{"id":206,"date":"2022-09-01T12:12:42","date_gmt":"2022-09-01T12:12:42","guid":{"rendered":"http:\/\/theclimatebook.org\/?page_id=206"},"modified":"2022-11-08T12:41:20","modified_gmt":"2022-11-08T12:41:20","slug":"2-24-what-happens-at-1-5-2-and-4c-of-warming","status":"publish","type":"page","link":"https:\/\/theclimatebook.org\/en-us\/endnotes\/how-our-planet-is-changing\/2-24-what-happens-at-1-5-2-and-4c-of-warming\/","title":{"rendered":"2.24 What Happens at 1.5, 2 and 4\u00b0C of Warming?"},"content":{"rendered":"
\n

Tamsin Edwards<\/a><\/p>\n

All online sources accessed on

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  1. \n

    \nThe kind of heat that was expected only once a decade<\/q> Intergovernmental Panel on Climate Change, \u2018Summary for policymakers\u2019<\/cite>, in Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change<\/span>, ed. V. Masson-Delmotte et al. (Cambridge: Cambridge University Press, in press), Fig. SPM.6: \u2018Hot temperature extremes over land\u2019<\/cite>, https:\/\/www.ipcc.ch\/report\/ar6\/wg1\/<\/a>. Hot temperature extremes are defined as daily maximum temperatures over land that were exceeded on average once per decade between 1850 and 1900.\n<\/p>\n

    \nExtreme heavy rain is now 30 per cent more likely<\/q> Ibid., Fig. SPM.6: \u2018Heavy precipitation over land\u2019<\/cite>. Extreme precipitation events are defined as the daily precipitation amount over land that was exceeded on average once per decade between 1850 and 1900.\n<\/p>\n

    \nDroughts \u2026 are 70 per cent more likely<\/q> Ibid., Fig. SPM.6: \u2018Agricultural and ecological droughts in drying regions\u2019<\/cite>. Drought events are defined as the annual average of total column soil moisture below the tenth percentile of the 1850\u20131900 period. Results are shown for drying regions only.\n<\/p>\n

    \nsome of which we have made three \u2026 times more likely<\/q> Otto, F. E. L., et al., \u2018Likelihood of Cape Town water crisis tripled by climate change\u2019<\/cite>, World Weather Attribution, 13 July 2018, https:\/\/www.worldweatherattribution.org\/the-role-of-climate-change-in-the-2015-2017-drought-in-the-western-cape-of-south-africa<\/a>.\n<\/p>\n

    \ndoubling them by the end of the century<\/q> CO2<\/sub> emissions from all sectors increase from around 40 gigatonnes to 80 gigatonnes between 2015 to 2100, i.e. an average of just under 0.5 gigatonnes per year (of which the vast majority are from fossil fuels, not deforestation). This is similar to the average increase of fossil fuel CO2<\/sub> emissions, from around 26 gigatonnes per year to around 36 gigatonnes per year during the twenty-year period 2000\u20132019, estimated in the global carbon budget for 2021: Global Carbon Project, \u2018Infographics: Global carbon budget 2021\u2019<\/cite>, https:\/\/www.globalcarbonproject.org\/carbonbudget\/21\/infographics.htm<\/a>.\n<\/p>\n

    \nWhen our ancestors were beginning to craft stone tools<\/q> Harmand, S., \u20183.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya\u2019<\/cite>, Nature<\/span>, 521 (7552), 2015: 310\u201315, https:\/\/doi.org\/10.1038\/nature14464<\/a>; Brahic, C., \u2018Human ancestors got a grip on tools 3 million years ago\u2019<\/cite>, New Scientist<\/span>, 22 January 2015, https:\/\/www.newscientist.com\/article\/dn26844-human-ancestors-got-a-grip-on-tools-3-million-years-ago<\/a>; Skinner, M. M., et al., \u2018Human-like hand use in Australopithecus africanus\u2019<\/cite>, Science<\/span>, 347 (6220), 2015: 395\u20139, https:\/\/doi.org\/10.1126\/science.1261735<\/a>.\n<\/p>\n

    \nhundreds of millions more people exposed to deadly heatwaves<\/q> Hoegh-Guldberg, O., et al., \u2018Impacts of 1.5\u00baC global warming on natural and human systems\u2019<\/cite>, in Intergovernmental Panel on Climate Change, Global Warming of 1.5\u00b0C: An IPCC Special Report on the Impacts of Global Warming of 1.5\u00b0C above Pre-industrial Levels and Related Global Greenhouse Gas Emission Pathways, in the Context of Strengthening the Global Response to the Threat of Climate Change, Sustainable Development, and Efforts to Eradicate Poverty<\/span>, ed. V. Masson-Delmotte (Cambridge: Cambridge University Press, 2018), https:\/\/www.ipcc.ch\/sr15\/chapter\/chapter-3\/<\/a>.\n<\/p>\n<\/li>\n

