Danger signs of global warming
• Global atmospheric concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning hundreds of thousands of years. The global increases in CO2 concentration are due primarily to fossil fuel use and land use change, while those of CH4 and N2O are primarily due to agriculture;