finding 7.3 : key-message-7-3

The resources and services that people depend on for their livelihoods, sustenance, protection, and well-being are jeopardized by the impacts of climate change on ecosystems (likely, high confidence). Fundamental changes in agricultural and fisheries production, the supply of clean water, protection from extreme events, and culturally valuable resources are occurring (likely, high confidence).

This finding is from chapter 7 of Impacts, Risks, and Adaptation in the United States: The Fourth National Climate Assessment, Volume II.

Process for developing key messages:

Topics for the chapter were selected to improve the consistency of coverage of the report and to standardize the assessment process for ecosystems and biodiversity. Chapter leads went through the detailed technical input for the Third National Climate Assessment and pulled out key issues that they felt should be updated in the Fourth National Climate Assessment. The chapter leads then came up with an author team with expertise in these selected topics. To ensure that both terrestrial and marine issues were adequately covered, most sections have at least one author with expertise in terrestrial ecosystems and one with expertise in marine ecosystems.

Monthly author calls were held beginning in December 2016, with frequency increasing to every other week as the initial chapter draft deadline approached. During these calls, the team came up with a work plan and fleshed out the scope and content of the chapter. After the outline for the chapter was created, authors reviewed the scientific literature, as well as the technical input that was submitted through the public call. After writing the State of the Sector section, authors pulled out the main findings to craft the Key Messages.

Description of evidence base:

Similar to the Third National Climate Assessment, results of this review conclude that climate change continues to affect the availability and delivery of ecosystem services to society through altered agricultural and fisheries production, protection from storms and flooding in coastal zones, a sustainable harvest, pollination services, the spread of invasive species, carbon storage, clean water supplies, the timing and intensity of wildfire, the spread of vector-borne diseases, and recreation.eae18d2c-125c-45d5-bd2d-36b4c87f9cce,30fe230f-9dc9-41fc-ad29-e584f1244b95,0b30f1ab-e4c4-4837-aa8b-0e19faccdb94,912dbad9-8981-4cb5-8044-eabf0e563dbf,41f0be78-707a-4169-8838-2446d6587a79,514a2503-fc83-4e60-81d1-04421ff8ebc2,0af0ae72-c467-4dc5-8aa8-1fc54e73ef7a

Provisioning services: Regional changes in critical provisioning services (food, fiber, and shelter) have been observed as range shifts occur. These result in spatial patterns of winners and losers for human communities dependent on these resources. For example, as the distribution of harvestable tree species changes over time in response to climate change, timber production will shift in ways that create disconnects between resource availability and ownership rights.50c190f6-01ab-41be-8a09-9e2978884b98Although fisheries are more often treated as common property resources (with attendant problems related to the overuse and mismanagement of common resources),e529b0dd-5c4d-4320-83ef-b3a61e054420 disconnects emerge with respect to the definitions of management units and jurisdictional conflict and uncertainty.f147452b-e846-4fdd-aad9-3110322e071c Shifting distribution patterns can potentially affect access to both harvested and protected natural resources, cultural services related to the rights of Indigenous peoples and to recreation, and the aesthetic appreciation of nature in general (Ch. 15: Tribes, KM 1).18b0c713-a454-42dc-9cbe-a810ae153c75

Additionally, changes in physical characteristics in response to climate change can impact ecosystem services. In the ocean, the combination of warmer water and less dissolved oxygen can be expected to promote earlier maturation, smaller adult body size, shorter generation times, and more boom–bust population cycles for large numbers of fish species.7badc287-a489-4f16-b031-edce65965a43 These changes would have profound ecosystem effects, which in turn would affect the value of ecosystem services and increase risk and volatility in certain industries.

Altered phenology can also impact ecosystem services. Based on standardized indices of the timing of spring onset,3307a62c-ed45-4399-bcb9-f77e71b1e626 2012 saw the earliest spring recorded since 1900 across the United States.3307a62c-ed45-4399-bcb9-f77e71b1e626,b63bcdf5-c0fe-49a3-9c2c-8e95fd1eb603 Much of the central and eastern parts of the contiguous United States experienced spring onset as much as 20 to 30 days ahead of 1981–2010 averages, and accelerated blooming in fruiting trees was followed by a damaging, but climatically normal, hard freeze in late spring, resulting in widespread reductions in crop productivity.2503c4af-8f06-4405-a047-a2455cd1ffa5 Mid-century forecasts predict that spring events similar to that of 2012 could occur as often as one out of every three years; because last freeze dates may not change at the same rate, more large-scale plant tissue damage and agricultural losses are possible.4d4ae7e2-bd4f-429c-a696-e60e0156d95f,dcd0b157-c8af-44c1-a0f9-ce824c551b03 Early springs with episodic frosts not only directly affect plant growth and seed production but can also indirectly alter ecosystem functions such as pollination.d05ab8a0-f695-4af5-8a33-3426ab4b8eb8,1d44bdf4-7bf5-4b3c-8db8-273b8356e144

