Category: Global Biodiversity and Ecosystem Services

Status and trends of terrestrial and marine ecosystems; biodiversity

July was hot!

Widespread heat set record temps globally

July was remarkably warm, in fact July’s average temperatures—for both land and sea–were the highest monthly temperatures ever recorded since 1850.  This image from NOAA illustrates some of the more noteworthy records set last month.


I should also mention that Berkeley Earth (, in their summary of 2018 global temperatures published early this year, estimated that 2019 would “…likely… be warmer than 2018, but unlikely to be warmer than the current record year, 2016.  At present it appears that there is roughly a 50% likelihood that 2019 will become the 2nd warmest years since 1850.” As of August 15, they are now predicting a 90% probability of this occurring.   This screenshot from Robert Rohde’s (BerkeleyEarth) Twitter feed illustrates long-term weather stations (those with at least 40 years of records) that have reported a daily, monthly or all-time record high temperature from May 1st to July 31st.  Looks like a sea of red!

Screenshot, August 19 @RARohde

Some of the more attention-grabbing aspects of the late July heat wave came from Greenland.

Warm air masses from Europe arrived over Greenland late in July and early August, causing record-setting melting across about 90% of the ice sheet during a five-day event.  Melt area reached 154,500 square miles, 18% larger than the 1988-2017 average. The record warmth established an all-time high melt event for this monthly period, and total ice mass loss for 2019 is nearly equal to that of 2012, the year of highest loss for the satellite-era.  (National Snow and Ice Data Center Greenland Today)

It’s not all about the records!

Considerable attention has been given to elevated Arctic temperatures, increased ice-sheet melt and its contributions to sea-level rise,  and low seasonal sea-ice coverage, but several other issues attending warming air and sea temperatures warrant discussion as well.   Over the longer term—decades, not days, warming temperatures are measurably impacting terrestrial and marine ecosystems.  These “slow” ecosystem changes aren’t as attention-grabbing as all-time records of high temperature or ice melt, but are one of the distinguishing characteristics of the Anthropocene. (see “The Anthropocene” tab on the Home page).  Let’s look at a couple of examples, one from terrestrial ecosystems, and one from marine ecosystems. 

In a July 10 article (Hydrologic Intensity) the authors demonstrate in a more complete fashion than previous work, the linkage between rising air temperatures and acceleration of the hydrological cycle.  Their model incorporates both the supply of water (precipitation) and demand (evapotranspiration) between the surface and the atmosphere.  Reinforcing other research that suggests hydrologic intensification is occurring, the new research shows “widespread hydrologic intenstification from 1979-2017 across much of the global land surface, which is expected to continue into the future.”  The findings add a little more support to the likelihood of a climate future where there is “increased precipitation intensity along with more days with low precipitation.”  The temporal and spatial distribution of hydrologic intensification will have important consequences ranging from urban flood control to the management of  agroecosystems—an issue of considerable importance as population rises this century. 

Marine fisheries are also significant food sources for global populations.  In an article published in March (Science researchers looked at 235 marine fisheries (fish and invertebrates) from 38 ecoregions, representing one-third of reported global catch.   They  concluded that there has been a statistically significant decline in the maximum sustainable yield of 4.1% from 1930 to 2010 that is linked to warming oceans. Five of the ecoregions had losses of 15 to 35%. The authors conclude that “ocean warming has driven declines in marine fisheries productivity and the potential for sustainable fisheries catches.”  These trends are exacerbated by overfishing, but sound management plans incorporating temperature-driven trends have the potential for remediating these changes. 

Both examples suggest that temperature-driven changes to key provisioning services of  terrestrial and marine ecosystems are of equal importance to the headline-grabbing temperature and ice-melt records of the last month.  These changes are “slow-motion” impacts of a warming world; like rising sea-levels, ecosystem changes will have profound impacts, but are invisible over short-term news and policy cycles in which we appear to be ensnared.   

