‘Landification’ – or ‘land emergence’: Even with sea level rise, around the world coastal land area has increased 13,000 square miles or about size of Belgium!

https://rogerpielkejr.substack.com/p/landification

By ROGER PIELKE JR.

What are long-term trends in global landification?

If sea level rise is ongoing and inexorable, then all else equal, the areal extent of global land areas should be shrinking, especially in low-lying continental areas and among tropical islands. Indeed that is the message that NASA is telling children, warning of the disappearance of large parts of the coastline, as shown below, with large parts of Florida and Louisiana succumbing to the seas.1

Sea levels around the world of course are rising and expected to continue to rise throughout the 21st century and beyond. However, from 1985 to 2015 — a period when global sea levels increased by about 60 millimeters (about 2.4 inches) — the areal extent of global coastal land increased by almost 34,000 square kilometers (about 13k square miles), or about the size of Belgium home to more than 11 million people.

If the notion of landification seems paradoxical or contrary to what you’ve read in the media, don’t worry, you won’t be not alone. I thought that also.

A team of Dutch researchers, Donchyts et al. 2016, warned that popular anecdotes can present a misleading picture of global trends in changes in the earth’s surface from land to water and vice versa. They write:

{G]eneral conclusions cannot be drawn from a limited sample of case studies. Instead, planetary-scale monitoring is needed to understand (and disentangle) the causes of detected changes and their attribution to natural variability, climate change or man-made change.

It turns out — as is so often the case on issues related to climate change — landification is influenced by many factors beyond just sea level rise. Many of these factors result from human activities other than those that influence climate change, especially the intentional or unintentional influence of human activities on land areas that might be far inland or in coastal regions.2

Climate reductionism once again seems to get in the way of a more nuanced and comprehensive understanding of global processes and dynamics. Let’s take a quick look at some relevant recent literature.

The literature on landification is in strong consensus that global land areas, even along coasts, are generally increasing in areal extent. For example, Mao et al. 2021 looked at global shorelines and found that instead of retreating on a global scale they are generally expanding:

In general, we found that accretion is the dominant trend over erosion across the world, suggested by the percentage of accretion/erosion along each latitude and longitude as well as the statistics for each continent (Fig. 9). The globally averaged shoreline change rate is about 0.26 m/yr, which is slightly larger than zero and suggests the global coastline is prograding. . . all continents except North America have coastlines that are, on average, accreting and have larger percentage of accretion than erosion.

In another study, Nienhuis et al. 2020 find a “net land gain” in river deltas around the world:3

Over the past 30 years, despite sea-level rise, deltas globally have experienced a net land gain of 54 ± 12 square kilometres per year (2 standard deviations), with the largest 1 per cent of deltas being responsible for 30 per cent of all net land area gains. Humans are a considerable driver of these net land gains—25 per cent of delta growth can be attributed to deforestation-induced increases in fluvial sediment supply.

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At the same time, the consequences of sea level rise for coasts around the world is not as simple as rising seas inexorably encroaching upon static land. Human influences such as sedimentation and reclamation make a big difference on outcomes. So too do natural processes of erosion and deposition. And there are other factors as well — for instance 2015 study argues that the Earth is expanding a little bit each year, to some degree offsetting the effects of sea level rise.6

Emphasizing sea level rise in the absence of these various other significant factors commits the same error that we have identified when future climate impacts are projected in the absence of adaptation to climate. Considering the effects of a single variable while ignoring other results is a sensitivity analysis, not a meaningful projection of the future.

Managing coastlines around the world will be a big challenge in the 21st century. It is also one that we are well prepared for.

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Kip Hansen: “Land emergence”  — or the gaining of dry land…Compare these two versions:  Google Translate version of the Japanese page with the English version provided by the publisher.

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Dr. Roger Pielke Jr.: “If sea level rise is ongoing and inexorable, then all else equal, the areal extent of global land areas should be shrinking, especially in low-lying continental areas and among tropical islands…However, from 1985 to 2015 — a period when global sea levels increased by about 60 millimeters (about 2.4 inches) — the areal extent of global coastal land increased by almost 34,000 square kilometers (about 13k square miles), or about the size of Belgium home to more than 11 million people.”

The literature on landification is in strong consensus that global land areas, even along coasts, are generally increasing in areal extent. For example, Mao et al. 2021 looked at global shorelines and found that instead of retreating on a global scale they are generally expanding:

At almost all latitudes and longitudes landification is winning out over erosion and SLR. Figure 9 from Mao et al. 2021.