Wikipedia:Reference desk/Archives/Science/2019 February 27

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February 27

is climate change actually this impending catastrophe that some people say?

I've looked at Effects of global warming and it's kinda vague and imprecise on what will actually happen. Can somebody educated on the subject say whether the claims of food shortage and failed states will actually happen? How bad actually is climate change. — Preceding unsigned comment added by 2.102.184.18 (talk) 00:05, 27 February 2019 (UTC)

Predicting the future is a risky business. You'll just have to wait and see. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:57, 27 February 2019 (UTC)

You can read the more specific article Climate change and agriculture. The main takeaway should really be that people are expected to starve from failures of management and distribution in the face of disruption, rather from there being less food. I mean, there could be less food, but climate change is not a magic crop-destroying force. Rather, it changes how well different crops and crop pests/pathogens grow in different areas, as well as increases the variability of the weather. I don't see anyone predicting that it will literally be impossible to feed the world. Rather, the changing weather climate will mandate changing agricultural patterns. If people are slow to catch up, there could be shortages. If an entire nation has to change where it gets its food, and it is slow to adopt that change, there could be shortages. Food could become more expensive, especially if efficient changes are not implemented on time, and this could leave people, communities, or entire countries unable to afford what they need. If other nations do not step up with aid, there could be shortages. Anyway, Bugs is right - predicting the future is hard. Especially when it depends on human behavior. The article I linked discusses specific issues related to agriculture and climate change, including low and high estimates of effects in specific contexts. This article also links to the reports from which those estimates were drawn, which you should read for more information about very specific issues. But as I said, this is the relatively easy part. No one knows how the economy or world governments will actually behave if these estimates are correct, and that's probably the most important factor. Take a look at the more recent entries on list of famines - it doesn't take a global catastrophe for people to starve on one place while unneeded food rots in another. It doesn't even always take a war. Someguy1221 (talk) 01:31, 27 February 2019 (UTC)

"Some people" say a lot of things; but we can focus on the word-choices of a specific world leader to determine whether climate change is a catastrophe, or to prognosticate about whether it will become a catastrophe. For example, we might choose to look at public statements by the current Secretary-General of the United Nations, António Guterres.

A brief statement, written by the Secretary-General of the United Nations, is available: Statement by the Secretary-General on the IPCC Special Report Global Warming of 1.5 ºC. It uses words like "urgent", "critical"; "unprecedented changes", and so on. In 2017, the Secretary-General used the word "catastrophe" to remark on the Aral Sea: "The Aral Sea’s progressive disappearance was not because of climate change, it was mismanagement by humankind of water resources. But it also shows that if in relation to climate change, we are not able to act forcefully to tame this phenomenon, we might see this kind of tragedy multiply around the world."

In 2018, the Secretary stated: "the runaway pace of climate change ... threatens the entire world with catastrophe," and referenced the IPCC report once again.

If we wish to remain on solid scientific footing, we can say that human-induced ecological change can become a "catastrophe" if we do not coordinate a valid and well-planned response. Anthropogenic global warming is one of the most widely discussed, but it is just one among many natural and anthropogenic ecological problems; and any one of these problems can be a catastrophe by themselves. In combination, we have many current and potential future catastrophes.

If you want to read more on this topic, the most thorough, well-known, and widely-respected scientific documents that summarize global climate change are the reports of the IPCC, available in their entirety online at zero cost. These reports include high-level summaries, policy analyses, and very technical peer-reviewed scientific research; so you can read as much as you want on each of these topics.

As far as diction, we might want to be more precise: using the word "catastrophe" or "catastrophism" carries a lot of scientific and cultural implications; but it hardly spells out exactly what will happen. If we really want to be scientific, we need to make precise, specific claims: for example, one IPCC report summarizes: "Human activities are estimated to have caused approximately 1.0°C of global warming"; "Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate"; and further, predicts that "climate-related risks to health, livelihoods, food security, water supply, human security, and economic growth are projected to increase with global warming of 1.5°C and increase further with 2°C." We don't need to employ fancy words to dramatize the situation: the truth is grim enough.

Nimur (talk) 01:56, 27 February 2019 (UTC)

Just imagine we manage to drive the Permafrost carbon cycle "over the edge"(Tipping point (climatology). It may double or even triple the amount of greenhouse gases carbon dioxide (CO2) and methane (CH4), which already troubles science, in the atmosphere in short time, which, as Nimur already described, would then be a Runaway climate change.

