🌼Environmental History Unit 10 – Climate Change and Biodiversity Challenges

Key Concepts and Definitions

• Climate change refers to long-term shifts in global or regional climate patterns, often attributed to increased levels of atmospheric carbon dioxide produced by the use of fossil fuels
• Greenhouse gases (carbon dioxide, methane, nitrous oxide) trap heat in the atmosphere, leading to rising global temperatures
• Global warming is the long-term heating of Earth's climate system, primarily caused by human activities that increase greenhouse gas levels
• Biodiversity encompasses the variety of life on Earth at all its levels, from genes to ecosystems, and the ecological and evolutionary processes that sustain it
• Ecosystem services are the benefits people obtain from ecosystems, including provisioning (food, water), regulating (climate, flood control), cultural (recreational, spiritual), and supporting services (nutrient cycling, soil formation)
• Anthropogenic factors are human activities that influence the environment, such as deforestation, urbanization, and fossil fuel combustion
• Tipping points are thresholds in the climate system that, when crossed, can lead to irreversible changes and accelerated warming
• Feedback loops are processes that either amplify (positive feedback) or diminish (negative feedback) the effects of climate change
  • Positive feedback example: melting Arctic ice reduces Earth's albedo, leading to more heat absorption and further melting
  • Negative feedback example: increased plant growth due to higher CO2 levels can absorb more carbon, slowing the rate of warming

Historical Context of Climate Change

• Earth's climate has naturally varied throughout its history due to factors such as volcanic eruptions, solar activity, and orbital variations
• The Industrial Revolution in the late 18th century marked a significant shift in human activities, with the increased burning of fossil fuels and land-use changes
• In the 1820s, Joseph Fourier first proposed the concept of the greenhouse effect, later refined by Svante Arrhenius in 1896
• The Keeling Curve, a graph of atmospheric CO2 concentrations measured at Mauna Loa Observatory since 1958, provided clear evidence of the rapid increase in greenhouse gases
• The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 to assess the scientific, technical, and socio-economic information relevant to understanding climate change
• The Kyoto Protocol, adopted in 1997, was the first international agreement to mandate country-by-country reductions in greenhouse gas emissions
• The Paris Agreement, signed in 2015, aims to keep global temperature rise well below 2°C above pre-industrial levels and pursue efforts to limit the increase to 1.5°C
• Recent years have seen an increase in public awareness and activism, with movements such as Fridays for Future and Extinction Rebellion demanding urgent action on climate change

Major Causes of Climate Change

• Burning of fossil fuels (coal, oil, natural gas) releases carbon dioxide into the atmosphere, trapping heat and causing global warming
• Deforestation removes trees that absorb CO2, while also releasing stored carbon when the wood is burned or decomposes
• Agriculture contributes to greenhouse gas emissions through livestock production (methane from cattle), rice cultivation (methane from flooded fields), and the use of nitrogen-based fertilizers (nitrous oxide)
• Urbanization leads to the urban heat island effect, where cities are warmer than surrounding rural areas due to heat-absorbing surfaces (asphalt, concrete) and reduced vegetation
• Industrial processes, such as cement production and chemical manufacturing, release greenhouse gases and contribute to air pollution
• Transportation, including cars, trucks, and airplanes, relies heavily on fossil fuels and is a significant source of CO2 emissions
• Waste management practices, such as landfills, produce methane as organic materials decompose under anaerobic conditions
• Population growth and increasing consumption patterns drive the demand for resources and energy, exacerbating the aforementioned causes of climate change

Impacts on Biodiversity

• Rising temperatures alter species' geographical ranges, causing some to shift towards the poles or to higher elevations in search of cooler habitats
• Changes in the timing of seasonal events (phenology), such as earlier spring arrival or delayed fall, can disrupt the synchrony between species' life cycles and resource availability
• Ocean acidification, caused by the absorption of atmospheric CO2, threatens marine biodiversity, particularly coral reefs and shellfish that rely on calcium carbonate for their skeletons and shells
• Habitat loss and fragmentation, often driven by human activities (deforestation, urbanization), reduce the available space for species and can lead to population declines or extinctions
• Invasive species may benefit from changing climatic conditions, allowing them to expand their ranges and outcompete native species
• Extreme weather events, such as droughts, floods, and heatwaves, can cause direct mortality and alter habitat suitability for various species
• Trophic cascades occur when the loss or decline of one species has ripple effects throughout the food web, potentially leading to ecosystem imbalances
• Biodiversity loss can compromise ecosystem services, such as pollination, pest control, and nutrient cycling, which are essential for human well-being