  2. \n

    \neven at 1.5\u00b0C of warming, sea ice \u2026 will almost disappear<\/q> Intergovernmental Panel on Climate Change, \u2018Summary for policymakers\u2019<\/cite>, in Climate Change 2021: The Physical Science Basis<\/span>, paragraph B.2.5: \u2018The Arctic is likely to be practically sea ice-free in September at least once before 2050 under the five illustrative scenarios considered in this report.\u2019<\/cite> Under the lowest of these emissions scenarios (SSP1-1.9), the global surface temperature relative to 1950\u20132000 is predicted to increase by 1.5\u00b0C in 2021\u201340, 1.6\u00b0C in 2041\u201360 and 1.4\u00b0C in 2081\u20132100, i.e. 1.5\u00b0C with limited overshoot: ibid., Table SPM.1.\n<\/p>\n

    \nAt 3\u20134\u00b0C of warming it will disappear entirely<\/q> Fox-Kemper, B., et al., \u2018Ocean, cryosphere and sea level change\u2019<\/cite>, in Intergovernmental Panel on Climate Change, Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change<\/span>, ed. V. Masson-Delmotte et al. (Cambridge: Cambridge University Press, in press), https:\/\/www.ipcc.ch\/report\/ar6\/wg1\/<\/a>, \u2018Executive summary\u2019<\/cite> : \u2018The practically ice-free state is projected to occur more often with higher greenhouse gas concentrations, and it will become the new normal for high-emissions scenarios by the end of this century (high confidence) \u2026 At sustained warming levels between 1.5\u00b0C and 2\u00b0C, the Arctic Ocean will become practically sea ice-free in September in some years (medium confidence) \u2026 At sustained warming levels between 2\u00b0C and 3\u00b0C, the Arctic Ocean will be practically sea ice-free throughout September in most years (medium confidence) \u2026 At sustained warming levels between 3\u00b0C and 5\u00b0C, the Arctic Ocean will become practically sea ice-free throughout several months in most years (high confidence).\u2019<\/cite>\n<\/p>\n

    \nEven at these temperatures<\/q> Lee, J.-Y., et al., \u2018Future global climate: scenario-based projections and near-term information\u2019<\/cite>, in Intergovernmental Panel on Climate Change, Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change<\/span>, ed. V. Masson-Delmotte et al. (Cambridge: Cambridge University Press, in press), doi: 10.1017\/9781009157896.006.<\/p>\n

    \n10\u00b0C hotter by the year 2300<\/q> Ibid., Table 4.9. Under the highest illustrative emissions scenario (SSP5-8), the best estimate (mean) for the increased in global air surface temperature by 2300 relative to 1950\u20132000 is 9.6\u00b0C, with a very likely (90 per cent) possibility of anywhere between 6.6 and 14.1\u00b0C.\n<\/p>\n<\/li>\n

  3. \n

    \n\u2018unless there are immediate, rapid, and large-scale reductions\u2019<\/q> Intergovernmental Panel on Climate Change, \u2018Climate change widespread, rapid, and intensifying\u2019<\/cite> (press release for the completion of the IPCC Working Group I report Climate Change 2021: The Physical Science Basis<\/span>), 9 August 2021, https:\/\/www.ipcc.ch\/2021\/08\/09\/ar6-wg1-20210809-pr<\/a>.<\/p>\n

    \nif those policies are successfully enforced<\/q> Carbon Brief, \u2018Analysis: do COP26 promises keep global warming below 2\u00b0C?\u2019<\/cite>, 10 November 2021, https:\/\/www.carbonbrief.org\/analysis-do-cop26-promises-keep-global-warming-below-2c<\/a>.<\/p>\n<\/li>\n<\/ol>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

    Tamsin Edwards All online sources accessed on 4 March 2022 The kind of heat that was expected only once a decade Intergovernmental Panel on Climate Change, \u2018Summary for policymakers\u2019, in Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, ed.…<\/p>\n","protected":false},"author":5,"featured_media":0,"parent":18,"menu_order":24,"comment_status":"closed","ping_status":"closed","template":"page-essay.php","meta":{"footnotes":""},"class_list":["post-206","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/theclimatebook.org\/en-us\/wp-json\/wp\/v2\/pages\/206","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/theclimatebook.org\/en-us\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/theclimatebook.org\/en-us\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/theclimatebook.org\/en-us\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/theclimatebook.org\/en-us\/wp-json\/wp\/v2\/comments?post=206"}],"version-history":[{"count":0,"href":"https:\/\/theclimatebook.org\/en-us\/wp-json\/wp\/v2\/pages\/206\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/theclimatebook.org\/en-us\/wp-json\/wp\/v2\/pages\/18"}],"wp:attachment":[{"href":"https:\/\/theclimatebook.org\/en-us\/wp-json\/wp\/v2\/media?parent=206"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}