Global Warming: Theory, Proof, and Effects

Contents
Global Warming Thesis

There has been a rapid increase in Earth’s average surface temperature since the mid-20th century, due primarily to greenhouse gases injected into the atmosphere by human activity.

Proof that Global Warming is Real
Simplified
  • Premise 1: Earth is warming.
  • Premise 2: The only plausible explanation of Earth’s warming is the increase in atmospheric greenhouse gases.
  • Premise 3: The only plausible explanation of the increase in atmospheric greenhouse gases is human activity.
  • Conclusion: Therefore, Earth is warming, for which the only plausible explanation is the increase in atmospheric greenhouse gases due to human activity.
Scientific Assessment
  • Sixth Intergovernmental Panel on Climate Change (UN, 2021)
  • Federal Report Warns of Financial Havoc From Climate Change (NYT, September 8, 2020)
    •  A report commissioned by federal regulators overseeing the nation’s commodities markets has concluded that climate change threatens U.S. financial markets, as the costs of wildfires, storms, droughts, and floods spread through insurance and mortgage markets, pension funds, and other financial institutions.
  • Fourth National Climate Assessment (US, 2017)
    • science2017.globalchange.gov/downloads/CSSR2017_FullReport.pdf
      • This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence. Page 10
  • Fifth Intergovernmental Panel on Climate Change (United Nations, 2013)
    • ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf
      • It is virtually certain that globally the troposphere has warmed since the mid-20th century. Page 5
        • Virtually certain = 99%-100% likelihood
      • It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. Page 17
        • Extremely likely = 95%-100% likelihood
Theory of Global Warming
Natural Greenhouse Effect (Established Science)
  • Sunlight passes through the atmosphere, heating the Earth.
  • The Earth radiates infrared radiation into the atmosphere. 
  • Greenhouse gases in the atmosphere (water vapor, CO2, methane) absorb some of that infrared radiation.
  • Greenhouse gases reradiate the infrared radiation in all directions, including back to Earth, further warming the Earth.
Theory of Global Warming, the Enhanced Greenhouse Effect
  • Human activity, especially the burning of fossil fuels, injects greenhouse gases (such as carbon dioxide and methane) into the atmosphere
  • As a result, the increased greenhouse gases in the atmosphere absorb more infrared radiation from Earth.
  • Therefore, more infrared radiation is reradiated back to Earth
  • Therefore, the temperature of the Earth’s surface increases even more than it would normally.
Proof that Global Warming is Real
Beyond a Reasonable Doubt
Synopsis
  • Premise 1: Earth’s average surface temperature has increased rapidly since the mid-20th century.
  • Premise 2: The only plausible explanation of the increase in Earth’s average surface temperature is the increase of atmospheric greenhouse gases since the Industrial Revolution, especially carbon dioxide and methane.
  • Premise 3: The only plausible explanation of the increase in atmospheric greenhouse gases is the injection of greenhouse gases into the atmosphere by human activity.
  • Conclusion: Earth’s average surface temperature has increased rapidly since the mid-20th century, for which the only plausible explanation is the injection of greenhouse gases into the atmosphere by human activity.
Premise 1

Premise 1: Earth’s average surface temperature has increased rapidly since the mid-20th century.

Evidence for Premise 1

  • Instrumental measurements of surface temperature on land and sea collected since 1880.
  • Reconstructions of earlier temperatures using “proxy” measurements, records of other natural phenomena that indirectly measure climate conditions, such as:
    • sediment cores
    • pollen records
    • glacial moraines
    • geothermal borehole temperatures
    • growth rings from trees
    • oxygen isotopes from corals and ice cores.

More on Premise 1

Premise 2

Premise 2: The only plausible explanation of the increase in Earth’s average surface temperature is the increase of atmospheric greenhouse gases since the Industrial Revolution, especially carbon dioxide and methane.

Argument for Premise 2

  • Premise 2A: Atmospheric greenhouse gases have increased since the Industrial Revolution, especially carbon dioxide and methane.
  • Premise 2B: The increase in atmospheric greenhouse gases since the Industrial Revolution explains the increase in Earth’s surface temperature
  • Premise 2C: There is no other plausible explanation of the increase in Earth’s surface temperature.
    • Volcanic Activity
    • Variations in Solar Output
    • Variations in Earth’s orbit (Milankovitch Cycles)
  • Conclusion: The only plausible explanation of the increase in Earth’s surface temperature is the increase in atmospheric greenhouse gases since the Industrial Revolution, especially carbon dioxide and methane.

More on Premise 2

Premise 3

Premise 3: The only plausible explanation of the increase in atmospheric greenhouse gases is the injection of greenhouse gases into the atmosphere by human activity.