Potential asynchronies may impact some pollination services, although other pollinator–plant relationships are expected to be robust in the face of shifting phenology.d05ab8a0-f695-4af5-8a33-3426ab4b8eb8,1baa970f-fd2f-4dc9-b2d0-dae62df7ac47,9c318197-7e82-4467-a50e-3c0346b20d08,12003667-a5e6-4d78-9503-852bbc404af8 For example, broad-tailed hummingbirds in Colorado and Arizona have advanced their arrival date between 1975 and 2011, but not sufficiently to track changes in their primary nectar sources.

Regulating services: Average carbon storage in the contiguous United States is projected to increase by 0.36 billion metric tons under RCP4.5 and 3.0 billion metric tons under RCP8.5.0b30f1ab-e4c4-4837-aa8b-0e19faccdb94 However, carbon storage is projected to decrease for U.S. forests (Ch. 6: Forests, KM 2). Increases in overall carbon storage are projected for the Northwest, and decreases are projected for the Northeast and Midwest.0b30f1ab-e4c4-4837-aa8b-0e19faccdb94 Furthermore, shorter winters and changing phenology may affect the incidence and geographic extent of vector-borne diseases (Ch. 14: Human Health, KM 1).514a2503-fc83-4e60-81d1-04421ff8ebc2,a8a59e34-901f-4ccf-a53e-49e01b7de317,953d1436-e0d0-426c-8dcc-68e5c02eef30,df236eb2-eed0-4f95-9101-adc5f0101ee1,5b9528ba-65c4-49b9-ae40-db9a6ccf21d5 Other examples of regulating ecosystem services that are impacted by climate include coastal protection from flooding and storm surge by natural reefs (Ch. 8: Coastal, KM 2),01e8cafb-45c1-4883-b794-68fbdb7bc740 the supply of clean water (Ch. 3: Water, KM 1),70253b30-e294-4c3e-ba2d-eb3e2dc5bc3c and controls on the timing and frequency of wildfires (Ch. 6: Forests, KM 1).48543b5c-c630-4e06-b814-2fe2f2995c2a

Cultural services: Climate change is expected to impact recreation and tourism in the United States, as well as cultural resources for Indigenous peoples (Ch. 15: Tribes, KM 1).0aa04555-0142-4697-a5cc-00c7cab4e9e8,0b30f1ab-e4c4-4837-aa8b-0e19faccdb94,bda7e68a-4a4b-47b3-941f-5f9827af1c3f While some changes may be positive (such as increased biking and hiking access in colder seasons or cold-weather areas), other changes will have negative impacts (such as reduced skiing opportunities).0aa04555-0142-4697-a5cc-00c7cab4e9e8,0b30f1ab-e4c4-4837-aa8b-0e19faccdb94

Supporting services: Climate change is impacting supporting services, which are the services that make all other ecosystem services possible. Climate change impacts include alterations in primary production and nutrient cycling.10bc8ec0-deed-40ff-9d4e-1b202da596bf,516db32d-e3f6-49b3-a09e-e9045b101703

New information and remaining uncertainties:

One of the major challenges to understanding changes in ecosystem services due to climate change arises from matching the scale of the ecosystem change to the scale at which humans are impacted. Local conditions may vary greatly from changes expected at larger geographic scales. This uncertainty can work in both directions: local estimates of changes in ecosystems services can be overestimated when local impacts of climate change are less than regional-scale impacts. However, estimates of local impacts on ecosystem services can be underestimated when local impacts of climate change exceed regional projections. Another major source of uncertainty is related to the emergent properties of ecosystems related to climate change. Since observation of human impacts of these emergent ecosystem properties is lacking, it is difficult to predict how humans will be impacted and how they might adapt.

Assessment of confidence based on evidence:

There is high confidence that the resources and services that people depend on for livelihoods, sustenance, protection, and well-being are likely jeopardized by the impacts of climate change on ecosystems.

There is high confidence that fundamental changes in agricultural and fisheries production, the supply of clean water, protection from extreme events, and culturally valuable resources are likely occurring.

This finding was derived from scenario rcp_4_5
This finding was derived from scenario rcp_8_5

References :

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