Climate Science Overview

Climate Science Course - University of Gondar

• Offered by the Forest and Climate change MSc Program
• Taught by Yirdaw Meride Teshome (Ph.D)
• Course date: 2024

What is Climate Science?

• Also known as climatology, it's the scientific study of Earth's climate.
• Examines how the climate system operates, its historical changes, and future projections.
• The climate system includes atmosphere, oceans, land surfaces, ice sheets, and biosphere.
• System components interact to determine Earth's climate.

What is Climate Science? - Tools and Techniques

• Climate scientists use various tools and methods:
• Observations of the atmosphere, oceans, and land surfaces
• Computer models of the climate system
• Paleoclimate data (like ice cores, tree rings)
• Theoretical studies of climate processes
• It's a multidisciplinary field drawing on meteorology, oceanography, physics, chemistry, biology, and geology.

Climate Change Importance

• Understanding how the climate system functions and changes is crucial.
• Informed decisions on adapting to and mitigating the effects of climate change are possible through this information.

Why Study Climate?

• To understand the type and location of human-managed ecosystems like agriculture.
• To understand rock weathering, soil formation, and soil type.
• To understand water quantity and quality for human use.
• To establish the severity of droughts, storms and floods
• To define and understand biomes (major terrestrial ecosystems).

Weather vs. Climate

• Weather describes the current state of the atmosphere (hours or days).
• Climate is a statistical description of temperature, precipitation, etc. over a long period (months to millions of years).
• The classical period for climate study is 30 years.
• Climate includes variability in the climate system.

Characteristics of Weather and Climate

• Temperature
• Wind
• Clouds
• Precipitation
• Humidity
• Storms (e.g. cyclones)

Meteorology - The Study of Weather

• A well-known field of atmospheric science.
• Primarily focused on the troposphere (lowest region of Earth's atmosphere).
• Factors influencing weather: Vertical, diurnal, seasonal variations of atmospheric density and temperature, solar heating, and horizontal variations on Earth's surface.
• Earth rotation and surface conditions (land, sea, topography) impact atmospheric winds and circulation.
• Weather monitoring satellites and supercomputers facilitate advancements in meteorology.

Climatology

• The study of climate differs from meteorology.
• Climatology considers long-term weather patterns over years, whereas meteorology looks at current weather conditions.
• Examples of diverse climates: Antarctica, Sahara Desert, Amazon River basin.
• Climate change is currently a pivotal area of study due to its effects on local, regional and global climates.

Historical Events Related to Climate Change

• Industrial Revolution (late 18th - early 19th centuries): marked the rise of large-scale fossil fuel use (coal), increased greenhouse gas emissions (chiefly carbon dioxide).
• 1896: Svante Arrhenius's Theory: a groundbreaking paper proposing rising atmospheric Co2 leads to global warming.
• Early 20th century: initial observations and data collection on global temperatures began revealing warming trends.
• Mid-20th century: Industrial development accelerated greenhouse gas emissions, and scientific concern regarding climate change emerged.
• 1960s-1970s: Expanding scientific evidence pointed towards human influence on climate change. Growing environmental awareness.
• 1988: Intergovernmental Panel on Climate Change (IPCC) Established; a significant step in international cooperation on climate change.
• 1997: Kyoto Protocol; the first treaty to set legally binding targets for cutting greenhouse gas emissions.
• 2007: IPCC and Al Gore shared Nobel Peace Prize for raising awareness on climate change.
• 2015: Paris Agreement; global commitment to limit global warming.
• Recent years: continued global temperature increase and heightened extreme weather events.

What is Climate Change?

• IPCC 3rd Assessment Report: Statistically significant variation in climate (mean state or variability) over an extended period (decades or longer), potentially due to:
• Natural internal processes.
• External forcings.
• Man-made changes (anthropogenic) to the atmosphere or land use.
• UNFCCC, Article 1: a change of climate that's attributed directly or indirectly to human activity altering the global atmosphere, distinct from natural climate variability.

What is Climate Variability?

• IPCC 3rd Assessment Report: Variations in climate mean state and statistics (including extremes) across all temporal and spatial scales greater than those of individual weather events.
• Variability can be due to natural internal processes within the climate system, or to changes in natural or anthropogenic external forcing.

Primary Indicators of Climate Change

• Global average temperature rise
• Sea level rising
• Glacier melt
• Snow cover decline
• Changes in sea ice extent
• Changes in ocean temperature
• Humidity
• Increased frequency and intensity of extreme weather events (e.g., droughts, floods, storms)

What are the Causes of Climate Change?