Measurements

  • The following have been measured for periods before and after the Industrial Revolution:
    • Inc =  Increase in atmospheric CO2
    • NatSrc = Atmospheric CO2 emitted from natural sources
    • NatSink = Atmospheric CO2 that disappears into natural sinks
    • HumSrc = Atmospheric CO2 emitted from human sources
  • For periods before the Industrial Revolution
    • Inc = NatSrc – NatSink
  • For periods since the mid-20th century:
    • Inc = NatSrc – NatSink + HumSrc
  • The same measurements have been made for methane, CH4.

The Argument

  • Before the Industrial Revolution
    • Inc = NatSrc – NatSink
  • But after the Industrial Revolution
    • Inc > NatSrc – NatSink
  • That is,
    • Inc = NatSrc – NatSink + X
  • Is there a quantity Q such that
    • Q = X
    • Q is a source of CO2
  • Yes, Q = HumSrc
  • So,
    • Inc = NatSrc – NatSink + HumSrc
  • The same reasoning goes for methane, CH4.

Analogy

  • For money in your safe:
    • Increase in Balance = Deposits – Withdrawals
  • You transfer the money to a savings account.  But now:
    • Increase in Balance > Deposits – Withdrawal
  • That is
    • Increase in Balance = Deposits – Withdrawals + X
  • Is there a quantity Q such that
    • Q = X
    • Q is a source of money
  • Yes, Q = Interest
  • So,
    • Increase in Balance = Deposits – Withdrawals + Interest

Carbon Dioxide: Sources and Sinks

  • Increase in atmospheric CO2 = CO2 from natural sources – CO2 into natural sinks + CO2 from human sources (Source Britannica)
    • Natural Sources
      • volcanoes
      • combustion and natural decay of organic matter
      • respiration by oxygen-using organisms
    • Natural Sinks
      • terrestrial vegetation (photosynthesis)
    • Human Sources
      • burning fossil fuels (oil, coal, natural gas) for use in transportation, heating, and generation of electrical power
      • production of cement
      • burning of forests and clearing of land

Methane: Sources and Sinks

  • Increase in atmospheric CH4 = CH4 from natural sources – CH4 into natural sinks + CH4 from human sources (Source Britannica)
    • Natural Sources
      • tropical and northern wetlands
      • methane-oxidizing bacteria that feed on organic material consumed by termites
      • volcanoes
      • seepage vents of the seafloor in regions rich with organic sediment
      • methane hydrates trapped along the continental shelves of the oceans and in polar permafrost
    • Natural Sinks
      • the atmosphere itself, as methane reacts with the hydroxyl radical (OH-) within the troposphere to form CO2 and water vapor (H2O).
      • the soil, where methane is oxidized by bacteria
    • Human Sources
      • rice cultivation
      • livestock farming
      • burning of coal and natural gas
      • combustion of biomass
      • decomposition of organic matter in landfills 
  • A study in Nature suggests that the actual of amount of methane produced by natural sources is much less than thought, meaning that human activity is producing more than previously thought, perhaps 25 to 40 percent more.

More on Premise 3

Conclusion

Conclusion: Earth’s average surface temperature has increased rapidly since the mid-20th century, for which the only plausible explanation is the injection of greenhouse gases into the atmosphere by human activity.

Predicted Effects of Global Warming
  • Global Warming makes extreme-weather events more likely
    • Why the Wilder Storms? It’s a ‘Loaded Dice’ Problem (NY Times, October 2018)
      • “It’s the classic loaded-dice analogy,” Said Raghu Murtugudde, a professor of Earth systems science at the University of Maryland. The dice are “throwing up some numbers more often” in the form of extreme weather.
  • Heatwaves
    • Global Warming > Warmer Air > More hot days and hotter hot days
  • Droughts
    • Global Warming > Warmer Air > Increased Rates of Evaporation
  • Heavy Rains
    • Global Warming > Warmer Air > More Water Vapor in Air
  • Floods
    • Global Warming > Elevated Sea Levels > Coastal flooding
    • Global Warming > Warmer Air > More Water Vapor in Air > Heavy rains > Flash floods & urban floods
  • Hurricanes
    • Global Warming > Warmer Air > More Water Vapor in Air
    • Global Warming > Elevated Sea Levels
    • Global Warming > Warmer Oceans
  • Wildfires
    • Global Warming > Warmer Air > Increased Rates of Evaporation > Droughts > Dead trees > Fuel for fire

