1. Historical Overview

1.1 Early Observations and Theories

  • Jean-Baptiste Joseph Fourier (1824): Proposed the atmosphere acts as an insulating layer, trapping heat (the greenhouse effect).
  • John Tyndall (1859): Demonstrated that gases like CO₂ and water vapor absorb infrared radiation.
  • Svante Arrhenius (1896): Calculated that doubling atmospheric CO₂ could significantly raise global temperatures.
  • Guy Stewart Callendar (1938): Linked rising global temperatures to increased CO₂ from fossil fuel combustion.

1.2 20th Century Developments

  • Charles David Keeling (1958): Initiated precise measurements of atmospheric CO₂ at Mauna Loa Observatory, revealing a steady annual increase (Keeling Curve).
  • 1970s-1980s: Growing scientific consensus on anthropogenic (human-caused) climate change; establishment of the Intergovernmental Panel on Climate Change (IPCC) in 1988.

2. Key Experiments and Evidence

2.1 Ice Core Analysis

  • Vostok Ice Core (Antarctica): Provided a 420,000-year record of temperature and atmospheric composition, showing a strong correlation between CO₂ levels and global temperature.
  • Greenland Ice Sheet Projects: Revealed rapid climate shifts (Dansgaard–Oeschger events) and provided evidence for abrupt climate change.

2.2 Direct Atmospheric Measurement

  • Keeling Curve: Continuous CO₂ monitoring since 1958, showing a rise from ~315 ppm (1958) to over 420 ppm (2023).
  • Satellite Observations: Since the late 1970s, satellites have measured global temperature trends, sea level rise, and ice sheet dynamics.

2.3 Oceanic and Biological Indicators

  • Ocean Heat Content: Over 90% of excess heat from global warming is absorbed by the oceans, leading to thermal expansion and sea level rise.
  • Phenology Studies: Shifts in plant blooming and animal migration patterns indicate changing climate conditions.

3. Modern Applications

3.1 Climate Modeling

  • General Circulation Models (GCMs): Simulate the Earth’s climate system, projecting future changes under various greenhouse gas emission scenarios.
  • Regional Climate Models (RCMs): Provide higher-resolution projections for specific areas, aiding in local adaptation strategies.

3.2 Renewable Energy Integration

  • Solar, Wind, and Hydro: Rapid deployment to reduce fossil fuel reliance.
  • Grid Decarbonization: Use of smart grids and battery storage to manage variable renewable energy sources.

3.3 Carbon Capture and Storage (CCS)

  • Direct Air Capture: Technologies that remove CO₂ directly from the atmosphere.
  • Geological Sequestration: Injecting captured CO₂ into deep underground rock formations.

3.4 Nature-Based Solutions

  • Afforestation and Reforestation: Large-scale tree planting to sequester carbon.
  • Wetland Restoration: Enhances carbon storage and provides ecosystem services.

4. Case Studies

4.1 The Paris Agreement (2015–Present)

  • Objective: Limit global warming to well below 2°C, preferably 1.5°C, above pre-industrial levels.
  • Impact: Nationally Determined Contributions (NDCs) submitted by countries to outline emission reduction targets.

4.2 The 2021 Pacific Northwest Heat Dome

  • Event: Unprecedented heatwave in Canada and the USA, with temperatures exceeding 49°C in Lytton, BC.
  • Attribution: Rapid analysis attributed the event’s intensity to anthropogenic climate change, with studies indicating such events are now 150 times more likely due to human influence.

4.3 Greenland Ice Sheet Melting

  • Observation: Satellite data (2021) show record melt events, contributing to global sea level rise.
  • Implication: Accelerated ice loss could trigger feedback loops, further destabilizing the climate.

4.4 Urban Heat Islands

  • Example: Cities like Tokyo and New York experience higher temperatures than surrounding areas due to altered land surfaces and waste heat.
  • Adaptation: Urban greening and reflective surfaces are being implemented to mitigate effects.

5. Practical Experiment: Measuring Local Urban Heat Island Effect

Objective: Quantify temperature differences between urban and rural environments.

Materials:

  • Two digital thermometers/data loggers
  • GPS-enabled smartphone
  • Notebook for observations

Procedure:

  1. Identify Locations: Select one site in a densely built urban area and another in a nearby rural or green space.
  2. Simultaneous Measurement: Place thermometers in shaded, well-ventilated spots at both locations.
  3. Data Collection: Record temperatures at hourly intervals over a 24-hour period.
  4. Analysis: Calculate average temperature difference; plot data to visualize diurnal patterns.
  5. Discussion: Relate findings to local land use, vegetation cover, and implications for urban planning.

6. Latest Discoveries and Developments

6.1 Tipping Points and Abrupt Change

  • Thwaites Glacier Instability: Research (Nature, 2022) warns of potential rapid collapse, which could raise sea levels by over half a meter.
  • Amazon Rainforest Dieback: Recent modeling (Science Advances, 2023) suggests parts of the Amazon are approaching a threshold beyond which forest-to-savanna transition could occur.

6.2 Extreme Weather Attribution

  • World Weather Attribution (WWA) Initiative: Uses real-time climate models to link specific extreme events to climate change. Recent studies (2022–2023) have attributed record floods in Pakistan and heatwaves in Europe directly to anthropogenic warming.

6.3 Carbon Dioxide Removal (CDR) Technologies

  • Enhanced Weathering: Spreading finely ground silicate rocks on croplands to accelerate natural CO₂ absorption (Nature, 2022).
  • Bioenergy with Carbon Capture and Storage (BECCS): Growing biomass for energy, capturing, and storing the resulting CO₂.

6.4 Recent Research Example

  • Cited Study: “Global Carbon Budget 2023” (Friedlingstein et al., Earth System Science Data, 2023) reports that global CO₂ emissions from fossil fuels reached a record high of 36.8 billion tonnes in 2022, despite increased renewable energy deployment.

7. Summary

  • Climate change is driven by rising greenhouse gas concentrations, primarily from human activities.
  • Key evidence includes ice core records, direct atmospheric measurements, and observed impacts on weather, ecosystems, and sea levels.
  • Modern responses encompass renewable energy, carbon capture, and adaptation strategies.
  • Case studies illustrate real-world impacts and policy responses.
  • Practical experiments can reveal local manifestations, such as urban heat islands.
  • Recent discoveries highlight the urgency of action, with new tipping points and technologies emerging.
  • Ongoing research underscores the scale of the challenge, as emissions continue to rise despite mitigation efforts.

Reference:
Friedlingstein, P., et al. (2023). Global Carbon Budget 2023. Earth System Science Data, 15, 5301–5365. https://doi.org/10.5194/essd-15-5301-2023