Sea level rising by ‘paddling’ levels over a century

NASA pub­lished data this week on a more recent series of satel­lite esti­mates that are six times high­er than the ABC claims. But even they don’t add up to more than a wad­ing-pool’s depth.

NASA recent­ly announced that it is prepar­ing to launch a sec­ond ocean sur­face mea­sure­ment exper­i­ment (Jason‑2). In the press release that accom­pa­nies the announce­ment, the actu­al rise in sea lev­els in the past 15 years, based on the cur­rent satel­lite data, is revealed: 

From Topex/Poseidon and Jason 1, we know that mean sea lev­el has been ris­ing by about three mil­lime­ters (.12 inch­es) a year since 1993. This is about twice the esti­mates from tide gauges for the pre­vi­ous cen­tu­ry, indi­cat­ing a pos­si­ble recent accel­er­a­tion in the rate of sea lev­el rise. 

Let’s put that in per­spec­tive. Three mil­lime­ters a year is 33 cen­time­ters per cen­tu­ry, or a tad over 1ft in impe­r­i­al measures. 

The NASA divi­sion respon­si­ble for this ocean-sur­face exper­i­ment goes on to say, in their press release:

Based on recon­struc­tion of past sea lev­el pat­terns using Topex/Poseidon and Jason 1 obser­va­tions, sci­en­tists have found that the accel­er­a­tion is like­ly to be part of the decadal vari­abil­i­ty of the ocean. But 15 years of data are sim­ply not enough to deter­mine long-term trends of sea lev­el change. OSTM/Jason 2 will con­tin­ue to mon­i­tor sea lev­el changes and allow us to bet­ter under­stand its long-term vari­a­tions”.[empha­sis added]

You might also be inter­est­ed to learn about the short-term and local vari­abil­i­ty of the sea-lev­el that far out­reach­es the long-term trend: 

Changes in the height of the glob­al ocean due to ocean cur­rents and ther­mal dif­fer­ences vary by as much as two meters (6.5 feet) from one place to the next. Before Topex/Poseidon and Jason 1, we didn’t know how much those heights fluc­tu­at­ed. We’ve learned that the height of sea sur­face over areas larg­er than the Unit­ed States can move up and down by 20 cen­time­ters (8 inch­es) in just 20 days.

If Kiri­bati or Tuvalu or the Sey­chelles reck­on that they’re threat­ened by a cen­tu­ry aver­age rise of 33 cm (if that’s what it turns out to be), they must count them­selves lucky they aren’t in the path of these much big­ger day-to-day and place-to-place bumps in the ocean.

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