« Criminals shouldn’t be allowed to investigate themselvesObamacare Targets Entitlements »

350 PPM CO2 THE UPPER LIMIT OF HUMAN HABITATS

October 22nd, 2009

Andrew Glikson

THE RISE OF ATMOSPHERIC CO2 ABOVE 350 PPM AT THE CURRENT RATE OF ABOUT 2 PPM/YEAR IS TRANSCENDING THE CONDITIONS THAT ALLOWED THE DEVELOPMENT OF HUMAN AGRICULTURE AND CIVILIZATION FROM ABOUT 8000 YEARS AGO.

Life on Earth depends on a delicate balance between the atmosphere, the oceans and the biosphere. The atmosphere acts like the “lungs” of the biosphere, while the ocean currents act as its “vein system”, modulating temperatures around the globe. Changes to the chemistry of the atmosphere, including greenhouse gases (CO2, methane, nitric oxides, ozone) and aerosols (mainly sulphur dioxide) through Earth’s history resulted in climate shifts between greenhouse states and glacial/interglacial states. Such changes were triggered by orbital shifts, solar cycles, volcanic events, asteroid impacts, release of methane from sediments and, on longer time scales, the distribution of oceans, continents and mountain ranges.

Sharp decline in CO2 34 million years ago and 15 million years ago to below 500 ppm has resulted in the development of the Antarctic ice sheet. About 2.8 million years ago a further decline in CO2 resulted in formation of the Greenland ice sheet and Arctic Sea ice. The current runaway climate change is a direct result of human emissions and land clearing. The emission of more than 320 billion tons of carbon (over 50% the original atmospheric inventory) since 1750 raised CO2 levels from 280 to 388 ppm, or 460 ppm CO2-equivalent (a value including the effect of methane).

Acceleration of climate change since the mid-1970s is leading toward a global temperature rise of +1.5oC above pre-industrial time, once the masking effects of sulphur aerosols are removed. The polar regions have already warmed by up to 4oC. This results in carbon cycle and ice/water melt feedback processes, with consequent (A) extreme rates of polar ice melting, including the Arctic Sea, Greenland, West and East Antarctica, which threatens accelerated sea level rise above the current rate of 0.35 cm/year; (B) a progressive shift of climate zones toward the poles, which extend the tropics, as indicated by intensified cyclones and floods, and enlarging desert regions as manifested by extreme droughts and fires. Given lag effects, looming threats include (1) ocean acidification, collapse of coral reefs and the marine food chain; (2) mountain snow and glacier melt and availability of freshwater; (3) destruction of native habitats, i.e. the Amazon; (4) ozone depletion; (5) atmospheric aerosol loading and (6) chemical pollution by metals, plastics, radioactive nuclei.

The consequences for human habitats include loss of arable land, fresh water supplies and extreme weather events. The loss of Himalayan snow and thereby decreased river flow, coupled with a failure of the monsoon and sea level rise, threatens more than one billion people in south and south-eastern Asia. As the polar regions warm, a release of methane from the many hundreds of billions of tons of carbon stored in permafrost and shallow lakes and seas, is imminent.

In the view of leading climate scientists there is no alternative to attempts at reducing atmospheric CO2 levels to below 350 ppm as soon as possible. What is urgently required is a combination of (A) urgent deep cuts in carbon emissions; (B) fast-track development of clean renewable energy systems; (C) an intensive global reforestation campaign; (D) application of a range of CO2 draw-down sequestration measures, including world-wide replantation and reforestation campaigns and chemical capture methods, solar-powered desalination plants, and long-range channel and pipe water transport systems.

Recent references

Schellnhuber, Oxford meeting, 28-30.10.09 http://www.eci.ox.ac.uk/4degrees/programme.php
British Antarctic Survey http://www.antarctica.ac.uk/press/press_releases/press_release.php?id=989 NASA/GISS). http://data.giss.nasa.gov/gistemp/
Copenhagen Synthesis Report http://www.anu.edu.au/climatechange/content/news/copenhagen-synthesis-report-released-today/
Hansen et al. 2008. Target CO2: Where Should humanity aim? http://www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf
Lenton et al., 2008. Tipping points in the Earth climate system. http://www.sciencedaily.com/releases/2008/02/080204172224.htm
Reports by NASA/GISS, Hadley_Met, Potsdam Ocean Institute, NSIDC, CSIRO, BOM.

Andrew Glikson
Earth and paleoclimate scientist
22 October, 2009

No feedback yet

Voices

Voices

  • Tracy Turner The Reclamation of the Republic When, in the Course of human events, it shall become absolutely necessary for the People to dissolve the political ties which have united them to a government that has betrayed its trust to obtain their…
  • Tracy Turner SMELE's (Slow-Motion-Extinction-Level-Events). Not yet common in academia, but it should be. I. Introduction: The Timebombs We Ignore "Not with a bang but a bureaucratic shrug, the world ends." - Revisionist reading of Eliot by the…
  • By David Swanson I wish U.S. academics would spend less time fantasizing choices between various murders with trollies, or playing games with theories about how greedy robots might do diplomacy, and more time on the impeachment problem. The United…
  • Cathy Smith Hidden Bombshells in Trump’s “Big Bodacious Pill” “The most dangerous place to be is between power and its reckoning.” —Rewritten maxim of Beltway survival In the dark guts of Trump’s 2025 legislative monolith—cheekily christened the Big…
  • Robert David A global exposé of how corporations distort science, erase truth, and turn human death into quarterly growth. I. Introduction: When Truth Becomes a Liability In an age when algorithms dictate belief and lobbyists author legislation, truth…
  • Robert David Polluters don’t just dump toxins. They dump stories—engineered by billion-dollar PR firms. They Poisoned the Planet—Then Hired Spin Doctors to Make You Forget When a chemical spill poisons a town, when a pipeline ruptures in a fireball,…
  • By David Swanson, World BEYOND War Switzerland got that way through NEUTRALITY Remarks at Neutrality Colloquium: A Call to Action for Active Neutrality & World Peace, June 26-27, 2025 in Geneva, Switzerland. I grew up in a town in the United States that…
  • Fred Gransville I. The Fluoride Question For decades, fluoride has had an uncontested official story: it is a beneficial, even benevolent substance—vital to healthy teeth. In toothpaste tubes to water supplies, fluoride has been presented as a dental…
  • Tracy Turner #SCOTUScorruption #FascistAmerica #EndCitizensUnited Bush started it. Obama enabled it. Trump perfected it. And the Court? It never checked power—it built it. I. Opening Jab: The Judicial Illusion "They wear robes to appear impartial. But…
  • Dr. Vladislav B. Sotirovic Carl von Clausewitz The focal questions about war In dealing with both theoretical and practical points of view about war, at least six fundamental questions arise: 1) What is war?; 2) What types of war exist?; 3) Why do wars…
July 2025
Sun Mon Tue Wed Thu Fri Sat
 << <   > >>
    1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31    

  XML Feeds

Multiblog engine
FAIR USE NOTICE: This site contains copyrighted articles and information about environmental, political, human rights, economic, democratic, scientific, and social justice issues, etc. This news and information is displayed without profit for educational purposes, in accordance with, Title 17 U.S.C. Section 107 of the US Copyright Law. Thepeoplesvoice.org is a non-advocacy internet web site, edited by non-affiliated U.S. citizens. editor
ozlu Sozler GereksizGercek Hava Durumu Firma Rehberi Hava Durumu Firma Rehberi E-okul Veli Firma Rehberi