Blog Image Source:

More veggies, less meat to help save forests and climate

The recently (Aug 7) released Special Report on Climate Change and Land by the IPCC ( offers a comprehensive review of the nexus between global warming/climate change and land use change.  As I have already suggested in the “About this blog,” land use changes are a critical aspect of global anthropogenic change; i.e. the Anthropocene. The new report stresses how a changing climate (increased air temperatures, evapotranspiration, altered precipitation regimes, etc.) impact soils and vegetation.  The latter underlie ecosystem health, including agroecosystems, as well as intact “undisturbed” terrestrial ecosystems such as rainforests, peatland, and coastal forests.  These are critical harbors of biodiversity, as well as essential elements in the provision of ecosystem services upon which human well-being depends, such as carbon sequestration and clean water. 

Land use changes associated with agriculture, forestry, livestock, road construction, and urbanization degrade these critical services, thereby threatening our ability to sustainably provide food, fiber and other essential goods and services to a continually growing, telecoupled global population.  Imprudent and ill-planned (or adhoc) conversion of various terrestrial ecosystems in pursuit of food, fiber and mineral resources has led to land degradation, desertification and biodiversity loss at both a scale and speed that are without precedent.

The report emphasizes the urgent need to rein in these unsustainable practices in order to both guarantee our ability to provide food for the world, as well as provide a crucial sink for growing carbon emissions.  According to the report, reducing forest deforestation and degradation are critical elements in mitigating green house gas emissions.  Furthermore, transitioning the global population to a much more plant-based diet from one that is significantly animal-sourced, will reduce risks from climate change as well as help reduce agricultural extensification. 

Only a wide-ranging and comprehensive approach to managing both our energy and land resources will provide sustainable, equitable and healthy outcomes for the global population.  Immediate steps need to be taken, because the longer business as usual behaviors continue, our ability to deploy a wide variety of remedies will be increasingly foreclosed.  Reducing green house emissions and altering detrimental land use practices are thus interconnected, inseparable and our failure to change both may lead to both irremediable impacts to ecosystems and the goods and services upon which humanity relies.

Image: Photo by Tobias Quartey on Unsplash


Rate and Scope of Extinction Source: (“Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services” published in draft form 29 May 2019.) Summary for Policymakers-Advance Draft

The global rate of species extinction is already at least tens to hundreds of times higher than the average rate over the past 10 million years and is accelerating (established but incomplete) {} 

  • Human actions have already driven at least 680 vertebrate species to extinction since 1500
  • The threat of extinction is also accelerating: in the best-studied taxonomic groups, most of the total extinction risk to species is estimated to arisen in the past 40 years (established but incomplete) {}.
  • The proportion of species currently threatened with extinction according to the IUCN Red List criteria averages around 25 per cent across the many terrestrial, freshwater and marine vertebrate, invertebrate and plant groups that have been studied in sufficient detail to support a robust overall estimate (established but incomplete) {, 3.2}
  • More than 40 per cent of amphibian species, almost a third of reef-forming corals, sharks and shark relatives and over a third of marine mammals are currently threatened {, 3}.
  • The proportion of insect species threatened with extinction is a key uncertainty,but available evidence supports a tentative estimate of 10 per cent (established but incomplete) {}.

            Those proportions suggest that, of an estimated 8 million animal and plant species (75% of which are insects), around 1 million are threatened with extinction   (established but incomplete) {}.

What is the reasoning behind the well-publicized (and controversial) estimate of “1 million threatened species?” (See explanations by Dr. Andy Purvis here:

  • The Living Planet Index, which synthesises trends in vertebrate populations, has declined rapidly since 1970, falling by 40% for terrestrial species, 84% for freshwater species and 35% for marine species (established but incomplete) {}.
  • On land, wild species that are endemic (narrowly distributed) have typically seen larger-than-average changes to their habitats and shown faster-than-average declines (established but incomplete) {,}.

A substantial proportion of assessed species are threatened with extinction and overall trends are deteriorating, with extinction rates increasing sharply in the past century. (A) Percentage of species threatened with extinction in taxonomic groups that have been assessed comprehensively, or through a ‘sampled’ approach, or for which selected subsets have been assessed, by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Groups are ordered according to the best estimate for the percentage of extant species considered threatened (shown by the vertical blue lines), assuming that data deficient species are as threatened as non-data deficient species. (B) Extinctions since 1500 for vertebrate groups. Rates for reptiles and fishes have not been assessed for all species. (C) Red List Index of species survival for taxonomic groups that have been assessed for the IUCN Red List at least twice. A value of 1 is equivalent to all species being categorized as Least Concern; a value of zero is equivalent to all species being classified as Extinct. Data for all panels derive from (see Chapter 3 Figure 3.4 and Chapter 2 Figure 2.7).

