Climate change is altering the length of days on Earth, according to new research
Nicole Fritsch
News Article: https://abcnews.go.com/US/climate-change-altering-length-days-earth-new-research/story?id=111843796
Original Journal
Article: https://doi.org/10.1073/pnas.2406930121
Beginning with the Industrial Revolution, the burning
of fossil fuels by humans has led to a rapid increase in atmospheric carbon
dioxide concentrations. This increase in carbon dioxide, a greenhouse gas, has
resulted in rapid global warming, and this anthropogenic climate change has a
number of impacts, including the melting of ice caps and subsequent sea level
rise. When polar ice melts in large quantities, it causes a redistribution of Earth’s
mass, as mass that was frozen at the poles enters the ocean and becomes
concentrated closer to the equator. Such mass redistribution can have quite
literally astronomical impacts: it affects the rate at which Earth rotates. The
length of day (LOD) is defined as the difference between the actual amount of
time that it takes the planet to rotate 360° about its axis and the 24-hour
period that humans define as “one day.” On a geological timescale, the tidal
pull of the moon and the slow movement of Earth’s mantle from equator to poles
have had the greatest impact on the LOD, but in recent years, sea mass
redistribution due to climate change has begun to have a tangible impact as
well. A recent article from ABC News covers a study in The Proceedings of
the National Academy of Sciences (PNAS) that examines the growing effects
of climate change on LOD, and how humanity’s future emissions may shape planetary
time going forwards.
In her article for ABC, Julia Jacobo summarizes the
most major points of the PNAS paper and explains how the changes to LOD they
discuss could impact the lives of the public. She also uses quotes and
paraphrases from a US-based author on the PNAS paper throughout the article to
contextualize the science and its impacts. Jacobo discusses how LOD has been
increasing for at least the past three thousand years at a rate of a few
milliseconds per century, and how the increasing effects of climate change have
led to a considerably more rapid increase in LOD since 2000. In a high
emissions scenario, Jacobo emphasizes, the rate of LOD increase from climate
change-induced ice melt could reach 2.62 ms/century by 2100, whereas in the 20th
century it varied between 0.3 and 1.0 ms/century. Jacobo concludes the article
by placing these very small numbers in a larger context. She links to ABC’s
coverage of a related Nature article, where the way that ice melt
changes Earth’s rotation and that the influence of that change on international
timekeeping standards is discussed. These potential changes to the way humans
measure time could have impacts on global communications, trade, and eventually
space travel, all topics which the general public might care more about than
the addition of a couple milliseconds at the end of a day.
The original PNAS article, from Shahvandi et al, goes
into much further detail on this climate change induced LOD increase. They summarize
historical increase in LOD based on the timing of eclipses, emphasizing a
growth in LOD increase due to climate change from +0.3 to +1.0 ms/century in
the 20th century to approximately +1.33 ms/century since 2000. They
estimate future climate-based contributions to LOD based on two scenarios, the low
emission RCP 2.6 and the high emission RCP 8.5. In the low emissions scenario,
they predict that LOD increase from ice melt will hover around 1.0 ms/century
and eventually decrease, while in the high emissions scenario, they predict
that climate-induced LOD increase will reach +2.62±0.79 ms/century by 2100,
higher than the +2.40±0.01 ms/century contribution of the moon’s gravitational
pull on Earth. In comparing these different scenarios, they make sure to emphasize
that actual change to LOD based on ice melt is likely to fall somewhere between
these two extremes.
Shahvandi et al also take their analysis further than
just the portion covered in the ABC article. They predict how various sources,
including the Antarctic Ice Sheet, the Greenland Ice Sheet, glaciers worldwide,
and terrestrial water storage (lakes, rivers, groundwater, etc.) will influence
LOD increase, noting that the melting of the Greenland Ice Sheet and global glaciers
currently have the greatest role in LOD change, though the Antarctic ice sheet
plays an important secondary role. They also use the differences between their
predictive models and actual satellite data to form an estimate of the influence
of Glacial Isostatic Adjustment (GIA) processes – the movement of mass in the
mantle from the equator towards the poles – on long term LOD change. It was
known that GIA had a shortening influence on the length of Earth’s days, but
the exact value is difficult to determine because so little is known about what
actually happens in Earth’s mantle. Shahvandi et al were able to predict a GIA
influence of -0.80 ms/century, which generally lined up with their
expectations.
