Compare and contrast the following statements. The first comes from the CU Sea Level Research Group: “It is well known from observations by altimetric satellites (predominantly TOPEX/Poseidon and Jason-1) that global sea level is rising. What is less well known is exactly how the observed sea level rise is partitioned between a steric contribution (sea level rising because of changes in ambient temperature and salinity) and a contribution arising from the addition of new water mass to the oceans. Strictly speaking, such a separation is not possible because of the non-linearity in the equation of state for sea water, but in practice the non-linearities are sufficiently small to allow this separation as a very good first approximation.A careful comparison of the World Ocean Circulation Experiment (WOCE) one-time survey with recent observations by the Argo array indicate a steric component to sea level rise of 2.2 mm y-1 between the early 1990s and 2006 to 2008. This is a significantly larger rise rate than previously estimated and, along with recent estimates of melt rate from ice sheets, is in much closer agreement with the total rise rate as reported by altimetric satellites, 3.2 ± 0.4 mm y-1 over this period.”
The second comes from JPL’s website dedicated to GRACE, or Gravity Recovery and Climate Experiment: “Over the last decade or so losses from land ice have been implicated in causing two thirds of the observed rise in sea level (Gardner et al., 2013 and Shepherd et al., 2012).
I’m not a scientist but I think that adds up to 4/3rds of the total.
When the GRACE satellite was first launched and started reporting data, it indicated that the Greenland and Eastern Antarctic ice caps were losing hundreds of gigatonnes a year of ice. This was picked up and reported eagerly by climate activists everywhere, all of whom neglected to mention that the reported loss was a fraction of one percent of the total.
I got in a protracted fight over at Michael Tobis’ blog, Only In It For The Gold, as I argued that it being a newly launched satellite it might be wise to wait for a couple of extra orbits before panicking over a reported loss of ice that amounted to 0.7% of the total mass involved. For this I was labeled a denier, a pimp, etc. (Most of you know the drill.)
About a day later, a press release was issued: “However, it now turns out that these results were not properly corrected for glacial isostatic adjustment, the phenomenon that the Earth’s crust rebounds as a result of the melting of the massive ice caps from the last major Ice Age around 20,000 years ago. These movements of the Earth’s crust have to be incorporated in the calculations, since these vertical movements change the Earth’s mass distribution and therefore also have an influence on the gravitational field.” They lowered the already minute percentage of ice loss by half.
Nobody unsaid any of the unkind things they had said. GRACE giveth, GRACE taketh away.
Since then, GRACE has been used a lot–In February of 2016 they announced “New measurements from a NASA satellite have allowed researchers to identify and quantify, for the first time, how climate-driven increases of liquid water storage on land have affected the rate of sea level rise.
A new study by scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, and the University of California, Irvine, shows that while ice sheets and glaciers continue to melt, changes in weather and climate over the past decade have caused Earth’s continents to soak up and store an extra 3.2 trillion tons of water in soils, lakes and underground aquifers, temporarily slowing the rate of sea level rise by about 20 percent.”
This was in sharp contrast to their statement in 2014: “Many Americans might not realize it, but the country is headed for a brutal reality check in terms of access to clean, cheap water. Climate change’s amplifying effects are turning dry regions into virtual deserts and wet ones into flood zones, setting the stage for a horde of “water-related catastrophes, including extreme flooding, drought, and groundwater depletion,” warn scientists at UC Irvine.”
To be fair, the first article was talking of the world while the second was about the U.S. only. But it does seem that GRACE is suffering from the New Toy syndrome, where every bit of data it collects is new and is reported somewhat breathlessly without much in the way of context.
Like many new techniques, there have been errors associated with it. But the need for new headlines meant the errors made it into print before they could be corrected. And while the scientists reported the errors and corrections, often the activists did not.
The idea that in 2016 a quick Google search on sea level rise would find two stories that between them report vastly different figures for steric vs. melt would have shocked me a few years ago. After all, isn’t the science settled?
No. It isn’t. Forensic science can go in after the fact and probably get incredibly useful information from GRACE, not to mention other measurement tools misused by activists in search of hysterical headlines.
But the way the data was misreported and taken out of context is enough to make me wish for a hymn to help me forgive.