SCI 201 Global Warming and Climate Change Lecture Notes PDF

University of Waterloo SCI 201 – “Global Warming and Climate Change” Dr. Yuri Leonenko Winter 2025  Main objective of the course: To provide students with an understanding of fundamental science related to global warming and climate change Introduction (main qu...

University of Waterloo SCI 201 – “Global Warming and Climate Change” Dr. Yuri Leonenko Winter 2025  Main objective of the course: To provide students with an understanding of fundamental science related to global warming and climate change Introduction (main questions, topics, objectives…)  Questions: Global Warming? What does it mean? Climate Change? Main Objective: To build scientific knowledge to be able Link? to answer (or to discuss) these questions Reasons? Natural or Human activity? Should we care? How to deal? …. Identifying Fundamental Laws Validation Facts (responsible for these Modeling (Compare with (gathering facts and explaining Experiment) information) these facts) Approximate Definite Answers Answers  Focus in our course: Identifying Facts Fundamental Laws (gathering (responsible for these Modeling information) facts and explaining these facts) Approximate Answers  Some topics to be covered Facts (gathering information) Weather versus Climate, Change, Variability Large time (geological) scales of climate change Methods of observations Current trends Natural and anthropogenic causes of climate change Basic science behind global warming (core) Some principles of Thermodynamics. temperature Identifying thermal equilibrium Fundamental Laws heat transfer (responsible for these facts and explaining these facts) Radiative Heat Transfer. Blackbody Radiation and Laws of Radiation Interaction of light with atmospheric gases. Absorption. Greenhouse Effect. Greenhouse Gases. Basic science behind global warming (core) The Layer Model Radiation balance Solar Constant. Albedo. Modeling Carbon on Earth The Perturbed Carbon Cycle Feedbacks Physical and Social Impacts of Climate Change range of current and future physical impacts, including sea level rise, increasing average global temperature, droughts, wildfires and other extreme weather events Global temperature projections Approximate Answers Options to reduce Global Warming Renewable energy CCS (Carbon Capture and Storage) Geo-Engineering Approximate Answers  Lecture 2A Identifying Facts Fundamental Laws (gathering (responsible for these Modeling information) facts and explaining these facts) Approximate Answers Topics: Weather versus Climate Variability and Changes Global Mean Surface Temperature Global warming  Weather vs Climate Both climate and weather deal with ATMOSPHERIC conditions (or State of the Atmosphere) which characterized by set of physical parameters, such as rainfall, pressure, temperature, humidity, precipitation…. Can be measured (thermometer) ATMOSPHERIC conditions ( State of Atmosphere) Temperature (t) Pressure (t) Precipitation (t) … … These parameters are constantly changing and so continuous function of time Can be averaged over different time scales t (min, hour, day, month, year, century….)  Weather vs Climate Both climate and weather deal with ATMOSPHERIC conditions (or State of the Atmosphere) which characterized by set of physical parameters, such as rainfall, pressure, temperature, humidity, precipitation…. ATMOSPHERIC conditions ( State of Atmosphere) Temperature (t) t=hour Pressure (t) Precipitation (t) … … t=day  Weather vs Climate Both climate and weather deal with ATMOSPHERIC conditions (or State of the Atmosphere) which characterized by set of physical parameters, such as rainfall, pressure temperature, humidity, precipitation…. ATMOSPHERIC conditions ( State of Atmosphere) Temperature (t) Pressure (t) Precipitation (t) … … Typically, short means scale below few months, long means over few years. Above is for some particular area (from local scales to global) The shorter time scale, the higher variability of all parameters, more chaotic behavior, which is very difficult to predict Longer times provide much smother behavior, and one can say climate is the long-term pattern of weather Variability Daily scale averaging Both weather and climate have variability -24 h “oscillations” related to Earth rotation Monthly scale -1 year “oscillations” related to Earth orbiting around Sun 15o -Short-term atmospheric “internal instabilities” (storms, averaging hurricanes…..) 1 2 3 4 5 years 1-year averaging 5-year averaging -for climate there are also reasons, but they are not that obvious (much longer in time and we don’t feel them, unless measured and 2o analyzed statistically) Could lead to wide areas of misinterpretation! Variability 1. Averaged data can be further processed, over some intervals of interest (decades, centuries, geological scales…..) Mean value 2. Over particular interval averaged data has mean and deviations from mean (variability) and can be described (statistically) in terms of PDF probability distribution function (smaller deviations from mean happening more frequently and so more probable; larger ones less frequent, and so less probable) Mean Variability vs Change If the shape of PDF is not changing in time, we don’t have charges over the intervals of interest, but still have variability Variability vs Change If the shape of PDF is changing in time, we have charges over the intervals of interest Global Mean Surface Temperature What is the temperature which is used in defining of Global Warming? Temperature of what? Averaged over what place? Averaged Over what time? Surface temperature Earth 1-5 years (land and ocean) Global Mean Surface Temperature Global warming (cooling) Statistically significant changes in Global mean surface temperature over a time scale of centuries. “Current” Global warming GMST has increased ~0.9 degrees over the last century  GMST measurements (over the last century) Temperature stations Large time (geological) scales of climate change Global warming is not a new phenomenon in the Earth's history! “Current” Global warming The geological record shows that when viewed over a time scale of thousands of years the climate is in continual change with major ice ages occurring approximately every 100 000 years. Natural and anthropogenic? causes of climate change How data collected? Direct observations: Shortly after the invention of the thermometer in the early 1600s, efforts began to quantify and record the weather. The first meteorological network was formed in northern Italy in 1653 and reports of temperature observations were published in the earliest scientific journals By the latter part of the 19th century, systematic observations of the weather were being made in almost all inhabited areas of the world. Formal international coordination of meteorological observations from ships commenced in 1853  How to measure past global temperature? Scientists use indirect evidence (data) during past time periods to determine the climate at that time period. These climate imprints are referred to as proxies ( or paleoclimate proxies) A proxy is a natural data set that mimics an environmental change, e.g. increased tree ring width and increased temperature and moisture  Tree Rings Sediment Pollen Cores Examples of Proxies Stable Ice Cores Isotopes Coral Reefs  Tree growth is influenced by climate. These patterns can be seen in tree ring width and isotopic composition. Trees generally produce one ring each year. Trees ring records can extend back to the last 1000 years.  Sediment cores can be taken from lakes or oceans In some cases the thickness of these layers can be used to infer past climate. In other cases, these layers are composed of organic material that can be analyzed for other climate proxies.  Pollen grains are well preserved in lake and ocean sediment. The analysis of each of these sediment layers provides information on the vegetation present at that time. Scientists can infer past climates (warm or cold) based on the distribution and changes in plant species.  The most common element used in climate studies is oxygen. The isotopes of oxygen are: – O18 (rare) – O17 – O16 (common) The ratio of O18 to O16 is affected by temperature and can be used as a climate proxy.  Corals are composed of calcium carbonate. This carbonate contains isotopes of oxygen that can be used to determine the water temperature when and where the corals grew. Coring Earth’s ice sheets  Ice Cores Coring mountain glaciers Bubbles Trapped in ice core Petit, Jean-Robert, et al (1999). “Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica”. Nature 399: 429-436.