Overall, I believe Jacobo does a nice job of
synthesizing the most important and relevant information from the PNAS article
to share with the public. While Shavandi et al’s findings on where ice melt-based
mass distribution change is coming from and their estimation of the impact of
mantle dynamics on LOD are interesting, including them would risk distracting
the general public from the very real impact these LOD changes could have on
their daily lives. I also really like that Jacobo chooses to withhold any
concrete numbers until a little more than halfway through the article. By doing
so, she allows readers to consider the meaning of these comparatively rapid LOD
changes before they dismiss them as only a few milliseconds. She also sandwiches
this numerical section with another emphasis on impact by transitioning into a
discussion of the Nature article and the importance of timekeeping, making
sure readers understand why a few milliseconds in a day makes a difference.
That being said, this article is not without its
shortcomings. Some of Jacobo’s wording implies that the climate’s influence on
LOD directly corresponds to actual LOD increase, which can be misleading, as
climate change is only one of a number of lengthening and shortening factors that
affect Earth’s long-term LOD. Additionally, Jacobo chooses to only report the value
from the highest emissions scenario when looking at future anthropogenic impacts
on LOD, without even reporting its rather large uncertainty. I understand why
she did so, as discussing the potential range of LOD increase based on
variations in future greenhouse gas emissions might risk muddying the article’s
message about the planetary scale of anthropogenic climate change, but it does create
a slight misrepresentation of the data presented in the paper. Even with these
shortcomings, however, I do feel that this article does a good job of
summarizing the most important points in the PNAS paper in a way that the
general public can both understand and care about, so I would probably rank it
as an 8.5 or 9 out of 10.
I think you did a fantastic job in your summary. I am really glad that I read your post first, because it made it a lot easier for me to understand the news article and the scientific journal article. The importance of a few milliseconds in the length of a day on Earth didn't seem very important to me as a reader until I read the context of universal computing systems. While it doesn't mean that we won't have daylight savings anymore or that clocks will never display the correct time, it does have important implications for any digital communication or transaction.
ReplyDeleteJacobo's article was a good summary, but I wish the sentences were broken up better. Every sentence seemed to be at least 3 lines long, so I had to read them multiple times. I felt like it could have explained things like the technical term for a length of day on earth or glacial isostatic adjustment better. I also really did not enjoy the use of pictures. They took up my whole computer screen and made it difficult to read the text. In addition to the pictures, the article had hyperlinks to other news articles that interrupted the text. It made it seem like ABC wanted me to read anything other than Jacobo's article.
Thanks, Genevieve! I definitely see what you are saying with both the length of the sentences and the images. I also to tend to write in pretty long, almost run on sentences (and ignore punctuation altogether), so it was not something I noticed on a first read, but you make a good point that things could be broken up better without disrupting the flow. As for the images, unfortunately I don't know that Jacobo had a better option. For a lot of these online news sources, it feels almost as though having a certain number of pictures is a requirement, and most of the figures in the PNAS paper would have required significant explanation.
DeleteRegarding the hyperlinks, I think you've hit it on the head. ABC would probably love if you read anything else, because they already have the ad revenue from you clicking on the first article. When you click into another, they get more money, and unfortunately that often seems to be the ultimate goal of many news organizations today.
Great job on this blog post. I liked how you defined LOD and wish the article had done the same. I agree that overall the ABC news article does a nice job of summarizing the key points from the research paper. While I wish it had talked a little more about the work to estimate other contributors to LOD like GIA, I agree that the main point might have not gotten across as strongly with this additional information. For the most part, I think the quotes from one of the study’s authors are a strong point of the article. Though it seemed like the focus became on expanding upon the potential impacts of an increasing LOD, which was not the main point of the research paper, but I think it is important to include and is something a reader would want to know.
ReplyDeleteThanks Sofia! I also really wish the article had more deeply defined LOD, it was part of why I made sure I defined in my analysis, since it was kind of a confusing concept to me at first. The quotes from the author is definitely a strong point, although I wish they had either reached out to a few more people or cut down a little on the paraphrasing. Jacobo is making great use of the strategy of having someone else explain the parts she's maybe not sure on and then translating that into language the public understands, but the over-paraphrasing of just one person can get a little repetitive.