  • The number of local varieties and breeds of domesticated plants and animals and their wild relatives has been reduced sharply as a result of land use change, knowledge loss, market preferences and large-scale trade (well established) {,}.
  • Human-driven changes in species diversity within local ecological communities vary widely, depending on the net balance between species loss and the influx of alien species, disturbance-tolerant species, other human-adapted species or climate migrant species (well established) {}.
  • Many organisms show ongoing biological evolution so rapid that it is detectable within only a few years on even more quickly – in response to anthropogenic drivers (well established) {,}. Management decisions that take those evolutionary changes into account will be noticeably more effective (established but incomplete)

Drivers of observed changes to nature and ecosystem services

 Direct and indirect drivers of change have accelerated during the past 50 years

The rate of global change in nature during the past 50 years is unprecedented in human history. The direct drivers of change in nature with the largest global impact have been (starting with those with most impact): changes in land and sea use; direct exploitation of organisms; climate change; pollution; and invasion of alien species. Those five direct drivers result from an array of underlying causes – the indirect drivers of change – which are in turn underpinned by societal values and behaviours that include production and consumption patterns, human population dynamics and trends, trade, technological innovations and local through global governance. The rate of change in the direct and indirect drivers differs among regions and countries.

Global Biodiversity and Ecosystem Services

Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services

(IPBES) 2019 Global Assessment Report on Biodiversity and Ecosystem Services

I have selected highlights from the policymaker summary and have largely followed the sequence in that summary.  I have reorganized some sections and (for the most part), follow the order and arrangement of the bold-faced sections in “Background” of the Summary, which begins on page nine of the IPBES policy summary.  The authors of the IPBES reports qualified their conclusions/findings with expressions such as “well established,” “established but incomplete,”and “inconclusive,” depending on the strength of studies and other criteria underlying each area of concern. (See Global Trends table below).  I include these comments, as well as the sections in the various reports which further elaborate these findings.  These sections are enclosed by { }.  There is a vast amount of material in the various reports, which are hyperlinked below. 

For those unfamiliar with the goals and scope of the IPBES effort, we include the link to the IPBES Global Assessment Preview, which summarizes the assessment.

Assessment Reports Links

1.  Assessment Report on Pollinators, Pollination and Food Production

2.  Global Assessment Report on Biodiversity and Ecosystem Services

3.  Assessment Report on Land Degradation and Restoration

4.  Assessment Report on Biodiversity and Ecosystem Services for Europe and Central Asia

5. Assessment Report on Biodiversity and Ecosystem Services for Asia and the Pacific

6.  Assessment Report on Biodiversity and Ecosystem Services for Africa

7.  Assessment Report on Biodiversity and Ecosystem Services for the Americas

8.  Assessment Report on Scenarios and Models of Biodiversity and Ecosystem Services

Status of Nature and Ecosystem Services—Highlights from the Summary for Policymakers

(“Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services” published in draft form 29 May 2019.) Summary for Policymakers-Advance Draft

Nature and its vital contributions to people, which together embody biodiversity and ecosystem functions and services, are deteriorating worldwide

Nature’s goods and services:  Global trends

Global trends in the capacity of nature to sustain contributions to good quality of life from 1970 to the present, which show a decline for 14 of the 18 categories of nature’s contributions to people analyzed. Data supporting global trends and regional variations come from a systematic review of over 2,000 studies {}. Indicators were selected on the basis of availability of global data, prior use in assessments and alignment with 18 categories. For many categories of nature’s contributions, two indicators are included that show different aspects of nature’s capacity to contribute to human well-being within that category. Indicators are defined so that an increase in the indicator is associated with an improvement in nature’s contributions.

