Global warming occurs when greenhouse gases like carbon dioxide trap heat from the sun in the lower atmosphere. Normally, the sun's heat would be reflected back into space, but greenhouse gases reflect it back to Earth, causing temperatures to rise. The effects of global warming include climate change, rising sea levels from melting glaciers, more extreme weather like floods and droughts, and threats to plants and animals. Current impacts include rising sea levels threatening islands, glacial retreat of 10-15cm per year in the Himalayas, and record forest fires in 2003 in Russia, America, and Portugal due to heat and drought. Solutions proposed include transitioning to renewable energy, promoting energy efficiency, and increasing carbon absorption through afforestation.