[Brutha]

Maybe you meant natural CO2 emissions ?
I'm talking about CO2 in the context of poisonous emissions from a vehicle engines.

It's the same CO2.

Put a tiny gas engine, say 1 cc, in a sealed garage. Any plants in there (and humans) wont be around for long.

Even if you filter out all CO2 from the engine the plant will still die.
Huge amounts of CO2 are certainly not beneficial but there not that big a deal as the amount of CO.

Can we please favor a solution that is less, uhm, risky?

Wikipedia
The 2005 report prepared by the Chernobyl Forum, led by the International Atomic Energy Agency (IAEA) and World Health Organization (WHO), attributed 56 direct deaths (47 accident workers, and nine children with thyroid cancer), and estimated that there may be 4,000 extra deaths due to cancer among the approximately 600,000 most highly exposed and 5,000 among the 6 million living nearby.

Pollution Causes 40 Percent Of Deaths Worldwide, Study Finds Air pollution from smoke and various chemicals kills 3 million people a year, according to a new Cornell study.

You have to put the risk in perspective. A lot of the air pollution comes from coal power plants.
Sure Chernobyl was bad but the risk of losing 5000 people in one bad event that happens because of terrible mismanagement is less severe than killing millions each year with burning fossil fuels.
If you kill millons each year that doesn't make a good news story, because it is just a statistic.
When Chernobyl blows up on the other hand it made a lot of news and got people freightend.
The longnow talk about the issue is really good.

The easiest and safest "geo-gambling" is getting rid of the problem in the first place. Pollution.
Which means switching over to non-Oil based locomotion.

The great thing about cutting pollution is that it isn't gambling. If we cut pollution we don't mess something up even when your prediction about global warming are a bit of.
To be exact non-fossil fuel based locomotion.
If you power your air car or electric car with power from a coal plant it still is a problem.

Concentrated Solar Power (CSP) has my vote!

I think the right think is to not vote for a single technology.
By investing in multiple things, we are far more likely to get something good.
And when we want to go of oil and coal fast we should do every non-fossil fuel thing to generate energy.