a systemic view 2
Trilemma
Governance Multiple-benefit strategies LEGEND
Biodiversity conservation
Food security Climate protection
Multiple-benefit- strategy approach Competition for land can be
overcome by integrated land stewardship
TRILEMMA
TO INTEGRATION
16
the focus of the flagship report entitled ‘Governing the Marine Heritage’ (WBGU, 2013).
2.1
Land resources under pressure: overexploitation, degradation, competition for use
The pressure on terrestrial ecosystems from overex-ploitation and competition for use has never been greater than it is today (UNCCD, 2017b; Olsson et al., 2019). Land ecosystems are “the terrestrial portion of the biosphere that comprises the natural resources (soil, near surface air, vegetation and other biota, and water), the ecological processes, topography, and human settle-ments and infrastructure that operate within that sys-tem” (FAO, 2007; UNCCD, 1994 quoted by van Die-men, 2019:816). Typical natural terrestrial ecosystems are temperate deciduous and coniferous forests, tropi-cal rainforests, grasslands (e.g. savannas and steppes), tundra, taiga and deserts, riverine landscapes and wet-lands. Managed terrestrial ecosystems are areas that are used for agriculture, forestry or grazing.
A considerable proportion of managed and natural terrestrial ecosystems has already been damaged and is further threatened by climate change and biodiversity loss. This trend is alarming, especially in view of the increased demand particularly for animal products (UNCCD, 2017b:11; Box 2.1-1).
The process of human-caused (anthropogenic) land degradation involves the long-term deterioration in the status of terrestrial ecosystems. This in turn impairs biological productivity, ecological integrity and biodi-versity, and thus also the benefits the land provides for humans (van Diemen, 2019). In view of the valuable services that terrestrial ecosystems provide for
sustaining the natural life-support systems and the well-being of humankind (Figure 2.1-1; Section 2.2.3), this is extremely worrying.
2.1.1
Scale of and trends in the degradation of terrestrial ecosystems
Around a quarter of the Earth’s ice-free land surface is affected by human-caused degradation (IPCC, 2019b).
A look at the loss of fertile soils gives an indication of the dynamics of land degradation: it is estimated that soil erosion on agricultural fields is currently 10 to 20 times (with no tillage) to more than 100 times (with conventional tillage) higher than the rate of soil forma-tion. At present, the degradation of the Earth’s land surface by human activities is affecting the well-being of at least 3.2 billion people. Closely linked to these degradation processes is the fragmentation and loss of habitats, which is simultaneously a key factor in the biodiversity crisis (Section 2.2.3).
Researchers agree that land degradation represents a serious global problem (Olsson et al., 2019:365).
However, to date there is no undisputed measure that reliably maps the scale and dynamics of terrestrial eco-system degradation. Moreover, the terms land and soil degradation are often used synonymously (Gomiero, 2016:24). There are conceptual (how is land degrada-tion defined?) and methodological reasons (how is land degradation measured?) behind this: in the early 1990s, degradation processes were predominantly measured in terms of soil degradation, i.e. focusing on the upper-most weathering layer of the Earth’s crust (e.g. Olde-man et al., 1990; WBGU, 1994). Compared to soil deg-radation, the term land degradation is more
compre-50%
100%
75%
25%
0%
Percentage of global ice-free land area
Wildlands
Semi-natural Rangelands
Croplands Densely settled
3000
6000BC 1000 0 1000 1500 1750 1900 1950 2000
Year
Figure 2-1
Transformation of the ice-free land surface by humans in the last 8,000 years.
Source: UNCCD, 2017b
17 hensive and includes the degradation of all terrestrial
ecosystems (IPBES, 2018a:662). Especially under the influence of the Millennium Ecosystem Assessment of 2005, the focus shifted to changes in ecosystem ser-vices. Neither the 1990 Global Assessment of Soil Deg-radation (GLASOD), nor the 2008 Global Assessment of Land Degradation and Improvement (GLADA) provided a comprehensive, quantitative and unequivocal picture of global land degradation (IPBES, 2018a:536).
