So what happened to their greenhouse gasses that once regulated their climate to something more "earthlike"?
Originally Posted by boardman
they didn't have enough texas-sized trucks spewing out CO2 by the gigaton..
no actually Mars got fucked by 3 things: low gravity, zero magnetic field, and no ozone layer.
the ozone layer on earth has a bunch of unstable oxygen-O3-which is great at soaking up ultraviolet radiation. without the ozone layer, all that uv came right into Mars' atmosphere, splitting water vapor into hydrogen and oxygen. hydrogen is so light it drifts up and up and finally peters off into space.
secondly, earth's magnetic field deflects numerous high energy packets of light around earth rather than allowing them to make it to earth, including more uv, a good amount of infrared, and other forms of light as well. Mars doesn't have a magnetic field, so none of that energy gets deflected, and it hits the planet directly, perfect for boiling off its oceans.
finally, Mars' weak gravity makes it hard to hold onto what's left of its atmosphere, allowing it to slowly be cooked off with all the unimpeded radiation hitting the planet.
voila no oceans, no atmosphere, and if it ever had anything living on it, it probably doesn't now.
as far as drinking the coolaid, it would take about 500 years to burn through all of our fossil fuels at current usage rates (coal would be the last fuel we'd run out of), with the exception of methane, which we may never burn through because it can be regenerated so easily. (think landfills.)
if we change nothing, ya we'll be fucked when all the ice sheets have melted. Massive storms regularly hitting cities like Houston that would make Harvey look like child's play. the major coastal cities would be underwater-Tokyo, NYC, London etc.
if we do a Manhattan Project type of approach for developing alternative energies, worse case scenarios can be avoided. we can use our economic power to get upstarts like China and India on board. eventually earth will probably heal itself. otherwise, in a couple hundred years, ya earth will be pretty fucked up. and it's happening faster than scientists projected. it's not coolaid, it's just science-straight cause and effect.
but ya, Mars could use some texas size trucks to spew out as much CO2 and water vapor as possible and maybe help rebuild its atmosphere. there's an oxygen problem but maybe we can send some oxygen canisters with the settlers when they head for redder pastures. hopefully there will be some left after all this covid fuckery..