Climate change

Climate change affects BFA and ecosystem ser-vices both directly and indirectly. Direct impacts include those caused by changes in rainfall,

13 the report cites Howard (2003).

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temperature and the frequencies of events such as droughts, cyclones/hurricanes, floods, fires and early or late frosts and by changes in plant flowering seasons and growing periods, animal breeding seasons, the oxidation rate of soil organic matter and the ranges and popula-tion dynamics of invasive species, pests, pathogens and disease vectors. Indirect impacts include those associated with climate change adaptation and mitigation strategies. For example, rising temper-atures in the tropics are pushing coffee growing towards higher elevations in mountainous areas, leading to replacement of natural vegetation (Läderach et al., 2017). This exposes more soil to erosion and degradation and affects water regu-lation, habitat provisioning and other ecosystem services. The ranges of some important pests, such

as the coffee berry borer (Hypothenemus hampei), have also extended to higher elevations – for example in East Africa (e.g. Jaramillo et al., 2011)

− prompting coffee farmers to spray pesticides in newly opened highland environments. Irrigation to counter the effects of a drier climate or more erratic rainfall may disrupt river flows and lead to negative effects on fisheries (Cochrane et al., eds., 2009).

Temperature changes associated with climate change can lead to shifts in flowering periods and mismatches between them and the active periods of pollinating insects, with negative consequences both for pollinator populations and for pollina-tion services (Kjøhl, Nielsen and Stenseth, 2011), although effects on pollination may be mitigated by the presence of a diverse range of pollinators box 3.1

Human-made grasslands as a cultural and ecological asset Switzerland’s species-rich mountain grasslands are a result

of hundreds of years of extensive agricultural activity that maintains open and semi-open habitats below the timberline. Without human interference, most of these habitats would quickly revert to their natural forest state, resulting in the loss of the existing biodiversity.

The primary function of these grasslands is to provide fodder for domestic grazing animals. However, landscapes and species diversity play an increasingly important role in attracting tourists, which creates additional income for mountain regions. With the ongoing intensification of agriculture in the surrounding lowlands, mountain grasslands increasingly function as refuges for species that were once common throughout Europe.

Mountain grasslands occupy 940 000 ha, or almost a quarter of the country’s total land area, and are still actively used. However, there is a trend towards intensification of grassland management near mountain farms and extensive use of marginal grasslands further away, and this is likely to increase. In particular, increases in the level of nitrogen input and altered grazing and/or mowing regimes have had significant negative effects on the extent and diversity of mountain grasslands.

To combat the decline of dry grasslands in general, and mountain dry grassland pastures in particular, the Federal Office for the Environment has established an inventory of dry grasslands of national importance. In 2010, the Federal Council approved a Federal Ordinance on the implementation of the Federal Inventory of Dry Grasslands.

The inventory includes 3 000 items representing 0.5 percent of the national territory (Federal Office for the Environment of Switzerland, 2018).

Mountain grassland in the Val d’Hérens, Canton of Valais. © Federal Office for Agriculture of Switzerland.

Source: Adapted from the country report of Switzerland.

SoB_book_dtp3.indb 79 04/02/19 09:22

(Bartomeus et al., 2013). Other seasonal abnor-malities such as more frequent cold or windy days in spring can also disrupt pollination services, with pollinator diversity again potentially playing a buffering role (Christmann and Aw-Hassan, 2012).

Shifting climatic zones are likely to require polli-nator species to alter their geographical ranges.

Some species may struggle to do this with suffi-cient speed (Bedford, Whittaker and Kerr, 2012).

The effects of climate change on soil ecosys-tems are complex and involve a large number of interacting processes and interactions with other drivers. Together with the diverse characteristics of soil ecosystems themselves, this means that it is dif-ficult to predict outcomes for soil biodiversity (Cock et al., 2011). Temperature, moisture and carbon- dioxide levels affect the composition of soil inverte-brate and micro-organism communities and many of the functions they perform, both directly and via their effects on other components of the ecosys-tem (e.g. plants). As climatic conditions change, the distribution of production systems can be expected to shift. Some existing relationships between plant species and soil micro-organism and invertebrate communities are likely to break down, as many soil invertebrates are relatively immobile and those that can move may not necessarily adapt well to new locations even if the climate is suitable, for example because of direct or indirect effects of photoperiod differences (ibid.).

