Sea level since 1993, seasonals removed

Claim: Sea Levels dropped significantly in 2010 and 2011, showing climate scientists' claims of higher CO2 means rising sea levels is seriously flawed.

Why This Claim is Wrong: This got a lot of play, in particular at the climate denialist blog "Watts Up With That", a blog by right-wing Fox News TV weatherman

This longer term graph shows sea level rise is actually accelerating upward, and the small dip in 2010 is almost lost in the small-scale noise.

Anthony Watts. Hundreds of denialists piled on, loudly claiming climate science was completely wrong about CO2 and human-caused global warming. The truth is that sea levels did indeed fall during those two years, but it was entirely understandable with basic science. The Earth had an unusually strong La Nina phase of the El Nino/Southern Oscillation in 2010-11, and this phase is normally associated with globally greater than normal rainfall and snowfall over land and cooler temperatures. This causes a transfer of water from the ocean to the continents. When it is this strong, this can actually more than compensate for the secular rise in sea level. Since

2011, we have had the ENSO phase shift mildly into the El Nino phase, and the resultant loss of continental ice and return of water off the continents to the ocean has more than compensated for the dip in sea level in 2010/11. Even without taking out the ENSO oscillation, it is clear from the sea level graph of the past 20 years (see at right) that the rise in sea levels continue. This graph plots mean sea level from satellite altimetry. Seasonal annual signals removed to reveal secular trend. the glacial isostatic adjustment of 0.3mm/yr is added to account for the slumping of ocean basins. Image from the AVISO website.

Take a look at the ~200+ comments entered after the posting in "Watts Up With That" linked above, and the smug, self-satisfied put-downs of the work of good climate scientists by the denialists who are positively giddy as they slander honest scientific work. This illustrates another climate denialist tactic - the normal wiggles in any data trend from the real world include "down wiggles", which are immediately trumpeted as disproving the hated "anthropogenic global warming" case, while the "up wiggles" are completely ignored. This is a hallmark of agenda-driven vs. evidence/logic/honesty driven argumentation. It is a common theme on any venue where they can get air time. For more detail, see the well-linked coverage of the sea level issue in Skeptical Science. I wouldn't expect to see an apology from WUWT upon seeing the accelerated return and overshoot to the mean sea level rise curve. Nor have I ever seen any apologies for the damage these people and their supporters do to honest scientific education, and to our future.

We are today at over 400 ppm CO2. The last time CO2 levels were this high was the Pliocene Epoch about 3 million years ago. The heating resulted in the loss of the entire Greenland and West Antarctic Ice sheets, and sea levels were 60 FEET higher than today, which will put under water nearly all coastal cities and even some inland cities (like Sacramento and Stockton). In 2014, the West Antarctic Ice Sheet lost its grounding and is in irreversible collapse, thanks to climate change. That progression may take centuries (or less) of constantly rising sea levels, making the building of ports necessary for ocean-going commerce very difficult or impossible. Think about that and think about the gross irresponsibility of climate denialists. These lies have real consequences for all future generations.

In Short: Sea level rise is not perfectly correlated with CO2 levels on a one or two year time scale because ENSO-associated oscillations in total rain and snow over the continents can temporarily move water from the oceans to land, and this was particularly dramatic in 2010-11, and has since reversed. Climate denialist claims here are another example of extreme short-period cherry-picking to advance their agenda, rather than evidence- and logic-driven pursuit of genuine understanding.


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