Climate Change/Greenhouse Gas News

New Index Provides Benchmark For Atmospheric Greenhouse Gases

Researchers at the National Oceanic and Atmospheric Administration's (NOAA) Climate Monitoring and Diagnostics Laboratory (CMDL) in Boulder, Colo., announced on Sept. 27 they have developed an index that provides a simple means of tracking the annual increase in greenhouse gases in the atmosphere.

The Annual Greenhouse Gas Index is based on an analysis of the atmospheric levels of all the major and minor, long-lived greenhouse gases, as measured since 1979 by NOAA/CMDL's global sampling network. These include carbon dioxide (CO2), methane, nitrous oxide and chlorofluorocarbons (CFCs) and the replacements for CFCs. NOAA plans to update the index in April of each year.

The newly developed index provides an easily understood and scientifically unambiguous point of comparison for tracking annual changes in levels of atmospheric gases that contribute to the so-called "greenhouse effect," in which the radiation emitted by Earth's surface is re-radiated by the atmosphere back to the surface.

"This index provides us with a valuable benchmark for tracking the composition of the atmosphere as we seek to better understand the dynamics of Earth's climate," said retired Navy Vice Admiral Conrad C. Lautenbacher, Jr., PhD, under secretary of commerce for oceans and atmosphere and NOAA administrator.

NOAA's five-year strategic plan commits the agency to understanding climate variability and change in order to enhance society's ability to plan and respond.

"The AGGI will serve as a gauge of success or failure of future efforts to curb carbon dioxide and other greenhouse gas increases in the atmosphere both by natural and human-engineered processes," said David Hofmann, CMDL director.

The index relates the total radiative forcing since pre-industrial times (defined as the year 1750) from all the gases sampled in a given year to the corresponding measurements taken in 1990. The 1990 baseline was chosen because greenhouse gas emissions targeted by the international Kyoto Protocol are also indexed to 1990.

Radiative forcing is the change in the balance between solar radiation coming into the atmosphere and Earth's radiation going out. Radiative forcing, as measured by the index, is calculated from the atmospheric concentration of each contributing gas and the per-molecule climate forcing of each gas.

For every million air molecules in samples analyzed by NOAA/CMDL, about 375 of them are carbon dioxide, about two are methane and less than one is a nitrous oxide molecule. The CFC's make up less than one molecule in a billion in the atmosphere but play a role in regulating Earth's climate and are a key factor in the depletion of the protective ozone layer.

Most of the increase in radiative forcing measured since 1990 is due to CO2, which now accounts for about 62 percent of the radiative forcing by all long-lived greenhouse gases. Hofmann noted that the AGGI value for 2004 was 1.20, representing a 20 percent increase in radiative forcing since 1990. The annual increase in the index from 2003 to 2004 was 1.12 percent.

The largest annual increase, 2.8 percent, occurred between 1987 and 1988, the smallest, 0.81 percent, from 1992 to 1993. While the index has increased in every year since NOAA's global measurements began in 1979, the increase during 2004 was on the low side.

Atmospheric greenhouse gas levels change from year to year depending on human-influenced processes as well as natural processes. The record high annual increase is believed to be related to the increased growth rate of CO2 following the 1987-1988 El Niño and the record low annual increase is related to the decreased growth rate of CO2 following the Pinatubo volcanic eruption in 1991.

NOAA's network of five global Baseline Observatories and approximately 100 global cooperative sampling sites extends from the high Arctic to the South Pole. NOAA/CMDL also takes samples at five-degree latitude intervals from three oceanic ship routes. All the air samples are analyzed in the Boulder laboratory for the major greenhouse gases by comparing the samples to NOAA's highly accurate world standards for these gases.

NOAA: http://www.noaa.gov

CMDL: http://www.cmdl.noaa.gov

Report Indicates That CO2 Storage May Minimize Climate Change

A new assessment report finalized on Sept. 26 by the Intergovernmental Panel on Climate Change (IPCC -- http://www.ipcc.ch) concludes that capturing and storing the carbon dioxide (CO2) produced by power plants and factories before it enters the atmosphere could play a major role in minimizing climate change.

"While the most important solutions to climate change will remain energy efficiency and cleaner energy sources, this new report demonstrates that capturing and storing carbon dioxide can supplement these other efforts," said Executive Director Klaus Töpfer of the United Nations Environment Programme (UNEP -- http://www.unep.org).

"Since emissions of carbon dioxide -- the most important cause of climate change -- continue to rise in many parts of the world, it is vital that we exploit every available option for reducing their impact on the global climate. CO2 capture and storage can clearly play a supporting role," said Secretary-General Michel Jarraud of the World Meteorological Organization (WMO).

According to a number of studies, carbon dioxide capture and storage technologies (known as CCS) could lower the costs of mitigating climate change over the next 100 years by 30 percent or more. In addition, capture and storage of CO2 in geological formations could account for 15 percent to 55 percent of all emission reductions (equal to 220 to 2,200 billion tonnes (Gt) of CO2) needed between now and 2100 for stabilizing greenhouse gas concentrations in the atmosphere.

Many components of carbon dioxide capture and storage technology are already mature, including several applications of CO2 capture, pipelines and gas injection into geological formations. Three CCS projects are already in operation, in Algeria, Canada and the North Sea off the Norwegian coast. CO2 capture from large-scale power plants will require further demonstration over the coming years and decades. Other possible applications, such as ocean storage or fixing CO2 in stable carbonates, are still in a research phase.

The potential of capture and storage could be limited by several important non-technology constraints. In particular, unless governments adopt climate change policies that put a cost on emitting CO2, there will be no incentive to use these technologies.

Furthermore, while the available storage capacity in geological reservoirs is "likely" to be sufficient, the true amount is yet uncertain. This is particularly so in some regions that are experiencing rapid economic growth, such as South and East Asia.

Because CCS process requires energy, its adoption may increase the use of fossil fuels. For the same level of electricity production, a power plant with CO2 capture would require 10 percent to 40 percent more energy than a plant without capture.

The most economically feasible storage options for CO2 are geological formations, particularly given the experience already gained by the oil and gas industry. Fortunately, a large proportion of existing power plants and other "point sources" lie within 300 km of areas that potentially contain storage reservoirs, such as oil and gas fields, unminable coal beds and deep saline water-bearing formations, according to the report.

As important as technology and cost issues are health, safety, environmental and legal concerns, would also need to be addressed to ensure public support. Potential risks include leakage from capture, transport and injection (comparable to the risk in similar existing industrial operations) and slow leaks from storage sites (a low risk if reservoirs are carefully selected and best available technologies are used). A key legal issue would be how international law would treat CO2 injection activities in international seas.

The "IPCC Special Report on Carbon Dioxide Capture and Storage" report was written by 100 experts from more 30 countries and reviewed by many experts and governments. The report assesses the most up-to-date literature available in scientific and technical journals around the world and was requested by the Parties to the United Nations Framework Convention on Climate Change (UNFCCC).

This article originally appeared in the 10/01/2005 issue of Environmental Protection.

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