicator though: whenever you see it on a website, you know they are trying to fool rather than inform you there.<\/p>\n

         <\/p>\n

        Weblink<\/strong>s
        \n        A quick \u2018n dirty guide to falsifying\u00a0AGW<\/a><\/p>\n

        Dot Earth: Warming Trend and Variations on a Greenhouse-Heated Planet<\/a><\/p>\n\n<\/div> ","protected":false},"excerpt":{"rendered":"

        The “World Climate Widget” from Tony Watts’ blog is probably the most popular deceptive image among climate \u201cskeptics\u201d. \u00a0We’ll take it under the microscope and show what it would look like when done properly. So called “climate skeptics” deploy an arsenal of misleading graphics, with which the human influence on the climate can be down […]<\/p>\n","protected":false},"author":10,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[1,35,9,34,4],"tags":[],"class_list":{"0":"post-17765","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-climate-science","7":"category-communicating-climate","8":"category-instrumental-record","9":"category-skeptics","10":"category-sun-earth-connections","11":"entry"},"aioseo_notices":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/17765","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/users\/10"}],"replies":[{"embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/comments?post=17765"}],"version-history":[{"count":24,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/17765\/revisions"}],"predecessor-version":[{"id":17848,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/posts\/17765\/revisions\/17848"}],"wp:attachment":[{"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/media?parent=17765"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/categories?post=17765"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.realclimate.org\/index.php\/wp-json\/wp\/v2\/tags?post=17765"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}