NASA's Earth Science News Team: Every year, some of the same questions come up about the temperature record. What are they?

Gavin Schmidt: First, do the annual rankings mean anything? Second, how should we interpret all of the changes from year to year -- or inter-annual variability -- the ups and downs that occur in the record over short time periods? Third, why does NASA GISS get a slightly different answer than the Met Office Hadley Centre does? Fourth, is GISS somehow cooking the books in its handling and analysis of the data?

NASA: 2009 just came in as tied as the 2nd warmest on record, which seems notable. What is the significance of the yearly temperature rankings?

Gavin Schmidt: In fact, for any individual year, the ranking isn't particularly meaningful. The difference between the second warmest and sixth warmest years, for example, is trivial. The media is always interested in the annual rankings, but whether it’s 2003, 2007, or 2009 that’s second warmest doesn't really mean much because the difference between the years is so small. The rankings are more meaningful as you look at longer averages and decade-long trends.

NASA: Why does GISS get a different answer than the Met Office Hadley Centre [a UK climate research group that works jointly with the Climatic Research Unit at the University of East Anglia to perform an analysis of global temperatures]?

Gavin Schmidt: It’s mainly related to the way the weather station data is extrapolated. The Hadley Centre uses basically the same data sets as GISS, for example, but it doesn't fill in large areas of the Arctic and Antarctic regions where fixed monitoring stations don't exist. Instead of leaving those areas out from our analysis, you can use numbers from the nearest available stations, as long as they are within 1,200 kilometers. Overall, this gives the GISS product more complete coverage of the polar areas.

NASA: Some might hear the word "extrapolate" and conclude that you’re “making up” data. How would you reply to such criticism?

Gavin Schmidt: The assumption is simply that the Arctic Ocean as a whole is warming at the average of the stations around it. What people forget is that if you don't put any values in for the areas where stations are sparse, then when you go to calculate the global mean, you’re actually assuming that the Arctic is warming at the same rate as the global mean. So, either way you are making an assumption.

Which one of those is the better assumption? Given all the changes we’ve observed in the Arctic sea ice with satellites, we believe it’s better to assume the Arctic Ocean is changing at the same rate as the other stations around the Arctic. That’s given GISS a slightly larger warming, particularly in the last couple of years, relative to the Hadley Centre.

NASA: Many have noted that the winter has been particularly cold and snowy in some parts of the United States and elsewhere. Does this mean that climate change isn't happening?

Gavin Schmidt: No, it doesn't, though you can't dismiss people's concerns and questions about the fact that local temperatures have been cool. Just remember that there's always going to be variability. That's weather. As a result, some areas will still have occasionally cool temperatures — even record-breaking cool — as average temperatures are expected to continue to rise globally.

NASA: So what's happening in the United States may be quite different than what's happening in other areas of the world?

Gavin Schmidt: Yes, especially for short time periods. Keep in mind that that the contiguous United States represents just 1.5 percent of Earth's surface.

NASA: GISS has been accused by critics of manipulating data. Has this changed the way that GISS handles its temperature data?

Gavin Schmidt: Indeed, there are people who believe that GISS uses its own private data or somehow massages the data to get the answer we want. That's completely inaccurate. We do an analysis of the publicly available data that is collected by other groups. All of the data is available to the public for download, as are the computer programs used to analyze it. One of the reasons the GISS numbers are used and quoted so widely by scientists is that the process is completely open to outside scrutiny.

NASA: What about the meteorological stations? There have been suggestions that some of the stations are located in the wrong place, are using outdated instrumentation, etc.

Gavin Schmidt: Global weather services gather far more data than we need. To get the structure of the monthly or yearly anomalies over the United States, for example, you’d just need a handful of stations, but there are actually some 1,100 of them. You could throw out 50 percent of the station data or more, and you’d get basically the same answers. Individual stations do get old and break down, since they're exposed to the elements, but this is just one of things that the NOAA has to deal with. One recent innovation is the set up of a climate reference network alongside the current stations so that they can look for potentially serious issues at the large scale – and they haven't found any yet.