DeleteSimilarly to Genevieve, I thought you did a great job summarizing the article and putting "a few milliseconds" in context. I agree that the news article benefitted from intentionally avoiding statements about the actual time shift, as many readers could accidentally dismiss the findings as inconsequential. Something I was confused by was the extent to which we have agency over the societal problems caused by adding additional milliseconds. The change from our current rate of increase (+1.33 ms/century) to a high emissions scenario (+2.62±0.79 ms/century) will both ultimately lead to a shift in time. In either scenario, low emissions or high emissions, there will be some shift in time. Even without human influences, the moon's gravitational pull will lead to a shift in time. No matter what we do, aren't we still subject to some time shift? Wouldn't we necessarily have to adjust UTC timekeeping and international communications with a leap second anyway? Clearly, the scientific article seeks to find the extent of the time shift, but I feel that the news article tried to express the severity of the time shift contextualized with the UTC timekeeping. I do not think the news article succeeded given that a time shift is inevitable. What are your thoughts?
ReplyDeleteI think that you're right that we would eventually have to adjust UTC timekeeping regardless of what we do, but I think this change is viewed as significant for a couple of reasons. One, with a greater shift in time due to factors like ice melt, we might have to alter UTC more frequently, which could lead to a greater impact on the computer systems that rely on it. Two, UTC was (as far as I know) only instituted in the 1960s, so this is likely the first time we are having to deal with this problem of temporal drift. Perhaps we'll be better able to estimate potential LOD changes and account for them in a routine manner in the future, but doing so might not yet be well-established practice.
DeleteGreat job on the post. This is more an issue with the original paper than the news article, but it feels like the paper was puffing up its own importance, talking about how this will require a change in timekeeping and space travel, just to get into a better publication, and it seems like the news paper ate it up uncritically. We already have LOD expansion happening that gets accounted for and there are already plans in place to change UTC based on acceleration of LOD increase will have. I also find the claim that this contextualizes climate change to also be faulty, if the dozens of climate changed disasters that have been occurring for decades did not emphasize how bad climate change is to a doubtful audience, then this will do nothing. I feel that the news article does a good job conveying the information of the article itself, I just feel that there should not be an uncritical parroting of the paper and its authors' claims.
ReplyDeleteI do think you have a fair point about papers overexaggerating their own importance, but I would argue this is more an issue with the Nature paper discussed later in the article than with the PNAS paper. The Nature paper deals specifically with changes to Earth's rotation and related changes to UTC, while the PNAS paper that is the main focus of the article is more concerned with where changes to ice melt-induced LOD change are coming from and how their models can also be used to tell us about what is happening below the planet's surface with Glacial Isostatic Adjustment. While Dr. Adhikari, the author they interviewed, does talk a little about timekeeping and space travel, my guess would be that they were asked specific questions about that topic or about the broader impact of their research.
DeleteGreat summary, Nicole! This was such a fascinating article/publication topic because it is an impact of climate change that (I feel) most people would never dream of, but when you break down the reasoning and the relevant factors that impact LOD it makes perfect sense that this is a possibility. I agree to some extent with most of your critiques of Jacobo's article. It seems like a general trend for these news articles to include only the upper or lower end of the data (whatever dramatizes the content) published in the original scientific journal. Jacobo is no different, reporting on only the projections from the highest emission scenario. Although this certainly does not accurately and fully report the findings of the authors, it makes sense to maintain a consistent, simplified narrative for everyday readers. I don't have a problem with reporting on only one result/set of results as long as it is adequately contextualized. Jacobo includes the quote:
ReplyDelete"By the end of 21st century, if in the high-emission scenarios, it could be that the climate impact alone will overtake the impact of the Earth-moon dynamics," Adhikari said.
This quote is doing a lot of work that I think, perhaps, should have been more clearly and explicitly stated elsewhere in the article. First, it explains that Jacobo is only referencing the 'high emissions' scenarios' and therefore implies, but does nothing to describe, the existence of other scenarios. Secondly, it explores the relative impact of climate change on LOD compared with other factors like Earth-moon dynamics. This is something that the article otherwise broadly ignores. Jacobo does list melting ice sheets as one of three relevant causes of LOD changes at the beginning of the article but does not really describe the relative impact of this anthropogenic source which is very important to the overall picture being described.
Thank you for mentioning this quote, Hannah! Even just dropping in the +2.40 influence of the moon in the more numerical section of the article would have relieved some of the burden of addressing non-climate change factors in LOD change that this quote shoulders. The work this quote is doing, and the fact that it's in rather convoluted language for a quote that expresses such key findings in the paper, was something that I originally wanted to address, but cut because I was worried about length, so I appreciate that someone noticed it and gave me the opportunity to talk about it!
