You've seen some closeups of Comet 67P/Churyumov-Gerasimenko, but this image gives an idea of what it might actually look like if you were onboard the Rosetta spacecraft. One of Rosetta's two solar panels provides context for its true apparent size and the dim light from a sun more than 300 million miles distant. Click on image for Phil's dissertive interocitation.
This week scientists at the World Meteorological Organization (WMO) confirmed that 2013 was a record year for the quantity of heat trapping carbon dioxide in our atmosphere. One obvious reason for that is humans keep pumping more into the air. But another factor may be
coming into play:
But the other possibility is a bit more surprising: According to the WMO, early data suggests that the world's oceans and forests are now absorbing a bit less of our extra carbon-dioxide than they used to — which means that more CO2 ends up in the atmosphere, where it traps heat and warms up the planet. So, somewhere on the hellish path to a cool Venus, the future Earth might have frothy seas of seltzer.
Traditionally, oceans and forests have acted as giant sponges, soaking up roughly half of our carbon-dioxide emissions each year. (Indeed, that's why oceans are now acidifying at the fastest rate in 300 million years, with dire consequences for marine life.) But if they're now starting to absorb less carbon-dioxide overall — and, again, it's still too early to say for certain — that could mean even more global warming going forward.
There is a potentially serious feedback issue here. A warmer atmosphere soon spells warmer oceans, especially at the surface. Warmer water holds less CO2 in solution, which means the oceans absorb even less, leading to higher concentrations in the atmosphere which in turn traps more heat, causing warmer air ... rinse and repeat.