More recent studies measure land degradation as the loss of net primary production, often using satellite data (Jackson and Prince, 2016). One way of estimating degradation trends in a region is to observe the dynam-ics of the land’s primary production. Net primary pro-duction describes the amount of carbon that ecosys-tems accumulate through photosynthesis, minus the carbon released by plant respiration. A study by the European Commission’s Joint Research Centre con-cludes that between 1999 and 2013 about 20% of the Earth’s vegetation-covered land surface showed persis-tently declining trends in land productivity (Cherlet et al., 2018). This indicates ongoing soil and/or land deg-radation. The changes observed in this long-term study of cropland, pasture, grassland and forest landscapes, broken down by continent, showed declining or
unsta-ble productivity, particularly in Australia and Oceania (affecting 37% of the area), South America (27% of the area) and Africa (22% of the area). Declining or unsta-ble productivity affected 14% of terrestrial ecosystems in Asia, 12% in Europe and 18% in North America.
Cherlet et al. (2018:114) describe it as “alarming that 20% of the world’s croplands show declining or stressed land productivity, particularly considering that immense effort and resources are being committed to maintain and enhance the productivity of arable and permanent cropland, as well as the fact that there are clear limita-tions to the further expansion of cropland.” Overall, the approaches and methods used to measure global land degradation vary, ranging from expert estimates to on-site observations and measurements, remote-sens-ing data and simulation models.
The third edition of the European Commission’s World Atlas of Desertification, with the participation of the UNCCD, attempts to present the different facets of deg-radation as a “convergence of evidence” against the background of the different methods (Cherlet et al., 2018:143). To this end, 14 “global change issues” (e.g.
tree loss, water stress, decreasing land productivity, live-stock density, population density) were selected whose interaction points to degradation processes. Further
0% 20% 40% 60% 80% 100%
a Human appropriation of production of biomass
Remaining areas of wilderness in 2009 (23.2% of total land area)
c Wilderness area
−80% −60% −40% −20% 0% Increase
No data
No data No data
No data b Change in soil organic carbon (SOC)
−100% −80% −60% −40% −20% 0%
d Loss of species richness Percent of potential NPP
(Appropriated for human use in 2000)
Percent change in soc from original condition to 2010 Percent of species lost from original condition to 2005
Figure 2-2
Effects of human activities on land surfaces.
Source: IPBES, 2018a: XXXIII
18
evaluation with the aim of identifying critical areas of soil or land degradation requires an analysis of the inter-play between the different indicators using additional (regionally specific) information (UNCCD, 2017b:53).
The key message is that soil and land degradation is a complex global phenomenon with marked differences between regions and between the most important sys-tems of land cover and land use, which cannot be mea-sured by one or a small number of indicators. The Global Land Outlook (GLO; UNCCD, 2017b), first published in 2017 – the next edition of which is planned for 2021 – also follows the “convergence of evidence” approach.
This approach includes the synopsis of data on land cover and land use as well as biophysical and socio-eco-nomic factors relevant to land degradation.
2.1.2
Drivers of land degradation and consequences The most important direct drivers of terrestrial ecosys-tem degradation (also land degradation) are the conver-sion of natural or near-natural vegetation into arable and pasture land, non-sustainable agricultural and for-estry practices, climate change, and in some regions the extraction of raw materials, as well as infrastructure
development and urban sprawl (IPBES, 2018a:XX).
Although human settlements occupy only about 5% of the Earth’s terrestrial surface, they are often located in particularly fertile areas (UNCCD, 2017b:42). Unsus-tainable cultivation of arable and pasture land ( Section 3.3) is currently the biggest direct driver of land degradation (IPBES, 2018a).
Between 1963 and 2005, the global area under food crops increased by about 270 million hectares. During this period, 26% of the expansion was attributed to dietary changes and 74% to population growth (Kast-ner et al., 2012, quoted in IPBES, 2018a:150). One example of massive soil erosion triggered by unsustain-able soil management was the Dust Bowl event in the USA and Canada in the mid-1930s (Worster, 1987).
