{"id":58742,"date":"2023-03-20T14:00:00","date_gmt":"2023-03-20T13:00:00","guid":{"rendered":"https:\/\/www.greenpeace.org\/international\/?p=58742"},"modified":"2025-01-21T11:18:25","modified_gmt":"2025-01-21T10:18:25","slug":"that-graph-on-fire","status":"publish","type":"post","link":"https:\/\/www.greenpeace.org\/international\/story\/58742\/that-graph-on-fire\/","title":{"rendered":"When climate scientists set the graphs on fire"},"content":{"rendered":"\n

After purple, will we be heading towards black? <\/em><\/strong><\/h3>\n\n

By definition, what is dangerous climate change? Dangerous to whom? By when? <\/p>\n\n

When do risks and impacts become intolerable? 

To answer these questions, scientists have developed, originally for the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) in 2001, a diagram that would illustrate, in one color-coded graph, their overall assessment on how global risks and impacts increase as temperature increases<\/strong>.<\/p>\n\n

The graph, named Reasons For Concern,<\/strong> soon became better known as \u201cThe Burning Embers\u201d<\/strong>.<\/p>\n\n

In the graphs scientists divide different climate-related risks into five pillars<\/strong>, or five Reasons For Concern  (RFC), each measuring different aspects of aggregated climate risks.<\/p>\n\n

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The burning embers diagram for five reasons for concern in the IPCC’s 2001 Third Assessment Report (TAR)<\/em>
\u00a9 IPCC<\/div><\/figcaption><\/figure>\n\n

The definitions for those pillars are described as following:<\/p>\n\n

RFC1<\/strong><\/td>Unique and threatened systems<\/strong><\/td>Risks to ecological and human systems, such as coral reefs, the Arctic and its Indigenous People, mountain glaciers and biodiversity hotspots.<\/td><\/tr>
RFC2<\/strong><\/td>Extreme weather events<\/strong><\/td>Impacts to human health, livelihoods, assets and ecosystems from extreme weather events such as heatwaves, heavy rain, drought and associated wildfires, and coastal flooding.<\/td><\/tr>
RFC3<\/strong><\/td>Distribution of impacts<\/strong><\/td>Aggregated risks\/impacts that disproportionately affect particular groups, such as vulnerable societies and socio-ecological systems, including disadvantaged people and communities in countries at all levels of development, due to uneven distribution of physical climate change hazards, exposure or vulnerability.<\/td><\/tr>
RFC4<\/strong><\/td>Global aggregate impacts<\/strong><\/td>Impacts to socio-ecological systems that can be aggregated globally into a single metric, such as monetary damages, lives affected, species lost or ecosystem degradation at a global scale.<\/td><\/tr>
RFC5<\/strong><\/td>Large-scale singular events<\/strong><\/td>Relatively large, abrupt and sometimes irreversible changes in systems caused by global warming, such as ice sheet disintegration or thermohaline circulation slowing and sometimes called tipping points or critical thresholds.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n

How it started vs. how\u2019s it going\u2026<\/strong><\/h3>\n\n

Back in 2001, when the IPCC first used this tool, they assessed that with 2\u00b0C risks would overall remain rather moderate: they wouldn\u2019t yet turn high, except gradually for unique and threatened systems. <\/p>\n\n

However, in their next iteration eight years later (2009), more embers were already on fire<\/strong>! According to improved understanding, 2\u00b0C could no longer be considered safe by any means. <\/p>\n\n

By the next round, 2014, a whole new color was introduced<\/strong> to the graph, purple, to even better communicate the deepening reasons for concern.

At each iteration, the IPCC has assessed risks and impacts to become higher at earlier warning levels.<\/strong>

Zommers et al (2020<\/a>) illustrates this by comparing the evolution of the pillars from TAR (2001) to the 1.5\u00b0C Special Report SR15 (2018). Notice how purple enters the picture, and the point at which risks turn from yellow (moderate) to red (high) at earlier temperatures for each pillar.<\/p>\n\n

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Burning embers: towards more transparent and robust climate-change risk assessments. <\/em>Nat Rev Earth Environ 1, 516\u2013529 (2020)<\/em><\/a>.<\/em>
\u00a9 Zommers, Z., Marbaix, P., Fischlin, A. et al. <\/div><\/figcaption><\/figure>\n\n

The most striking change since TAR (2001) has been with the fifth pillar (RFC5). In 2001, the IPCC still assessed that the temperature at which risks associated with large-scale singular events<\/strong> (such as ice-sheet collapse) would become high at around 5.5 \u00b0C<\/strong>. By 2018 (in their 1.5\u00b0C special report) the risk assessment had changed profoundly: the risk was now assessed to start turning high already below<\/strong> 2\u00b0C<\/strong>, following new findings in climate science.<\/p>\n\n

This was explained, among other things, by new evidence about ice-sheet loss during the last interglacial period at no more than 2\u00b0C average global warming above pre-industrial. By now, observations suggest that the West Antarctic Ice Sheet is already in the early stages of marine-ice-sheet instability<\/strong>.New findings about the slowdown of the Atlantic meridional overturning circulation, the El Nino-Southern Oscillation and the role of the Southern Ocean in the global carbon cycle also contributed to the finding that risk levels at lower temperatures had increased.<\/p>\n\n

So what does the Sixth Assessment Report say about this?<\/strong><\/h3>\n\n

The 6th Assessment Report has updated the burning embers again. And it\u2019s not good news. <\/p>\n\n

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\u00a9 IPCC<\/div><\/figcaption><\/figure>\n\n

Compared to previous reports (AR5 and SR15)<\/em><\/p>\n\n