1.4: Climate change

• Carbon dioxide (CO2) is released into the air when plants die or are burned as fuel.
• Carbon dioxide (CO2) and methane (CH4) are greenhouse gases that trap heat in Earth's atmosphere, contributing to the greenhouse effect and maintaining the planet's temperature within a habitable range.
• The burning of fossil fuels, such as coal, oil, and natural gas, releases large amounts of carbon dioxide into the atmosphere, exacerbating the greenhouse effect and leading to climate change.
• Over geological timescales, carbon from the atmosphere can become stored in fossil fuels through processes like sedimentation and burial, forming coal, oil, and natural gas deposits that can remain underground for millions of years.
• When these fossils fuels are extracted and burned, they release carbon back into the atmosphere, increasing atmospheric concentrations of CO2 and other greenhouse gases.
• When fossil fuels are extracted and burned for energy, carbon that had been stored in them is released back into the atmosphere in the form of carbon dioxide, contributing to the greenhouse gas concentration and amplifying the greenhouse effect.
• Trees play a crucial role in absorbing CO2 from the atmosphere through photosynthesis, but deforestation reduces their ability to do so.
• Human activities have increased the amount of carbon dioxide in the atmosphere, causing an increase in temperatures on Earth known as global warming.
• Burning fossil fuels releases carbon dioxide and other pollutants into the environment, contributing to global warming and environmental degradation.
• Increasing levels of carbon dioxide and other greenhouse gases in the atmosphere have resulted in global warming, rising temperatures, altered precipitation patterns, more frequent extreme weather events, and other impacts on Earth's climate system.
• Earth's climate has undergone significant changes in the past, including periods of global cooling and warming. Ice ages, characterized by extensive glaciation, alternated with warmer interglacial periods where ice sheets retreated.
• "Snowball Earth" refers to hypothesized periods in Earth's history, possibly around 650 million years ago, when the entire planet may have been covered in ice and snow, or at least experienced extensive glaciation. The exact causes and mechanisms behind such extreme climate events are still subjects of scientific research and debate.
• Climatic conditions during the last ice age were much colder than today, with average temperatures around -5°C lower than present-day values.
• Scientists use evidence such as tree rings, ocean sediments, and ice cores to reconstruct past climates and understand how they changed over time.
• Global warming can lead to sea level rises, melting of polar ice caps, ocean acidification, coral bleaching, extinction of species, and other negative consequences.
• Recent decades have seen unprecedented rates of temperature rise due to anthropogenic (human-caused) factors like burning fossil fuels, deforestation, agriculture, and industrial processes.
• The most recent ice age occurred about 2.7 million years ago and lasted approximately 100,000 years.
• About 470 million years ago, a collision between two asteroids between Earth and Mars resulted in the production of significant dust quantities, diminishing sunlight and heat reaching Earth's surface and initiating an ice age.
• Following the collision, Earth experienced widespread cooling, with ice caps expanding and sea levels dropping due to reduced temperatures.
• Approximately 67 million years ago, an asteroid struck Earth, leaving a significant impact zone along the Mexican coast, causing extensive devastation akin to a massive explosion with shockwaves and high temperatures emanating from the crater.
• Ice ages occur when there are fewer greenhouse gases in the atmosphere, resulting in less solar radiation being trapped by the planet.
• The impact's global repercussions included the ejection of vast amounts of rock and dust into the atmosphere, leading to a reduction in sunlight reaching Earth's surface and the creation of a massive tsunami, affecting oceans worldwide.
• Diminished sunlight hindered photosynthesis, disrupting food chains and resulting in reduced food availability for animals, while colder temperatures further impacted Earth's ecosystems.
• Some scientists believe that the impact may have triggered volcanic eruptions on land, further contributing to climate changes.
• Many scientists attribute the climate changes following the asteroid collision to the mass extinction event that led to the demise of dinosaurs and numerous other species, with up to 75% of Earth's species becoming extinct.
• The asteroid collision's global impact underscores its role in shaping Earth's biodiversity and geological history, marking a significant event in the planet's evolution.
• Methane gas can also be released through natural processes such as decomposition or volcanoes.
• Objects smaller than asteroids, known as meteoroids, can collide with Earth, creating meteors when entering the atmosphere.
• While most meteors burn up harmlessly due to atmospheric friction, larger ones can generate shockwaves and occasionally cause local damage, as demonstrated by the 2013 meteor explosion over Russia.
• Meteoroids that survive atmospheric entry and reach Earth's surface are called meteorites, with around 500 of them reaching the surface annually, and careful monitoring of potentially hazardous objects by scientists began in 1998, focusing on factors like mass, diameter, and proximity to Earth to assess the risk of impact.
• Over the past 2000 years, Earth's climate has generally remained stable, with predictable patterns of rainfall and temperature changes, aiding agricultural planning and crop selection
• In recent times, however, Earth's average temperatures have been rising due to an increase in atmospheric carbon dioxide concentration.
• Carbon dioxide acts as a greenhouse gas, trapping heat energy near the Earth's surface, and as its concentration increases, more heat is retained, contributing to global warming.
• • Changing climate patterns are disrupting rainfall patterns, making it challenging for communities to predict and rely on consistent rainfall for agriculture. Late or absent rains, as well as unexpected heavy rainfall, can lead to crop failures, threatening livelihoods and food security in affected regions.
• Climate change is leading to more frequent and severe extreme weather events due to increased energy in the atmosphere, potentially resulting in catastrophic events such as hurricanes and typhoons.
• Climate change-induced disruptions in rainfall patterns can lead to crop failures and increase the risk of wildfires during long droughts, impacting both humans and ecosystems.
• Rising global temperatures contribute to the expansion of seawater volume, resulting in higher sea levels, exacerbated by the melting of ice caps and glaciers.
• Melting glaciers and ice caps, exemplified by the retreat of glaciers, contribute additional water to the oceans, further elevating sea levels.
• Sea levels have been rising at a rate of approximately 3 mm per year, posing significant flooding risks to coastal areas and endangering more than 600 million people by the end of the century.
• Coastal megacities such as Shanghai, Mumbai, and Los Angeles are particularly vulnerable to sea level rise due to their geographical location, putting millions of inhabitants at risk of inundation and displacement.