• Anthropogenic activities (human-induced):
  • Burning fossil fuels
  • Deforestation
  • Land use changes (e.g. agriculture)
• Natural Factors:
  • Volcanic eruptions
  • Variations in Earth's orbit, tilt, and spin (affecting solar energy received)
  • Ocean currents

Greenhouse Effect

• GHGs (greenhouse gases) like water vapor, carbon dioxide, methane, and nitrous oxide trap outgoing longwave radiation from Earth.
• This helps maintain habitable temperatures.
• Increased GHG concentrations lead to a strengthened greenhouse effect and global warming.
• CO2 levels have risen from preindustrial levels of roughly 280 ppm to about 364 ppm in 1997.

Climate Change Impacts on Water

• Impacts on water resources (quality and quantity)
• Increased risk of water shortages
• More frequent and severe glacial melt-related floods
• Slope destabilization
• Decreased river flows
• Changed precipitation patterns (including changes in precipitation type — more rain, less snow).
• Surface temperature changes modify atmospheric vapor capacity and snowfall/precipitation ratios.

Impacts of Climate Change on Ecosystems

• Land use and cover changes: Conversion of forests and woodlands to agriculture and grazing, followed by further conversions.
• Nitrogen deposition: Excess nitrogen from land-based sources, sewage, and industrial runoff affect terrestrial ecosystem productivity.
• Global species extinctions: Climate change increasing extinction rates.
• Habitat alteration: Climate change alters species habitats due to changes in distribution, species distribution, and habitat quality.

Impacts of Climate Change on Coastal Systems

• Rising sea levels: caused by thermal expansion and glacier melt.
• Coastal flooding, erosion, and wave overtopping exacerbated by rising sea levels.
• Increased physical impacts on coasts (e.g., increased flooding, erosion, wave overtopping, rainfall runoff).

Impacts of Climate Change on Temperature

• Ecosystem changes largely result from organism responses to temperature changes.
• Information about organism thermal sensitivities, limits, and functional properties is needed.
• Climate change impacts on species distributions, abundances, and diversity, and impacts on trophic interactions and community assemblages.
• Changes to physical environments (stratification, reduced sea ice cover, and freshening).

Impacts of Climate Change on Precipitation

• Increased precipitation across much of Asia; decreased precipitation in central Asia during summer.
• Increased frequency of intense precipitation events in parts of South and East Asia.
• Decreasing snow and ice in Himalayan and Tibetan glaciers.
• Precipitation will change and become more extreme.

Impacts of Climate Change on Extreme Events

• Rising frequency and intensity of extreme events (droughts, heatwaves, intense rainfall).
• More intense and longer heat waves (particularly in East Asia).
• Increased frequency of landslides and severe floods.

Climate Change Impacts on Agriculture and Food Security

• Decreased crop yields in many parts of the globe, increasing hunger risk for millions.
• Reduced soil moisture and evapotranspiration amplify land degradation and desertification.
• Agriculture productivity might improve in certain northern regions.
• Risk of food insecurity and breakdowns in food systems worsened by warming, drought, flooding, and erratic precipitation.

Human Health Impacts of Climate Change

• Direct impacts (heat, drought, intense rainfall)
• Impacts mediated by natural systems (disease vectors, waterborne diseases, and air pollution)
• Impacts mediated by human systems (occupational risks, undernutrition, mental stress)
• High risk for severe ill health and vulnerable livelihoods in several regions due to inland flooding.
• Climate change contributes to undernutrition, diarrhea, and malaria deaths globally.

Ethiopia's Contribution to and Vulnerability to Climate Change

• Ethiopia's contribution to global greenhouse gas emissions is low; however the nation is highly vulnerable to harm from climate change, largely due to: increasing population density, fragile environmental conditions, reliance on climate sensitive sectors (e.g. agriculture), and a limited capability to adapt to climate change.
• Temperature increase projections (0.5 - 3.6°C by 2070), and projected reduction in average daily rainfall.

Why Climate Change Adaptation is Necessary

• Less mitigation—higher greenhouse gas production leads to more severe climate change effects and greater impacts on humans and the environment. More adaptation required.
• More mitigation—lower greenhouse gas production leads to less serious climate change effects and lesser impacts on humans and the environment. Less adaptation required.

What Has Been Done to Address Climate Change and Variability?

