|March For Science|
That estimation ("the major cause") is one quantity that has been thrown around a lot, but some of the latest scientific papers have brought thermal expansion down to one-third with Cryosphere melt (2/3) as the major cause:
"Observations from the Jason series have revolutionized scientists' understanding of contemporary sea level rise and its causes. We know that today's sea level rise is about one-third the result of the warming of existing ocean water, with the remainder [two-thirds] coming from melting land ice."(NASA, emphasis added; cf Thermal Expansion Causes About One-Third Of Global Sea Level Rise1). Even that 1/3 is an overestimate due to not knowing about "ghost water" (NASA Busts The Ghost).
When government scientists or administrators make a statement about science, they can be held accountable in court:
On March 9, 2017, Scott Pruitt, the Administrator of the Environmental Protection Agency (“EPA”), appeared on the CNBC program “Squawk Box” and stated, regarding carbon dioxide created by human activity, that “I would not agree that it’s a primary contributor to the global warming that we see,” and “there’s a tremendous disagreement about of [sic] the impact” of “human activity on the climate.” ... Noting that these public statements by the EPA Administrator “stand in contrast to published research and conclusions of the EPA,” ... the plaintiff, Public Employees for Environmental Responsibility (“PEER”), a “non-profit organization dedicated to research and public education concerning the activities and operation of [the] federal . . . government,”... submitted a request to EPA, pursuant to the Freedom of Information Act (“FOIA”), 5 U.S.C. § 552, for agency records “relied upon by Administrator Pruitt in making these statements and any EPA documents that support the conclusions that human activity is not the largest factor driving global climate change,” ... EPA has performed no search for and produced no records in response to the plaintiff’s FOIA request. ... Nonetheless, on this record, EPA now seeks summary judgment, ... and the plaintiff has cross-moved for summary judgment, ... For the reasons set forth below, the plaintiff’s cross-motion is granted, and EPA’s motion is denied. [pp. 1-2](PEER vs Pruitt, PDF). That is a recent decision by the chief judge in a court in the District of Columbia.
EPA has failed to demonstrate a viable legal basis for its refusal to conduct any search whatsoever in response to the plaintiff’s straightforward FOIA request. When the head of an agency makes a public statement that appears to contradict “the published research and conclusions of” that agency, ... the FOIA provides a valuable tool for citizens to demand agency records providing any support, scientific or otherwise, for the pronouncement, and to oblige agencies to search for and produce any non-exempt responsive records. Compliance with such a request “would help ‘ensure an informed citizenry, vital to the functioning of a democratic society.’” [p. 18]
[ORDER:] EPA is directed: (1) by July 2, 2018, to conduct and complete the search for records responsive to both parts of the plaintiff’s amended FOIA request; (2) to disclose promptly to the plaintiff on a rolling basis any responsive, non-exempt records; and (3) by July 11, 2018, to produce to the plaintiff, an explanation for any documents withheld in full or in part. The parties shall, by July 31, 2018, file jointly a status report notifying the Court of any outstanding issues in dispute and, if necessary, propose a schedule to govern any further proceedings in this matter. [pp. 18-19]
Officials can also be held accountable for silencing (or trying to) the public when the public calls them out on public matters (Knight v Trump, PDF).
I think that it is time for scientists who are making assertions that "thermal expansion is the major cause of sea level rise" to put up the science or shut up about it (The Pillars of Knowledge: Faith and Trust?).
Because, among other things, it has been pointed out that the origin of the hypothesis is an old model's tale (e.g. On Thermal Expansion & Thermal Contraction - 33).