Related Links:
› 2009: Second Warmest Year on Record; End of Warmest Decade (Related article)
› Gavin Schmidt Background
› GISS Surface Temperature Analysis Home
› GISSTEMP Source Code and Documentation
› Raw Station Data
› LIST of GISS Surface Temperature Analysis References

When astronauts venture out into space—whether to the International Space Station, the moon, Mars or beyond—they receive specialized first-aid and medical training to ensure they can care for health issues that might confront themselves or other crew members. NASA spacecraft are equipped with medical equipment and supplies, including saline solution. However, saline solution cannot be stored indefinitely, and given that NASA is developing vehicles and planning for exploration missions progressively further away from Earth, a method is needed to create sterile saline solution on spacecraft or the space station.

NASA's Glenn Research Center in Cleveland, Ohio is preparing to launch their IntraVenous Fluid Generation (IVGEN) technology demonstration hardware to the space station on shuttle mission STS-131, currently scheduled for March. IVGEN represents years of dedicated work by Glenn scientists and engineers and their industry partner, ZIN Technologies, Inc. of Middleburg Heights, Ohio. IVGEN will be tested on the space station to validate its performance in microgravity, and could eventually become a key component of the medical equipment carried on long-duration space flights.

"IVGEN is important because medical requirements stipulate that exploration missions carry over 100 liters of IV fluid. The vehicle cannot afford the mass and volume necessary to meet that requirement," says DeVon Griffin, the Exploration Medical Capability Project Manager at Glenn and the project manager for IVGEN. "IVGEN technology will consume much less mass and volume, while allowing the crew to generate the needed treatment fluid should that become necessary."

The goal of IVGEN is to generate U.S. Pharmacopeia (USP) grade IV solution using "in situ" resources—to make sterile saline solution using the water that is available on the space station. This solution is normal saline, or a mix of .9% salt and water. The saline must meet strict medical requirements and weigh less and take up less space than pre-prepared solution would (it’s expensive to launch liquid into space because it's heavy.)

DeVon Griffin, his Glenn team and ZIN Technologies have developed, designed and extensively tested their invention. IVGEN has exceeded expectations in its Earth bound trials as well as in reduced gravity flight tests aboard the NASA C-9 aircraft. Now, it is ready to be tested in the long duration microgravity environment on the space station.

To operate, the device is hooked up to the Water Processor Assembly (WPA) on the space station because USP regulations require using potable, or drinkable, water. The water first flows into an accumulator—a plastic bag within a container. Nitrogen from the space station pressurizes the accumulator between the inner wall of the container and the outer wall of the bag, to push the water out of the container and through the first filter. The IVGEN team also developed concepts to provide fluid flow in the event of an emergency where nitrogen is not available.

This Glenn-designed filter, called a deionizing filter, is a high-tech version of a water softening filter that is commonly used on Earth. The filter contains beads coated in special chemicals to remove impurities and sterilize the water. The water flows through additional filters to remove air (to prevent bubbles which could lead to embolisms during injection) and any remaining particles.

The water then flows into an IV bag, similar to the kind that are used in hospitals on Earth. This bag, which contains a stir bar and salt, is then pressurized to evenly and thoroughly mix the saline solution. After a final filtration to ensure the solution is completely bacteria-free, the sterile saline solution is complete.

During the upcoming testing on the space station, crew members will run the device several times. For the purposes of this flight test, additional computers and sensors have been installed to take on-orbit data of all solution created and measure the equipment performance. Two bags of the sterile saline solution will return to Earth on a shuttle for additional testing.

The ability to manufacture sterile saline solution—of the same high quality that can be made on Earth—has the potential to influence even more than life aboard the space station. It could quite possibly change the way we explore space, helping enable our astronauts to travel farther than ever before.

"IVGEN is currently the number one priority of the Exploration Medical Capabilities Element of the Human Research Program," DeVon Griffin says.

Although 2008 was the coolest year of the decade -- due to strong cooling of the tropical Pacific Ocean -- 2009 saw a return to near-record global temperatures. The past year was only a fraction of a degree cooler than 2005, the warmest year on record, and tied with a cluster of other years --1998, 2002, 2003, 2006 and 2007 1998 and 2007 -- as the second warmest year since recordkeeping began.

