[Soft_Landing]

This material was posted in another forum. I thought it might be handy to have here as well. They represent an attempt to quantify carrying capacity.

THE LIVING PLANET REPORT 2002 and SUSTAINABLE POPULATIONS BY COUNTRY

Notes and explanation of spreadsheet

Question & Answer series

Snip..

Question 28: Well, I think I now have eco-footprinting just about wrapped up. My overview of the world scene is this. If we maintain our present level of per capita carbon dioxide emissions, population needs to be about 2 billion in order to stabilize the concentration of carbon dioxide in the atmosphere. Eco-footprinting indicates that we need about that level of population in order that all should be able to live sustainably and enjoy an acceptable lifestyle.

Answer: Your summary is absolutely correct.

{URL visibility touch up; EE}

[backstop]

Soft_Landing - Sadly the CO2 issue has further components, known as (positive) feedback loops, that make a >60% cut in CO2 output insufficient to stabilize atmospheric CO2 (at present 380 ppmv).

The concentration took off in the late C18 from 280 ppmv; one of these feedbacks (the expulsion of carbon from Peat Bogs) started up in the early 1960s, when Atmos. CO2 was at about 320ppmv. That output has been rising globally at 6% pa. If unchecked (for instance if Sasol oil and mass nuclear build replaced pollution lost to depletion), by about 2035 Ex-Peat CO2 will predictably swamp the 40% of our present annual output that the planet now consumes in its natural 'sinks'. (See New Scientist article in Geo-atmospheric Climate)

There are various other feedback loops interacting with global warming and climate change. If they're allowed between them to swamp the sinks, then we'll have no prospect of stabilizing atmospheric CO2, or of avoiding runaway climatic destabilization.

Therefore all I could say for sure about eventual carrying capacity is that each year's delay in getting off fossil fuels probably cuts that capacity greatly.

regards,

Backstop

[gg3]

Tonight a news item that atmospheric CO2 levels have been increasing at a much more rapid rate over the past two years than in previous years. Scientists speculate this is due to reduction of the capacity of ecosystems to absorb excess CO2 from the atmosphere, which in turn appears to be a result of hotter than normal summers over the past two years.

In other words, it appears that another positive feedback loop is now underway.

Scientists who have studied the data are quite worried.