Humanity is a dominant global influence on life on earth, and has caused natural terrestrial, freshwater and marine ecosystems to decline (well established)

Other drivers of global change

Source: (“Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services” published in draft form 29 May 2019.) Summary for Policymakers-Advance Draft {} refer to chapters in the summary

  1. Climate change is already having an impact on nature, from genes to ecosystems. It poses a growing risk owing to the accelerated pace of change and interactions with other direct drivers (well established) {2.1.12, 2.1.18,}.
  2. Unsustainable use of the Earth’s resources is underpinned by a set of demographic and economic indirect drivers that have increased, and that furthermore interact in complex ways, including through trade (well established) {2.1.6}.
  • Due to expansions of infrastructure, extensive areas of the planet are being opened up to new threats (well established) {2.1.11}
  • Long-distance transportation of goods and people, including for tourism, have grown dramatically in the past 20 years, with negative consequences for nature overall (established but incomplete).
  • Distant areas of the world are increasingly connected, as consumption, production, and governance decisions increasingly influence materials, waste, energy, and information flows in other countries, generating aggregate economic gains while shifting economic and environmental costs, which can link to conflicts (established but incomplete)
  • Governance has at many levels moved slowly to further and better incorporate into policies and incentives the values of nature’s contributions to people. However, around the globe, subsidies with harmful effects on nature have persisted (well established) {2.1, 3, 5, 6.4}.
  • Governance has at many levels moved slowly to further and better incorporate into policies and incentives the values of nature’s contributions to people. However, around the globe, subsidies with harmful effects on nature have persisted (well established) {2.1, 3, 5, 6.4}.


Mangrove Deforestation between 2000 and 2012 Source: Section; http://

USGS ecologists produced this map of mangrove deforestation in Burma’s (Myanmar’s) Irrawaddy Delta using an older version of the Global Land Survey dataset. Recent improvements are allowing them to map mangrove deforestation worldwide. (Map adapted by Robert Simmon from Giri et al., 2008.)  NASA Earth Observatory  

Significance:  Mangroves represent a unique ecosystem in coastal area supporting a rich biodiversity and providing a range of nature’s contribution to people including provisioning, regulating and supporting, crucial for the sustenance of local communities.  There ecosystem service benefits have been valued at an average of 4200 US$/hectare/year.*  They provide coastal protection against storms and flooding, are critical nursery habitats for fish, birds and marine mammals, act as effective nutrient filters.* South-East Asian mangroves are among the most species diverse in the world, having 268 plant species including 52 taxa growing exclusively in mangrove habitat. Mangrove forests and forests soils can also store significant amounts of organic carbon.*

Status:  Recent changes in land use primarily for aquaculture has led to transformation of mangroves (up to 75 per cent in the last 3 decades.  Mangroves exist in coastal areas where development demand is high and are being highly threatened by land-use change (see 4.1.2; 4.4.1). An estimated 1,140 km2 of mangroves have been lost between 2000 and 2012 in South-East Asia, with an average rate of 0.7-3.0 per cent per year.

Source: http://

Threats include rapid urbanization (Philippines, Thailand, Vietnam), aquaculture (e.g., shrimp farming), paddy farming (Myanmar), expansion of oil palm (Malaysia and Indonesia, including new development in Papua) (See Figure above and chart below) In Asia, more than 50 per cent of mangroves have been lost to support aquaculture, with 40 per cent of mangroves in the Philippines lost to agriculture.

Indirect anthropogenic changes include those related to climate change—drought (e.g., Gulf of Carpentaria, Australia Nov-Dec 2016); rising sea levels pose a threat to mangroves in Bangladesh, New Zealand, Vietnam and China. Loss of mangrove forests and soils also removes carbon storage; Indonesia, Malaysia and Myanmar contributed 77% of global mangrove organic carbon storage loss between 2000-2015.*

*Source:  Jonathan Sanderman et al 2018 A Global map of mangrove forest soil carbon at 30m resolution. Environ. Res. Lett. 13 055002

Top 20 nation rankings for (a) total mangrove area lost between the years 2000 and 2012, (b0 area loss as a percent of year 2000 mangrove area, (c) total soil organic carbon stocks, (d) carbon loss as a percent loss of year 2000 soil carbon stock. Range in values for (c) and (d) come from 25%-100% loss of carbon in upper meter in pixels identified as being deforested between the years 2000 and 2015.

