A salty climate “bonbon”

Wor­ried by Ross Gar­naut’s claim in his revised review that sea lev­els are ris­ing faster than even the U.N. predicted: 

Ris­ing sea lev­els will con­tin­ue to increase the fre­quen­cy and inten­si­ty of coastal flood­ing events dur­ing the 21st cen­tu­ry. Obser­va­tions indi­cate that there­has been a sig­nif­i­cant increase in the fre­quen­cy of extreme high sea lev­els with­in Australia”?

Well, if you look at the data instead of the mod­els, the facts don’s sup­port any such alarms. Here is a pic­ture of sea lev­els at Syd­ney since 1992 from the JASON satel­lite (NASA) mon­i­tor­ing facil­i­ty at the Uni­ver­si­ty of Col­orado, that I hope will make you feel a lot bet­ter.

Sea Levels at Sydney from the NASA JASON satellite

That’s right: the lat­est satel­lite data shows over that peri­od there has been a fall in sea lev­els at Syd­ney (lon­gi­tude 151 E, lat­i­tude 33 S) at a rate of 0.14 cm per year. The grey line is the un-smoothed data.Here’s the data for the picture.

Global sea levels from the NASA satellite series

Over a wider geo­graph­ic range of the sea there is a pos­i­tive trend in sea-lev­els that the satel­lites mea­sure for the peri­od since 1992 at 3.1 mm/year (+/- 0.4 mm). That’s about 1ft per cen­tu­ry in the old cur­ren­cy—pad­dling depth. Even the cur­rent slow rate of sea-lev­el rise is like­ly to be high­er than we’d see if we had such accu­rate mea­sure­ments for a longer time-frame because this rise has been observed dur­ing a peri­od of warm­ing in the sea sur­face. Ther­mal expan­sion accounts for at least half (and in future maybe most) of the rise in sea levels.

GISS Sea Surface Temperatures

As it hap­pens, glob­al sea sur­face tem­per­a­tures are falling, as the NASA (GISS) data show, per­haps reflect­ing the rever­sal of the Pacif­ic decadal oscillation.

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