- Climate
Story on congressman's incorrect claims about sea level rise could have corrected them more explicitly
Reviewed content
Headline: "Republican lawmaker: Rocks tumbling into ocean causing sea level rise"
Published in E&E News, Science Magazine, by Scott Waldman, on 2018-05-17.
Scientists’ Feedback
SUMMARY
This article in the news section of Science—syndicated from E&E News—covers a hearing of the U.S. House of Representatives Science, Space, and Technology Committee. During the hearing, some committee members made a number of incorrect claims about climate change and sea level rise. Most notably, Representative Mo Brooks claimed that the erosion of coastal rock and sediment could be the real cause of sea level rise. The article focuses on creating an account of statements made by those present at the hearing.
Scientists who reviewed this article provided varying ratings, as the article generally noted that these claims were false but did not always explicitly explain the actual state of scientific knowledge. For example, providing references to published research directly contradicting these claims could have helped readers ascertain the truth.
This is part of a series of reviews of 2018’s most popular climate stories on social media.
See all the scientists’ annotations in context. You can also install the Hypothesis browser extension to read the scientists’ annotations in context.
REVIEWERS’ OVERALL FEEDBACK
These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article.
Professor, University of Leeds
The article itself is I believe a well-intentioned attempt to report on what seems to have been a rather chaotic committee meeting; although the meeting topic was intended to be on technologies to mitigate climate change, the discussion concentrated on basic climate change principles and conjecture which the witnesses could reasonably have not expected.
Although the article is good in places, I have graded it as very low credibility because there are several committee member statements that are false and not adequately corrected in the printed article.
1) The article opens with three apparently controversial statements attributed to a committee member that are not immediately corrected with facts, when they could have been: the Earth is warming. Sea level rise due to coastal erosion is insignificant in comparison to other known sources and sinks. The Antarctic ice sheet is not growing.
2) A committee member objects to the suggestion that global warming is man-made, stating that “basically we should all be open to different points of view”. This statement should have been rebutted, as the evidence to the contrary is overwhelming and it is not reasonable to assert that objection to scientific fact or consensus amounts to an alternative point of view.
3) A committee member suggests that land erosion is causing sea level rise: while the witness (Duffy) responds that he is “pretty sure” this is not the case, a factual correction could have been offered to shoot the suggestion down.
4) A committee member suggests that “there are plenty of studies that have come that show with respect to Antarctica that the total ice sheet, particularly that above land, is increasing, not decreasing.” As leader of the international community effort responsible for charting polar ice sheet contributions to sea level rise, I can assure you that this statement is false. There is in fact only one study that reports growth of the Antarctic ice sheet, against all others (dozens) that report that it has lost ice. And the one study[1] that reported mass gains was effectively rebutted by a separate study[2]. For a summary of ice sheet mass balance data, see Figure 1 here.
- [1]-Zwally et al (2015) Mass gains of the Antarctic ice sheet exceed losses, Journal of Glaciology
- [2]-Scambos and Shuman (2016) Comment on ‘Mass gains of the Antarctic ice sheet exceed losses’ by H. J. Zwally and others, Journal of Glaciology
Professor, Earth Observatory of Singapore
The article was an appropriate discussion of some very misleading and ill-informed comments by Republicans on the U.S. House of Representatives Science, Space and Technology Committee.
Research Fellow, Nanyang Technological University
This article is mostly a descriptive depiction of an exchange between some members of the Space, Science and Technology Committee and a climate scientist. The comments from the members of the Committee suffer from severe inaccuracies and misconceptions, and citations of the invited climate scientist mostly address those issues.
In general, the views that go against our understanding of the climate change process are underlined and presented as such by the author, but rarely supported by statements or explanations that go beyond the immediate replies from the invited climate scientist. Some of the inaccurate statements quoted in the text are thus left with an incomplete challenge. In particular, the concluding statement should have been challenged. The explanations sometimes suffer from imprecise language (land/sea ice, sea level rise timescales) but they are usually adequate.
Notes:
[1] See the rating guidelines used for article evaluations.
[2] Each evaluation is independent. Scientists’ comments are all published at the same time.
Annotations
The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity).
“I’m being extremely practical — if we let the planet warm 2 or 3 degrees, we will have tens of meters of sea-level rise, and the community where I live will essentially cease to exist.”