Coral Reefs

Source: Section; Karki, et al., http://

  • Coral reefs are the most diverse coastal ecosystems on earth and of disproportionate ecological, economic and food security importance to the Asia-Pacific region which has an inordinate proportion of the world’s healthy coral reefs.  Coral diversity is highest in the Asia-Pacific region.
  • The death of reef-forming corals undermines resilience of coastal communities, and can lead to the collapse of important coastal ecosystems.
  • One third of reef- building corals in the region are threatened.
  • Loss of habitat quality, heavy damage to entire reefs are major threats in the region. In the case of El Niño event in 1998, 16 per cent of the world’s coral reefs and 50 per cent of those in the Indian Ocean were destroyed
  • Increase in sea temperature and ocean acidification have been projected as major drivers of change along coastal environments which may lead to decline in coral reefs.
  • Increasing outbreaks of crown of thorns starfish, a native predator that has boom bust cycles linked to environmental pollution from farm lined estuaries affected The Great Barrier Reef.
  • Coral bleaching events are also increasingly devastating to the northern two thirds of the reef over the last few years where coral-algae associations are disrupted by high sea temperature.  Habitats and communities in the Great Barrier Reef ranged from poor to worsening at the end of 2015, although some species like green turtle populations improved.
  • Among the most serious emerging threats to coral reefs are coral diseases, which have devastated coral populations throughout the Caribbean since the 1980s and accompanied the mass coral bleaching there in 2005 and 2006. Over 90 per cent of the main reef forming corals in the Caribbean have now died due to coral disease with the severity of disease outbreaks commonly correlated with corals stressed by bleaching.  Coral diseases are also being observed more frequently on Indo-Pacific reefs in heretofore unrecorded places such the Great Barrier Reef, areas of Marovo Lagoon in the Solomon Islands and the Northwestern Hawaiian Islands. The outbreaks seem to be related to bacterial infections and other introduced disease organisms, increasing pollution, human disturbance and increasing sea temperature, all of which have put reef-forming corals at serious risk.

Marine Ecosystems

Marine ecosystems, from coastal to deep sea, now show the influence of human actions, with coastal marine ecosystems showing both large historical losses of extent and condition as well as rapid ongoing declines (established but incomplete) {,}

  • Direct exploitation of fish and seafood has the largest relative impact in the oceans (well established) {}.
  • The direct driver with the second highest impact on the oceans is the many changes in the uses of the sea and coast land (well established) {} (See Summary of Observed Changes)

Distribution Of Changes In The Global Ocean

Source:  Halpern  (B. S., Walbridge, S., Selkoe, K. A., Kappel, C. V., Micheli, F., D’Agrosa, C., … Watson, R. (2008). A Global Map of Human Impact on Marine Ecosystems. Science, 319(5865), 948–952.doi:10.1126/science.1149345 

1.  Every square kilometer of the ocean is affected by some anthropogenic driver of ecological change

2.  Over 41% of the world’s oceans have medium to very high cumulative impacts:

  • North and Norwegian seas, South and East China seas, Eastern Caribbean, North American eastern seaboard, Mediterranean, Persian Gulf, Bering Sea, and the waters around Sri Lanka.

3.  Lowest impact areas include high-latitude Arctic and Antarctic poles, but this may change due to future polar ice loss

4.  Ecosystems with highest impacts include hard and soft continental shelves and rocky reefs, and coral reefs.

Summary of Observed Changes

Temperature Changes

  •  Rising sea surface temperatures; reduction in oxygen content; stratification; coral bleaching
  • Heat content increasing deeper into the ocean
  • Global ocean animal biomass consistently declines with climate change, and that these impacts are amplified at higher trophic levels (Source: Lotze, et al., Global ensemble projections reveal trophic amplification of ocean biomass declines with climate change. Ocean biomass declines with climate change
Source: Ocean biomass declines with climate change

Rising Sea Levels (“Looking past the horizon of 2100” Nature Climate Change)

  • Thermal expansion (warmer water expands)
  • Increased runoff from land-based ice sheets
    • Greenland
    • Antarctica
    • Mountain Glaciers

