Pictures and video included with that post showed the helicopter burning in a field, emitting dark black plumes of smoke.

Now it is possible to put millions of nanotubes into a blood sample and have them emit different wavelengths of light based on what sticks to them.

As water levels recede, the exposed lake bed is dry and dusty, and frequently emits a hold-your-nose rotten-egg stench, the result of natural processes, according to the South Coast Air Quality Management District.

Scientists also have learned from measurements of sulfur particles emitted by ships’ exhaust, which create wispy, reflective, contrail-like clouds, similar to what marine cloud brightening could achieve.

"We know that for the last 20 years we haven't been able to get the financing from the larger emitting countries, so we've got to look for ways to protect ourselves."