Maybe wise to become Russian and buy some land high up north in Siberia, as long as its still possible. --Kharon (talk) 05:56, 27 February 2019 (UTC)

Wikipedia tends to stick to the broad consensus as can be found in tertiary review articles, which can mean that more recent insights haven't yet been covered well in Wikipedia. On this particular topic there are new arguments for a far more catastrophic outcome than just the usual things like disruption of agriculture, sea level rise posing problems for low lying areas, etc. It has been argued in quite a few publications that a business as usual scenario for CO2 emissions will more likely to lead to a mass extinction that's more similar to the worst ones than the milder ones in Earth's geological history. E.g. we can read here: "In terms of past and future mass extinctions and recovery times of biotic diversity, we have argued that the Anthropocene will more likely resemble the End-Permian and End-Cretaceous disasters, rather than the PETM. If civilization is to avoid such a fate, carbon emission rates must reverse within the next few decades in order to keep total emissions below a certain limit."

And here we can read: "The history of the Earth system is a story of change. Some changes are gradual and benign, but others, especially those associated with catastrophic mass extinction, are relatively abrupt and destructive. What sets one group apart from the other? Here, I hypothesize that perturbations of Earth’s carbon cycle lead to mass extinction if they exceed either a critical rate at long time scales or a critical size at short time scales. By analyzing 31 carbon isotopic events during the past 542 million years, I identify the critical rate with a limit imposed by mass conservation. Identification of the crossover time scale separating fast from slow events then yields the critical size. The modern critical size for the marine carbon cycle is roughly similar to the mass of carbon that human activities will likely have added to the oceans by the year 2100."

So, it's good to keep the Permian–Triassic extinction event in mind as quite a reasonable worse-case scenario if we don't take strong measures to curb CO2 emissions and not as some hyped far-out scenario that's extremely unlikely to actually happen. Count Iblis (talk) 10:16, 27 February 2019 (UTC)

• See also Boiling frog. People tend to mis-understand threats that are not instantaneous and impressive. Similar to the way that people fear flying, but not driving (yet it is MUCH safer to travel by plane than car), people have a psychological barrier towards accepting the danger posed by anything which is not occuring on a timescale they can directly observe. Similar to how a plane crash is a catastrophe, but 100 deaths by motor vehicle per day barely registers, a massive earthquake or a hurricane may be a catastrophe, but incremental melting of polar ice caps is met with a "meh" by people who aren't looking at the data with a critical eye and understanding what it means for them, personally, tomorrow. Melting polar ice caps doesn't affect how the mom in Iowa is going to feed her children this week. --Jayron32 12:07, 1 March 2019 (UTC)

• Note that there is quite serious research that ties the Arab spring and accompanying destabilisation of the Middle East at least partially to food shortages linked to current effects of climate change. See several of the references here, e.g. [1] from just last month. And as a follow-on, the European refugee crisis (largely driven by people fleeing the Syrian civil war) lead to a rise in strongly nationalist parties in parts of Europe. Of course, the Middle East has not been a particularly restful area anyways, so exact attribution is hard, and the longer the chain of causation, the more complex the situation becomes. It may well be that we will be mired in an avalanche of negative effects while maintaining plausible deniability about the root cause. Also see Fermi paradox. --Stephan Schulz (talk) 13:55, 1 March 2019 (UTC)

The Arab spring was blamed on multiple unfortunate developments. There where however no real "food shortages" anywhere but global food price changes caused by massive Speculations around a conversion of corn into ethanol aka Biodiesel. There was however no capacity to process that much corn to ethanol but that did not stop the speculators to double worldwide food and especially middle east bread prizes, which are the main food source for poor people there. [2]

So no sample for climate weather change but one impressive for "political weather" changes with huge impact. --Kharon (talk) 23:37, 1 March 2019 (UTC)

Are you saying that middle east bread was made from field corn, i.e. maize? ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:51, 2 March 2019 (UTC)

We need more refs & less spooting. This is about the topic at hand but a bunch of MEGO blah. This is full of the sort of math and real statistics that one would expect a farmer to follow, but for the rest of us it is hard to draw a bottom line. There is a lot in the literature to look through and there should be clearer answers somewhere Wnt (talk) 11:52, 3 March 2019 (UTC)

Wikipedia in general gives what is fairly certain and agreed. However if you were a field marshal you would not plan to defend against only the fairly certain dangers. For instance a sea level rise of one or two feet is pretty likely by the end of the century. But it is quite possible that it could be something like six feet - we simply don't know yet exactly how the ice sheets in Antarctica will act. How much should be spent on more research? At what point does one start spending on mitigation balancing possible effects and risks and costs? And unfortunately we have to cope with people as well, who can predict the various possibility and chances of what they'll do in the next century and factor that in? That's the sort of problem a field marshal has but here it is considerably worse. Dmcq (talk) 14:31, 3 March 2019 (UTC)