Quote:
Originally Posted by sounding
|
While exactly how Earth’s climate changed during the K-Pg extinction remains under debate, scientists do know that climate change today is both real and caused by human activity. Often omitted from discussions is how they know. Here are the key points leading to their conclusion:
• Air samples show that the atmospheric concentration of carbon dioxide (CO2) is rising on Earth
• CO2 absorbs infrared radiation (heat). Adding more infrared-absorbing compounds, or greenhouse gasses, to Earth’s atmosphere throws off it’s energy balance and causes the planet to absorb more energy.
• This added energy should (among other things) raise the global average temperature, increase ocean temperatures, and spur more extreme weather. Absorbed CO2 should also make the oceans more acidic. All are happening.
• Both modern and ancient air samples – the latter from air bubbles in ice cores reaching back several thousand years-confirm that the CO2 levels have spiked since the Industrial Revolution.
• The rate of atmospheric CO2 increase matches that released by human activities for the same time period.
• The relative amounts of carbon’s three isotopes-carbon 12, carbon 13, and carbon 14, in the atmosphere will be different depending on where the carbon in the CO2 comes from. Volcanoes and the burning of fossil fuels for example, will lead to different proportions of carbon 13 and carbon 14 relative to carbon 12. Chemical analysis of Earth’s atmosphere matches fossil fuels.
Jeffrey Bennett’s A Global Warming Primer.