{"id":80463,"date":"2016-10-03T12:00:09","date_gmt":"2016-10-03T11:00:09","guid":{"rendered":"https:\/\/www.transcend.org\/tms\/?p=80463"},"modified":"2016-09-29T12:05:25","modified_gmt":"2016-09-29T11:05:25","slug":"the-world-passes-400-ppm-threshold-permanently","status":"publish","type":"post","link":"https:\/\/www.transcend.org\/tms\/2016\/10\/the-world-passes-400-ppm-threshold-permanently\/","title":{"rendered":"The World Passes 400 PPM Threshold. Permanently"},"content":{"rendered":"

27 Sep 2016 – <\/em>In the centuries to come, history books will likely look back on September 2016 as a major milestone for the world\u2019s climate. At a time when atmospheric carbon dioxide is usually at its minimum, the monthly value failed to drop below 400 parts per million.<\/p>\n

That all but ensures that 2016 will be the year that carbon dioxide officially passed the symbolic 400 ppm mark, never to return below it in our lifetimes, according to scientists.<\/p>\n

\"9_27_16_brian_400pmm4eva_720_492_s_c1_c_c-carbon-dioxide-climate-change\"<\/a><\/p>\n

Because carbon pollution has been increasing since the start of the Industrial Revolution and has shown no signs of abating, it was more a question of \u201cwhen\u201d rather than \u201cif\u201d<\/a> we would cross this threshold. The inevitability doesn\u2019t make it any less significant, though.<\/p>\n

September is usually the month when carbon dioxide is at its lowest after a summer of plants growing and sucking it up in the northern hemisphere. As fall wears on, those plants lose their leaves, which in turn decompose, releasing the stored carbon dioxide back into the atmosphere. At Mauna Loa Observatory, the world\u2019s marquee site for monitoring carbon dioxide, there are signs that the process has begun but levels have remained above 400 ppm.<\/p>\n\n\n\n
RELATED<\/strong><\/td>\nCO2 Nears Peak: Are We Permanently Above 400 PPM?<\/a><\/strong>
\nFlirting with the 1.5\u00b0C Threshold<\/a><\/strong>
\nAntarctic CO2 Hit 400 PPM For First Time in 4 Million Years<\/a><\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Since the industrial revolution, humans have been altering this process by adding more carbon dioxide to the atmosphere than plants can take up. That\u2019s driven carbon dioxide levels higher and with it, global temperatures, along with a host of other climate change impacts.<\/p>\n

\u201cIs it possible that October 2016 will yield a lower monthly value than September and dip below 400 ppm? Almost impossible,\u201d Ralph Keeling, the scientist who runs the Scripps Institute for Oceanography\u2019s carbon dioxide monitoring program, wrote in a blog post<\/a>. \u201cBrief excursions toward lower values are still possible, but it already seems safe to conclude that we won\u2019t be seeing a monthly value below 400 ppm this year \u2013 or ever again for the indefinite future.\u201d<\/p>\n

We may get a day or two reprieve in the next month, similar to August when Tropical Storm Madeline blew by Hawaii and knocked carbon dioxide below 400 ppm for a day<\/a>. But otherwise, we\u2019re living in a 400 ppm world. Even if the world stopped emitting carbon dioxide tomorrow, what has already put in the atmosphere will linger for many decades to come.<\/p>\n

https:\/\/www.transcend.org\/tms\/wp-content\/uploads\/2016\/09\/InexperiencedFalseGypsymoth-mobile-climate-change-nasa-co2.mp4<\/a><\/video><\/div>\n

An animation showing how carbon dioxide moves around the planet.
\nCredit: NASA<\/a>\/YouTube<\/p>\n

\u201cAt best (in that scenario), one might expect a balance in the near term and so CO2 levels probably wouldn’t change much \u2014 but would start to fall off in a decade or so,\u201d Gavin Schmidt<\/a>, NASA\u2019s chief climate scientist, said in an email. \u201cIn my opinion, we won\u2019t ever see a month below 400 ppm.\u201d<\/p>\n

The carbon dioxide we\u2019ve already committed to the atmosphere has warmed the world about 1.8\u00b0F since the start of the industrial revolution. This year, in addition to marking the start of our new 400 ppm world<\/a>, is also set to be the hottest year on record<\/a>. The planet has edged right up against the 1.5\u00b0C<\/a> (2.7\u00b0F) warming threshold, a key metric in last year\u2019s Paris climate agreement<\/a>.<\/p>\n

Even though there are some hopeful signs<\/a> that world leaders will take actions to reduce emissions, those actions will have to happen on an accelerating timetable in order to avoid 2\u00b0C (3.6\u00b0F) of warming. That\u2019s the level outlined by policymakers as a safe threshold for climate change. And even if the world limits warming to that benchmark, it will still likely spell doom for low-lying small island states<\/a> and have serious repercussions around the world, from more extreme heat waves to droughts, coastal flooding and the extinction of many coral reefs<\/a>.<\/p>\n

It\u2019s against this backdrop that the measurements on top of Mauna Loa take on added importance. They\u2019re a reminder that with each passing day, we\u2019re moving further from the climate humans have known and thrived in and closer to a more unstable future.<\/p>\n

__________________________________<\/p>\n

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\nGreenland is Losing More Ice Than Scientists Thought<\/a> <\/em><\/p>\n

Brian Kahn is a Senior Science Writer at Climate Central. He previously worked at the International Research Institute for Climate and Society and partnered with\u00a0climate.gov<\/a>\u00a0to produce multimedia stories, manage social media campaigns and develop version 2.0 of\u00a0climate.gov<\/a>. His writing has also appeared in the <\/em>Wall Street Journal, Grist, the<\/em> Daily Kos, Justmeans and the<\/em> Yale Forum on Climate Change in the Media. In previous lives, he led sleigh ride tours through a herd of 7,000 elk and guided tourists around the deepest lake in the U.S. He holds an M.A. in Climate and Society from Columbia University.\u00a0<\/em><\/p>\n

Go to Original \u2013 climatecentral.org<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

2016 is the year that carbon dioxide officially passed the symbolic 400 ppm mark, never to return below it in our lifetimes, according to scientists. Because carbon pollution has been increasing since the start of the Industrial Revolution and has shown no signs of abating, it was more a question of \u201cwhen\u201d rather than \u201cif\u201d we would cross this threshold. The inevitability doesn\u2019t make it any less significant, though.<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61],"tags":[],"class_list":["post-80463","post","type-post","status-publish","format-standard","hentry","category-environment"],"_links":{"self":[{"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/posts\/80463","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/comments?post=80463"}],"version-history":[{"count":0,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/posts\/80463\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/media?parent=80463"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/categories?post=80463"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/tags?post=80463"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}