1997 WARMEST YEAR OF CENTURY, NOAA REPORTS

1997 was the warmest year of this century, based on land and ocean surface temperature data, reports a team of scientists from the National Oceanic and Atmospheric Administration's National Climatic Data Center in Asheville, N. C.

Led by the center's Senior Scientist Tom Karl, the team analyzed temperatures from around the globe during the years 1900 to 1997 and back to 1880 for land areas. For 1997, land and ocean temperatures averaged three-quarters of a degree Fahrenheit above normal. (Normal is defined by the mean temperature, 61.7 degrees F, for the 30-years 1961-90.) The 1997 figure exceeds the previous record warm year, 1990, by 0.15 degrees Fahrenheit.

The record-breaking warm conditions of 1997 continues the pattern of very warm global temperatures. Nine of the past eleven years have been the warmest on record.

"Land temperatures did not break the previous record set in 1990, but 1997 was one of the five warmest years since 1880," said Karl. Including 1997, the top ten warmest years over the land have all occurred since 1981, and the warmest five years all since 1990. Land temperatures for 1997 averaged three-quarters of a degree above normal, falling short of the 1990 record by one-quarter of a degree.

Ocean temperatures during 1997 also averaged three-quarters of a degree above normal, which makes it the warmest year on record, exceeding the previous record warm years of 1987 and 1995 by 0.3 of a degree Fahrenheit.

With the new data factored in, global temperature warming trends now exceed 1.0 degree Fahrenheit per 100 years, with land temperatures warming at a somewhat faster rate. "It is likely that the sustained trend toward increasingly warmer global temperatures is related to anthropogenic increases in greenhouse gases," Karl said.

Annual Global Temperature Index

National Climatic Data Center / NESDIS / NOAA

1997: +0.42 °C (+0.76 °F)

The global average temperature of 62.45 degrees Fahrenheit for 1997 was the warmest on record, surpassing the previous record set in 1995 by 0.15 degrees Fahrenheit. The chart reflects variations from the 30-year average (1961

Q1.2 Please provide a copy of the Goddard Institute for Space Studies/NASA confirmation and accompanying data/statistics referred to in your statement above.

A1.2 Attached is a copy of the analysis of global temperatures for 1997 prepared by scientists at the National Aeronautics and Space Administration's Goddard Institute for Space Studies.

Research

NASA Goddard Institute for Space Studies

Earth Observations

Global Temperature Trends

The focus of GISS research is the study of climate -- the normal or average state of the atmosphere — and climate change. A major problem for the detection of climate trends is the enormous variability of the atmosphere, which can overshadow and disguise any trends, especially in regional studies.

In climate model experiments, this problem can be dealt with in various ways, depending on the nature of the experiment. For sensitivity studies one can increase the forcing to get a good signal-to-noise ratio; for studies of transient phenomena one may look at an ensemble of many model runs with slightly differing initial conditions; and for control or equilibrium runs one may average over a long time period.

For observational studies, the problem is more difficult. Data from meteorological stations are available only from about 1850 to the present, with incomplete coverage in space and often with temporal gaps as well. GISS has set up a system to get the most out of the available surface air temperature data, developing and refining techniques to eliminate outliers and station discontinuities, and to combine the data into one coherent data set.

1997 Temperature Observations

Global surface air temperature in 1997 was warmer than any previous year this century, marginally exceeding the temperature of 1995. The 1990s are significantly warmer than any previous decade in the period of instrumental data, with the four warmest years of the century being 1990, 1991, 1995 and 1997. Regionally, the eastern part of the United States was

Fig. 1: Near-global annual-mean surface air Fig. 2: Global land-ocean surface
temperature change, based on meteorological
station network. (Click on figure to view full-size
Image.)

temperature index, which combines sea
surface temperature measurements for ocean
areas with surface air temperature
measurements at meteorological stations.
(Click on figure to view full-size image.)

Our estimated global surface temperature change for the calendar year (Jan-Dec) is shown in Figures 1 and 2. Figure 1 is based on the land-based meteorological station network. Figure 2 combines satellite measurements of ocean surface tempeature with the land data to obtain a more representative global-mean temperature index (Reynolds and Smith 1994).

In most years the land-based and the land-plus-ocean analyses are in close agreement. However, they differ noticeably in 1997 because of the unusually high temperatures in the tropical Pacific Ocean associated with one of the strongest El Niño events on record.

In the land-based-analyses (Figure 1), 1997 is the fourth warmest year in the record. In the land-ocean temperature index, 1997 is the warmest year, being slightly (about 0.01°C) warmer than 1995.

The temperature differences among the warmest years are small and not significant in all cases, as the relative uncertainties are estimated to be a few hundredths of a degree Celsius. However, it is noteworthy that the 1990s are significantly warmer than the 1980s or any previous decade in the century.

Temperature Maps

The monthly temperature anomalies in 1997, relative to the period 1951-1980 are shown in Figure 3. These maps highlight the appearance and rapid growth of the El Niño warming off