sea level rise

Is Greenland Melt “Off the Chart?”

That’s what the second author said about a new paper on Greenland’s ice, which arrived just in time for the annual meeting of the signatories of the UN’s 1992 treaty on climate change, this time in Katowice, Poland. Appearing in Nature, Rowan University Geologist Luke Trusel and several coauthors claimed ice-core data from Central-Western Greenland revealed melting in the recent two decades that has been “exceptional over at least the last 350 years.” The paper appeared in the December 6 issue of Nature.

How exceptional?

“Our results show a pronounced 250% to 575% increase in melt intensity over the last 20 years” as measured in four ice cores in west-central Greenland. Three of the cores were in the Jakobshavn Glacier, the largest-discharging glacier in the entire Northern Hemisphere. The Ilulissat icefjord, created by the glacier, some 25 miles in length, has historically calved nearly 50 cubic kilometers of ice per year into Disko Bay, near the town of Ilulissat. 

They then correlated their ice-core data with a model for ice behavior in all of Greenland. The correlations, while significant, were modest, with the explained variance of the island-wide melting maxing at around 36%. The melt reached its maximum in the very strange summer of 2012, where the amount at the Summit site, near Greenland’s highest elevation, was the largest since the summer of 1889—worth noting because that was well over 100 years ago.

There’s a long-standing quality weather station at Ilulissat, and it certainly shows summer warming of about 2⁰C from its beginning around 1850 to the 1920s.

For a broader comparison, we looked at the summer temperature anomalies for the 5 X 5 degree gridcell that includes Disko Bay and the icefjord. Because it is relatively hospitable and settled, there are a number of stations within the cell so the data is quite reliable. The data we show is from the Climate Research Unit at the University of East Anglia, version HadCRUT4.

There’s very little to see in this temperature record. The authors are well-aware of this and offer a rather unsatisfactory explanation:

The non-linear melt-temperature sensitivity also helps explain why episodes of mid-twentieth-century warmth resulted in less intense and less sustained melting compared to the last two decades, despite being only marginally cooler…Additional factors, such as recent sea-ice losses, as well as regional and teleconnected general circulation changes may also play a part in amplifying the melt response.

You Ought to Have a Look: How-to Guides to Undoing the Climate Action Plan, Fixing the National Flood Insurance Program, and Killing Mosquitoes

You Ought to Have a Look is a regular feature from the Center for the Study of Science.  While this section will feature all of the areas of interest that we are emphasizing, the prominence of the climate issue is driving a tremendous amount of web traffic.  Here we post a few of the best in recent days, along with our color commentary.

With news of the past week or so dominated by announcements and then post-announcement scrutiny of Trump’s cabinet picks, we highlight a few pieces that go into deeper waters on these (and other) topics.

First up is an informative piece by Vox’s Brad Plumer that’s built from an interview he conducted with Jody Freeman, a Harvard law school professor and former climate adviser to President Obama. Over the course of their conversation, Plumer and Freeman pretty much lay out a road map as to how the Trump Administration could go about undoing much of President Obama’s ill-advised (in our opinion) Climate Action Plan. The selection of Scott Pruitt to head the EPA is definitely a big step in that direction.

A Historic Perspective on the Greenland Ice Sheet and its Contribution to Global Sea Level

One of the most feared of all model-based projections of CO2-induced global warming is that temperatures will rise enough to cause a disastrous melting/destabilization of the Greenland Ice Sheet (GrIS), which would raise global sea level by several meters. But how likely is this scenario to occur? And is there any way to prove such melting is caused by human activities?

On the Bright Side: A Deceleration of Sea Level Rise Along the Indian Coastline

Parker and Ollier (2015) set the tone for their new paper on sea level change along the coastline of India in the very first sentence of their abstract: “global mean sea level (GMSL) changes derived from modelling do not match actual measurements of sea level and should not be trusted” (emphasis added). In contrast, it is their position that “much more reliable information” can be obtained from analyses of individual tide gauges of sufficient quality and length. Thus, they set out to obtain such “reliable information” for the coast of India, a neglected region in many sea level studies, due in large measure to its lack of stations with continuous data of sufficient quality.

A total of eleven stations were selected by Parker and Ollier for their analysis, eight of which are archived in the PSMSL database (PSMSL, 2014) and ten in a NOAA sea level database (NOAA, 2012). The average record length of the eight PSMSL stations was 54 years, quite similar to the average record length of 53 years for the eleven NOAA stations.

Results indicated an average relative rate of sea level rise of 1.07 mm/year for all eleven Indian stations, with an average record length of 51 years. However, the two Australian researchers report this value is likely “overrated because of the short record length and the multi-decadal and interannual oscillations” of several of the stations comprising their Indian database. Indeed, as they further report, “the phase of the 60-year oscillation found in the tide gauge records is such that sea level in the North Atlantic, western North Pacific, Indian Ocean and western South Pacific has been increasing since 1985-1990,” which increase most certainly skews the rate trend of the shorter records over the most recent period of record above the actual rate of rise.