The impacts of climate change on aquatic ecosys-tems include those associated with changes in the temperatures of lakes, rivers and oceans, which may affect species’ reproductive patterns and growth, and their physiology, morphology and behaviour more generally (e.g. Spalding, Ravilious and Green, 2001; Speed et al., 2016). Impacts on aquatic bio- geochemical processes are expected to affect the roles of aquatic ecosystems as carbon sinks or sources (Boyd and Hutchins, 2012; Erickson et al., 2015; Wrona et al., 2006). Ocean acidification as a result of increased absorption of carbon dioxide threatens marine organisms that use carbonate min-erals to form shells and skeletons (CBD Secretariat, 2009). Climate change can also be expected to lead to reductions in wetland areas, changes in flooding

periods, water levels, mixing regimes, water clarity and food webs and greater risk of alien-species invasions (Speed et al., 2016). Climate change is a major threat to the world’s coral reefs, for example via the effects of higher water temperatures, ocean acidification and increasing frequency of extreme weather events (Heron, Eakin and Douver, 2017;

Wilkinson, 2008) (see also Section 4.5.4).

Countries were invited to provide informa-tion on cases in which associated biodiversity is believed to be affected by climate change, indicat-ing the severity and frequency of the effects and the production systems in which they occur. Fifty-five countries provided information. The follow-ing specific threats are mentioned in the country reports: changes in temperature (37 reports);

changes in precipitation patterns (34); droughts (31); pests and diseases (22); floods (20); changes in sea level (18); changes in phenology (8); soil erosion (8); wildfires (8); changes in nutrient cycles (7); and unspecified extreme events (6). Less fre-quently reported threats include desertification, strong winds and changes in snow cover. The most frequently reported climate change-related threats to associated biodiversity vary by region.

Figure 3.1 shows a breakdown of responses by production system and region.

Information provided by countries on the impact of climate change on the supply of eco-system services is summarized in Table 3.7. In almost all cases impacts are reported to be neg-ative. Pest and disease regulation, natural-hazard regulation, water cycling, habitat provisioning and pollination are the ecosystem services most frequently reported to be affected by climate change. Several countries provide information on threats affecting particular regions and ecosystems within their national territories. For example, Peru mentions the threat that climate change is posing to high Andean ecosystems (vital to water- and climate-regulation services) as a result of rising temperatures and obstacles to altitudinal migra-tions. In the case of the Amazonian forests, it notes that climatic changes are predicted to lead to

“savannization”, which would affect the supply of wild foods, including fish, medicinal plants and

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FiGure 3.1

Reported climate change-related threats to associated biodiversity, (A) by region and (B) by production system

Extreme events(unspecified)

Changes in nutrient cycles

Soil erosion Wildfires Changes in phenology

Other

Changes in sea level Floods

Pests and diseases Droughts

Changes in precipitationChanges in temperature

Africa Asia Europe Latin America and the Caribbean Near East and North Africa North America Pacific

Crops systems Forestry systems Livestock systems Aquaculture Fisheries Mixed systems Agriculture (unspecified) Not specified 40

35 30 25 20 15 10 5

Number of countries

A

B

Number of responses

0

60

50

40

30

20

10

0

Notes: Part A of the figure shows the total number of countries that reported the respective threat for at least one production system, broken down by region. A given country may have reported a given threat for more than one production system category. Part B of the figure shows the total number of responses referring to the respective threat, broken down by production system. Fifty-five out of a total of 91 reporting countries reported at least one threat.

Source: Country reports prepared for The State of the World’s Biodiversity for Food and Agriculture.

other goods, as well as regulating services such as air purification, temperature regulation, water cycling and flood regulation, with serious consequences for the local population. In the case of marine eco-systems, expected impacts of climate change are reported to be potentially catastrophic owing to rising temperatures and intense rains in the north of the country: ecosystem services predicted to be affected include climate regulation and the supply of fish and other products, with impacts on human nutrition, particularly among resource-poor coastal populations. China reports that in recent decades

there has been a marked warming and drying of the climate in the vicinity of Hulun Lake (a large lake in Inner Mongolia), with a decline in the size of the lake, deterioration of the grasslands around it, desertification and a reduction in vegetation cover.

These changes are reported to be a severe threat to several terrestrial species.

