Scenarios for the Fourth NCA: Climate
The Fourth National Climate Assessment (NCA4) presents a range of scenarios that explore various future climate conditions, primarily based on different levels of greenhouse gas (GHG) emissions and the resulting atmospheric concentrations. These scenarios are used to project changes in temperature, precipitation, sea-level rise, and other climatic factors.
High Emission Scenarios:
These scenarios assume continued growth in GHG emissions, typically associated with strong economic growth and limited implementation of policies to reduce emissions.
They project significant warming, with global temperatures potentially increasing by 4°C or more by the end of the century.
Such scenarios often result in more frequent and severe heatwaves, reduced snow and ice cover, and more intense storm events.
Intermediate Emission Scenarios:
These scenarios assume some efforts to mitigate emissions, possibly through a combination of policy measures, technological advances, and changes in energy use and land management.
Temperature increases in these scenarios are projected to be moderate, possibly around 2°C to 3°C by 2100.
The impacts are less severe than in high emission scenarios but still include increased risks of extreme weather events and significant ecological and societal challenges.
Low Emission Scenarios:
These scenarios are optimistic, assuming significant and sustained reductions in GHG emissions, which might be achieved through aggressive policy interventions, widespread adoption of renewable energy, and major advances in technology.
Global temperature increases might be limited to well below 2°C, in line with international goals such as those set by the Paris Agreement.
The projected impacts are milder, with fewer and less severe extreme weather events compared to higher emission scenarios.
No Mitigation Scenarios:
These scenarios assume no significant efforts are made to mitigate climate change, providing a baseline against which the benefits of mitigation efforts can be measured.
They are characterized by the highest levels of warming and the most severe climate impacts, including substantial sea-level rise, loss of biodiversity, and widespread disruption to ecosystems and human societies.
Mitigation Scenarios:
These scenarios explore the potential impacts of various mitigation strategies, such as carbon pricing, reforestation, or rapid technological transformation in the energy sector.
They help to identify the most effective strategies for reducing emissions and limiting warming, as well as the trade-offs and co-benefits associated with different approaches.
Adaptation Scenarios:
While not focused on the climate itself, these scenarios consider how societies might adapt to changing climate conditions.
They explore the effectiveness of different adaptation strategies, such as building sea walls, developing drought-resistant crops, or improving water management, in reducing the negative impacts of climate change.
Socioeconomic Scenarios:
These scenarios consider how changes in population, economic growth, technology, and other socioeconomic factors might influence GHG emissions and vulnerability to climate impacts.
They are often integrated with emission scenarios to provide a more comprehensive picture of potential futures.
The scenarios in the NCA4 are based on climate models that incorporate a wide range of physical, biological, and social processes. They are designed to help policymakers, businesses, and the public understand the potential risks and uncertainties associated with climate change and to inform decision-making around mitigation and adaptation strategies.
Name
Scenarios for the Fourth NCA: Climate
Description
The NCA4 provides a range of possible future climate conditions, based on different levels of greenhouse gas emissions and how much those emissions will affect the atmosphere. These scenarios are used to predict how temperature, precipitation, sea level, and other climate factors will change.
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Broader topics
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