• Adaptation— adjusting to actual or anticipated climate changes, and their effects.
  • Human systems adaptation aims to mitigate harm or exploit beneficial opportunities.
  • Intervention in natural systems.
• Adaptive measures protect countries and communities from climate change disruption.
• Adaptive Capacity — a system's ability to adjust to climate change (variability and extremes), moderate damages, seize opportunities, and manage repercussions.
• Measures to assess adaptive capacity: Economic condition, social situation, and institutional capacity/strength

Types of Adaptation

• Anticipatory adaptation— measures undertaken in advance of detectable climate change impacts, considered proactive planning and preparation for the future.
  • Includes: infrastructure improvements (coastal protections), water resource management (drought resistance crops), land use planning (restricting development in flood prone areas), early warning systems.
• Benefits of anticipatory adaptation: reduced vulnerability, cost effectiveness, and increased resilience.
• Autonomous adaptation—changes made by individuals or groups in response to climate change without deliberate planning by governments or agencies; spontaneous natural occurrence.
• Key aspects: spontaneous, individual-driven, and reactive.
  • Examples: farmers adjusting planting dates, people raising homes in coastal regions, communities diversifying livelihoods.
  • Importance: complements planned adaptation, reveals flexibility and innovation of communities, and serves as baseline for evaluation.
• Planned adaptation—results from a deliberate, policy-driven decision recognizing that conditions have changed or are likely to shift, and that action to achieve or regain a wanted condition is necessary.
  • Key aspects: deliberate actions, structured approach (assessment of risks, developing strategies, implementation, and monitoring).
  • Includes: infrastructure development (sea walls), water resource management (drought resistant crops), land use planning (limiting development in prone areas).
  • Importance: reduces vulnerability, enhances resilience, cost-effectiveness, and promotes sustainable development.

Adaptation Involves…

• Reducing risk and vulnerability.
• Seeking opportunities.
• Building capacity at national, regional, city, private sector, community, individual, and natural systems levels.

Adaptation Options - 1 Structural and Physical

• Focuses on structural and engineering methods, discrete technologies, use of ecosystems, and service delivery (national, regional, local). Examples: Building seawalls, raising dykes, developing flood defenses, drought-tolerant crops, using ecosystem services, and adjusting building locations in vulnerable areas.

Adaptation Options - 2 Technological

• Technological options include: efficient irrigation, fertilization methods, plant breeding (greater drought tolerance). Strategies include adjusting crop planting dates based on anticipated yields. New technologies as well as indigenous and local ones are potentially useful for climate change adaptation.

Adaptation Options - 3 Service

• Provision of basic services (water, sanitation, waste disposal, transportation, and power).

Adaptation Options - 4 Social

• Social protection schemes (transfer of income/assets to the poor) to support vulnerable populations threatened by extreme weather events. Initiatives to protect livelihoods and raise the social status of marginalized groups.

Adaptation Options - 5 Institutional

• Policies, regulations, and measures that can enable adaptation (taxes, subsidies, insurance, protected areas, building codes, and re-zoning)

The Adaptation Process

• A process consisting of interconnected steps (education, vulnerability assessment, adaptation planning, implementation). Collaboration between scientists and managers is central to effective adaptation.

Adaptation Strategies for the Agricultural Sector

• Measures to allow the agricultural sector to adapt to future climate change. This includes: changing planting dates, selecting alternative crop species, drought and heat-resistant varieties, increasing intercropping, and using sustainable fertilizer/tillage practices to improve soil drainage. Other strategies are improved crop residue and weed management, better ways to harvest and conserve water, and improving pest/disease control of crops.

Adaptation Strategies – Forests

• Adaptation for forests: reducing negative impacts on the forest, maintaining ecosystem function, and preserving ecosystem services. Forests' involvement in adaptation: providing ecosystem services that lessen local community and broader societal vulnerability.

Barriers to Climate Change Adaptation

• Financial limitations (funding shortages for projects)
• Private economic interests.
• Inadequate institutional capacity (administrative and political).
• Social and cultural resistance.
• Technological limitations (insufficient tools and information).

Vulnerability

• Vulnerability definition: the degree of susceptibility of a system to dealing with the effects of climate change including variability and extremes.
• Components of vulnerability: Exposure to climatic stressors, importance of affected systems, and limited ability to adapt.

Exposure, Sensitivity, Adaptive Capacity

• Exposure is the vulnerability to something (potential damage from climate change).
• Sensitivity—effect of climate change and exposure on a system.
• Adaptive capacity is the capability to adjust to climate change impacts.

How to Move From Vulnerability to Adaptation

• Vulnerability assessment — identifying risks, conditions, and the target area; monitoring progress
• Adaptation assessment — considering future vulnerability, adaptation options, strategies and priorities.