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That is somebody doing an incompetent summary of IPCC's Special Report "Global Warming of 1.5 °C -- an IPCC special report on the impacts of global warming of 1
by acqq 7y ago
That is somebody doing an incompetent summary of IPCC's Special Report "Global Warming of 1.5 °C -- an IPCC special report on the impacts of global warming of 1.5 °C above pre-industrial levels"
https://www.ipcc.ch/sr15/ https://www.ipcc.ch/sr15/
Published 2018. Just to quote the few actual lines from the report summary:
"A.1 Human activities are estimated to have caused approximately 1.0°C of global warming above
pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C
between 2030 and 2052 if it continues to increase at the current rate. (high confidence) (Figure
SPM.1) {1.2}"
"A.2 Warming from anthropogenic emissions from the pre-industrial period to the present will persist for
centuries to millennia and will continue to cause further long-term changes in the climate system,
such as sea level rise, with associated impacts (high confidence), but these emissions alone are
unlikely to cause global warming of 1.5°C (medium confidence). (Figure SPM.1) {1.2, 3.3, Figure 1.5}"
"A.3 Climate-related risks for natural and human systems are higher for global warming of 1.5°C than
at present, but lower than at 2°C (high confidence). These risks depend on the magnitude and rate
of warming, geographic location, levels of development and vulnerability, and on the choices and
implementation of adaptation and mitigation options (high confidence). (Figure SPM.2) {1.3, 3.3,
3.4, 5.6}"
And so on.
As you see, very precise and very conservative. It is about what will happen between 10 and 30 years from now, due to the emissions that the humanity is just going to make (see A.2 quoted -- what was already emitted is not what is going to raise the average temperature for the next half a degree).
- ForHackernews 7y agoI don't think it's an inaccurate summary at all. You're objecting to the use of dramatic language, but the content is accurate: Watts: "Only 350 million more urban dwellers will be exposed to severe drought and “deadly heat” events. Only 130-140 million will be inundated." https://www.ipcc.ch/site/assets/uploads/sites/2/2019/05/SR15_Chapter3_Low_Res.pdf https://www.ipcc.ch/site/assets/uploads/sites/2/2019/05/SR15... "Limiting global warming to 1.5°C instead of 2°C could result in around 420 million fewer people being frequently exposed to extreme heatwaves, and about 65 million fewer people being exposed to exceptional heatwaves" Watts: "If we cut carbon emissions by half over the next decade, eliminate them entirely by 2050..." https://www.ipcc.ch/site/assets/uploads/sites/2/2019/05/SR15_Chapter2_Low_Res.pdf https://www.ipcc.ch/site/assets/uploads/sites/2/2019/05/SR15... "Limiting warming to 1.5°C implies reaching net zero CO2emissions globally around 2050 and concurrent deep reductions in emissions of non-CO2 forcers, particularly methane (high confidence) ... In comparison to a 2°C limit, the transformations required to limit warming to 1.5°C are qualitatively similar but more pronounced and rapid over the next decades (high confidence). 1.5°C implies very ambitious, internationally cooperative policy environments that transform both supply and demand "
- acqq 7y agoThe actual quote from IPCC text about hundreds of millions people affected is: "Liu et al. (2018) studied the changes in population exposure to severe droughts in 27 regions around the globe for 1.5°C and 2°C of warming using the SSP1 population scenario compared to the baseline period of 1986–2005 based on the Palmer Drought Severity Index (PDSI). They concluded that the drought exposure of urban populations in most regions would be decreased at 1.5°C (350.2 ± 158.8 million people) compared to 2°C (410.7 ± 213.5 million people)." So it says: in case of 1.5 deg 350 million, in case of 2 deg 410 million. So it doesn't support your "Watts" quote of: "Only 350 million more urban dwellers will be exposed to severe drought" It's just a clear and inaccurate distortion of the original text, so distorted that it's wrong. And we also know why it's so wrong and distorted: because these "commenters" just want to confuse people and muddy the waters, they aren't interested in the truth or accurately discussing the actual scientific work.
- ForHackernews 7y agoIt's not "distorted" at all! At +1.5 C, they're predicting that "only" 350.2 million more people will be exposed to severe drought compared to the baseline period. That's exactly what Watts says. What do you think is distorted? You're mad that he didn't mention the ±158.8 million error bars on that estimate? I feel like I'm talking to a crazy person here -- how do you read the exact same text and see "distortion" when it literally restates the same thing the dry scientific prose says.
- acqq 7y ago“Only” is a distortion enough, and also using the number from +2 deg prediction in the +1.5 deg context. If I’d go through it I could find many more of these “muddying the water” techniques. As I’ve quoted the IPCC in that specific case reports the results of the specific scientific paper which is much more precise than what is “distortedly” presented. There are exact criteria specified under which the estimates hold, they are precisely calculated and if you don’t trust the paper you are free to point to the scientific errors, if you find any, which I doubt. But summarising it like it’s just some random guess is precisely the distortion I point to.