There are many reasons why the earth is now starting to heat up too much. This is mainly due to pollution of the environment which has in turn affected the ozone layer. This is causing global warming.
If there were no greenhouse gases in the atmosphere, the Earth's temperature would be much colder than it is now. Greenhouse gases trap heat from the sun, so without them, the Earth would lose more heat and the average temperature would be significantly lower.
The sun
There are no exact amount if mountains on Earth. Some are even forming now, so you wouldn't now how much mountains there are on Earth.
Earth is about 1.2 degrees Celsius warmer now compared to 1880.
yes
Now what you are doing and be organized
If it was reduced by half now, then nothing would happen - it would just take longer to cool down from now on. If the heat loss had been halved right from the start, then Earth would now be somewhat hotter than it is. Considering that the Earth now is not that much different (in terms of plate tectonics, surface temperatures, etc.) to how it was hundreds of millions of years ago, chances are it would be broadly similar. Magmas might be somewhat more fluid, and large intrusions would take longer to crystallise. However, life may be vastly different. It would have taken longer for the Earth to cool enough for the oceans to form, and hence longer for life to begin. Whether the different heat flow would have affected the advance from stromatolites to more complex life forms, I don't know.
There is no guarantee that plants will grow bigger. When we have heat waves now many plants die from the heat.
Trapping infrared radiation (rising from the surface of the earth) keeps the atmosphere warm enough for life. This has been happening for hundreds of millions of years. This is a good thing.(When too much heat is trapped, as is happening now, then the atmosphere starts getting warmer. This is called global warming. This is a bad thing!)
Stating data in a word form is usually known either as speaking or writing. Look, I'm doing it right now!
Now we have far more in the way of greenhouse gases in the atmosphere than during the ice age. Carbon dioxide (CO2) levels over thousands of years have never changed much from 280 ppm (parts per million). Now they are approaching 400 ppm. Extra greenhouse gases in the atmosphere are causing global warming and climate change.
Greenhouse gases trap infrared heat (from the sun) rising from the surface of the earth. More greenhouse gases trap more heat, and this is the situation now. Increasing levels of carbon dioxide (CO2) in particular are trapping more heat and causing a global warming.