@cicerone imposter,
cicerone imposter wrote:
Question: Is global warming a normal cycle or man-made? Here's one answer: The Earth’s natural climate cycle
Over the last 800,000 years, there have been natural cycles in the Earth’s climate. There have been ice ages and warmer interglacial periods. After the last ice age 20,000 years ago, average global temperature rose by about 3°C to 8°C, over a period of about 10,000 years.
We can link the rises in temperature over the last 200 years to rises in atmospheric CO2 levels. Rises in temperature are now well above the natural cycle of the last 800,000 years.
From one perspective, you can classify causes as either natural or man-made; but from another perspective there is only sunlight and all the various ways that the energy is absorbed/stored and/or re-emitted to go someplace else.
So if you have a forest, sun shines on the tree canopy and they reflect most of it as green light, but they also absorb some and allow some to filter down through the canopy where it gets absorbed by other plants.
Then if you clear the forest and turn it into farms, the energy characteristics of the land changes. Energy and CO2 aren't being absorbed/stored as much as with (growing) hardwood. They are being absorbed and stored as crops, which are being harvested and consumed re-releasing the energy and carbon that was briefly stored up in them.
Now if you develop the farmland into paved cities and suburbs, the pavement and buildings are not even going to absorb and store any energy and carbon whatsoever, so that carbon and energy that used to get absorbed and stored by that soil when it was forest (or even farmland) is now kept as CO2 and latent heat in the atmosphere.
What's more, all the cars and other machines, including the factories that produce stuff to buy and carry in the cars and trucks, as well as the ships that sail between ports carrying stuff from the factories and fuels and other raw materials, as well as the heaters and air-conditioners and other appliances/machines running in the buildings; are all running on fuel that's taken out of the ground, where it sedimented to store carbon and energy for underground processes.
So now you're moving carbon and energy from underground where it's solid or liquid form and you're converting into gas form in the atmosphere.
So all those changes to the natural cycles of carbon, energy, water, soil, etc. all have effects on climate. You can't really say that climate is changed by EITHER natural OR man-made causes, because humans work with natural resources to procure industrial societies.
E.g. if humans take solid and liquid carbon/energy out of the ground and convert it into CO2 and heat, then nature is going to take that CO2 gas and heat and do what she does with those. The heat is going to cause more water to evaporate while the CO2 is going to make it more difficult for the energy to radiate out of the atmosphere. It's all 'natural mechanics,' but human activities have changed how the land functions and how carbon/energy sediments and functions in the long-term geological climate that's going on underground.