Large-scale cultivation of the Great Plains prairie land-scapes primarily to grow wheat, intensified by years of drought, led to soil erosion (deep-rooted prairie grass had previously protected the soil) and devastating sandstorms. Harvests were destroyed and numerous farms were almost buried in sand. Many farmers had to leave their land. As a reaction, the US Soil Conservation Service (today Natural Resources Conservation Service) was founded a few years later.
The Green Revolution, which has achieved signifi-cant successes in increasing the production of rice,
Retingula
g at M
liaer
Non material
Ecosystem-service
Habitats
Pollination Air quality
Climate
Ocean acidification Quantity
of freshwater
Soils Diseases
Extrem e eve
nts Energy
Food
Quality of fresh
water Materials
Medicine Education
Physis un d Psyche
to hom e Em
otional attachm
ent Optio
ns fo r the
future
! ?
Figure 2.1-1 There are a total of 18 ecosystem services which can be divided into three categories: ‘regulating’ (e.g.
climate and water quality),
‘material’ (natural resourc-es) and ‘non-material’ (e.g.
education).
Source: WBGU, based on IPBES, 2019a
19 wheat and maize since the 1960s, has also contributed
greatly to land degradation. Examples of these degra-dation processes include the lowering of the water table as a result of irrigation, salinization due to irrigation errors, soil erosion caused by using flawed tillage meth-ods and the exposure of uncovered soil to the effects of weather, the monocultivation of maize, the contamina-tion of the environment through the excessive use of fertilizers and liquid manure (over-fertilization), the overuse of pesticides, and the impoverishment of spe-cies and varietal diversity as a result of the spread of monocultures. Soil and land degradation are also gener-ated by ‘soil mining’, i.e. the cultivation of crops with-out adequately replacing the nutrients removed by the crops (under-fertilization, as in the case of resource-poor subsistence farms). The expansion of industrial agriculture was accompanied by the de-integration of functions in cultivated landscapes. Well-known exam-ples of this are the land consolidation process in West Germany from 1954 onwards and the consolidation of agricultural land during the establishment of agricul-tural production cooperatives in the GDR in the 1950s.
These land-consolidation measures, during which the landscape was adapted to the use of machinery by clearing hedges and orchards, destroying field margins or canalizing watercourses, exacerbated biodiversity loss and soil degradation through wind and water ero-sion. Overall, the creation of large-scale agricultural units led to a loss or monotonization of historical cul-tural landscapes. This is a pattern of landscape transfor-mation that can be observed worldwide, but varies in its mani festation.
The main drivers of forest degradation and loss (Box 2.1-1) are changes in land use (e.g. for agriculture, including slash-and-burn and settlements) and timber production for use as construction material or fuel.
55% of the global timber harvest is used exclusively for cooking and heating with firewood and charcoal – this affects 2.8 billion people (Bailis et al., 2015), mainly on the African continent.
Finally, the degradation of terrestrial ecosystems is both a driver and a consequence of climate change (IPBES, 2018a:XIII). The effects of virtually all direct causes of land degradation are exacerbated by climate change. These include accelerated soil erosion on degraded land as a result of extreme weather events, an increased risk of forest fires and changes in the distri-bution of invasive species, harmful insects and patho-gens. Examples include the granaries of Asia, e.g. rice cultivation in the Indus and Ganges deltas (salinization;
Patel, 2011), rice cultivation in the Mekong delta (sea-level rise; Bindoff et al., 2007) and increased droughts in the rice-growing regions of northern China (Lin et al., 2013).
Climate change can limit possible ways of combating land degradation, such as ecosystem restoration or the conservation of protected areas. In the long term, changes in the climate in the 21st century threaten to become an increasingly important driver of soil degra-dation (IPBES, 2018a:XLII). The degradegra-dation of terres-trial ecosystems also contributes to climate change, since large amounts of carbon are released into the atmosphere when forests are cleared, peatlands drained or pastureland overused (Figure 2.1-2).