Image Credit science2017.globalchange.gov/downloads/CSSR2017_FullReport.pdf

Climate Change in 2020
  • Global Climate Report – Annual 2020 NOAA
    • With a slightly cooler end to the year, the year 2020 secured the rank of second warmest year in the 141-year record, with a global land and ocean surface temperature departure from average of +0.98°C (+1.76°F). This value is only 0.02°C (0.04°F) shy of tying the record high value of +1.00°C (+1.80°F) set in 2016 and only 0.03°C (0.05°F) above the now third warmest year on record set in 2019.
    • The seven warmest years in the 1880–2020 record have all occurred since 2014, while the 10 warmest years have occurred since 2005. 
    • The global annual temperature has increased at an average rate of 0.08°C (0.14°F) per decade since 1880 and over twice that rate (+0.18°C / +0.32°F) since 1981.
    • The 2020 Northern Hemisphere land and ocean surface temperature was the highest in the 141-year record at +1.28°C (+2.30°F) above average. This was 0.06°C (0.11°F) higher than the previous record set in 2016. Meanwhile, the annual Southern Hemisphere land and ocean surface temperature was the fifth highest on record.
  • 2020 Ties 2016 as Hottest Yet, European Analysis Shows, NYT
    • According to Copernicus, a program of the European Union, the global average temperature in 2020 was 1.25 degrees Celsius (about 2.25 degrees Fahrenheit) warmer than the average from 1850 to 1900, before the rise of emissions from spreading industrialization.
    • The 2020 average was very slightly lower than the average in 2016, too small a difference to be significant.
    • Copernicus uses a technique called re-analysis, which uses fewer temperature measurements than Berkeley Earth, NOAA, and NASA, but adds other weather data like air pressure, and feeds it all into a computer model to compute its temperature averages.
  • Top climate stories of 2020, News Analysis, WaPo
    • With Joe Biden’s victory, the United States is set for an about-face on climate change policy.
    • The coronavirus caused a temporary drop in emissions and devastated oil companies.
    • Climate changed fueled extreme weather in the United States.
      • Wildfires in the West and hurricanes on the Gulf and East coasts destroyed homes, shut down power grids and forced a record number of Americans into emergency shelters. 
      • Scientists worry the West is approaching a new normal, as climate change leads to hotter and drier conditions. California’s frequency of fall days with extreme-fire weather has doubled since the 1980s.
      • The past six years are likely to be the six warmest on record, according to the U.N. World Meteorological Organization climate report, and there’s a chance that once December data is incorporated, some agencies will rank 2020 as the warmest year ever recorded.
      • Meanwhile, the Gulf Coast and Eastern Seaboard grappled with the busiest Atlantic hurricane season on record. This year saw 30 named storms, compared with an annual average of 12, as well as the most U.S. landfalls on record.
    • Companies and countries promised dramatic cuts to their emissions.
      • AT&T, Apple, Ford, McDonald’s and Walmart are among companies that announced new net-zero targets this year, amid growing pressure from activists and investors. TheBusiness Roundtable, a lobbying group representing more than 200 companies, endorsed a carbon tax and a goal of an 80 percent emissions reduction by 2050. Even fossil fuel companies got in on the action: Royal Dutch Shell and BP have promised to slash their emissions to net zero by 2050. 
    • Financial institutions started to take into account the risks of climate change.
      • The Federal Reserve called out climate change as a financial risk for the first time this year, warning that floods, hurricanes, wildfires and a rapidly changing climate could threaten the stability of the financial system. The central bank also announced on Tuesday that its board had voted to join an international effort to price climate risk into investments. 
  • Covid-19 Took a Bite From U.S. Greenhouse Gas Emissions in 2020, NYT
    • America’s greenhouse gas emissions from energy and industry plummeted more than 10 percent in 2020, reaching their lowest levels in at least three decades as the coronavirus pandemic slammed the brakes on the nation’s economy, according to an estimate published Tuesday by the Rhodium Group.
Trump Administration Rollbacks
  • What Trump’s Environmental Rollbacks Mean for Global Warming (NYT, September 17, 2020)
    • President Trump has made dismantling federal climate policies a centerpiece of his administration. A new analysis from the Rhodium Group finds those rollbacks add up to a lot more planet-warming emissions.
  • The Trump Administration Is Reversing More Than 100 Environmental Rules. Here’s the Full List (NYT)

Image Credit nytimes.com/interactive/2020/climate/trump-environment-rollbacks-list.html

