Answers to Question 15. Will the seas rise evenly across the planet?
Justin Gillis answer to Question 16. Is it really all about carbon?
“Here’s a quick explainer.
The greenhouse gases being released by human activity are often called “carbon emissions,” just for shorthand. That is because the two most important of the gases, carbon dioxide and methane, contain carbon. Many other gases also trap heat near the Earth’s surface, and many human activities cause the release of such gases to the atmosphere. Not all of these actually contain carbon, but they have all come to be referred to by the same shorthand.
By far the biggest factor causing global warming is the burning of fossil fuels for electricity and transportation. That process takes carbon that has been underground for millions of years and moves it into the atmosphere, as carbon dioxide, where it will influence the climate for many centuries into the future. Methane is even more potent at trapping heat than carbon dioxide, but it breaks down more quickly in the air. Methane comes from swamps, from the decay of food in landfills, from cattle and dairy farming, and from leaks from natural gas wells and pipelines.
While fossil-fuel emissions are the major issue, another major creator of emissions is the destruction of forests, particularly in the tropics. Billions of tons of carbon are stored in trees, and when forests are cleared, much of the vegetation is burned, sending that carbon into the air as carbon dioxide.
When you hear about carbon taxes, carbon trading and so on, these are just shorthand descriptions of methods designed to limit greenhouse emissions or to make them more expensive so that people will be encouraged to conserve fuel.”
My answer to Question 16. Is it really all about carbon?
Climate change has very little to do with carbon. The term “carbon pollution” is a misnomer set up to simplify the argument to put the blame for climate change on increased CO2.
Coming out of the ice age both temperature and CO2 rose, but, and this is important, temperature rose first, and then, with a 300 to 800 year lag CO2 rose. When temperatures had risen to a couple of degrees higher than today, temperature stopped rising, CO2 caught up and has been stable until about 1700 A.D, when coal mining started in earnest. During this time of CO2 stability we have had the Minoan warm period, a cooldown, the Roman warm period, sharp cooldown during the dark ages, the Medieval warm period, the little ice age, and finally today’s warming period, called “Climate change.” Each warming period was a little cooler than the previous, and each cooling period a little colder than the previous. We are now well into the bog building phase of the interglacial period, during which time the CO2 levels used to decrease until the Milankovitch cycles ended the interglacial period. The unprecedented increase in CO2 levels experienced since the start of the industrial era might get us back to the Medieval warming period, but the long term trend is lower temperatures, and the nest cooling period might trigger the next ice age.
What is putting a limit on temperature rise? One have to remember that the major greenhouse gas, bar none, is water vapor. In the tropics water vapor is more than ten times as abundant as when temperatures reach the freezing point. In the tropics water can be measured in percent, at the poles in parts per million. This has tremendous ramifications. Water vapor is lighter than air, and humid air tend to rise, get cooled down as temperature falls with altitude, and when saturation occurs clouds will form if there are condensation points, such as pollen, soot or cosmic radiation. The amount of CO2 does not matter in the tropics, if clouds or, better yet, thunderstorms occur there is a negative feedback keeping the temperatures stable, near the temperature of the oceans. Not so in the deserts and at the poles. Where water vapor is lacking CO2 plays a role. In the deserts the long term temperatures will increase at the full 0.9 degree C for every doubling pf CO2, at the poles far more, not so much because of increased CO2, but increased water vapor will cause it to snow more, releasing additional heat, causing more snow. And we can see that snowfall over the northern hemisphere is increasing, but the spring melt is also earlier.
In short, climate change so far has been all to the good.