51.   The gases allow sunlight in but trap the heat that Earth emits back toward space.

52.   The gases, mostly from combustion of fossil fuels, trap heat in the atmosphere.

53.   The theory is that these gases can trap heat from the sun, causing the planet to warm.

54.   The theory holds that the gases will trap the heat from sunlight like the glass on a greenhouse and lead to ever-warmer weather.

55.   These gases create a barrier in the atmosphere which trap heat.

56.   These gases are thought to trap solar heat and increase global warming.

57.   When they are present in the atmosphere, such gases trap solar heat around the Earth instead of allowing it to escape into space.

58.   Global warming is believed caused by so-called greenhouse gases like carbon dioxide and methane that trap heat in the atmosphere, increasing temperatures.

59.   This has the effect of trapping heat, so that the earth gradually warms up.

60.   The gases linger in the atmosphere, trapping heat from the sun and driving up the temperature of the atmosphere, sea and land.