DeleteGreat summary of the article and the paper! I think the topic itself is already eye-catching--Something that we (the general audience) would never think of when talking about climate change. I also agree with Leo that the original paper do seem to be pushing on its own importance, but I also understand the incentive for it as they want a higher impact on the article for their own career/want their data and work to be acknowledged. I also agree that the article should not only include the worst outcome scenario, but I also understand the incentive behind it, and since they have covered the main points of the article very well, I would give it a high score just like you did. On another note, 2.62 milliseconds are very short, and for the general audience, it is hard to quantifiable (only 2.62 seconds after 1000 centuries), and I think it does not interfere with the overall understanding of the article even when they used the worst outcome possible.
ReplyDeleteVery nice analysis these two pieces! I found this topic highly interesting.
ReplyDeleteHowever, I do not fully agree with your high rating. I think I might just be being nit-picky, but I found the constant relation to the research paper redundant and almost annoying. Almost every paragraph ended with something to the effect of "Adhikari said" or "the study found". At first I appreciated the fact that they are citing information, however on the second read I started to notice the heavy repetition. Paragraph 4, 5, & 6 all end with the exact phrase "Adhikari said." I personally felt this continuous repetition interrupted the flow of ideas. It made me feel as though the author of the article does not want to take any sort of stance on the issue and therefore must ensure the the reader knows these conclusions are coming from someone else. Or, the author is simply trying to improve her ethos.
On top of this, I did not enjoy the fact that the article reference another article from Nature, but the hyperlink goes to an ABC article about the reference article.
I do agree that the article could have benefitted from reaching out to a wider variety of sources than just the one study author, if only to improve feelings of redundancy, but I do not feel referencing the author to the extent Jacobo does is necessarily a drawback. If Jacobo does not feel equipped to adequately explain the concepts involved in the paper she is writing about, I think leaning on the expertise of someone who can is a good move. Additionally, Jacobo is clearly trying to translate Adhikari's explanations into something more easily understood by the public, as her paraphrasing of Adhikari's words is often couched in more accessible language than the direct quotes from Adhikari.
DeleteGreat job with your post! As others have expressed already, I agree that the overall article did a good job with summarizing the findings while also expressing the implications of these findings in a way that the readers would be able to understand. Though, one thing I noticed is that the abcnews article provided only images of sea ice and an eroded glacier, which felt somewhat repetitive and almost irrelevant to have a similar type of image twice instead of having 2 separate images/figures (content wise) that are relevant to the article. Do you think replacing one of the images (or adding another) with a diagram/figure more related to the research of some sort would have strengthened the article? If you were to replace one image, what type of content would you replace it with?
ReplyDeleteI definitely agree that the repeated images of glaciers felt rather simplistic and did not really further the article's message, but looking only at figures from the PNAS paper, I do not necessarily think there was a better alternative. The paper has no graphical abstract, and most of its figures are multipart and require a fair deal of explanation to be understandable. A nice alternative might have been to replace one of the images with a figure from another source, but I cannot say that I am familiar enough with the specific field to recommend a source for more helpful figures.
DeleteFantastic job on the blog post! I really appreciated your explanation of how the redistribution of Earth’s mass impacts its rotation and correlates to the Length of Day (LOD). However, I found the article somewhat confusing and felt it could have done a better job providing foundational concepts for the public.
ReplyDeleteI also noticed that the link to the scientific paper in the first paragraph didn’t lead to the actual study, which was odd. While reading the article, I had to go over some sections multiple times to fully understand and connect the ideas. Improvement could be done on explaining how such small numbers as milliseconds can have a bigger impact.
We all know that quoting authors adds credibility, but using quote lines repeatedly made it hard to stay focused. Due to the ending of almost all paragraphs with “Adhikari said” I lost my attention couple of times and I think others might feel the same way. A smoother narrative would really help tie everything together. Things started to click for me when I read both the blog post and the paper, so I believe there’s still room for improvement in clarity in the news article. Overall, I’d give it a 6 out of 10.