33.3 372
30 191
37.3 588
9.5 121
14.8 117
6.2 657
2 10
Woods Grassland Deserts, semi-deserts
Wetlands, peatlands
Farmland
Land for settlements Area [million km2]
Stored carbon [Gt C]
Tundra
Figure 2.1-2
Carbon storage in terrestrial ecosystems.
Source: Bodenatlas, 2015; Bartz/Stockmar, CC BY-SA 3.0
20
Box 2.1-1
Deforestation: status and trends
Global deforestation is continuing albeit at a slower speed. An estimated 420 million hectares of forest were lost worldwide between 1990 and 2020. From 2015 to 2020, the annual deforestation rate was estimated at 10m ha, compared to 12m ha from 2010 to 2015 (FAO, 2020h; Figure 2.1-3). Tropical forests are the most seriously affected. An intercontinental comparison of the situation over the last decade reveals the following (FAO, 2020h):
> From 2010 to 2020, Africa had the highest rate of annual net forest loss by intercontinental comparison: 3.9m ha.
The main reason is the conversion of forest into arable land and the production of charcoal for lack of other fuels.
> From 2010 to 2020, South America had an annual net for-est loss of 2.6m ha, although the rate of loss has decreased considerably and is today about half the rate it was from 2000 to 2010.
> Asia had the highest net gain in forest area between 2010 and 2020.
> Oceania recorded net losses of forest cover in the decades 1990 to 2000 and 2000 to 2010.
The most likely hotspots of global deforestation in the future will be Amazonia, the Congo Basin, parts of East Africa, Sumatra, Borneo, New Guinea, parts of Southeast Asia and eastern Australia (Figure 2.1-4).
Million ha per year
1990–2000 15
10 5 0 -5 -10 -15 -20
8
-16
10
-15
7
-12
5
-10
Forest expansion Deforestation
2015–2020 2010–2015
2000–2010 Year
Figure 2.1-3
Annual rate of deforesta-tion and forest expansion.
Source: FAO, 2020g
Deforestation fronts + projected deforestation (2010–2030) Forest
Amazon 23–48 million ha
Cerrado 15 million ha
Congo Basin 12 million ha
East Africa 12 million ha Chocó-Darién
3 million ha
Borneo 22 million ha
Sumatra 5 million ha
New Guinea 7 million ha Greater Mekong 15–30 million ha
Atlantic Forest Gran Chaco 10 million ha
Eastern Australia 3–6 million ha
Figure 2.1-4
Expected hotspots of global deforestation up to 2030.
Source: IPBES, 2018a: 285; © Text and graphics: 2015 WWF
21 2.1.3
Land Degradation Neutrality as a goal of international sustainability policy
The fight against land degradation and the issue of sus-tainable land stewardship are an integral part of the UNCCD in particular. With the inclusion of the goal of Land Degradation Neutrality (LDN) in the list of SDGs, the target of achieving a “land degradation-neutral world” by 2030 was agreed in 2015 (SDG 15 and 15.3).
This goal is about offsetting land degradation caused by economic development in a different location (e.g. by ecosystem restoration), so that overall no further deg-radation takes place and the net effect in terms of land degradation is zero (Wunder et al., 2018b). Land deg-radation neutrality “is a state whereby the amount and quality of land resources necessary to support ecosys-tem functions and services and enhance food security remain stable or increase within specified temporal and spatial scales and ecosystems” (UNCCD, 2015). The goals of land degradation neutrality are (Cherlet et al., 2018:237)
> to maintain or improve ecosystem services;
> to maintain or improve land productivity in order to enhance food security;
> to increase the resilience of terrestrial ecosystems, for example against natural disasters;
> to search for synergies with other environmental objectives;
> to strengthen good governance of land tenure.