“There’s always an interest in the annual temperature numbers and on a given year’s ranking, but usually that misses the point,” said James Hansen, the director of GISS. “There's substantial year-to-year variability of global temperature caused by the tropical El Niño-La Niña cycle. But when we average temperature over five or ten years to minimize that variability, we find that global warming is continuing unabated."

January 2000 to December 2009 was the warmest decade on record. Throughout the last three decades, the GISS surface temperature record shows an upward trend of about 0.2°C (0.36°F) per decade. Since 1880, the year that modern scientific instrumentation became available to monitor temperatures precisely, a clear warming trend is present, though there was a leveling off between the 1940s and 1970s.

The near-record temperatures of 2009 occurred despite an unseasonably cool December in much of North America. High air pressures in the Arctic decreased the east-west flow of the jet stream, while also increasing its tendency to blow from north to south and draw cold air southward from the Arctic. This resulted in an unusual effect that caused frigid air from the Arctic to rush into North America and warmer mid-latitude air to shift toward the north.

"Of course, the contiguous 48 states cover only 1.5 percent of the world area, so the U.S. temperature does not affect the global temperature much,' said Hansen.

In total, average global temperatures have increased by about 0.8°C (1.4°F) since 1880.

“That’s the important number to keep in mind,” said Gavin Schmidt, another GISS climatologist. “In contrast, the difference between, say, the second and sixth warmest years is trivial since the known uncertainty -- or noise -- in the temperature measurement is larger than some of the differences between the warmest years."

Decoding the Temperature Record

Climate scientists agree that rising levels of carbon dioxide and other greenhouse gases trap incoming heat near the surface of the Earth and are the key factors causing the rise in temperatures since 1880, but these gases are not the only factors that can impact global temperatures.

Three others key factors -- including changes in the sun’s irradiance, oscillations of sea surface temperature in the tropics, and changes in aerosol levels -- can also cause slight increases or decreases in the planet's temperature. Overall, the evidence suggests that these effects are not enough to account for the global warming observed since 1880.

El Niño and La Niña are prime examples of how the oceans can affect global temperatures. They describe abnormally warm or cool sea surface temperatures in the South Pacific that are caused by changing ocean currents.

Global temperatures tend to decrease in the wake of La Niña, which occurs when upwelling cold water off the coast of Peru spreads westward in the equatorial Pacific Ocean. La Niña, which moderates the impact of greenhouse-gas driven warming, lingered during the early months of 2009 and gave way to the beginning of an El Niño phase in October that’s expected to continue in 2010.

An especially powerful El Niño cycle in 1998 is thought to have contributed to the unusually high temperatures that year, and Hansen’s group estimates that there’s a good chance 2010 will be the warmest year on record if the current El Niño persists. At most, scientists estimate that El Niño and La Niña can cause global temperatures to deviate by about 0.2°C (0.36°F).

Warmer surface temperatures also tend to occur during particularly active parts of the solar cycle, known as solar maximums, while slightly cooler temperatures occur during lulls in activity, called minimums.

A deep solar minimum has made sunspots a rarity in the last few years. Such lulls in solar activity, which can cause the total amount of energy given off by the sun to decrease by about a tenth of a percent, typically spur surface temperature to dip slightly. Overall, solar minimums and maximums are thought to produce no more than 0.1°C (0.18°F) of cooling or warming.

“In 2009, it was clear that even the deepest solar minimum in the period of satellite data hasn’t stopped global warming from continuing,” said Hansen.

Small particles in the atmosphere called aerosols can also affect the climate. Volcanoes are powerful sources of sulfate aerosols that counteract global warming by reflecting incoming solar radiation back into space. In the past, large eruptions at Mount Pinatubo in the Philippines and El Chichón in Mexico have caused global dips in surface temperature of as much as 0.3°C (0.54°F). But volcanic eruptions in 2009 have not had a significant impact.