View Trump Rollbacks of Air Pollution and Emissions Rules

Paris Climate Accord
  • Timeline
    • Nations approve Paris Climate Accord, Dec 2015 (NYT)
    • Trump announces withdrawal from the Paris Climate Accord, June 2017 (WH)
    • Syria joins Paris Climate Accord, leaving only U.S. opposed, Nov 2017 (NYT)
  • Arguments for withdrawing from the Paris Climate Accord, from Trump’s June 1, 2017 Statement
    • Compliance with the agreement would cost millions of jobs and cost the US economy $3 million in lost GDP
    • The agreement gives other countries a financial advantage over the US
    • Compliance with the agreement would block the development of clean coal
    • Compliance with the agreement would expose the US to massive future legal liability
    • Renewable sources of energy will not be able to meet the demand for energy if the economy grows at 3%, putting the US at grave risk of brownouts and blackouts
    • If the Paris Agreement were implemented in full, with total compliance from all nations, it is estimated it would only produce 0.2  Celsius reduction in global temperature by the year 2100.
  • Argument against withdrawing from the Agreement
    • The planet is facing an urgent global problem that requires a global solution.
      • Global Warming
        • There has been an unusually rapid increase in Earth’s average surface temperature since about 1900, due primarily to greenhouse gases injected into the atmosphere by human activity
      • We are experiencing the predicted effects
        • Melting sea ice in the Arctic, melting Antarctic ice sheet, retreating mountain glaciers, shrinking permafrost
        • Warming oceans
        • Rising sea level
        • More extreme weather:  heat waves, droughts, extreme precipitation, and floods
        • Increased intensity of hurricanes
      • Reducing GHG emissions will slow global warming and mitigate the predicted effects
      • Paris Climate Agreement is projected to slow global warming by reducing GHG emissions
  • Assessment of Trump’s Arguments
    • Compliance with the agreement would cost millions of jobs and cost the US economy $3 million in lost GDP
      • The claim is based on a report, funded by opponents of the Paris Accord, which critics argue makes unrealistic assumptions, for example that the economy wouldn’t benefit from energy-efficient innovations.
    • The agreement gives other countries a financial advantage over the US
      • The Accord is nonbinding. Each nation sets its own targets.
    • Compliance with the agreement would block the development of clean coal
      • The agreement does not prohibit US from building coal plants.
    • Compliance with the agreement would expose the US to massive future legal liability
      • There is no liability mechanism in the Paris Agreement.
    • Renewable sources of energy will not be able to meet the demand for energy if the economy grows at 3%, putting the US at grave risk of brownouts and blackouts
      • Even the most optimistic scenarios do not envision a grid powered entirely by renewables until far into the future.  But a series of recent studies have found that the U.S. grid could operate reliably with large amounts of renewable generation.
    • If the Paris Agreement were implemented in full, with total compliance from all nations, it is estimated it would only produce 0.2  Celsius reduction in global temperature by the year 2100.
      • This is based on 2015 MIT research which in fact says the Paris Agreement could lower the expected temperature increase by 0.6 to 1.1 C The accord is supposed to be just a start, with nations scheduled to increase their commitments every five years.
Resources
National Climate Assessment
Intergovernmental Panel on Climate Change (IPCC)
  • The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change.
    • Ipcc.ch
    • Sixth Assessment Report (2021)
    • Fifth Assessment Report (2014)
    • Fourth Assessment Report (2017)
    • Special Report Global Warming of 1.5 ºC
    • britannica.com/topic/Intergovernmental-Panel-on-Climate-Change
      • Intergovernmental Panel on Climate Change (IPCC), United Nations panel established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization(WMO) in 1988. Headquartered with the WMO in Geneva, Switz., the IPCC assesses peer-reviewed literature and industry practices to determine the impact of and possible responses to climate change. While it produces no research of its own, its members—divided into three working groups and a task force—assemble reports from hundreds of scientists and policymakers from around the globe. These are analyzed and distributed as special papers or as more-comprehensive assessment reports. In 2007 the IPCC shared, with Al Gore, the Nobel Peace Prize for disseminating knowledge about man-made climate change
WMO (World Meteorological Organization)
  • The World Meteorological Organization (WMO) is an agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics.
  • Global Climate Observing System
    • GCOS regularly assesses the status of global climate observations and produces guidance for its improvement. 
    • gcos.wmo.int
NOAA (National Oceanic and Atmospheric Administration)
NASA
Berkeley Earth
Copernicus Climate Change Service 
  • The C3S mission is to support adaptation and mitigation policies of the European Union by providing consistent and authoritative information about climate change.
News and Analysis
Britannica
  • britannica.com/science/global-warming
    • Global warming, the phenomenon of increasing average air temperatures near the surface of Earth over the past one to two centuries. Climate scientists have since the mid-20th century gathered detailed observations of various weather phenomena (such as temperatures, precipitation, and storms) and of related influences on climate (such as ocean currents and the atmosphere’s chemical composition). These data indicate that Earth’s climate has changed over almost every conceivable timescale since the beginning of geologic time and that the influence of human activities since at least the beginning of the Industrial Revolution has been deeply woven into the very fabric of climate change.