Changes in the Salinity of Seawater

  • Changes to the thermohaline circulation
  • Increased likelihood of seawater stratification

Threats to Coastal Populations and Infrastructure

  • Salt-water intrusion
  • Drowning forests
  • Inland migration of wetlands

Arctic Sea Ice is Shrinking

  • Warming air temperatures increase rate of melting
  • Positive feedback albedo loop

Increasing Ocean Acidity

  • Absorption of CO2 from atmosphere
  • Impacts to shell-forming species, including coralsAbsorption of CO2 from atmosphere

Land-Based Impacts

1.  Inorganic and organic pollutants

2.  Nutrient runoff (point and non-point) and associated hypoxia

Gulf of Mexico Dead Zone

3.  Aquaculture

4.  Invasive species

5.  Habitat destruction and alteration; e.g., coastal engineering; tourist development;  salt marshes, mangroves, seagrass beds, coral reefs

6.  Input and transfer of waterborne pathogens (runoff, aquaculture)

7.  Air pollution

a.  Toxic chemicals; e.g., POP’s over the Arctic zone by airborne volatilization;

b.    Mercury                          

Source:  Lavoie, R.A., Bouffard, A., Maranger, R., Amyot, M., 2018. Mercury transport and human exposure from global marine fisheries. Sci. Rep. 8, 6705.

Significance:  Human activities have increased the global circulation of mercury, a potent neurotoxin. Mercury can be converted into methylmercury, which biomagnifies along aquatic food chains and leads to high exposure in fish-eating populations.

Trends:  Mercury export from the ocean increased over time as a function of fishing pressure, especially on upper-trophic-level organisms. In 2014, over 13 metric tonnes of mercury were exported from the ocean. Asian countries were important contributors of mercury export in the last decades and the western Pacific Ocean was identified as the main source.

Estimates of per capita mercury exposure through fish consumption showed that populations in 38% of the 175 countries assessed, mainly insular and developing nations, were exposed to doses of methylmercury above governmental thresholds.

Given the high mercury intake through seafood consumption observed in several understudied yet vulnerable coastal communities, we recommend a comprehensive assessment of the health exposure risk of those populations.

Temporal trends (1950‒2014) of marine fisheries catches (dashed lines) and mercury exported (full lines). (a) Entire ocean (blue) and coastal (red) and high seas (orange) with breakpoint (circle) ± standard error (horizontal line). (b) Entire ocean (blue) and trophic levels (TL) rounded to the nearest integer: 4 (red), 3 (orange), and 2 (green).

Nutrients (N,P): Eutrophication, Dead Zones

Plastics (shipping, fishing, land-based sources)

  • Microplastics (nanoparticles; food chain)
  • Macroplastics (ingestion, entanglement, habitat loss (shorelines))
    • Great Pacific Garbage Patch

Source:   Lebreton, L, Slat, B, Ferrari, F, Sainte-Rose, B, Aitken, J, Marthouse, R, Hajbane, S, Cunsolo, S, Schwarz, A, Levivier, A, Noble, K, Debeljak, P, Maral, H, Schoeneich-Argent, R, Brambini, R & Reisser, J 2018, ‘Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic‘, Scientific Reports, vol. 8, no. 4666.

  • Ocean plastic can persist in sea surface waters, eventually accumulating in remote areas of the world’s oceans.
  • Our model, calibrated with data from multi-vessel and aircraft surveys, predicted at least 79 (45–129) thousand tonnes of ocean plastic are floating inside an area of 1.6 million km2; a figure four to sixteen times higher than previously reported.
  • Over three-quarters of the GPGP mass was carried by debris larger than 5 cm and at least 46% was comprised of fishing nets. Microplastics accounted for 8% of the total mass but 94% of the estimated 1.8 (1.1–3.6) trillion pieces floating in the area.
  • Plastic collected during our study has specific characteristics such as small surface-to-volume ratio, indicating that only certain types of debris have the capacity to persist and accumulate at the surface of the GPGP.

Finally, our results suggest that ocean plastic pollution within the GPGP is increasing exponentially and at a faster rate  than the surrounding waters.

