Featured Research

from universities, journals, and other organizations

Most-Serious Greenhouse Gas Is Increasing, International Study Finds

Date:
April 27, 2001
Source:
University Of Washington
Summary:
Scientists know that atmospheric concentrations of greenhouse gases such as carbon dioxide have risen sharply in recent years, but a study released this week in Paris reports a surprising and dramatic increase in the most important greenhouse gas – water vapor – during the last half-century.

April 24, 2001 -- Scientists know that atmospheric concentrations of greenhouse gases such as carbon dioxide have risen sharply in recent years, but a study released today in Paris reports a surprising and dramatic increase in the most important greenhouse gas – water vapor – during the last half-century.

The buildup of other greenhouse gases (those usually linked with climate change) is directly attributable to human activity, and the study indicates the water vapor increase also can be traced in part to human influences, such as the buildup of atmospheric methane. However, other causes not directly related to humans must also be at work, said Philip Mote, a University of Washington research scientist who is one of seven lead authors on the report.

"Half the increase in the stratosphere can be traced to human-induced increases in methane, which turns into water vapor at high altitudes, but the other half is a mystery," said Mote. "Part of the increase must have occurred as a result of changes in the tropical tropopause, a region about 10 miles above the equator, that acts as a valve that allows air into the stratosphere."

Readings of water vapor increases 3 to 10 miles up are more ambiguous, Mote said.

The international study, produced by 68 scientists in seven countries as part of the World Climate Research Programme, examined only the changes at higher altitudes, 3 to 30 miles above sea level.

Although carbon dioxide has been relatively easy to monitor and increases have been observed since the 1950s, water vapor has proven much more difficult to monitor. The new effort for the first time was able to draw conclusions about the behavior of water vapor based on a large number of measurements during a long period of time. The report covered both the upper troposphere (3 to 10 miles high), where trends are harder to detect, and the stratosphere (10 to 30 miles high).

"A wetter and colder stratosphere means more polar stratospheric clouds, which contribute to the seasonal appearance of the ozone hole," said James Holton, UW atmospheric sciences chairman and expert on stratospheric water vapor. "These trends, if they continue, would extend the period when we have to be concerned about rapid ozone depletion."

Atmospheric heating happens when the Earth's atmosphere and surface absorb solar radiation, while cooling occurs when thermal infrared radiation escapes the atmosphere and goes into space. If certain key gases that absorb and emit infrared radiation, the most important being water vapor and carbon dioxide, were not present in the atmosphere, Earth's temperature would cool to minus 19 degrees celsius, or minus 2 degrees Fahrenheit. The global annual mean temperature is 14 degrees celsius.

Key findings of the water vapor assessment are:* Ground-based, balloon, aircraft and satellite measurements show a global stratospheric water vapor increase of as much as 2 parts per million by volume in the last 45 years, a 75 percent jump.* Modelling studies by the University of Reading in England show that since 1980 the stratospheric water vapor increase has produced a surface temperature rise about half of that attributable to increased carbon dioxide alone.* Methane, which has been increasing in the atmosphere since the 1950s, could be contributing to the water vapor increase. Chemical conversion of methane to water vapor occurs in the stratosphere but can only account for at most half of the water vapor increase.

A satellite record of relative humidity data for the upper troposphere shows a 2 percent increase during the last 20 years in the equatorial region. However, the uncertainty in this determination is too large to allow a clear conclusion as to whether this is part of a long-term trend.

Among other things, the report recommends continuing to launch balloons monthly from Boulder, Colo., as a means to measure water vapor, a low-cost effort that nevertheless faces possible discontinuation. The balloon measurements, dating from 1981, are the only continuous record of water vapor.

Holton said the report is significant because, by careful comparison, it largely has resolved contradictions in measurements among a number of instruments.


Story Source:

The above story is based on materials provided by University Of Washington. Note: Materials may be edited for content and length.


Cite This Page:

University Of Washington. "Most-Serious Greenhouse Gas Is Increasing, International Study Finds." ScienceDaily. ScienceDaily, 27 April 2001. <www.sciencedaily.com/releases/2001/04/010427071254.htm>.
University Of Washington. (2001, April 27). Most-Serious Greenhouse Gas Is Increasing, International Study Finds. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2001/04/010427071254.htm
University Of Washington. "Most-Serious Greenhouse Gas Is Increasing, International Study Finds." ScienceDaily. www.sciencedaily.com/releases/2001/04/010427071254.htm (accessed July 22, 2014).

Share This




More Earth & Climate News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Orleans Plans to Recycle Cigarette Butts

New Orleans Plans to Recycle Cigarette Butts

AP (July 21, 2014) New Orleans is the first U.S. city to participate in a large-scale recycling effort for cigarette butts. The city is rolling out dozens of containers for smokers to use when they discard their butts. (July 21) Video provided by AP
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 21) Video provided by AP
Powered by NewsLook.com
Spectacular Lightning Storm Hits London

Spectacular Lightning Storm Hits London

AFP (July 19, 2014) A spectaCular lightning storm struck the UK overnight Friday. Images of lightning strikes over the Shard and Tower Bridge in central London. Duration: 00:23 Video provided by AFP
Powered by NewsLook.com
A Centuries' Old British Tradition Is Far from a Swan Song

A Centuries' Old British Tradition Is Far from a Swan Song

AFP (July 19, 2014) As if it weren't enough that the Queen is the Sovereign of the UK and 15 other Commonwealth realms, she is also the owner of all Britain's unmarked swans. Duration: 02:18 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins