It assesses the associated impacts and projected costs of implementing each technology and categorizes them into three time frames for implementation. View This Source. The National Academies. Source Library. View All Sources. Agricultural adaptation strategies that increase yields such as altering crop varieties, irrigation practices, and fertilizer application , particularly in already high-yielding regions including North America, can have mitigation benefits Ch. In buildings and industrial facilities, adaptation measures such as investments in energy efficiency for example, through efficient building materials would reduce building energy demand and therefore emissions , as well as lessen the impacts of extreme heat events.
Adaptation and mitigation can also interact negatively. For example, if mitigation strategies include large-scale use of bioenergy crops to produce low-carbon energy, higher irrigation demand can lead to an increase in water stress that more than offsets the benefits of lessened climate change.
Higher air conditioning demands are projected to increase annual average and peak demands for electricity, putting added stress on an electrical grid that is already vulnerable to the effects of climate change Ch. Multisector impacts modeling frameworks can systematically address specific mitigation and adaptation research needs of the users of the National Climate Assessment.
Improved coordination amongst multidisciplinary impact modeling teams could be very effective in informing future climate assessments.
Assessing Economic Impacts of Greenhouse Gas Mitigation: Summary of a Workshop (). Proceedings. Assessing Economic Impacts of Greenhouse Gas. Read chapter A Workshop Agenda: Many economic models exist to estimate the Assessing Economic Impacts of Greenhouse Gas Mitigation: Summary of a.
The recent multisector impacts modeling frameworks described above have demonstrated several key advantages for producing policy-relevant information regarding the potential for mitigation to reduce climate change impacts. First, the use of internally consistent scenarios and assumptions in quantifying a broad range of impacts produces comparable estimates across sectors, regions, and time.
Second, these frameworks can simulate specific mitigation and adaptation scenarios to investigate the multisector effectiveness of these actions in reducing risk over time. Third, these frameworks can be designed to systematically account for key dimensions of uncertainty along the causal chain—a difficult task when assessing uncoordinated studies from the literature, each with its own choices of scenarios and assumptions. While not an exact analog to this chapter, the Third National Climate Assessment NCA3 included a Research Needs chapter as part of the Response Strategies section that recommended five research goals: 1 improve understanding of the climate system and its drivers, 2 improve understanding of climate impacts and vulnerability, 3 increase understanding of adaptation pathways, 4 identify the mitigation options that reduce the risk of longer-term climate change, and 5 improve decision support and integrated assessment.
For example, research findings related to climate system drivers and the characterization of uncertainty have helped to differentiate the physical and economic outcomes along alternative mitigation pathways. However, challenges remain in accounting for the reduced risks and impacts associated with nonlinearities in the climate system, including tipping points such as destabilization of the West Antarctic ice sheet or rapid methane release from thawing permafrost.
Adaptation pathways are better understood but continue to be a source of uncertainty related to understanding climate risk and local adaptation decision-making processes. Decision support for climate risk management, especially under uncertainty, is an area of active research, , and despite the limitations of integrated assessment models, , they offer useful insights for decision-makers.
Despite ongoing progress, this assessment finds that significant knowledge gaps remain in many of the research goals and foundational crosscutting capabilities identified in NCA3. Going forward, it will be critically important to reduce uncertainties under different mitigation scenarios in 1 avoided sectoral impacts, such as agriculture and health, and 2 the capacity for adaptation to reduce impacts.
Gaps in information on social vulnerability and exposure continue to hamper progress on disaster risk reduction associated with climate impacts. Specific examples deserving further study include marine ice sheet instability and transformation of specific terrestrial carbon sinks into sources of greenhouse gas emissions. Gaps remain in quantifying combined impacts and natural feedbacks.
Interdisciplinary collaboration can play a critical role in addressing these knowledge gaps such as coordinating a research plan across physical, natural, and social sciences. Barriers to implementation arise from data limits for example, the need for long-term observational records , as well as computational limits that increase model uncertainties. All prospective authors were interviewed with respect to their qualifications and expertise.
Authors were selected to represent the diverse perspectives relevant to mitigation, with the final team providing perspectives from federal and state agencies, nonfederal climate research organizations, and the private sector. The author team sought public input on the chapter scope and outline through a webinar and during presentations at conferences and workshops.
The chapter was developed through technical discussions of relevant evidence and expert deliberation by the report authors during extensive teleconferences, workshops, and email exchanges. These discussions were informed by the results of a comprehensive literature review, including the research focused on estimating the avoided or reduced risks of climate change.
The authors considered inputs submitted by the public, stakeholders, and federal agencies and improved the chapter based on rounds of review by the public, National Academies of Sciences, Engineering, and Medicine, and federal agencies. The author team also engaged in targeted consultations during multiple exchanges with contributing authors from other chapters of this assessment, as well as authors of the Climate Science Special Report CSSR.
For additional information on the overall report process, see Appendix 1: Process. Mitigation-related activities are taking place across the United States at the federal, state, and local levels as well as in the private sector very high confidence. Since the Third National Climate Assessment, a growing number of states, cities, and businesses have pursued or deepened initiatives aimed at reducing emissions very high confidence. Since NCA3, state, local, and tribal entities have announced new or enhanced efforts to reduce greenhouse gas GHG emissions. While some policies with emissions co-benefits have been eliminated, on net there has been an increase in initiatives aimed at reducing emissions.
Figure The underlying state information is sourced from the U.
Forest Service. Emissions trading systems are scheduled in Massachusetts and under consideration in Virginia. Federal budget levels for activities that have reduced GHG have remained steady over recent years.
There is uncertainty around the implementation of federal initiatives, in part owing to the implementation of Executive Order Likewise, 59 U. As indicated in the Education Institutions Reporting Database, a growing number of universities have made emissions reduction commitments or deepened existing commitments as well as publicized the progress on their efforts. The size, scope, time frame, and enforceability of the measures vary across states. Some state efforts and the majority of city efforts are voluntary, and therefore standards for reporting are heterogeneous.
Efforts are underway to provide a rigorous accounting of the cumulative scale of these initiatives. Historically, state, local, and corporate policies change on different cycles. There is very high confidence that state, local, and private entities are increasingly taking, or are committed to taking, GHG mitigation action. Public statements and collated indices show an upward trend in the number of commitments, as well as the breadth and depth of commitments over the past five years. Under scenarios with high emissions and limited or no adaptation, annual losses in some sectors are estimated to grow to hundreds of billions of dollars by the end of the century high confidence.
It is very likely that some physical and ecological impacts will be irreversible for thousands of years, while others will be permanent very high confidence. Recent scientific and economic advances are improving the ability to understand and quantify the physical and economic impacts of climate change in the United States, including how those risks can be avoided or reduced through large-scale GHG mitigation.
While the projected impacts of climate change across sectors and regions are well documented throughout this assessment, several multisector modeling projects are enabling the comparison of effects through the use of consistent scenarios and assumptions. These estimated damages increase over time, especially under a higher scenario RCP8. For sectors where positive effects are observed in some regions or for specific time periods for example, reduced mortality from extreme cold temperatures or beneficial effects on crop yields , the effects are typically dwarfed by changes happening overall within the sector or at broader scales for example, comparatively larger increases in mortality from extreme heat or many more crops experiencing adverse effects.
See Chapter 6: Forests for a discussion on the weight of evidence regarding projections of future wildfire activity, which generally show increases in annual area burned over time. See Chapter Southwest for a discussion on aridification toward the end of this century under high emissions. There is robust and consistent evidence that climate change is projected to adversely affect many components of the U. Increasing temperatures, sea level rise, and changes in extreme events are projected to affect the built environment, including roads, bridges, railways, and coastal development.
For example, coastal high tide flooding is projected to significantly increase the hours of delay for vehicles. For example, projected declines in coral reef-based recreation , , would lead to decreases in tourism revenue; shorter seasons for winter recreation would likely lead to the closure of ski areas and resorts; , , , and increased risks of harmful algal blooms can limit reservoir recreation Ch. An increasing body of literature indicates that impacts to human health are likely to have some of the largest effects on the economy.
Studies consistently indicate that climate-driven changes to morbidity and mortality can be substantial.
A large fraction of total health damages is due to mortality, quantified using the Value of a Statistical Life VSL approach based on standard VSL values used in federal government regulatory analysis. Although less studied compared to the research on the direct effects of temperature on health, climate-driven impacts to air quality 72 , and aeroallergens , are also projected to have large economic effects, due to increases in medical expenditures such as emergency room visits and premature mortality Ch.
Multiple lines of research have also shown that some climate change impacts will very likely be irreversible for thousands of years. For some species, the rate and magnitude of climate change projected for the 21st century is projected to increase the risk of extinction or extirpation local-scale extinction from the United States.
The rapid and widespread climate changes occurring in the Arctic and Antarctic are leading to the loss of mountain glaciers and shrinking continental ice sheets. This Key Message reflects consideration of the findings of several recent multisector modeling projects e. Despite these improvements to quantify the physical and economic impacts of climate change across sectors, uncertainty exists regarding the ultimate timing and magnitude of changes, particularly at local to regional scales. The sources of uncertainty vary by sector and the modeling approaches applied.
swatupcerlora.tk Each approach also varies in its capacity to measure the ability of adaptation to reduce vulnerability, exposure, and risk. While the coverage of impacts has improved with recent advancements in the science, many important climate change effects remain unstudied, as do the interactions between sectors Ch. There is very high confidence that climate change is projected to substantially affect American livelihoods and well-being in the future compared to a future without climate change. The evidence supporting this conclusion is based on agreement across a large number of studies analyzing impacts across a multitude of sectors, scenarios, and regions.
The literature clearly indicates that the adverse impacts of climate change are projected to substantially outweigh the positive effects. Although important uncertainties exist that affect our understanding of the timing and magnitude of some impacts, there is very high confidence that some effects will very likely lead to changes that are irreversible on human timescales.
Many climate change impacts and associated economic damages in the United States can be substantially reduced over the course of the 21st century through global-scale reductions in greenhouse gas emissions, though the magnitude and timing of avoided risks vary by sector and region very high confidence. The effect of near-term emissions mitigation on reducing risks is expected to become apparent by mid-century and grow substantially thereafter very high confidence.
There are multiple lines of research and literature available to characterize the effect of large-scale GHG mitigation in avoiding or reducing the long-term risks of climate change in the United States.
Recent multisector impacts modeling projects, all of which feature consistent sets of scenarios and assumptions across analyses, provide improved capabilities to compare impacts across sectors and regions, including the effect of global GHG mitigation in avoiding or reducing risks. For most sectors, this effect of mitigation typically becomes clear by mid-century and increases substantially in magnitude thereafter.
In some sectors, mitigation can provide large benefits. Beyond these multisector modeling projects, an extensive literature of sector-specific studies compares impacts in the United States under alternative scenarios. A careful review of these studies, especially those published since the Third National Climate Assessment, finds strong and consistent support for the conclusion that global GHG mitigation can avoid or reduce the long-term risks of climate change in the United States.
For example, mitigation is projected to reduce the risk of adverse impacts associated with extreme weather events, 29 , temperature-related health effects, 99 , , agricultural yields, , , and wildfires.