Meanwhile, other types of aerosols, often produced by burning fossil fuels, can change surface temperatures by either reflecting or absorbing incoming sunlight. Hansen’s group estimates that aerosols probably counteract about half of the warming produced by man-made greenhouse gases, but he cautions that better measurements of these elusive particles are needed.

Data Details

To conduct its analysis, GISS uses publicly available data from three sources: weather data from more than a thousand meteorological stations around the world; satellite observations of sea surface temperature; and Antarctic research station measurements. These three data sets are loaded into a computer program, which is available for public download from the GISS website. The program calculates trends in temperature anomalies -- not absolute temperatures — but changes relative to the average temperature for the same month during the period of 1951-1980.

Other research groups also track global temperature trends but use different analysis techniques. The Met Office Hadley Centre, based in the United Kingdom, uses similar input measurements as GISS, for example, but it omits large areas of the Arctic and Antarctic, where monitoring stations are sparse.

In contrast, the GISS analysis extrapolates data in those regions using information from the nearest available monitoring stations, and thus has more complete coverage of the polar areas. If GISS didn't extrapolate in this manner, the software that performs the analysis would assume that areas without monitoring stations warm at the same rate as the global mean, an assumption that doesn't line up with changes that satellites have observed in Arctic sea ice, Schmidt explained. Although the two methods produce slightly different results in the annual rankings, the decade-long trends in the two records are essentially identical.

"There's a contradiction between the results shown here and popular perceptions about climate trends," Hansen said. "In the last decade, global warming has not stopped."

Related Links

GISS Surface Temperature Analysis
› data.giss.nasa.gov/gistemp/

Annual Temperature Summation for 2008
› data.giss.nasa.gov/gistemp/2008/

The Elusive Absolute Surface Air Temperature
› data.giss.nasa.gov/gistemp/abs_temp.html

James Hansen Biography
› http://www.giss.nasa.gov/staff/jhansen.html

Q&A Session: NASA Climatologist Gavin Schmidt
› http://www.nasa.gov/topics/earth/features/gavin-schmidt.html

For a reporter package of background data and video on this topic, visit NASA Goddard's Scientific Visualization Studio site

In 2007, Vintage was selected as a NASA Explorer School. Explorer Schools develop and implement three-year action plans to address local challenges in science, technology, and mathematics education. The goal is to bring educators, administrators, students, and families together in sustained involvement with NASA's education programs.

Students have been preparing for the event by participating in NASA Digital Learning Network events and hosting a NASA Community Night. Students also participated in an "Ask an Astronaut" contest to develop the best questions to ask during the event, presenting their suggestions to a panel of students, scientists and administrators who helped choose the winning questions. Following the event, students will construct a space station model that will be displayed in the auditorium to commemorate the event.

The event is part of a series with educational organizations in the U.S. and abroad to improve teaching and learning in science, technology, engineering and mathematics. It is an integral component of Teaching From Space Project. The project promotes learning opportunities and builds partnerships with the kindergarten through 12th grade education community using the unique environment of human spaceflight.

NASA Television will air video of Williams, Creamer and Noguchi during the downlink. For NASA TV downlink, schedule and streaming video information, visit:

Journalists will be able to observe and photograph tests of prototype rovers designed to prospect for ice in craters and systems to manufacture oxygen from soil. Engineers involved in the systems' development will be available for interviews.

Reporters should contact Kimberly Land at 757-746-4749 (kimberly.w.land@nasa.gov), or Ashley Edwards at 202-358-1756 (ashley.edwards-1@nasa.gov) by Friday, Jan.22, to attend. Access to the test site requires an escort and a letter of assignment on company letterhead for credentials.

This second round of Hawaii field tests highlights international collaboration. U.S., Canadian, and German scientists and engineers will test concepts for survival, transportation, communication, fuel production, and construction on other planetary bodies. The Pacific International Space Center for Exploration Systems, or PISCES, at the University of Hawaii, Hilo, hosts the collaborative mission.

NASA's In Situ Resource Utilization project develops methods for explorers to take advantage of resources at potential landing sites. For more information about NASA's exploration plans, visit: