JPL’s Josh Willis Looks Ahead to Continuing Sea Level Rise

In the first of a new series, Jet Propulsion Lab climate scientist Josh Willis provides context for 2011′s small decline in sea level rise. Bottom line: Drop not long-lived, and further sea level rise inevitable. See the video.

“For the past 18 years, the U.S./French Jason-1, Jason-2 and Topex/Poseidon spacecraft have been monitoring the gradual rise of the world’s ocean in response to global warming,” NASA’s Jet Propulsion Laboratory said in a 2011 release.

“While the rise of the global ocean has been remarkably steady for most of this time, every once in a while, sea level rise hits a speed bump,” it continued. In 2011, “ it’s been more like a pothole” as global sea level fell by about a quarter of an inch, or half a centimeter between the summers of 2010 and 2011.”

“So what’s up with the down seas, and what does it mean?”

In the accompanying video by Peter Sinclair, independent videographer, NASA/JPL climate scientist Josh Willis points to the cycle of El Niño and La Niña in the Pacific.

Willis said that while 2010 had begun with a sizable El Niño, by year’s end it was replaced by one of the strongest La Niñas in recent memory. According to JPL, in Pasadena, Ca., that sudden shift in the Pacific changed rainfall patterns across the globe, bringing “massive floods to places like Australia and the Amazon basin, and drought to the southern United States.”

JPL pointed to data from the “Grace” spacecraft indicating that extra rain piled onto the continents in the early parts of 2011.

“By detecting where water is on the continents, Grace shows us how water moves around the planet,” Steve Nerem, a sea level scientist at the University of Colorado in Boulder, said in the JPL press statement.

The extra water flooding Brazil and Australia actually came from the ocean, JPL said.

“Each year, huge amounts of water are evaporated from the ocean. While most of it falls right back into the ocean as rain, some of it falls over land.

“The continents got an extra dose of rain, so much so that global sea levels actually fell over most of the last year,” Carmen Boening, a JPL oceanographer and climate scientist, said.

Willis put the kibosh on those thinking a long-term decline in global sea level is in the works. Sea level drops such as this one cannot last, and over the long-run, the trend remains solidly up, he said.

JPL’s quick take: “Water flows downhill, and the extra rain will eventually find its way back to the sea. When it does, global sea level will rise again.”

“We’re heating up the planet, and in the end that means more sea level rise,” Willis added. “But El Niño and La Niña always take us on a rainfall rollercoaster, and in years like this they give us sea-level whiplash.”

AUTHOR
Peter Sinclair is a veteran videographer who originated the “Climate Crock of the Week” series and now contributes regularly to The Yale Forum.

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18 Responses to JPL’s Josh Willis Looks Ahead to Continuing Sea Level Rise

  1. Dekka says:

    My friend is sceptical about the amount of water that would remain on the land after rain. He thinks the fall in sea levels can’t be explained by the water on the land. Most of the water would runoff back to the sea, he says. Can you quantify the amounts of water involved or give me a pointer to a paper that does so? Thanks.

    • EOttawa says:

      The map in this article shows the changes in water over land determined from GRACE satellite data. Is your friend questioning the data?

      The Global Land Data Assimilation System (GLDAS) documentation and data is available at JPL GRACE website

      I also thought that Dr. Willis provided a very good explanation in the video. I believe this article is largely based on a ‘poster’ that Willis and his colleagues presented at the GRACE Scientists forum and the AGU fall meeting.

    • Dekka, to some extent the map shows what you are asking; the anomaly in soil moisture. The scale is in meters of water depth. Column equivalent water depth is the usual hydrological measure of soil moisture. Anomalies larger than 5 cm. are shown.

      In other words, if you could suck all the water out from the ground and put it on the surface, you’d see a couple inches more than usual in the bluest spots on the map and a couple inches less than usual in the reddest ones.

      So, spread out over the ocean (and accounting for the swing from dry anomalies the previous year) apparently this works out to a half centimeter.

      It doesn’t seem implausible to me. However, it is an unusually large blip.

      Excellent work, Peter! Thanks! I think the format here is excellent and compelling.

      That said, I agree with Dekka that links back to the literature and other sources would be helpful.

