Climate Tipping Point? Concentration of Carbon Dioxide Tops 400 ppm For First Time in Human History

[limpyhobbler]

Published on May 13, 2013
http://www.democracynow.org - Scientists are warning the planet has now reached a grim climate milestone not seen for two or three million years. The National Oceanic and Atmospheric Administration says the amount of heat-trapping carbon dioxide in the atmosphere has topped 400 parts per million. The 400 ppm threshold has been an important marker in U.N. climate change negotiations, widely recognized as a dangerous level that could drastically worsen human-caused global warming. We speak to leading climate scientist Michael Mann, distinguished professor of meteorology at Penn State University and author of the recent book, "The Hockey Stick and the Climate Wars: Dispatches from the Front Lines." Mann warns that, "We have to go several million years back in time to find a point in Earth's history where CO2 was as high as it is now. ... If we continue to burn fossil fuels at accelerating rates, if we continue with business as usual we will cross the 450 parts per million limit in a matter of maybe a couple of decades. With that amount of CO2 in the atmosphere, we commit to what could truly be described as dangerous and irreversible changes in our climate."

[Curmudgeoness]

1. If there were an asteroid heading for the earth

all the nations of the world would be united to protect the earth from devastation.

This is the same as an asteroid on a collision course with earth, but it just isn't as obvious. No one is paying attention, and no one is willing to do whatever it takes to stop this. It just boggles the mind.

[limpyhobbler]

3. Good point.

Really it's too late to stop it. But we do need to stop making it worse, and start adapting for life on a hot planet.

[Curmudgeoness]

6. That is still debatable.

I hear from some sources that we are not past the tipping point, and others that say it is already too late. I don't have the knowledge to know which is right.

But I do know that continuing on the course we are on now has to be stopped. Allowing it to get worse is absolutely not a viable option.

[blackspade]

5. Yep, an asteroid we built and aimed directly at earth.

[reteachinwi]

2. Who we were

the last time CO2 was at this concentration in the atmosphere.

[cprise]

4. The last time the atmosphere reached 400ppm

...the concentration was changing far more slowly than it is now. That may be the biggest problem of all with man-made global warming (AGW): Most living things probably won't have time to adapt.

Our particular species is adapted more to the relative cold. Its why we can have extra-large brains.

[Curmudgeoness]

7. Explain.

Why does having extra-large brains correlate with relative cold?