Comments on: “Stabilizing climate requires near-zero emissions”

By: Paul K

Paul K — Mon, 03 Mar 2008 07:27:24 +0000

Is Anthropocene a recent coinage?

By: David B. Benson

David B. Benson — Sun, 02 Mar 2008 18:50:50 +0000

Beefeater — The climate has been remarkably stable throughout the Holocene. During the introduction and spread of agriculture. Now that humans have caused the Anthropocene instead, agriduculture (and lots else) is in big trouble.

By: Joe

Joe — Sat, 01 Mar 2008 13:11:00 +0000

I’ll do a post on geoengineering when the Salon piece comes out.

By: RhapsodyInGlue

RhapsodyInGlue — Sat, 01 Mar 2008 04:01:13 +0000

Joe,

“Jade — it won’t be easy. Geo-Engineering could possibly be a small part of the solution, but only if we make deep emissions cuts first.”

Is this statement based on something scientific or merely your opinion about political expediency. Why must efforts of “geo-engineering”… such as trying to increase ocean CO2 uptake or enhance the albedo of clouds… only start after deep emissions cuts.

I think the urgency of deep emissions cuts is extremely serious and should be implemented as fast as possible with a goal of complete decarbonization. However, already the earth’s environment and species are suffering from increased heat. Why not employ whatever technologies we have if they can help in the short term by avoiding ecosystem damage and provide a bit extra margin against hitting tipping points such as massive albedo flip or methane release?

By: Beefeater

Beefeater — Fri, 29 Feb 2008 19:54:26 +0000

how can anything but negative net emissions bring the carbon cycle into balance and return Earth toward a stable climate system again?
Hal,
Again? When exactly has the earths climate ever been “stable”?
Who is going to define stability, average or normal?

By: David B. Benson

David B. Benson — Fri, 29 Feb 2008 18:21:00 +0000

Hal — There is no recent (last 600,000 years) paleoclimate data that suggests stability above 300 ppm, AFAIK. Climate models predict an eventual quasi-equilibrium for the climate at every potential level of CO2. We won’t like the long-term results at anything above about 315 ppm CO2, in my (only partly knowledgable) opinion.

The issue is not eventual stability, but rather restoring the climate to the best state for agriculture, i.e., conditions prevailing during the Holocene rather than those in the just-started Anthropocene.

By: Jim

Jim — Fri, 29 Feb 2008 08:57:39 +0000

Venus, surface pressure: 90,000 mbar; temperature: 735K
Temperature of terrestrial air compressed from 288K/1,000mbar to 90,000mbar: 887K
735K/887K = 82.9%

By: Jim

Jim — Fri, 29 Feb 2008 08:51:52 +0000

Ratio of available solar energy Venus/Earth: 190%

Venus receives almost twice as much heat as we do.

Earth, surface pressure: 1000 mbar; temperature: 288K
Venus, 50km altitude pressure: 1000 mbar; temperature: 330K
330K/288K = 114%

By: Hal

Hal — Fri, 29 Feb 2008 08:46:17 +0000

1. Where is there evidence that a global average CO2 concentration above 300 ppm can be climate-forcing neutral (with all other known critical factors held constant)?

2. Given that some other known critical factors (e.g., sinks) are not constant and will continue to change toward reducing carbon flux into terrestrial and marine carbon sinks for decades (or longer) due to current accumulated atmospheric carbon (383 ppm global average), how can anything but negative net emissions bring the carbon cycle into balance and return Earth toward a stable climate system again?

By: David B. Benson

David B. Benson — Thu, 28 Feb 2008 23:38:17 +0000

Earl Killian — The anthropomorphic additions to the active carbon cycle are removed (in the medium term) into the deep ocean. In the long term, via calcification. So given long enough, the additions are eliminated.

But that is much too long for world civilization to wait for.

I take the point of the paper is the revision from a target of 80% (or whatever) to 100%. The sooner the better.

And then, IMO, sequester some additional carbon to cool things off, reverse ocean acidification, regrow glacier ice, etc.