  2. Tom Moriarty says:

    The most commonly quoted sea level rise projection for the 21st century is from Vermeer and Rahmstorf (PNAS, 2009). They relied on 20th century sea level data from Church and White (Geophysical Research Letters, 2006). Church and White built their sea level data from the tide gauge data at the Permanent Service for Mean Sea Level (PSMSL).

    You can see the entire set of PSMSL tide gauge data, set to music no less, here…

    http://climatesanity.wordpress.com/2012/01/29/sea-level-data-set-to-music-yeah-thats-right/

    It is a fun way to look for sea level rise acceleration.

    • Sean says:

      How can you talk about “acceleration” when the slope since 2006 is less than the end of the last century and last year has hit a pothole and actually went down a bit??

  3. John T says:

    Looking at one year of data from March 2010 to March 2011 doesn’t explain the slow down in sea level rise since 2004. Here is the Envisat measurement showing that the Northern Hemisphere trended downward at -.301 mm/year while the Southern Hemisphere MSL trended upward +1.1 mm/year.

    NH Trend:
    http://www.aviso.oceanobs.com/fileadmin/images/news/indic/msl/MSL_Serie_EN_North_IB_RWT_NoGIA_Adjust.png

    SH Trend:
    http://www.aviso.oceanobs.com/fileadmin/images/news/indic/msl/MSL_Serie_EN_South_IB_RWT_NoGIA_Adjust.png

    Envisat, Grace, Jason 2 and Argo are showing similar recent slow down to ~ .9 mm/year in recent years from a long term ~ 3 mm/year MSLR while Jason 1 seems to overstate the rise.

    http://www.gfz-potsdam.de/portal/gfz/Struktur/Departments/Department+1/sec12/topics/gravity_field_determination/sea_level_budget/image_sea_level1/Grossbild;jsessionid=A829271989ABB972838F2C00C1465E2C?binary=true&status=300

    Wouldn’t the effects of El Nino and La Nina shifts cancel each other out as far as influence in MSLR over the above 8 year period? The recent SST still shows overall warming over the last 8 years even with La Nina effects so what caused the slow down in MSLR?

    http://weatherdem.files.wordpress.com/2012/01/surface-temperature-anomalies-hansen-201201.png

  4. Dekka says:

    Thanks all.

    My friend is questioning the claim that the global sea level decrease over the last two years is a result of rain falling on land: “You know that 99% of the floods in Oz saw the water run straight out to sea within days. Do some basic math. Total volume of sea water by [sic] 6mm down and try and tell me that all that fell on land and is still on the land. Mad as batshit.”

    He argues that some other as-yet-unidentified natural influence is affecting sea levels and that anthropogenic warming has got little to do with it. He regards sea level data as particularly important because it’s been used by “alarmists” so often to scare the population about global warming.

    The public debate is at a point where ways of communicating the complexity of the climate and associated research needs to be done. We need something like a model of the climate models that lets people see what variables go into the model, how they affect the processes, and some of the lag intervals between the effects.

    Any comments would be welcome.

    • Bernard J. says:

      …tell me that all that fell on land and is still on the land

      The point is that during the current La Niña a lot of the water still is, on average, on land. For example, take a look at the eastern coast of Australia at the moment:

      http://www.rte.ie/news/2012/0205/australia.html

    • Gaz says:

      The big dams across Australia were all getting very low before La Nina, now they are just about full. The ground has soaked up a lot of water, the rivers are up and the dams on many farms are now full too. There is a heck of a lot of water still not anywhere near the sea yet. Dekka, you could suggest to your friend that scientists who have been studying this stuff all their working lives might actually know what they are talking about.

      • Dekka says:

        Unfortunately, the “leave it to the scientists” approach isn’t working for large proportions of the US and Australian populations. The case has to be communicated – by the scientists and those who respect the scientific process.

  5. Josh Willis says:

    The top figure shown above has been seasonally adjusted for the exchange of water between land and ocean. However, without adjusting for this regular exchange, you can see that each year the ocean loses and gains about 1 cm of water: http://sealevel.colorado.edu/content/2011rel4-global-mean-sea-level-time-series-seasonal-signals-retained
    as rain falls over places like the Amazon and the Congo. The time scale for these basins to drain back to the ocean is long enough that it causes a yearly rise and fall of about 1 cm in global sea level. In fact, if all of the water that rained down over land remained there, instead of running back into the ocean it would cause 12 centimeters of global sea level fall. So the 5 to 6 mm of sea level drop that we found represents only about a 3 % change in the global hydrologic cycle. Our paper on this is currently under review and we hope to have it published soon.