Decadal evolution of microplastic concentration in the GPGP. Mean (circles) and standard error (whiskers) of microplastic mass concentrations measured by surface net tows conducted in different decades, within (light blue) and around (dark grey) the GPGP. Dashed lines are exponential fits to the averages expressed in g km−2: f(x) = exp(a*x) + b, with x expressed in number of years after 1900, a = 0.06121, b = 151.3, R2 = 0.92 for within GPGP and a = 0.04903, b = −7.138, R2 = 0.78 for around the GPGP.

Land Loss in Coastal Areas

Source:  Mentaschi, et al., Global long-term observations of coastal erosion and accretion, Scientific Reports volume 8, Article number: 12876 (2018)

On a global scale, between 1984 and 2015, the loss of permanent land in coastal areas amounts to almost 28,000 km2, roughly equivalent to the surface area of Haiti (Fig. a). This is almost twice as large as the surface of gained land (about 14,000 km2) over the same period. On the other hand, the overall surface of gained active zone (about 25,000 km2) is more than two times larger than the surface of lost active zone (about 11,500 km2). Overall, the gain of active zone roughly balances the loss of land, and the gain of land balances the loss of active zone. This translates into a net loss of approximately 14,000 km2 of surface for human settlements and terrestrial ecosystems (Fig. b).

Source:  Mentaschi, et al., Global long-term observations of coastal erosion and accretion, Scientific Reports volume 8, Article number: 12876 (2018)
On a global scale, between 1984 and 2015, the loss of permanent land in coastal areas amounts to almost 28,000 km2, roughly equivalent to the surface area of Haiti (Fig. a). This is almost twice as large as the surface of gained land (about 14,000 km2) over the same period. On the other hand, the overall surface of gained active zone (about 25,000 km2) is more than two times larger than the surface of lost active zone (about 11,500 km2). Overall, the gain of active zone roughly balances the loss of land, and the gain of land balances the loss of active zone. This translates into a net loss of approximately 14,000 km2 of surface for human settlements and terrestrial ecosystems (Fig. b).

Size distribution of cross-shore transition length above 50 m, for erosion and accretion of land (a) and active zone (b). Lost (c) and gained (d) land around the world; lost (f) and gained (g) active zone; balance gained – lost land (e) and active zone (h). Maps show the length of cross-shore erosion and accretion aggregated on coastal segments of 100 km. In all the maps the 4 spots with the highest local transition along a 250 m transect are indicated.

Drivers of shoreline change around the world

List of local cases of erosion/accretion discussed in Mentaschi, et al The legend provides for each spot a brief summary of the drivers of shoreline change
Land Loss in Coastal Areas: Shoreline modification “masks” true rates of shoreline change along the Atlantic Seaboard

Source:  Armstrong, S. B., &  Lazarus, E. D. 2019).  Masked shoreline erosion at large spatial scales as a collective effect of beach nourishmentEarth’s Future,  7,  74– 84

 (R)ecent rates of shoreline change along the U.S. Atlantic Coast are, on average, less erosional than historical rates. This shift has occurred despite evidence of intensified environmental forcing, including acceleration in rates of relative sea‐level rise and increased significant wave height in offshore wave climates. We suggest that the use, since the 1960s, of beach nourishment as the predominant form of mitigation against chronic coastal erosion in the United States…could explain the unexpected reversal in shoreline‐change trends.

Using U.S. Geological Survey shoreline records from 1830–2007 spanning more than 2,500 km of the U.S. Atlantic Coast, we calculate a mean rate of shoreline change, prior to 1960, of −55 cm/year (a negative rate denotes erosion). After 1960, the mean rate reverses to approximately +5 cm/year, indicating widespread apparent accretion despite steady (and, in some places, accelerated) sea‐level rise over the same period.

Cumulative sediment input from decades of beach‐nourishment projects may have sufficiently altered shoreline position to mask “true” rates of shoreline change. Our analysis suggests that long‐term rates of shoreline change typically used to assess coastal hazard may be systematically underestimated. We also suggest that the overall effect of beach nourishment along of the U.S. Atlantic Coast is extensive enough to constitute a quantitative signature of coastal geoengineering and may serve as a bellwether for nourishment‐dominated shorelines elsewhere in the world.