Good all-around review, I think this is a really cool article you found. I never would have guessed that climate change would impact the length of our days, but as the research and pop media articles explain the movement of seawater does make sense! The pop media article did a decent job of laying out the most relevant facts for readers, and I appreciated all of the quotes they included. While some of the article sentences did run-on a bit making some sections tedious to read, all of the writing did make sense and do a good job of breaking down the research findings. As some other commenters pointed out, the article did leave out some statistics that we might deem important, such as the amount LOD will change in a best-case scenario vs worst case scenario for climate change. However, they made no out-right lies and included a decent number of stats to get the main points across. They also did not include any particularly informative graphics, which I believe the article could benefit from. While they do describe how shifting seawater mass will change LOD, a diagram to show this, for example, could be beneficial because day lengthening is a crazy concept to accept. Because of these few shortcomings, I would give this article a slightly lower score than you at 8/10.
ReplyDeleteThis is a really great post and as others have said, it supplements both pieces of writing in a very cohesive manner. I see where certain commenters are coming from in their critique of the ABC article's supposed 'over-reliance' on the Shahvandi paper, but I also don't believe that the author of the article is necessarily intending something significantly more ambitious than a short summary of the article (with a certain degree of background, of course). I think that if anything, the critique here could be levied at a repetitive syntax, though this seems a tad besides the point. The entire section and focus of the article on the impacts of these LOD changes on timekeeping were quite chilling! Entire spheres of time-dependent production could really be thrown out of order by these changes, and it really makes me wonder how global systems of circulation, many of which are increasingly dependent on UTC technology, will be affected by this in the coming years.
ReplyDeleteThis post and article are really interesting and talk about topics I have not really thought about. I really enjoyed the article and how the author states different causes of LOD changes. I would like to author to explain a little more about how LOD changes with climate change and the direct impact of this. To my understanding the change occurs due to increasing water content on the surface but the real impact on day to day life I thought was misleading. I liked your take away from the article and paper and I do agree that withholding specific data is quite beneficial until later in this article.
ReplyDeleteGreat review overall! You did a great job summarizing both the scholarly article and the ABC news article. I feel that the author did a great job in general summarizing the scholarly article; however, I agree with other commenters that the article was at times difficult to read. It was a bit repetitive at times (and I agree with another commenter that two photos of ice melting is not the most effective use of images to enhance the summary of the article), and many of the sentences felt like run-on sentences, convoluting their underlying message. Overall though, I agree with your high rating of an 8.5/10 for this article, as it does a great job summarizing the paper with key statistics and communicating an otherwise complex topic: that small changes in the length of days caused by climate change can have profound impacts on our computing systems.
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ReplyDeleteYou have done a great job in providing background information on the articles and the paper. I found that after reading your blog, both the article and the paper are easier to interpret. I like how you define the length of day (LOD). About the news article, I agree with Sam that it is annoying that the reference in the article directs readers to another news article instead of an academic paper. This article is worth only 8 out of 10. But your analysis is great!
ReplyDeleteGreat job on the blog post! I think you did an excellent job summarizing both the article and the paper. In fact, I quite preferred how you relayed the key topics as opposed to the article. I do still think that the article did a decent job with summarizing and explaining the data, but I felt that She relied to heavily on the quotes from author of the paper and could have elaborated/lengthened the paper slightly. My biggest critique is that the explanation and data presentation felt rushed, I assume because the author felt readers would struggle to care about the issue. But I think the author's choice to do this would actually just lead to confusion, because if I was an average reader, I think I would have struggled to see the implications that melting ice is having on the length of day. But, I do think that the second half of the paper was very redeeming as it really tied in why the reader should care and the importance of this topic quite well. For these reasons, I think I would lower the article's rating slightly, but overall, I do agree with your analysis.
ReplyDeleteGreat job on the blog post- First I would like to commend you on your choice of article and research paper. I did not know that global warming could influence things like LOD, so it is interesting to see that sea levels rise have affects things other than extreme weather. I agree that the article summarized the key points of the research article in a really interesting way, so I would agree with the score you gave it of around an 8.5/10. I do wish that the news article talked about how LOD could impact timekeeping a bit earlier in the piece- for the first half of the article, I was wondering why I should care about LOD which caused me to care a bit less as I was reading.
ReplyDeleteGreat analysis of these pieces! I found this to be a interesting read! I am curious what you think of the little pop up video in the news article. At first I saw it as an annoyance, hard to click out of, but it kept autoplaying. However after reading the article, I wonder how many readers absorb the key takeaways from the video. Do you think that this is a productive method of distilling information? How might this video alter reader's perception of the issue?
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