NASA - National Aeronautics and Space Administration

For more information contact:

Elvia Thompson
Headquarters, Washington
(Phone: 202/358-1696)

Rob Gutro
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-4044; at AGU: 415/905-1007)

Caption for Image 1: Unusually low solar activity between 1645-1715 likely triggered the 'Little Ice Age' in regions like Europe and North America. A lag time of arguably 10-30 years allowed for the climate system to be affected by an increased ozone layer that altered the heating of the oceans. According to the model, diminished jet stream winds caused by a dimmer sun created cold land temperatures by reducing the transport of warm Pacific air to America and warm Atlantic air to Europe. During this shift, winter temperatures cooled as much as 2 to 4 degrees F - enough to freeze rivers and alter agriculture, economy, disease, etc.

Pictured is the climate model used by researchers to watch temperature anomalies. As such, 1780 was used as an arbitrary baseline; the ice age period, then, is colder/bluer and 1780 is white or neutral. Redder colors in more modern times reflect warmer temperatures. Credit: NASA

Caption for Image 2: The Sun shows signs of variability, such as its eleven-year sunspot cycle. In that time, it goes from a minimum (seen here in 1996) to a maximum (2000) period of activity that affects us everyday. When particularly active, solar storms can spew tons of radiation to Earth in the form of Coronal Mass Ejections (CMEs) that can affect power grids, spacecraft, and communication systems. Credit: NASA / ESA

Caption for Image 3: The lack of activity on the Sun was strongly felt during the Little Ice Age, yet scientists credit greenhouse gases and global warming with having such an impact on us today. Most experts point to 1850, start of the industrial age, to when the major influence of climate started to shift from the Sun to ourselves. Click on the image to take you to the NASA Carbon Cycle Initiative site. In the first graph on the site, a flat line reflects steady carbon measurements prior to 1850. The other graphs show a stable increase of ambient carbon dioxide oscillating as a general trend, but still rising and falling with seasonal change. Credit: NASA / ORBIMAGE

Caption for Image 4: This computer model shows the dispersion of the volcanic plume from the Mt. Pinatubo volcano. The 1991 Pinatubo eruption was sulfur-rich, producing volcanic clouds that lasted a number of years in the stratosphere. The Pinatubo eruption widely expanded the area of ozone loss over the Arctic and Antarctic. Red colors indicate higher elevations and blue colors indicate lower elevations for the plume. Credit: NASA

Caption for Image 5: The eruption of Mt. Pinatubo blasted a huge cloud of sulfur dioxide, shown in red, into the stratosphere. This data taken from NASA's Total Ozone Mapping Spectrometer (TOMS) instrument shows that initial burst of sulfur dioxide and its international path in the days following the eruption, from June 16th to June 30th. The sulfur gas cloud dissipates as the gas turns into droplets of sulfuric acid. Both the gas and subsequent acid were contributors to the overall dust cloud that cooled the global climate. Image Credit: NASA

Caption for Image 6: During the year and a half after the eruption, global stratospheric ozone levels decreased as a result of chemical reactions with the ozone and the sulfur dioxide gases released by the volcano. However, the initial effect of the injection of sulfur dioxide into the atmosphere was so strong, that a small hole was created in the ozone layer, (from June 15th, 1991 through June 30, 1991) as seen here, in blue, using TOMS data. This visualization shows global ozone levels before and after the eruption. After the hole dissipates, continued low levels of ozone, in very light blue, can be seen around the tropics. Credit: NASA

Caption for Image 7: The Arctic Ozone "Hole" The blue colors in this sequence depict the depleted region of ozone over the North Pole that occurred in the winter of 2000. Though ozone "holes" appear each year over the South Pole, low levels of ozone only occasionally form over the northern polar regions during very cold winters. Scientists say the northern ozone hole may reappear for several consecutive years after a period of high volcanic activity. A northern ozone hole could be significant because more people live in Arctic regions than near the South Pole. The data for these images were collected by the Total Ozone Mapping Spectrometer (TOMS) satellite.Credit: NASA

The Top Story Archive listing can be found by clicking on this link.

All stories found on a Top Story page or the front page of this site have been archived from most to least current on this page.

For a list of recent press releases, click here.

December 10, 2003 - (date of web publication)

SCIENTISTS "RECONSTRUCT" EARTH'S CLIMATE OVER PAST MILLENNIA

	Item 1
	Movie of North America Movie of flat world map

Using the perspective of the last few centuries and millennia, speakers in a press conference at the Fall Meeting of the American Geophysical Union in San Francisco will discuss the latest research involving climate reconstructions and different climate models.

The press conference features Caspar Ammann of the National Center for Atmospheric Research (NCAR), Boulder, Colo.; Drew Shindell of NASA's Goddard Institute for Space Studies, New York; and Tom Crowley of Duke University, Durham, N.C. The press conference is at 5 p.m. EST, Thursday, December 11 in the Moscone Convention Center West, Room 2012.

	Item 2

Changes in the sun's activity have been considered responsible for some part of past climatic variations. Although useful measurements of solar energy are limited to the last 25 years of satellite data, this record is not long enough to confirm potential trends in solar energy changes over time. Tentative connections between the measured solar activity, with sunspots or the production of specific particles in the Earth's atmosphere (such as carbon-14 and beryllium-10), have been used to estimate past solar energy.

	Item 3

Ammann will discuss how he used a set of irradiance estimates with the NCAR coupled Ocean-Atmosphere General Circulation computer model to show the climate system contains a clearly detectable signal from the sun. Ammann's work with the model also demonstrates that smaller, rather than larger, background trends in the sun's emitted energy are in better agreement with the long-term climate record, as obtained from proxy climate records, such as tree-ring data.

	Item 4
	Hi res TIF image (11.2 MB) Click here for animation.

Shindell will discuss how he used a climate model that included solar radiation changes, volcanic eruptions, and natural internal variability to arrive at a more accurate look at Earth's changing climate today. Shindell said that while solar radiation changes and volcanoes exert a similar influence on global or hemispheric average-temperature changes, the solar component has the biggest regional effect over time scales of decades to centuries, while volcanoes cause the largest year-to-year changes.

	Item 5
	Hi res of sulfur cloud Click here for animation.

Crowley will discuss one of the goals of climate modeling, to test whether moderately reliable predictions of regional climate change can be made under global warming scenarios. Using paleoclimate data, scientists can in some cases test computer climate-model performance. This testing would occur for a time period in which models accurately predict the larger (hemispheric-scale) response to changes in the Earth's radiation balance.

NASA's Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather and natural hazards using the unique vantage point of space.

	Item 6
	Hi res of ozone hole Click here for animation.

NCAR is a research laboratory operated by the University Corporation for Atmospheric Research, a consortium of 67 universities offering doctoral programs in the atmospheric and related sciences. NCAR's primary sponsor is the National Science Foundation.

	Item 7
	Click here for animation.

Back to Top