Watts Up With That?

One of the few things that BOTH sides of the Carbon Dioxide and AGW debate seem to be able to agree on is the belief that CO2, as a trace gas, is “well-mixed” in the atmosphere. Keeling’s measurements at Mauna Loa and other locations worldwide rely on this being true, so that “hotspots” aren’t being inadvertently measured.

As support for this, if you do some Google searches for these phrases, you’ll get hundreds of results of the usage together:

CO2 + “well mixed”

“carbon dioxide” + “well mixed”

You’ll find complete opposites using the same “well mixed” phrase, for example:

Gavin Schmidt of Real Climate writes in comment # 162 of this thread on Realclimate.org

“A full doubling of CO2 is 3.7 W/m2, and so by looking at all well-mixed GHGs you get about 70% of the way to a doubling.”

Roger Pielke Sr. writes in April 2008:

“…and thus are not providing quantitatively realistic estimates of how the climate system responds to the increase in atmospheric well mixed greenhouse gases in terms of the water vapor feedback.”

You’ll also find the phrase in use in titles of scientific papers, for example this one published in the AGU:

New Estimates of Radiative Forcing Due to Well Mixed Greenhouse Gases

And you’ll find the phrase used in popular media, such as this article from the BBC:

Carbon dioxide continues its rise

In describing the emasurements of CO2 at Mauna Loa Observatory: “The thin Pacific air is ideal for this research since it is “well-mixed”, meaning that there is no obvious nearby source of pollution, such as a heavy industry, or a natural “sink”, such as forest which would absorb CO2.”

Hmm, “no obvious nearby source of pollution” I suppose the volcanic outgassing nearby doesn’t count as “pollution” since it is natural in origin.

So it seems clear that there is a broad agreement on the use of the term. I suppose you’d call that “scientific consensus”.

So it was with some surprise that I viewed this image from NASA JPL, a global CO2 distribution as measured by satellite: Read the rest of this entry »

From this page (h/t Dave Hagen)

The U.S. Environmental Protection Agency (EPA) is inviting comment from all interested parties on options and questions to be considered for possible greenhouse gas regulations under the Clean Air Act. EPA is issuing an advance notice of proposed rulemaking (ANPR) to gather information and determine how to proceed.

The Advance Notice

The ANPR is one of the steps EPA has taken in response to the U.S. Supreme Court’s decision in Massachusetts v. EPA. The Court found that the Clean Air Act authorizes EPA to regulate tailpipe greenhouse gas emissions if EPA determines they cause or contribute to air pollution that may reasonably be anticipated to endanger public health or welfare. The ANPR reflects the complexity and magnitude of the question of whether and how greenhouse gases could be effectively controlled under the Clean Air Act.

The document summarizes much of EPA’s work and lays out concerns raised by other federal agencies during their review of this work. EPA is publishing this notice at this time because it is impossible to simultaneously address all the agencies’ issues and respond to the agency’s legal obligations in a timely manner.

Key Issues for Discussion and Comment in the ANPR:

• Descriptions of key provisions and programs in the CAA, and advantages and disadvantages of regulating GHGs under those provisions;
• How a decision to regulate GHG emissions under one section of the CAA could or would lead to regulation of GHG emissions under other sections of the Act, including sections establishing permitting requirements for major stationary sources of air pollutants;
• Issues relevant for Congress to consider for possible future climate legislation and the potential for overlap between future legislation and regulation under the existing CAA; and,
• Scientific information relevant to, and the issues raised by, an endangerment analysis.

EPA will accept public comment on the ANPR for 120 days following its publication in the Federal Register.

Background

In April 2007, the Supreme Court concluded that GHGs meet the CAA definition of an air pollutant.  Therefore, EPA has authority under the CAA to regulate GHGs subject to the endangerment test for new motor vehicles – an Agency determination that GHG emissions from new motor vehicles cause or contribute to air pollution that may reasonably be anticipated to endanger public health or welfare.

A decision to regulate GHG emissions for motor vehicles impacts whether other sources of GHG emissions would need to be regulated as well, including establishing permitting requirements for stationary sources of air pollutants.

How to Comment Read the rest of this entry »