🌡️Climatology Unit 10 – Climate Impacts and Adaptation

Key Climate Concepts

• Climate change refers to long-term shifts in temperature, precipitation patterns, and other measures of climate that occur over several decades or longer
• Greenhouse gases (carbon dioxide, methane, water vapor) trap heat in the atmosphere leading to global warming
• Radiative forcing quantifies the difference between solar irradiance absorbed by the Earth and energy radiated back to space
  • Positive radiative forcing (from greenhouse gases) leads to warming, while negative radiative forcing (from aerosols) leads to cooling
• Climate sensitivity measures how much the Earth's temperature changes in response to a doubling of atmospheric carbon dioxide concentrations
• Tipping points are thresholds beyond which a system reorganizes, often abruptly and/or irreversibly (melting of Arctic sea ice, collapse of the Atlantic Meridional Overturning Circulation)
• Climate models simulate the interactions of the atmosphere, oceans, land surface, and ice to project future climate under different scenarios
  • Models are based on physical principles and validated against observations

Climate Change Impacts

• Rising sea levels due to thermal expansion of oceans and melting of land-based ice (glaciers, ice sheets) increase coastal flooding and erosion
• More frequent and intense heatwaves lead to increased heat-related illnesses and deaths, especially among vulnerable populations (elderly, low-income)
• Changes in precipitation patterns can cause more frequent and severe droughts in some regions (Mediterranean, Southwest US) and flooding in others (South Asia)
• Warmer temperatures alter the geographic range and seasonal activities of many plant and animal species
  • Species may shift to higher latitudes or elevations, and spring events (flowering, migration) may occur earlier
• Ocean acidification from absorption of atmospheric carbon dioxide threatens marine ecosystems, particularly coral reefs and shellfish
• Extreme weather events (hurricanes, wildfires) are expected to become more frequent and intense in a warmer world
  • Hurricane Harvey (2017) and the Australian bushfires (2019-2020) are recent examples

Vulnerable Sectors and Ecosystems

• Agriculture is highly sensitive to changes in temperature, precipitation, and extreme events, with impacts varying by crop and region
  • Warmer temperatures may benefit crops in high latitudes but reduce yields in the tropics
• Coastal communities and infrastructure are vulnerable to sea level rise, storm surges, and saltwater intrusion into freshwater aquifers
• Forests are affected by changes in temperature, precipitation, and disturbances (fires, pests), with impacts on biodiversity and ecosystem services
  • Boreal forests are particularly vulnerable to warming and drying
• Human health is impacted by heat stress, air pollution, and the spread of vector-borne diseases (malaria, dengue fever) to new areas
• Tourism and recreation industries dependent on natural resources (ski resorts, coral reefs) are vulnerable to changing conditions
• Developing countries and marginalized communities often have limited resources and capacity to adapt to climate impacts
  • Small island nations (Maldives, Kiribati) face existential threats from sea level rise

Adaptation Strategies

• Adaptation involves adjusting to actual or expected climate change effects to moderate harm or exploit beneficial opportunities
• Protecting and restoring natural ecosystems (wetlands, mangroves) can buffer against sea level rise and storm surges while providing co-benefits (biodiversity, carbon sequestration)
• Improving water management through efficiency measures (drip irrigation), storage (reservoirs), and diversification of sources (desalination) can help address changing precipitation patterns
• Developing heat action plans and early warning systems can reduce the health impacts of heatwaves, particularly for vulnerable populations
• Promoting climate-resilient agriculture through practices like crop diversification, agroforestry, and soil conservation can help farmers adapt to changing conditions
• Mainstreaming climate considerations into decision-making across sectors (transportation, energy, urban planning) can build resilience
  • For example, designing infrastructure to withstand future sea levels and storm intensities
• Nature-based solutions (green roofs, urban forests) can help cities adapt to rising temperatures and flooding while providing multiple benefits (air quality, recreation)

Case Studies and Real-World Examples

• The Netherlands has implemented a comprehensive flood protection system, including the Delta Works project, to adapt to sea level rise and storm surges
  • The Maeslantkering is a massive storm surge barrier that automatically closes to protect Rotterdam during high water events
• California's Sustainable Groundwater Management Act (2014) requires local agencies to develop plans for sustainably managing groundwater resources, many of which are being depleted due to drought and overuse
• The city of Medellín, Colombia has implemented a Green Corridors program to create a network of urban forests, parks, and vegetated walkways to reduce the urban heat island effect and improve air quality
• The Sahel region of Africa has promoted farmer-managed natural regeneration (FMNR) of trees on agricultural land to improve soil fertility, reduce erosion, and provide fodder and fuelwood
  • FMNR has been adopted on millions of hectares, increasing crop yields and resilience to drought
• The Maldives has developed a National Adaptation Program of Action (NAPA) to address the threats of sea level rise, including measures like coastal protection, water management, and coral reef conservation
• The city of Copenhagen, Denmark has implemented a Cloudburst Management Plan to adapt to increasing heavy rainfall events, using a combination of green infrastructure (parks, wetlands) and gray infrastructure (tunnels, pumps) to manage stormwater

