Climate Change
Chapter 1: Introduction
Climate change is a term that is often used but not well understood
The speaker aims to explain the facts about climate change using simple language and without bias
The speaker will not promote veganism or use complicated diagrams
Chapter 2: Measuring Earth's Temperature
Humans have been measuring the Earth's temperature for the past 100 years
The British East India Company collected weather and climate records from their ships in the late 1800s and early 1900s
These records provide valuable data on temperature changes
Other ships also collected weather data during their voyages
The Earth's temperature has been getting warmer over the past century
Chapter 3: The Sun's Role
The Sun is a possible cause of temperature increases on Earth
NASA has been measuring the amount of energy reaching Earth from the Sun since the 1970s
The data shows that the energy from the Sun has been slowly decreasing since the 1950s
Despite this, the Earth's average surface temperature has been steadily increasing
Chapter 4: Earth's Natural Cycle
The Earth's temperature could be increasing as part of its natural cycle
Ice cores from Greenland and Antarctica provide information on past temperatures
By examining the layers in the ice cores, scientists can determine the temperature when the ice froze
Shells of animals in sediment under the sea also provide information on past temperatures
The Earth's temperature has varied significantly over the past 800,000 years
Chapter 5: Milankovitch Cycles
Milankovitch cycles, invented by Milutin Milankovitch, explain the big changes in the Earth's temperature in the past
These cycles are related to changes in the Earth's orbit, tilt, and precession
The speaker suggests that the current increase in temperature could be another natural jump, similar to those in the past
Chapter 1: Earth's Temperature Changes over the Last 400,000 Years
Earth's temperature follows a pattern every hundred thousand years or so
Glacial period: Earth gets colder for around ninety thousand years
Interglacial period: Earth gets warm for about ten thousand years
Most of the time, the Earth is actually five to ten Celsius colder than it is today
Canada was almost completely covered in ice until roughly ten thousand years ago
Chapter 2: Milankovitch Cycles and Earth's Orbit
Milankovitch cycles are about the Earth and its orbit as it travels around the Sun
Earth has obliquity, which means its tilt on its axis
Earth's tilt varies over the course of a year, causing different amounts of sunlight on different hemispheres
Earth's tilt changes from 22.1 degrees to 24.5 degrees and back again in a cycle of 41,000 years
Other planets' gravity causes the Earth to wobble up and down, affecting its tilt
High Earth tilt causes warmer summers and ends glacial periods
Chapter 3: Changes in Earth's Tilt and Temperature
Earth's tilt changes very slowly, taking almost 20,000 years for a change of just two degrees
As the Earth comes out of glacial periods, its temperature rises by about 4 to 7 degrees over 5,000 years
In the past 100 years, Earth's temperature has risen by about 1.1 degrees, much faster than usual
The increase in temperature is not explained by the changes in Earth's tilt
Chapter 4: Greenhouse Gases and CO2
Greenhouse gases, including CO2, keep the Earth warm by absorbing and radiating heat energy
Earth's gravity holds these gases around it, preventing them from escaping into space
Without greenhouse gases, the average temperature on Earth would be around minus eighteen Celsius
CO2 concentration in the Earth's atmosphere can be measured by analyzing gas trapped in ancient ice
Chapter 5: Changes in CO2 Concentration
CO2 concentration on Earth has changed over the past 800,000 years
Ice in Antarctica contains trapped gas bubbles that provide snapshots of past CO2 levels
Analyzing the amount of CO2 in ancient ice gives insights into the Earth's atmosphere in the past
Chapter 1: The Relationship Between CO2 and Temperature
Over the last 800,000 years, CO2 levels and Earth's average temperature are closely related
When Earth's temperature increases, so does the concentration of CO2, and vice versa
Graphs show that temperature leads CO2 levels initially, but a major increase in CO2 levels leads to 90% of Earth's warming
CO2 does not drive the Earth getting warmer or colder
Chapter 2: The Role of CO2 in Temperature Rise
Temperature rise at the end of the last glacial period was likely caused by Milankovitch cycles
Warm liquids can't hold on to as much gas as cold liquids, so warmer Earth causes seas to release more CO2
CO2 increase after initial warming leads to a further increase in Earth's greenhouse effect and temperature
Graphs show CO2 levels leading to Earth's temperature increase
Chapter 3: Unprecedented Increase in CO2 Levels
CO2 concentration in the atmosphere has never exceeded 300 ppm in the last 800,000 years
In the last 100 years, CO2 levels have increased to over 400 ppm, 33% higher than ever before
Temperature rise of around 1.1 Celsius has occurred five to ten times faster than previous global temperature rises
Increase in CO2 and temperature rise happening despite tilting away from the Sun and reduced solar energy
Chapter 4: CO2 as the Likely Cause of Temperature Increase
Various factors like sun's orbit, volcanoes, deforestation, land use, and ozone layer show no significant impact on CO2 or temperature changes
Based on past CO2-temperature relationship and lack of other culprits, CO2 is deemed the most likely cause of recent temperature increase
Chapter 5: Burning of Fossil Fuels as the Source of Increased CO2
Fossil fuels are plants and animals that died millions of years ago and turned into coal and oil
Burning fossil fuels releases carbon dioxide, contributing to the increase in CO2 levels
Industrial Revolution marked the start of burning fossil fuels in bulk, coinciding with the increase in CO2 levels
Air contains carbon-14, and fossil fuels have almost no carbon-14, providing evidence that burning fossil fuels caused the increase in CO2
Chapter 1: Carbon-14 and Carbon-13 Levels
Graph shows average amounts of carbon-14 in the atmosphere since the 1880s
Carbon-14 levels have been steadily reducing since the Industrial Revolution
Indicates that the atmosphere is being filled with carbon dioxide from burning fossil fuels
Nuclear bombs detonated since the 1950s make it unreliable to measure carbon-14 levels
Carbon-13 levels in the atmosphere have also dropped steadily, unaffected by nuclear bombs
Chapter 2: Climate Change and Perception
Climate change is often portrayed as bad news and warnings
Conflicting messages about the impact of individual actions (e.g., going vegan vs. eating avocados)
Earth warming a few degrees will bring various issues worldwide (e.g., melting ice caps, heatwaves, forest fires)
Chapter 3: Reducing CO2 Emissions
Need to reduce CO2 emissions, but what changes should be made?
Majority of CO2 emissions (72%) come from energy use
43% of energy use emissions are from making electricity and burning fossil fuels for heating and cooking
17% of emissions are from transportation (cars, planes, boats)
Focus should be on reducing fossil fuel usage and increasing renewable energy
Chapter 4: Renewable Energy
Renewable energy includes biofuels, solar panels, and wind turbines
Once set up, renewable energy sources can generate power effectively forever
Energy is derived from sources like the Sun and wind, eliminating the need for mining coal or extracting oil
Renewable energy provides an endless source of low-cost energy
Chapter 1: Renewable Energy vs Fossil Fuels
Renewable energy is not as expensive as perceived
Fossil fuel industry received $360 billion in subsidies in 2016
Renewable energy received $140 billion in subsidies in 2016
Renewables are the fastest-growing energy resource in America
Solar energy is the fastest-growing energy resource in the world
Chapter 2: Renewable Energy for Electricity
26.5% of the world's electrical energy comes from renewables
146 out of 197 countries have set targets to increase renewable energy for electricity
Chapter 3: Renewable Energy for Heating and Cooking
Only 10.3% of the energy used for heat comes from renewable sources
Renewable gas