200 years ago the planet was covered in forests and all those plants released oxygen (O2) into the atmosphere and trapped carbon dioxide (CO2) in their stems and branches. They also created cloud through transpiration and encouraged rainfall by forcing the clouds higher into the sky where they condense and create rain.
There was a much smaller human population back then and nobody was driving cars, trucks, buses, planes or trains that release huge amounts of CO2 and other harmful gasses into the atmosphere.
Electricity wasn't around in the abundant form we know today and even though small amounts of coal and wood was burnt, it wasn't a lot and the plants and trees on Earth were able to use whatever the people produced.
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Jump forward to now (present day) and 95% of the trees and plants on this planet have been cut down and burnt. The trees and plants have been replaced by brick and concrete buildings and black bitumen roads. These all absorb heat during the day and hold it for long periods of time after the sun has gone down compared to normal grass, soil and rocks.
All the buildings have electrical appliances in them that produce heat even if they are plugged into a live power socket but aren't being used. More heat is produced by these appliances when they are turned on and running. There are trillions of electrical appliances running continuously all over the world and each one is producing heat.
There are power stations all over the world continuously producing power. They produce huge amounts of heat and that is used to create electricity to run all the electrical appliances. Most of the power stations run on coal, oil, gas or uranium. Coal, oil and gas power stations release huge amounts of CO2, which builds up in the atmosphere as a greenhouse gas. Uranium based power stations don't release CO2 but do produce massive amounts of heat and radioactive waste that has a half life of 10,000+ years. This radioactive waste is extremely dangerous to all life on Earth and causes massive genetic damage to living cells.
There are billions of cars, trucks and buses using the roads every day of the year. Each vehicle produces massive amounts of heat from the engine, radiator, exhaust system, tyres rolling on the road, brakes when slowing the vehicle, and heat transferred out of the vehicle by air-conditioning units. In addition to these heat sources, there is heat and toxic gasses (including CO2) coming out of the exhaust pipes of these vehicles.
There are also motorbikes, lawn mowers, whipper snippers, leaf blowers and other machines powered by internal combustion engines that produce heat.
There are planes that use highly refined fossil fuels and the engines and exhaust get so hot when flying through the air, they actually burn holes in the atmosphere. Planes kill thousands of birds every year and pollute huge areas around landing strips due to dumping fuel before landing. Planes have air-conditioning too and have numerous electronic devices on board that use power.
City trains mostly run on electricity, which comes from burning fossil fuels. Trains used in remote areas still run on diesel. Modern trains have a huge amount of electronic devices on them and they produce massive amounts of heat through rolling resistance (wheels on tracks). The trains are made of metal and run on metal tracks that heat up in the sun. The temperature of the tracks gets a lot hotter than the surrounding ground and much hotter than would naturally occur if there were trees around. But the trees got cleared for the train tracks.
There are boats and ships that use fossil fuel and they use a lot more than land vehicles to travel the same distance because it is harder to push something through water than to drive on a hard flat stable surface. There are sailing ships but very few are big enough to carry huge amounts of cargo from China to other countries, and they are slow by comparison to fossil fuel powered ships.
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There is significantly less shade for the ground since the trees have been removed so the Earth's surface is getting more sunlight hitting it and the soil warms up more from the sun. This is raising average temperatures all over the globe.
Cities are becoming heat sinks due to lack of shade, too many brick, concrete and metal buildings, black bitumen roads and so many vehicles and electronic devices being used. In many parts of the world, city temperatures are noticeably higher than the outer suburbs where there are fewer vehicles, fewer houses, and more trees.
eg: In January 2018, Sydney the capitol city of New South Wales, got to over 47C and was the hottest place on Earth. This was also the highest temperature ever recorded there.
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Because there are very few terrestrial trees and plants left, there is not as many plants to use up the CO2 that is being released. 99% of the oxygen we breath now, is being produced by phytoplankton in the oceans and rivers, and that is struggling to cope with the amount of CO2 in the air. The CO2 levels are going up rapidly now.
There is more soil erosion, landslides and stronger hotter winds due to the lack of trees. There are more dust storms now and they are bigger than previously.
There is less rainfall in many parts of the world due to the pollution in the air and lack of trees releasing water vapour. The fine particles of pollution in the air are trapping moisture in the upper atmosphere and not letting it go. Back in the 1970s we got rain in Perth all through winter. We got rain whenever there was cloud. Now 50 years later, we get lots of dark stormy clouds but very little rain. The dust particles in the clouds are stopping the moisture from condensing and falling to Earth as rain. The lack of rain is killing plants and animals and making bush fires more likely and more devastating when they occur. The dark gloomy clouds are helping trap heat and are reflecting light back down to Earth at night, which is messing up the circadian rhythms of plants and animals.
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There are massive bush fires (wild fires) happening all over the planet and these are much bigger than we have ever experienced. They release huge amounts of heat and CO2, and they kill everything in them. The bush fires on the east coast of Australia in 2019-2020 got so hot, the ground is still scorched from the heat nearly 3 years later and not a lot has grown back. The soil has literally been sterilised by heat.
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Lots of glaciers around the world have either melted completely, or are close to being gone. The polar ice caps (Arctic & Antarctic) are melting and it is getting worse every year. When the ice caps melt completely, there will be nothing to stop the temperature rising and there will be a massive jump in global temperature that will cause chaos and death.
Think of the ice caps as a couple of blocks of ice in a glass of water. Put the glass outside in the sun. The water stays cold as long as the iceblocks are there. However, as the iceblocks melt and get smaller, the water temperature starts to increase. The smaller the iceblocks, the faster the water temperature rises. When the iceblocks melt completely, the water temperature suddenly goes up. This is what is happening to the Earth right now. The iceblocks (north & south poles) are melting. The water in the glass (oceans and rivers) are warming up. When the polar ice caps melt, the Earth's water, land and air temperature will skyrocket literally overnight.
The lack of glaciers on Earth means less sunlight gets reflected back into space so more sunlight warms the Earth.
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The CO2 levels in the atmosphere have jumped significantly during the last 20 years and are higher than any time during the last 100,000 years.
The average temperature of the planet has increased over 1.5 degrees Celsius in the last 30 years.
Just about every place on Earth has experienced higher than normal temperatures during the last 20 years.
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Most life on this planet will die if the temperature gets to 60C, and most will die when it's only 50C. If the human body gets to 45C your usually dead. A lot of plants die at 45C. These temperatures are in the shade so it's 10C+ hotter in the sun.
Phytoplankton (single celled algae in water) can only tolerate certain temperatures and certain conditions. When the water temperature gets over 40C, the phytoplankton dies. When the pH of the water changes suddenly, the phytoplankton dies.
The pH of the oceans is dropping due to excessive CO2 getting into the water. Currently the pH is decreasing very slowly. However, the rate of acidification (pH drop) in the oceans is increasing and has been for the last 10 years. Soon, the oceans will not have enough buffering power (KH or carbonate hardness) to stop the CO2 dropping the pH of the ocean water. When that happens, the pH of the oceans will drop rapidly and this will cause the phytoplankton, along with most of the fish, crabs, shrimp, corals and other life forms to die. The dead organisms will release more CO2 and cause the pH to drop even more.
When the phytoplankton dies, there will be virtually nothing left on the planet to remove the CO2 from the atmosphere and every aerobic (requiring oxygen) organism on Earth will die from CO2 poisoning. When this happens, the CO2 levels in the atmosphere will go even higher and there will be a runaway greenhouse effect on Earth. Temperatures will increase. Water will evaporate, rivers will dry up. Oceans will heat up, potentially dry up, and become salt lakes or salt flats devoid of life. The planet will turn into a baron wasteland and the only life that might exist will be anaerobic organisms living around volcanic vents at the bottom of the oceans, assuming there are any oceans left.
This is what will happen before the end of this century if humans do not change their ways immediately. There will be too much CO2 in the air to breath. The pH of the oceans will drop. The phytoplankton will die and everybody on Earth will suffocate to death. The planet's temperature will also skyrocket by 20-30C and turn the Earth into a bigger version of Venus.
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Yes the planet has hot and cold periods that last thousands or even millions of years. Most are caused by massive volcanic eruptions, or asteroid impacts. They only happen rarely and are natural events. However, everything listed above has been caused by people burning fossil fuels during the last 100 years and in particularly during the last 50 years. Up until 50 years ago, everything was pretty stable, but during the last 20 years, there has been a massive and sharp increase in temperatures and greenhouse gasses, all caused by people.
Is global warming caused by people? Absolutely it is. The global warming and climate change we see today is caused by modern humans using fossil fuels, chopping down trees, building heat sink cities, and overpopulating the planet. Animals, birds, fish and plants didn't do this. Volcanos didn't do this. Asteroids didn't do this and aliens didn't do this. Man and his machines did this. Nobody else was involved in the damage humans have done to Earth.
The big question is, will humans learn from their past and present mistakes and fix this in time, or will humans destroy this planet and become extinct like most of the other creatures that humans have wiped out?
www.nature.com
www.scientificamerican.com
