I have found that most scientists believe that the earth's climate has been changing constantly over the last five billion years.When thefirst people arrived in America somewhere between 15,000 and 30,000 years ago most of it was covered by great sheets of ice. Within a few thousand years after that the ice began to melt rather quickly.By 7,000 years ago the ice was completely gone. With this end to the ice age came drastic changes to the earth and the earth's climate.
Recently, on an average most scientists believe that that the earth has been warming at a rate of about 1 degree Fahrenheit over the last one hundred years. The four warmest years have been in the 1990s which really supports the idea of global warming since this was not to long ago.Climatologists believe that global warming is caused by greenhouse gases that the people on earth produce and increased heat from the sun that has been making the earth warmer.
Another factor that scientists have been noticing is that the sea levels upon the earth have been gradually rising.This also is believed to be from the warming of the earth from global warming. Over the last 100 years the level of the sea has risen about 6-8 inches worldwide.This has two contributing factors.Scientists believe that this is from the melting glaciers that are releasing more water into the sea. The other factor is that as the earth warms so does the water on the earth. Heat causes water to expand and when the ocean expands from being heated up it takes up more space.
Together the melting glaciers, rising seas and computer models of the earth give of good clues of global warming on the earth.When these are studied by scientists they find that the Earth's temperature will continue to rise as long as we continue increasing the amount of greenhouse gases in the atmosphere.It appears now that global warming is inevitable and we need to adapt to the changing ear…