Numerous other countries highlight climate change as a major threat to biodiversity in inland- water and coastal ecosystems. Predicted effects relate mainly to drier summers or to more intense rainfall that may result in floods and landslides table 3.7

Reported effects of climate change on the provision of regulating and supporting ecosystem services, by production system

Production systems (PS)

Effects of climate change on ecosystem services

Pollination Pest and disease regulation Water purification and waste treatment Natural-hazard regulation Nutrient cycling Soil formation and protection Water cycling Habitat provisioning Production of oxygen/ gas regulation

livestock grassland-based systems - - -

-livestock landless systems - - -

-Proportion of countries reporting

the Ps that report any effect of the

driver (%)

naturally regenerated forests - - -

-Planted forests - - -

-self-recruiting capture fisheries - - -

-Culture-based fisheries - - - 10–17

Fed aquaculture +/- - - ^18–25

non-fed aquaculture - - - 26–33

irrigated crop systems (rice) - - - ^34–42

irrigated crop systems (other) - - -

-rainfed crop systems - - -

-Mixed systems - - -

-Notes: Countries were invited to report the effects (positive, negative or “no effect”) of this driver on the provision of each ecosystem service in each production system. If 50% or more of the responses for a given combination of production system and ecosystem service indicate the same trend (positive [+], negative [-] or “no effect” [0]) then this trend is indicated in the respective cell of the table. In other cases, mixed effects (+/-) are indicated. The colour scale indicates the proportion of countries reporting the presence of the respective system that report any effect of the driver (positive, negative or “no effect”) on the provision of the respective ecosystem service. See Section 1.5 for descriptions of the production systems and a discussion of ecosystem services. Analysis based on a total of 91 country reports.

Source: Country reports prepared for The State of the World’s Biodiversity for Food and Agriculture.

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that affect habitats such as lakes. With regard to marine ecosystems, the Netherlands reports that rising sea temperatures in the southern North Sea have resulted in changes in the fish community, with species that prefer warmer temperatures (e.g. sea bass) becoming more common and those that prefer cooler waters (e.g. plaice and cod) becoming less common or moving to deeper water.¹⁴ Similarly, Egypt reports that rising tem-peratures will lead to northwards shifts in the ranges of fish species, with impacts on fishery production. Mexico notes that its fisheries sector is considered highly vulnerable to climate change via the effects of current and predicted changes in water temperature, salinity, nutrient availabil-ity and other factors that influence the number and distribution of marine and freshwater biota.

Several countries from the Pacific region mention the effects of coral bleaching, particularly during El Niño years.

A number of island nations mention the severe threats they face from climate change. For example, the Bahamas reports that out of all the identified threats to biodiversity, climate change is consid-ered to be the most serious: 80 percent of the country’s landmass is within 1.5 metres of sea level and 90 percent of its freshwater lenses¹⁵ are within 1.5 metres of the land surface, making ground- water resources highly vulnerable to contamina-tion. It further notes that it is very vulnerable to climate-related threats such as coral bleaching, increasingly powerful hurricanes and rising sea levels. Saint Lucia mentions that rising tempera-tures and changing ocean currents have led to an increase in the quantity of Sargassum seaweed along the eastern coasts of Caribbean islands. It notes that marine plants and animals become trapped and die in thick sheets of seaweed and that under anaerobic conditions the seaweed degrades and emits a stench that creates problems for coastal communities. It also mentions, however, that the

14 the report cites Dulvy et al. (2008) and ter Hofstede and rijnsdorp (2011).

15 a freshwater lens is a body of freshwater that has percolated through the soil and floats on top of denser seawater below (bailey, Jenson and Olsen, 2009).

seaweed has increased fish populations and thus led to larger catches for some fishers.

Aside from species targeted by capture fisher-ies, a number of other wild foods are reported to be threatened by climate change-related effects.

For example, Eswatini reports that altered precip-itation patterns and erratic rainfall are predicted to hinder the germination of wild fruits and other wild food plants. Peru notes that changes to fruiting seasons are expected to reduce the availability of wild fruits such as camu-camu (Myrciaria dubia), humarí (Poraqueiba sericea) and pijuayo (peach palm – Bactris gasipaes).

Finland notes that climate change-related threats associated with the country’s northern position include declines in the availability of wild mush-rooms and berries as a result of poleward move-ment of the coniferous zone. It also move-mentions that earlier flowering when there is still a risk of frost exposure may also negatively affect the availability of wild berries.