Climate change

Introduction to Climate Change

• Definition of Climate:

  • Refers to the weather conditions in a region over a long period of time, specifically several decades.

• Climate Change:

  • Occurs when weather conditions in a region change significantly over a long period.

  • Changes historically linked to factors such as atmospheric gas concentrations and volcanic activity.

  • Recent changes, specifically since the mid-1800s, attributed to human activities.

  • Often refers to global warming caused by human activities.

  • Changes in global climate patterns result in alterations to local weather patterns (e.g., rainfall and temperature).

  • Since the mid-1800s, average global temperature increases are largely human-caused.

Evidence for the Causes of Climate Change

• Current Hypothesis:

  • Global warming is in progress due to increased greenhouse gas concentrations from human activities.

• Types of Evidence:

  • Records of atmospheric carbon dioxide levels.

  • Records of average global temperatures.

  • Records of changing plant communities through pollen sampling.

  • Dendrochronology (analysis of tree growth rings) for historical climate insights.

Atmospheric Carbon Dioxide

• Fluctuations in Levels:

  • Atmospheric CO₂ levels have fluctuated due to natural events (e.g., volcanic eruptions, weathering).

  • Analyses of bubbles in ancient ice cores inform on historical gas composition.

  • Current CO₂ levels are above 400 ppm, a record high since the start of the industrial revolution.

  • Historical maximum CO₂ concentration was approximately 300 ppm before this period.

• Correlation with Temperature:

  • There is a correlation between CO₂ levels and temperature over thousands of years.

  • However, CO₂ is not the sole climate factor; others like solar winds and sunspots have less impact.

  • Overall evidence strongly suggests CO₂ from human activities is causing global temperature rises.

Average Global Temperatures

• Measurement:

  • Various thermometer recordings from around the world show historical temperature changes over time.

  • Data from the mid-1800s indicates an upward trend in global temperatures, with some short dips but overall increasing.

Paleoecological Evidence

• Pollen Analysis in Peat Bogs:

  • Peat bogs accumulate plant matter under acidic conditions, preserving pollen over time.

  • Cores can be analyzed for past plant communities to infer past climate conditions.

  • Changes in plant species can indicate cooling or warming trends (e.g., warmer climate plants increase, cooler plants decrease).

• Dendrochronology:

  • Tree growth measured through ring analysis provides climate data over time.

  • Trees exhibit wider rings during warm years and narrower rings during cooler years, indicating past climates.

The Greenhouse Effect

• Definition:

  • This effect occurs when solar radiation is absorbed and re-emitted by the Earth's surface, with greenhouse gases trapping this heat in Earth's atmosphere, akin to the glass in a greenhouse.

  • Essential for life; without it, Earth would experience extreme temperature fluctuations.

• Human Impact:

  • Increase in greenhouse gases like CO₂ and methane from human activities results in anthropogenic climate change.

Major Greenhouse Gases

• Carbon Dioxide (CO₂):

  • Levels are historically highest since the industrial revolution.

  • Strong correlation between rising CO₂ levels and increasing global temperatures.

• Methane (CH₄):

  • A hydrocarbon produced naturally and through human activities (e.g., livestock digestion, landfills, fossil fuel extraction).

  • Warming from the melting permafrost releases additional methane.

Numerical Evidence and Worked Example

• ppm and ppb Definitions:

  • ppm: parts per million (CO₂).

  • ppb: parts per billion.

• Graph Analysis Example:

  • Data trends include an increase in atmospheric CO₂ since about 1000 CE from 280 ppm to 380 ppm and an average global temperature rise from 13.8°C to 14.4°C.

  • Indicates a correlation where higher CO₂ concentrations correspond with warmer global temperatures but highlights fluctuations that suggest other influencing factors.

Models of Future Climate Change

• Extrapolation of Data:

  • Existing data allows predictions about future temperature changes.

  • Possible future scenarios inform how to prepare for climate changes (e.g., flood defenses, renewable energy initiatives).

  • IPCC scenarios suggest:

  • With serious reductions in fossil fuel use, temperature increase could be limited to ~1°C.

  • If no changes occur, the rise might exceed 4°C.

• Limitations of Models:

  • Uncertainty remains on human success in reducing emissions and potential effectiveness of new tech for carbon capture.

  • Predicting global climate patterns is complex; factors not yet understood (e.g., volcanic eruptions, other tipping points).

The Effects of Climate Change

• Increased Warming:

  • Results in extreme weather events, changes in ocean currents, and rainfall patterns.

  • Alters ecosystems, prompting animal migrations and threatening biodiversity.

• Changes in Biological Cycles:

  • Seasonal shifts like timing of flowering and breeding cycles; leads to mismatches in food availability for migratory species.

• Polar Ice Melting:

  • Threatens water supplies and causes rising sea levels due to thermal expansion and ice melt.

Temperature & Enzyme Activity

• Enzyme Dynamics:

• Changes in temperature significantly influence enzyme activity.

  • Optimum Temperature: Enzymes function best at specific temperatures and can denature above these points.

  • Denaturation disrupts enzyme function, impacting metabolism, photosynthesis, and overall organism survival.

• Practical Investigation:

  • Investigating the effect of temperature on enzyme activity using catalase to decompose hydrogen peroxide.

  • Methodology: Control variables, vary temperatures, measure oxygen production.

  • Calculate reaction rates through volume of oxygen produced over time.

Practical: Temperature & Development of Organisms

• Experimentation on Seedlings:

  • Investigate how varying temperatures affect growth rates of seedlings or hatching rates in brine shrimp, controlling other environmental factors.

Climate Change & the Scientific Community

• Consensus:

  • General agreement that greenhouse gas emissions cause climate change, despite some dissenting views.

• Evaluation of Claims:

  • Assess credibility, reliability, and bias in data sources.

  • Recognize the complexity of climate influences and personal stakes in climate issues.

Carbon Cycle & Reduction of Atmospheric Carbon Dioxide

• Carbon Cycle Processes:

  • CO₂ exists in the atmosphere, bodies of water, and living organisms.

  • Key processes include photosynthesis, respiration, and decomposition.

• Reduction Strategies:

  • Implement measures to reduce atmospheric CO₂ by limiting fossil fuel combustion, enhancing carbon sinks, and promoting reforestation.

Reducing Climate Change

• Action Steps:

  • Urgent need to reduce carbon emissions and increase carbon removal efficacy.

  • Explore biofuels as an alternative to fossil fuels, weighing arguments for and against.

• Renewable Energy Sources:

  • Transition to other energy forms like wind, solar, geothermal, and tidal has potential, but each comes with limitations.

  • Improve carbon capture and storage technologies and enhance global photosynthesis rates through practices like reforestation.