Staff Contributors
Guest Contributors

Tipping points

Posted by David Roberts at 5:14 PM on 07 Jul 2006

Read more about: James Hansen

RealClimate has a great post up on climate "tipping points," a notion that has been used and abused with great frequency lately by laymen and journalists -- including yours truly. It goes into detail picking apart positive feedbacks, tipping points, and points of no return.

The most valuable bit for me was clarifying what James Hansen has in mind when he says that we have ten years to fundamentally change course:

The '10 year' horizon is the point by which serious efforts will need to have started to move the trajectory of concentrations away from business-as-usual towards the alternative scenario if the ultimate warming is to stay below 'dangerous levels'. Is it realistic timescale? That is very difficult to judge. Wrapped up in the '10 year' horizon are considerations of continued emission growth, climate sensitivity, assumptions about future volcanic eruptions and solar activity etc. ... While the '10 years' shouldn't be read as an exact timetable, it is surely in the right ballpark. 30 more years of business-as-usual will make it impossible to keep temperatures from rising beyond Eemian levels (see here for some discussion of stabilisation scenarios), and decisions (on infrastructure, power stations, R&D, etc.) that are being made now will determine the emissions for decades to come.

As the post goes on to explain, there isn't so much a single tipping point as a variety of tipping points at various levels, some more dangerous than others, some more reversible than others.

Of course, what matters most at this point are not the purely physical tipping points but the ones that involve us. When will our concern pass the threshold of serious action? Nobody can predict that for us.

Beware


    The danger of letting people think that they have ten years before "serious efforts need to have started" should be obvious.

    For many people, that means they don't have to "start" to think about the problem for ten years.

    That the process of deciding what to do doesn't need to "start" for ten years.

    That the planning for what to do doesn't need to "start" for ten years.

    Not what I think Dr. Hansen has in mind, but a real danger to beware of in terms of discussion.

patrick

Tipping Points May Be Key To Setting Policy

These tipping points may be the key to intelligent policy making regarding reductions in CO2 and other behaviors that drive global warming.

misrepresenting James Hansen

Yes, Patrick, you are quite right.  "We do not really need to start serious efforts for another ten years" is not at all the same as "We need to have begun serious efforts within the next ten years."  To me at least, James Hansen seems to be saying something like the latter statement.  But no doubt his advice is even now being misrepresented to sound like the former.

Chickens deserve our true friendship! So do fish! So do other sentient beings! Let us learn to be kind.
You are not logged in. Thus, you cannot post a comment. If you have an account, log in. If you don't have an account, well, by all means go make one! Meet you back here in five.
sign in
Search Gristmill
Subscribe
  • subscribe via RSSStay updated with the Gristmill RSS feed.
  • Add to My Yahoo!
  • Subscribe with Bloglines
  • Subscribe in NewsGator Online
  • Subscribe in Netvibes
  • Subscribe in Google
Using Gristmill
  • What is Gristmill?
  • Posting rules
The comments of Gristmill users reflect the opinions of those individuals only, and do not necessarily reflect the viewpoints of Grist, its staff, its board members, their psychotherapists, or their aestheticians. Got it?

Gristmill is powered by Scoop.

ADVERTISING POLICY


About Grist | Support Grist | Job Board | Archives | Grist by Email | RSS | Podcast
Gristmill Blog | In the News | Ask Umbra | Muckraker | Victual Reality | 'Tis the Season | The Grist List | The Bottom Line



Grist: Environmental News and Commentary
a beacon in the smog (tm) ©2008. Grist Magazine, Inc. All rights reserved. Gloom and doom with a sense of humor®.
Webmaster | Sitemap | Privacy Policy | Terms of Service | Trademarks