Policy and Governance

• The Paris Agreement (2015) is an international treaty in which countries committed to limiting global warming to well below 2°C above pre-industrial levels and pursuing efforts to limit it to 1.5°C
  • Countries submit Nationally Determined Contributions (NDCs) outlining their emissions reduction targets and adaptation plans
• The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body that assesses the scientific, technical, and socio-economic information relevant to climate change
  • The IPCC produces comprehensive assessment reports every 5-7 years, as well as special reports on specific topics (1.5°C warming, oceans and cryosphere)
• National adaptation plans (NAPs) are a process for countries to identify medium- and long-term adaptation needs and develop and implement strategies to address those needs
• Adaptation finance refers to the flow of funds to support adaptation actions in developing countries, which often have limited resources
  • The Green Climate Fund (GCF) is a key mechanism for delivering adaptation finance under the Paris Agreement
• Mainstreaming adaptation into development planning can ensure that investments in sectors like agriculture, water, and infrastructure are resilient to future climate conditions
• Participatory approaches that engage local communities and stakeholders in adaptation decision-making can lead to more effective and equitable outcomes
  • For example, using traditional knowledge to inform adaptation strategies in indigenous communities

Challenges and Limitations

• Uncertainty in climate projections, particularly at local scales, can make it difficult to plan and implement adaptation actions
  • The range of possible future scenarios (Representative Concentration Pathways) can lead to different adaptation needs and priorities
• Adaptation can be costly, and there are often trade-offs between short-term costs and long-term benefits
  • For example, relocating coastal communities to avoid sea level rise has high upfront costs but can prevent future damages
• Maladaptation refers to actions that may lead to increased risk of adverse climate-related outcomes, either now or in the future
  • For example, building sea walls can protect against coastal flooding in the short term but may encourage development in vulnerable areas and exacerbate erosion in the long term
• Limits to adaptation occur when adaptive actions are no longer able to provide an acceptable level of security from risks to the objectives and needs of actor(s)
  • For example, some low-lying island nations may face limits to adaptation if sea levels rise beyond a certain threshold
• Distributional impacts of adaptation can arise when the costs and benefits of adaptation actions are not evenly distributed across society
  • For example, wealthy households may be able to afford air conditioning during heatwaves while low-income households cannot
• Institutional barriers, such as lack of coordination between government agencies or limited capacity for implementation, can hinder adaptation efforts
  • For example, many developing countries lack the technical and financial resources to develop and implement comprehensive adaptation plans

Future Outlook and Emerging Trends

• The need for adaptation is expected to increase as the impacts of climate change become more severe and widespread
  • Even if global warming is limited to 1.5°C or 2°C, significant adaptation will still be required to deal with the impacts that are already locked in
• Transformational adaptation may be needed in some cases, involving fundamental changes to systems and behaviors rather than incremental adjustments
  • For example, relocating entire communities or shifting to new agricultural systems in response to changing conditions
• Nature-based solutions are increasingly recognized as a way to address both adaptation and mitigation goals while providing co-benefits for biodiversity and human well-being
  • For example, restoring coastal wetlands can protect against sea level rise while also sequestering carbon and providing habitat for wildlife
• Climate services, which provide climate information and tools to support decision-making, are becoming more sophisticated and widely available
  • For example, seasonal forecasts and early warning systems can help farmers make planting decisions and prepare for extreme events
• Adaptation finance is expected to increase in the coming years as the impacts of climate change become more apparent and the need for action becomes more urgent
  • However, there is still a significant gap between the amount of funding available and the estimated costs of adaptation in developing countries
• Monitoring and evaluation of adaptation actions will be important for learning what works and what doesn't in different contexts
  • Developing metrics and indicators for measuring adaptation progress and effectiveness is an active area of research and practice
• Equity and justice considerations are increasingly being incorporated into adaptation planning and implementation
  • This includes ensuring that adaptation actions do not exacerbate existing inequalities and that the needs of marginalized and vulnerable communities are prioritized