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A two-hour introduction to the climate change

Last night, I gave a "Science Café" public talk about global warming and climate change and stuff like that (in Czech) which was substantially longer than any previous presentation of mine about the topic – it was something like two hours plus a discussion.

One may talk about lots of the sociology and history of the movement and it's interesting – and often infuriating. But I still think it's more relevant to focus on the hard science and the physical basis of all the phenomena.




Some of the comments I made aren't found on the slides – my audible statements during any talk never quite agree with what is written on the slides. I think it's a virtue – it allows the audiences to gain a multi-dimensional perspective and/or a more detailed information if you listen and read the slides.




Here is collection of topics that I covered and that you may want to cover in similar talks:

  • Why it is relevant for a physicist to talk about an interdisciplinary "applied" field such as climatology
  • Weather: observables, synoptic maps
  • Climate and weather: the difference and why the timescale 30 years is just a convention
  • Example: Weather today in Pilsen and what the climate predicts (high, low, average, how they differ throughout the year, warmest and coolest weather stations in Czechia)
  • How the temperature changes at nights and during days, how quickly the Earth would cool down if the Sun disappeared
  • Seasons and the tilted axis
  • The need of averaging to get the quasi-monotonically increasing curves: averaging over days, dates, and locations is needed, otherwise everything is noise
  • Once you suppress the noise, the variations of the averaged temperature are modest, comparable to variations of the human body's temperature; stretching the graphs in the vertical direction is how things are made "look dramatic" although they aren't
  • Global mean temperature 1850-2018: the warming episodes 1900-1945 and 1975-2018 are similar, despite quadrupled emissions
  • Satellite record, 1.3 °C/century trend, El Niño 1997/1998 in the middle
  • Hiatus 1997-2015: warming isn't reliable and persistent, the "noise" is too big
  • Global warming temperature isn't the best quantity: pole-to-equator difference changed from 20 °C to 60 °C, the global mean temperature just in a smaller interval between 6 °C and 14 °C; differences drive processes in the atmosphere
  • Timescales and drivers of temperature: galactic spiral arms and the 140-million-year periodicity
  • Continental drift (including explanation and comments about the flawed anti-Wegener group think): Antarctica mostly warm in recent 100 million years
  • Ice ages: graphs of temperature, CO2, CH4 in 650,000 years
  • Milanković's theory: tilt and eccentricity oscillate
  • June irradiation near the Arctic circle varies, the ice sheets over there respond, the Earth's albedo and temperature follows
  • Gerard Roe-style fix: derivative needed to Milanković functional relations, perfect agreement
  • Graphs are obtained from sediments or ice cores (Vostok pictures, comparison of ice core and annual rings)
  • Correlation of CO2 and temperature: temperature is the cause: outgassing explained
  • CO2 can't be the cause: there'd be no explanation for CO2-CH4 agreement
  • CO2 can't be cause: 100 ppm would have to warm planet by 8 °C but we recently added 120 ppm and warming was just 0.8 °C
  • CO2 isn't the cause: the 800-year delay
  • The greenhouse effect: 1824 Fourier, 1896 Arrhenius – a wrong explanation of ice ages
  • The greenhouse effect: how it resembles the greenhouse or the quilt and how it differs
  • Layers of the atmosphere, growth and decrease of temperature
  • Energy fluxes in the atmosphere, analogy with trade between countries, balanced account balances
  • Energy fluxes: 1366/4 = 342 W/m2; the denominator is \(4\pi r^2/\pi r^2 = 4\), why
  • Composition of atmosphere: nitrogen, oxygen not greenhouse gases
  • Three-atomic molecules needed, H2O main greenhouse gas, 30 °C, what it means
  • CO2 is the second, 3-5 °C in total, including around 1 °C of man-made so far
  • Negligible other greenhouse gases, infrared absorption spectra
  • Wrong fingerprint of the greenhouse effect: 10 km above equator should warm most quickly, is observed not to
  • Climate sensitivity as warming from CO2 doubling
  • CO2 concentrations: ppm(v) as a unit, 180 ppm in ice ages, why plants die near 150 ppm, 280 ppm interglacials, 405 ppm today, 2 ppm growth, 560 ppm in 2080, 700 ppm in room, 6,000-10,000 ppm in distant past, 10,000-50,000 ppm people faint, 40,000 ppm what we breathe out; 20% increase of agriculture from 40% increase of CO2, reducing CO2 to 280 ppm overnight is Stalin on steroids
  • Arguments that the sensitivity is near 1-1.5 °C
  • Higher climate sensitivities in the literature and why these values reflect societal pressures
  • Logarithmic dependence of the greenhouse effect, painting analogy, decreasing problem
  • Positive and negative feedbacks, examples, biased treatment by the IPCC
  • Climate models: predict 3 °C per century, what is seen is 1-1.5 °C century, no one fixes the discrepancy by picking the more accurate ones because climate models aren't treated as tools of science
  • Additional drivers: volcanos, Mt Piñatubo, 0.5 °C cooling for five years, volcanos emit just 2% of CO2 per year than humans do, eruptions could have been more frequent – cooler weather
  • Oceans: 2/3 of surface, absorb 1/2 of excess heat, 1/2 of new CO2 (4 ppm of emissions vs 2 ppm/year rise)
  • Oceans, cycles: PDO and correlation with the warming/no-warming epochs since 1850
  • Oceans: El Niño, La Niña, definitions, (existence of) local meteorological effects, effect on global mean temperature after a 6-month delay
  • Global conveyor belt and the 1,500-year periodicity
  • Solar activity: introduction to sunspots and magnetic fields, solar cycles
  • Maunder minimum and Little Ice Age; Dalton minimum, picture of frozen Thames
  • How it could work: cosmoclimatology, cosmic rays shielded by the Sun, but create cloud condensation nuclei, application to the spiral arm 140 million year periodicity
  • Combined predictions from several effects, uncertainties
  • Consequences of global warming: melting continental ice, sea was 120 meters lower 20,000 years ago
  • Oceans almost stopped rising 6-8 thousand years ago, rise of civilization
  • Sea level rise seems to be 30 cm/century now, was 2 meters some 10,000 years ago
  • Remaining ice – Himalayan and Alps glaciers, Greenland, Antarctica, how much sea level rise, why the latter can't melt
  • Trends of polar ice: Arctic was going down, Antarctic mostly up very slowly, comments on the biased reporting
  • Failure of predictions about ice-free summers, cheap ways to save polar bears
  • Impact on ecosystems: Pilsen-Prague temperature difference is 3 °C and is believed to be zero, Pilsen would "become" Prague, transfer of ecosystems would solve problems if any
  • Influence on extreme and undesirable events, droughts, torrential rains, wildfires, tropical cyclones – show graphs with non-existent trends (or "improving" trends whenever policies have affected those)
  • The 2005 hurricane season and how cataclysmic predictions about the "new normal" were made in 2005, how they turned out to be completely wrong
  • Actual effects that work: energy consumption per capita is correlated with GDP per capita very clearly, also with literacy rate, decreases infant mortality, children per mother – graphs
  • Summary: global warming panic has a scientific core, the greenhouse effect, that is taken out of the context, blown out of proportion, dozens of similar effects are overlooked, censored, and suppressed; most of the "secondary" alleged effects due to CO2 don't take place and aren't predicted by proper science
  • Summary: try to think, be critical

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