{"id":449,"date":"2015-01-23T12:11:33","date_gmt":"2015-01-23T12:11:33","guid":{"rendered":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/?p=449"},"modified":"2015-01-23T17:45:53","modified_gmt":"2015-01-23T17:45:53","slug":"with-climate-models-simpler-isnt-necessarily-better","status":"publish","type":"post","link":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/2015\/01\/23\/with-climate-models-simpler-isnt-necessarily-better\/","title":{"rendered":"With climate models, simpler isn&#8217;t necessarily better"},"content":{"rendered":"<p><em><a href=\"http:\/\/www.imperial.ac.uk\/grantham\">Grantham Institute<\/a>\u00a0Co-Director <a href=\"http:\/\/www.imperial.ac.uk\/people\/j.haigh\">Professor Joanna Haigh<\/a> discusses <a href=\"http:\/\/www.scibull.com:8080\/EN\/abstract\/abstract509579.shtml\">a recent\u00a0paper<\/a>\u00a0which argues that \u00a0existing climate models &#8216;run hot&#8217; and overstate the\u00a0extent of manmade climate change.<\/em><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"200\" height=\"300\" class=\" size-medium wp-image-451 alignright\" src=\"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/files\/2015\/01\/smoking-chimney-200x300.jpg\" alt=\"Retro filtered picture of smoky chimneys silhouettes against sun\" \/>It is perplexing that some climate change sceptics, who expend much energy in decrying global circulation (computer) models of the climate, on the basis that they cannot properly represent the entire complexities of the climate system and\/or that they contain too many approximations, are now resorting to an extremely simplified model to support their arguments.<\/p>\n<p>The model used in the <a href=\"http:\/\/www.scibull.com:8080\/EN\/abstract\/abstract509579.shtml\">Sci. Bull. article<\/a> is a very useful tool for conceptualising the factors which contribute to the relationship between increasing concentrations of carbon dioxide in the atmosphere and global average temperature &#8211; indeed, we use such models as teaching aids for students studying atmospheric physics &#8211; but it is in no way fit for purpose as an accurate predictor of climate change. \u00a0It requires as input the values of a number of parameters and, fundamentally, the choice of these values determines the predicted temperatures<\/p>\n<p>Key here is the \u201cfeedback parameter\u201d which represents the knock-on effects of changes in the atmosphere on the initial response to greenhouse gas warming.\u00a0 A positive feedback will make the temperature change larger and a negative one reduce it.\u00a0 For example, as the atmosphere warms it can hold more water vapour which itself is a greenhouse gas, acting to enhance the initial carbon dioxide-induced warming and thus giving a positive feedback.\u00a0 The physics of this process is very well-understood.\u00a0 There are a number of other, both positive and negative, feedback processes but overall, analyses of meteorological observations, modelling and understanding of the physical processes point to a significantly positive value.\u00a0 In the present paper the authors choose a very small value, based on temperatures measured in ice cores over the 810,000 year period of ice ages and inter-glacials.\u00a0 Their analysis is incomplete\u00a0but anyway not relevant to changes in global climate over decadal-to-century timescales.<\/p>\n<p>Thus by choosing an inappropriate value of the feedback parameter, and also judicious choices of other parameters, the authors end up with their \u201cmodels run hot\u201d conclusion.\u00a0 Must try harder.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Grantham Institute\u00a0Co-Director Professor Joanna Haigh discusses a recent\u00a0paper\u00a0which argues that \u00a0existing climate models &#8216;run hot&#8217; and overstate the\u00a0extent of manmade climate change. It is perplexing that some climate change sceptics, who expend much energy in decrying global circulation (computer) models of the climate, on the basis that they cannot properly represent the entire complexities of [&hellip;]<\/p>\n","protected":false},"author":741,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17115,8855],"tags":[],"class_list":["post-449","post","type-post","status-publish","format-standard","hentry","category-climate-scepticism","category-media"],"_links":{"self":[{"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/posts\/449","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/users\/741"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/comments?post=449"}],"version-history":[{"count":7,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/posts\/449\/revisions"}],"predecessor-version":[{"id":457,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/posts\/449\/revisions\/457"}],"wp:attachment":[{"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/media?parent=449"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/categories?post=449"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/tags?post=449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}