These goals are also set out in the UNCCD Strategic Framework 2018-2030 (UNCCD, 2017a). In summary, the protection, sustainable use and restoration of ter-restrial ecosystems are a prerequisite for protecting bio-diversity and the climate and for establishing a sustain-able food system. The pressure to act is greater in the Anthropocene than ever before in the history of humankind.
2.2
The trilemma of land use
In its analyses on land stewardship, the WBGU focuses on three global crises: the climate crisis (Section 2.2.1), the food-system crisis (Section 2.2.2) and the biodiver-sity crisis (Section 2.2.3). The current destruction, deg-radation and fragmentation of terrestrial ecosystems is accelerating anthropogenic climate change, driving bio-diversity loss and impairing food security. All three crises, each in its own way, are related to the use of land or terrestrial biomass and, in turn, have an impact on global land use and terrestrial ecosystems. Attempts to mitigate these crises can further increase the pressure
on the land and increase competition: ‘negative emissions’, i.e. measures for the removal of CO2 from the atmosphere, which are increasingly being discussed in the context of climate-change mitigation, add another new and potent ‘customer’ for the services of terrestrial ecosystems and land. The conservation of biodiversity is not possible without an expanded and upgraded sys-tem of protected areas, comprehensive ecosyssys-tem res-toration and the sustainable use of cultivated areas.
Right up to today, the task of feeding a growing world population has been accompanied by a continuous increase in land-intensive dietary habits. As a result, there are warnings against growing global competition for land use (Smith, 2018). In the present report, the WBGU refers to the potential competition between these three dimensions as the ‘trilemma of land use’
( Figure 2.2-1). Further demand – e.g. for space for hous-ing and roads or from the bioeconomy – intensifies this competition.
The WBGU has chosen the term ‘trilemma’ because it initially looks as if each of these crises can only be overcome at the expense of the other two. For example, in many cases it seems we have to make a choice:
expand agricultural land or expand protected areas;
produce animal feed or create carbon reservoirs; pro-tect near-natural areas or increase the use of biomass.
Finding solutions here will be a determining factor for sustainable land stewardship.
The global land surface is limited, as is the amount of biomass that can be produced by the ecosystems.
Humans currently use about a quarter of potential ter-restrial net primary production for their needs such as food, feeds, fibre, wood and energy (IPCC, 2019b:5;
Krausmann et al., 2013). An unlimited expansion of use is obviously not possible, so it must be a matter of rec-onciling and, where necessary, prioritizing the different increasing claims. This also means that the drivers of these claims on use must be taken into account to reveal ways of reducing uses. The following sections initially examine the three crises and their systemic linkages, before a positive vision for land stewardship is devel-oped in Section 2.3.
2.2.1
The climate crisis
Anthropogenic climate change continues unabated despite the political agreement reached in Paris in 2015. The last decade was the warmest decade on record and 2015 to 2019 were the five warmest years since records began. The global average increase in tem-perature since the beginning of industrialization is cur-rently 1.1°C (WMO, 2019). The Intergovernmental
22
Panel on Climate Change’s Special Report ‘Global Warming of 1.5°C’ published in 2018 shows unequivo-cally that the impacts and risks of climate change already significantly intensify with an increase of between 1.5°C and 2°C, and will rise even more sharply if temperatures increase above this level (IPCC, 2018).
This can lead to so-called tipping points being exceeded, beyond which distinct system changes occur that would no longer be reversible even if the temperature were to fall – e.g. the melting of the Greenland ice sheet (Len-ton et al., 2019). A study (Steffen et al., 2018) also indicates the possible existence of a threshold value beyond which a greatly accelerated rise in temperature could be triggered by biogeophysical feedback
This can lead to so-called tipping points being exceeded, beyond which distinct system changes occur that would no longer be reversible even if the temperature were to fall – e.g. the melting of the Greenland ice sheet (Len-ton et al., 2019). A study (Steffen et al., 2018) also indicates the possible existence of a threshold value beyond which a greatly accelerated rise in temperature could be triggered by biogeophysical feedback