Ecosystem Responses and Adaptations

• Species may adapt to changing conditions through evolutionary processes, such as natural selection favoring traits that confer a survival advantage in the new environment
• Phenotypic plasticity allows some organisms to modify their behavior, physiology, or morphology in response to environmental changes without requiring genetic changes
• Range shifts occur when species move to new areas that become suitable as climatic conditions change, often towards higher latitudes or elevations
• Community composition may change as some species thrive under new conditions while others decline, leading to altered species interactions and ecosystem functioning
• Ecosystem engineers, such as beavers or elephants, can modify their habitats in ways that buffer against climate change impacts or create refugia for other species
• Ecological resilience refers to an ecosystem's ability to absorb disturbances and maintain its basic structure and functioning, while resistance is the capacity to withstand change without significant alteration
• Assisted migration involves the intentional movement of species to new areas that are predicted to be suitable under future climate scenarios, aiming to prevent extinctions
• Ecosystem-based adaptation focuses on conserving and restoring natural ecosystems to help human communities adapt to climate change impacts, such as using mangroves for coastal protection or urban green spaces for cooling

Human Contributions and Consequences

• Anthropogenic climate change is primarily driven by human activities that increase greenhouse gas emissions, such as burning fossil fuels, deforestation, and industrial processes
• The carbon footprint is a measure of an individual's or organization's total greenhouse gas emissions, often expressed in terms of carbon dioxide equivalents
• Climate change disproportionately affects vulnerable populations, such as low-income communities, indigenous peoples, and developing nations, exacerbating existing inequalities
• Food security is threatened by climate change impacts on agriculture, including reduced crop yields, increased pest and disease outbreaks, and water scarcity
• Water resources are affected by changes in precipitation patterns, glacial melt, and sea-level rise, leading to increased risk of droughts, floods, and saltwater intrusion
• Human health is impacted by climate change through increased exposure to heatwaves, air pollution, vector-borne diseases, and mental health stressors
• Climate migration and displacement may occur as people are forced to leave their homes due to sea-level rise, extreme weather events, or resource scarcity
• Economic impacts of climate change include damage to infrastructure, reduced agricultural productivity, and increased costs of adaptation and disaster response

Current Mitigation and Conservation Efforts

• Renewable energy sources, such as solar, wind, and hydropower, are being increasingly adopted to reduce reliance on fossil fuels and lower greenhouse gas emissions
• Energy efficiency measures, including improved insulation, LED lighting, and smart grid technologies, help reduce energy consumption and associated emissions
• Carbon pricing mechanisms, such as carbon taxes and cap-and-trade systems, aim to incentivize emissions reductions by putting a price on carbon dioxide emissions
• Reforestation and afforestation efforts involve planting trees to sequester carbon, restore habitats, and provide ecosystem services
• Protected areas, such as national parks and wildlife reserves, help conserve biodiversity and maintain ecosystem functioning in the face of climate change
• Sustainable land management practices, like agroforestry and regenerative agriculture, can enhance soil carbon storage, improve water retention, and support biodiversity
• International agreements, such as the Paris Agreement and the Convention on Biological Diversity, provide frameworks for global cooperation on climate change mitigation and biodiversity conservation
• Public awareness and education campaigns aim to increase understanding of climate change and biodiversity issues, encouraging individual and collective action

Future Projections and Challenges

• Climate models project a range of possible future scenarios, depending on the level of greenhouse gas emissions and the effectiveness of mitigation efforts
• The IPCC's Representative Concentration Pathways (RCPs) describe different 21st-century pathways of greenhouse gas emissions, from stringent mitigation (RCP2.6) to high emissions (RCP8.5)
• Sea-level rise is expected to continue, with projections ranging from 0.26 to 0.82 meters by 2100, depending on the emissions scenario and the response of ice sheets
• Extreme weather events, such as heatwaves, droughts, and heavy precipitation, are projected to become more frequent and intense in many regions
• Tipping points in the climate system, such as the melting of the Greenland ice sheet or the collapse of the Amazon rainforest, could lead to rapid and irreversible changes if critical thresholds are crossed
• Biodiversity loss is projected to accelerate, with up to one million species facing extinction by the end of the century, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES)
• Adaptation challenges include the need for substantial financial resources, technological innovations, and institutional capacity building, particularly in developing countries
• Climate justice and equity considerations are crucial in addressing the uneven distribution of climate change impacts and ensuring a fair transition to a low-carbon future