<span>I found these studies about d</span>eforestation in 2009<span>, 2/3 of the world forests were in 3 top countries: 1) </span>Russia<span>, 2) </span>Brazil<span>, 3) </span>Canada
Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again.
for better research go to under NOAA - Climate.gov
This is a short paraphrased summary of the article about ice cores in that website.
Answer: Researchers in labs may melt or crush bits of the ice core a little at a time, each deeper layer shows the time in the Earth's climate history. Tiny pieces of pollution, metals, radoiactive fallout, pebbles, sea salt, volcanic ash and even air bubbles all present important information that researchers can look for to track changes in the atmosphere's composition and temperature.