The Spin Cycle: Accelerating Sea Level Rise

The Spin Cycle is a reoccurring feature based upon just how much the latest weather or climate story, policy pronouncement, or simply poo-bah blather spins the truth. Statements are given a rating between 1-5 spin cycles, with less cycles meaning less spin. For a more in-depth description, visit the inaugural edition.

A popular media story of the week was that sea level rise was accelerating and that this was worse than we thought. The stories were based on a new paper published in the journal Nature Climate Change by an author team led by the University of Tasmania’s Christopher Watson.

Watson and colleagues re-examined the satellite-based observations of sea level rise (available since the early 1990s) using a new methodology that supposedly better accounts for changes in the orbital altitude of the satellites—obviously a key factor when assessing sea levels by determining the height difference between the ocean’s surface and the satellites, the basic idea behind altimetry-based sea level measurements.

So far so good.

Their research produced two major findings, 1) their new adjusted measurements produced a lower rate of sea level rise than the old measurements (for the period 1993 to mid-2014), but 2) the rate of sea level rise was accelerating.

It was the latter that got all of the press.

But, it turns out, that in neither case, were the findings statistically significant at even the most basic levels used in scientific studies. Generally speaking, scientists report a findings as being “significant” if there is a less than 1-in-20 chance that the same result could have been produced by random (i.e., unexplained) processes. In some fields, the bar is set even higher (like 1 in 3.5 million). We can’t think of any scientific field that accepts a lower than a 1-in-20 threshold (although occasional individual papers do try to get away with applying a slightly lower standard).

You Ought to Have a Look: Science Round Up—Less Warming, Little Ice Melt, Lack of Imagination

You Ought to Have a Look is a feature from the Center for the Study of Science posted by Patrick J. Michaels and Paul C. (“Chip”) Knappenberger. While this section will feature all of the areas of interest that we are emphasizing, the prominence of the climate issue is driving a tremendous amount of web traffic. Here we post a few of the best in recent days, along with our color commentary.

Repeating News Story: Eroding Shorelines and Imperiled Coastal Villages in Alaska

U.S. Secretary of the Interior Sally Jewell was in Alaska last week at the invite of the Alaska Federation of Natives to discuss climate change and other issues. During her visit, she made a side trip to the 400 or so person town of Kivalina, located on a low-lying barrier island along Alaska’s northwest coast. The settlement sprung up about a century ago when the Interior Department decided to erect a school there under a program to promote the “education of natives in Alaska.” The same program established schools in other coastal location such as Golovin, Shishmaref, and Barrow.

Now these locations are in the news (see this week’s Washington Post story for example) because they are being threatened by coastal erosion coming at the hands of global warming—and are discussing relocating and who should be responsible for the footing the bill (incidentally, the courts have ruled out the energy industry).

With or without human-caused climate change, bluffs and barrier islands along the coast of northwestern Alaska are inherently unstable and not particularly good places to establish permanent towns. This is probably one of the reasons the natives were largely nomadic.

“Were,” we say, because ironically, as pointed out by the Post’s Chris Mooney, research indicates that the abandonment of the nomadic ways was encouraged/hastened by the establishment of government schools!

Evidenced-based Sea Level Rise Projections Remain Low

Global Science Report is a feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

When it comes right down to it, the biggest potential threat from a warming climate is a large and rapid sea level rise. Everything else that a changing climate may bring we’ve seen before (or at least the likes of it), recovered from, and are better off for it (i.e., gained experience, learned lessons, developed new technologies, etc.). In fact, the more often extreme weather occurs, the more adaptive is our response (see for example, decreasing mortality in heat waves). So in that sense, climate change may hasten our adaptive response and reduce our overall vulnerability to it.

A large and rapid sea level rise is a bit of a different story—although perhaps not entirely so.

While we do have a large amount of infrastructure (e.g., big cities) in low-lying coastal regions, it is completely wrong to show them underwater in the future—a typical device used by climate activists. What will happen is that we will act to protect the most valued portions of that infrastructure, as shown in a recent report from leading experts (including from the U.S. Environmental Protection Agency) on sea level rise and response.

But, while targeted action will save our big cities, there is still a lot of real estate that will be lost if sea level rises a large amount in a short amount of time (say, by more than a meter [a little more than 3 feet] by the end of the 21st century).

We therefore keep a vigilant eye on sea level rise research. And what we’ve concluded is that sea level rise by the year 2100 is very likely to be quite modest, say about 15 inches—an amount that should allay concerns of a catastrophe. We’ve detailed literature in support of our conclusions here, there, and elsewhere.

This week, a new paper has come to our attention that further supports our synthesis.

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