    Cheers,
    Josh Willis

  6. Jean Demesure says:

    Everything is evidence of global warming, wether there is sea rise or drop, heat wave or snow storm, dry spell or inundation.
    It’s computer assisted climate animism.

  7. George W Nixon. says:

    Yes CO2 is assisting to keep our planet warm and yes we have considerably increased the percentage of that gas in the atmosphere. I for one am grateful for my carbon content.
    Even so, it is my belief that we are being misled when we are informed that CO2 is mainly responsible for the relatively recent changes to climate changes.
    With regards to a total understanding of physics let alone knowledge of climate science, we are only beginning to gain a partial understanding.
    My 68 years of work on Matter and Associated Mysteries is compressed into 160 pages. Along with its ability to provide an explanation for all anomalies known to myself, there is an explanation and demand that there exists a Gravitational Thermal Effect, the magnitude of which is varied by the inverse of the square of a planets distance from the Sun. There is a warming effect when the direction of motion is towards the Sun, and a cooling when the direction of motion is away from the Sun. The velocity too or from the Sun is of paramount importance due to rate of radiation loss. The Thermal effect is slightly varied by the position of the Great planets. Thermal activity on Moons, Comets etceteras result from the referred to phenomenon.
    There are several ways the veracity of the Gravitational Thermal Effect can be ascertained; one is as follows. Astronomers can combine with those whom have information derived from reliable temperature charts. They can find two equally opposite positions of the Earth relative to the distance from and approach to and retreat from the Sun. After allowing for the red and blue changes (increase and decrease in impact) to the Suns radiation due to the Earth’s rate of approach and retreat, they should find an anomalous changing in thermal activity in excess of radiation warming from the Sun. The changes to temperature of the oceans would be most relevant.
    In answer to your silent question; 16 years of endeavour to gain an evaluation has not been rewarded by a single comment, it appears that the work is too disruptive to presently believed physics.

  8. George W Nixon. says:

    If sea levels can actually be measured with such accuracy and because the large amount of flood waters stays on the affected area of Australia for several days, then any changes must also account for the rate of buoyancy changing of the Australian plate floating on the supporting magma. If all the water stayed on land permanently, then the Australian plate would slowly sink until reaching gravitation equilibrium.

  9. Alec Rawls says:

    As usual with anti-CO2 alarmists, Josh Willis is not telling you the most important thing: that historically, sea level drops when the sun goes quiet. Take a look at the Medieval Warm Period and the Little Ice Age in this sea level reconstruction. It’s very clear:

    http://planetearth.nerc.ac.uk/news/story.aspx?id=293

    Sea level also flattened or dropped a bit in the early 1900′s when solar activity dipped, and it seems to have done the same during the Dalton Minimum.

    It might seem counterintuitive that the same thing could happen now, when we are at just passing the peak of the Modern Warm Period. If we are at the peak, shouldn’t melting continue? It wouldn’t seem to be enough for the planet to be headed in the cooling direction. It would have to actually have to be cold before things start freezing up again, right?

    Not so. You have to look at the mechanism involved. The alternative to the CO2 theory says that the planet cools when the sun goes quiet because the weak solar wind is letting a lot more cosmic rays reach the atmosphere, where they ionize the atmosphere and seed a significant increase in cloudiness, blocking some sunlight from reaching the surface. Well, sunlight melts ice and snow, so the effect on melting rates can be immediate and somewhat independent of temperature.

    “Melting” is probably not the right word, since ice an snow can sublimate directly into water vapor, and now that we are again seeing sea level drop during a period of quiet sun, this is the likely explanation.

  10. “Whatever sea level rise has taken place during the course of my own life would be unlikely to cause the demise of a single person. Dozens and dozens of tide gauges bear this out. Measuring at Midway Atoll in the Central Pacific, the National Oceanic and Atmospheric Administration found that sea level rose .7 millimeters a year from 1947 to 2006. At this rate, in a hundred years, the oceans would rise a little less than three inches. Again, such modest, unthreatening rises have taken place hundreds of times in the past, and will again.” — from Don’t Sell Your Coat, by yours truly, available here: http://amzn.to/xam4iF