{"id":25,"date":"2013-10-17T10:10:34","date_gmt":"2013-10-17T10:10:34","guid":{"rendered":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/?p=25"},"modified":"2014-08-05T08:19:55","modified_gmt":"2014-08-05T08:19:55","slug":"transient-climate-response-an-incomplete-measure-of-climate-change","status":"publish","type":"post","link":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/2013\/10\/17\/transient-climate-response-an-incomplete-measure-of-climate-change\/","title":{"rendered":"Transient Climate Response: an incomplete measure of climate change"},"content":{"rendered":"<p><strong>By <a href=\"http:\/\/www.imperial.ac.uk\/AP\/faces\/pages\/read\/Home.jsp?person=simon.buckle&amp;_adf.ctrl-state=10k9ja4d0n_3&amp;_afrRedirect=1134199761823570\">Dr Simon Buckle<\/a><\/strong><\/p>\n<p>It may help to clarify some of the facts related to the <a href=\"http:\/\/www.theguardian.com\/environment\/2013\/oct\/14\/honest-debate-on-climate-change\">lively exchange between Bob Ward and Lord Ridley<\/a> about the Transient Climate Response (TCR). The TCR is defined by the IPCC as \u201cthe change in the global mean surface temperature, averaged over a 20-year period, centred at the time of atmospheric carbon dioxide doubling, in a climate model simulation in which CO<sub>2 <\/sub>increases at 1% yr\u00a0<sup>\u2013\u00a01<\/sup>.\u201d<\/p>\n<p>Lord Ridley is right that the IPCC in its recently published AR5 Working Group I report gave an estimated <em>likely<\/em> (66\u2013100% probability) range for TCR of 1\u00a0&#8211;\u00a02.5\u00b0C.\u00a0 The IPCC also increased its confidence that the TCR is not greater than 3.0\u00b0C though it is not immediately clear what confidence the IPCC places on the 1\u00b0C lower limit, rather than the range it provides.<\/p>\n<p>As Bob Ward notes, however, the TCR is unlikely to reflect how global mean surface temperatures might increase during this century, as claimed by Lord Ridley. This is for two reasons. First, our carbon dioxide emissions are rising by around three percent not one percent per year.\u00a0 Second, the TCR only refers to changes due to carbon dioxide; climate change will be greater than this due to increases in other greenhouse gases such as methane and nitrous oxide, though it is also offset to some degree by atmospheric aerosols.<\/p>\n<p>Our current emissions are broadly in line with the most emissions intensive of the IPCC\u2019s scenarios for AR5 \u2013 the so-called RCP8.5 scenario.\u00a0 This is likely to lead to an average increase in global mean surface temperature for the final two decades of this century of 3.2-5.4\u00b0C relative to the second half of the nineteenth century.\u00a0 This is a huge change and will be even larger in high latitudes and over continents.\u00a0 The scale of change is broadly comparable to that which separates our present climate from that of the Ice Age.<\/p>\n<p>I don\u2019t think we have any clear idea of what the full economic, social and political impact of such huge changes would be.\u00a0 I am all in favour of policies that lift people out of poverty, insecurity and hunger now.\u00a0 But that does not mean we should ignore the huge risks we are taking with the climate to which humans have become adapted. Presenting this as a sharp dichotomy is wrong.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>By Dr Simon Buckle It may help to clarify some of the facts related to the lively exchange between Bob Ward and Lord Ridley about the Transient Climate Response (TCR). The TCR is defined by the IPCC as \u201cthe change in the global mean surface temperature, averaged over a 20-year period, centred at the time [&hellip;]<\/p>\n","protected":false},"author":647,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17115],"tags":[],"class_list":["post-25","post","type-post","status-publish","format-standard","hentry","category-climate-scepticism"],"_links":{"self":[{"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/posts\/25","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\/647"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/comments?post=25"}],"version-history":[{"count":7,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/posts\/25\/revisions"}],"predecessor-version":[{"id":290,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/posts\/25\/revisions\/290"}],"wp:attachment":[{"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/media?parent=25"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/categories?post=25"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs-staging.imperial.ac.uk\/climate-at-imperial\/wp-json\/wp\/v2\/tags?post=25"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}