Research Fellow, Nanyang Technological University
Sea level rise is undoubtedly one of the most severe consequences of anthropogenic climate change, but this statement should discuss timescales and present a revised amplitude. In fact, over the 21st century, estimates of global mean sea level rise are rather in the 1-2 m range[1]. Considering the global mean sea level rise commitment induced by these conditions up to 2300 leads to estimates reaching several meters[1]. Such a change in mean sea level will significantly impact coastal communities around the world.
During episodes in the geological past with similar temperature and CO2 conditions, like the mid-Pliocene around 3 million years ago, sea level may have reached significantly higher values (raising questions about the long-term equilibrium of sea level), but constraining precisely this quantity using the geological record remains challenging.
- [1] Horton et al (2018) Mapping Sea-Level Change in Time, Space, and Probability, Annual Review of Environment and Resources
“I don’t think anybody disputes that the Earth is getting warmer; I think what’s not clear is the exact amount of who caused what, and getting to that is, I think, where we’re trying to go with this committee.”
Research Fellow, Nanyang Technological University
The various contributions to recent climate change have been studied extensively by the scientific community, and there is ample evidence of the human influence on the recent climate. The IPCC has identified human activity as the dominant cause of the observed warming since the mid-20th century with an extremely high degree of confidence.
At one point, Smith showed a slide of two charts that he said demonstrated how the rate of sea-level rise does not equal the sharp spike in the consumption of fossil fuels.
Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology
This statement is blatantly false: sea-level rise in the 20th century is faster than any time during the last 3000 years[1], while the present-day rate is already three times faster than the 20th-century rate[2].
- [1] Kopp et al (2016). Temperature-Driven Global Sea-Level Variability in the Common Era, PNAS
- [2] Dangendorf et al (2017) Reassessment of 20th Century Global Mean Sea Level Rise, PNAS
Duffy pointed out that his chart was from a single tide gauge station, near San Francisco, and that sea levels rise at different rates around the world
Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology
This is an important and true statement: sea-level changes differ from place to place. Furthermore, single records often contain a lot of internal variability, which makes it difficult to distinguish anthropogenic changes from the internal variability. Nevertheless, the San Francisco tide gauge shows a sea-level acceleration that is in line with the global-mean value.
- Hogarth (2014) Preliminary Analysis of Acceleration of Sea Level Rise through the Twentieth Century Using Extended Tide Gauge Data Sets, Journal of Geophysical Research: Oceans
He said the California coastline and the White Cliffs of Dover tumble into the sea every year, and that contributes to sea-level rise
Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology
Although this effect is not zero, about 1,000 cubic kilometers (i.e. 1,000 rocks of a kilometer long, a kilometer wide, and a kilometer tall) of Dover cliffs must tumble into the ocean to explain the present-day rate of sea-level change. This is many orders of magnitude larger than the ongoing erosion rate.
He also said that silt washing into the ocean from the world’s major rivers, including the Mississippi, the Amazon and the Nile, is contributing to sea-level rise.
Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology
Sediment deposition has been acknowledged by scientists, but again, this effect is many orders of magnitudes too small to explain the ongoing rate of sea-level rise.
Duffy responded: “I’m pretty sure that on human time scales, those are minuscule effects.”
Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology
Duffy is right: these effects are minuscule compared to ice-mass loss and thermal expansion of the oceans, both of which are directly measured, and explain the observed present-day sea-level rise.
- WCRP Global Sea Level Budget Group (2018) Global Sea-Level Budget 1993–Present, Earth System Science Data
Brooks added that Antarctic ice is growing.
Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology
While the extent of Antarctic sea ice is slightly growing, this growth does not affect sea level, because of Archimedes’ law. The land ice of the Antarctic Ice Sheet is shrinking at an accelerating pace, which does result in sea-level rise.
- The IMBIE team (2018) Mass Balance of the Antarctic Ice Sheet from 1992 to 2017, Nature
- Bamber (2018) The Land Ice Contribution to Sea Level during the Satellite Era, Environmental Research Letters
“Well, I’ve got a NASA base in my district, and apparently, they’re telling you one thing and me a different thing,” Brooks said. “But there are plenty of studies that have come that show with respect to Antarctica that the total ice sheet, particularly that above land, is increasing, not decreasing.
Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology
The increasing rate of Antarctic mass loss has been confirmed by multiple independent observation systems.
“What do you say to people who theorize that the Earth as it continues to warm is returning to its normal temperature?”
Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology
This is a fallacy, which has been correctly rebutted by Duffy. What matters is that a large increase in global temperatures is problematic for us humans, who have built a civilisation in a relatively stable climate, and which we are now perturbing far outside this stable range.
