We reported last month on a new study out of the Netherlands showing that there is no evidence for an acceleration in sea levels when examining tide gauge data corrected for land level shifts. And we received a nice note from one of the study authors who thanked us for our accurate summary of the research. Which inspired us to devote an episode of our #HaveItBothWays series to sea level rise, specifically the acceleration issue. The average rate of sea level rise is low enough that most places around the world have no cause to panic nor will locals even notice any foreseeable change, posing a challenge for alarmists who responded by saying ah but it’s accelerating and coming for you, particularly in a 2005 study that claimed to have, and show, the receipts. But not to worry, this being climate science now you see it, now you don’t.
The 2005 paper made it clear that finding evidence of accelerating sea level rise was not for the fainthearted. You couldn’t just go and look at the water and go aha! here it comes. Instead you have to combine computer-model data with careful selection of starting points:
“A reconstruction of global sea level using tide-gauge data from 1950 to 2000 indicates a larger rate of rise after 1993 and other periods of rapid sea-level rise but no significant acceleration over this period. Here, we extend the reconstruction of global mean sea level back to 1870 and find a sea-level rise from January 1870 to December 2004 of 195 mm, a 20th century rate of sea-level rise of 1.7 ± 0.3 mm yr−1 and a significant acceleration of sea-level rise of 0.013 ± 0.006 mm yr−2. This acceleration is an important confirmation of climate change simulations which show an acceleration not previously observed.”
In plain language, the climate models say sea level rise should be accelerating. But the tide-gauge data since 1950 didn’t show it. So the authors used their dark arts to extend the “record” back to 1870 with non-data data and still only found a gol-durn rate of sea level rise of 1.7 mm per year, or less than 20 cm over a century, not sufficient even to yell “Saunter for the hills.” But if they squinted just so, they claimed, they could find a brief increase in the annual sea level rate late in the sample of 0.013 mm per year over the previous level. Yes, that’s right, the rate of increase is supposedly itself going up by just over one one-hundredth of a millimeter every year.
Even if the matter ended there, we would roll our eyes at the claim of being able to detect a change in the global rate of sea level rise with that much precision. Especially as the ocean is big and rolling with currents and tides and the shore is bumpy and has waves. But it did not end there.
It continued, because in 2011 another study looking at U.S. coastal data from the very same sea level archive concluded that instead of acceleration the data show deceleration. Aaack. Sea level rise is slowing down not speeding up? Noooooo!
Since that conflicted with what all the cool kids were yelling, the authors extended their analysis to the rest of the world and found that, yup, sea level rise is decelerating, not accelerating, at the global scale. Blast those oceans. Have they been talking to the ice?
Either way the changes are very small and one study does not make a field. So we’re not going to declare one side or the other the last word on the subject. We just present this as yet another example that with climate science if you’re patient enough you can always #HaveItBothWays. Or even all three if you also insist that the science is “settled”.
