State of the Climate
Global Analysis
July 2007

National Oceanic and Atmospheric Administration

National Climatic Data Center

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Global Highlights:

Based on preliminary data, the globally averaged combined land and sea surface temperature was the second warmest on record for the January-July year-to-date period and the seventh warmest for July.
July 2007 temperatures were above average in the western U.S., central and southeastern Europe, eastern Brazil, northwestern Africa, southeastern Australia, and most of Asia. Cooler-than-average conditions occurred in the southern Plains to the eastern Great Lakes of the contiguous U.S., southern parts of South America, eastern parts of Asia, and northern Australia.
Precipitation during July 2007 was variable in many areas. It was above average in northern Europe, the southern U.S., western parts of Africa, and southern and eastern parts of Asia. Drier-than-average conditions were observed in eastern Australia, north central and mid-Atlantic U.S., eastern Asia, parts of India, and South America.
El Niño/Southern Oscillation (ENSO) conditions were in a neutral phase during July.

The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. The most current data may be accessed via the Global Surface Temperature Anomalies page.

Introduction

Temperature anomalies for July 2007 are shown on the dot maps below. The dot map, below left, provides a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) data set of land surface stations using a 1961-1990 base period. The dot map, below right, is a product of a merged land surface and sea surface temperature anomaly analysis developed by Smith and Reynolds (2005). Temperature anomalies with respect to the 1961-1990 mean for land and ocean are analyzed separately and then merged to form the global analysis. Additional information on this product is available.

Anomalously warm temperatures have covered much of the globe throughout the year. The January-July 2007 map of temperature anomalies shows the presence of warmer-than-average temperatures across all land areas, with the exception of Argentina. Warmer-than-average Sea Surface Temperatures (SSTs) occurred in the Atlantic, Indian, and the Northwest Pacific oceans. Cooler-than-average conditions were observed in the Niño 1+2 and 3 regions, the northeastern Pacific and some areas in the southern oceans.

During July, there were above average temperatures across the western U.S., central and southeastern Europe, eastern Brazil, northwestern Africa, southeastern Australia, and most of Asia. The western U.S. and central and southeastern Europe suffered from severe heat waves which caused temperatures to exceeded 40°C (104°F) during July. Additional details on the effects of the heat waves can be found on the July Global Hazards page. Cooler-than-average conditions occurred in the southern Plains to the eastern Great Lakes of the contiguous U.S., southern parts of South America, eastern parts of Asia, and northern Australia. Meanwhile, SST anomalies in the Niño 3.4 region cooled slightly in July, but a neutral ENSO phase persisted. Please see the latest ENSO discussion for additional information.

July's Land Surface Temperature Anomalies in degree Celsius

July's Land Surface Temperature
Anomalies in degrees Celsius

July's Blended Land and Sea Surface
Temperature Anomalies in degrees Celsius

The mean position of the upper level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500-millibar height anomalies on the July map) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products see the Climate Monitoring Global Products page.

Images of sea surface temperature conditions are available for all weeks during 2007 at the weekly SST page.

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Temperature Rankings and Graphics

Effective with the February 2006 report, NCDC transitioned from the use of the Operational Global Surface Temperature Index (Quayle et al. 1999) to the blended land and ocean dataset developed by Smith and Reynolds (2005). The differences between the two methods are discussed in Smith et al. (2005).

July 2007 ranked as the seventh warmest July since records began in 1880 for combined global land and ocean surface temperatures. The July land surface temperature ranked fifth warmest on record, while the ocean surface temperature ranked ninth warmest in the 127-year record. The global surface temperature for the combined January-July year-to-date period tied with 2002 and 2005 as the second warmest January-July on record, while the global land surface temperature ranked warmest on record for January-July 2007.

Current Month / Year-to-date

July	Anomaly	Rank	Ties	Warmest (or Next Warmest) Year on Record
Global Land Ocean Land and Ocean	+0.67°C (+1.21°F) +0.39°C (+0.70°F) +0.47°C (+0.85°F)	5th warmest 9th warmest 7th warmest		1998 (+0.98°C/1.76°F) 1998 (+0.55°C/0.99°F) 1998 (+0.67°C/1.21°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.79°C (+1.42°F) +0.42°C (+0.76°F) +0.56°C (+1.01°F)	5th warmest 8th warmest 6th warmest		2002 (+1.02°C/1.84°F) 2005 (+0.64°C/1.15°F) 2005 (+0.76°C/1.37°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.33°C (+0.59°F) +0.37°C (+0.67°F) +0.37°C (+0.67°F)	26th warmest 9th warmest 13th warmest	1987	1984 (+0.97°C/1.75°F) 1998 (+0.57°C/1.03°F) 1998 (+0.62°C/1.12°F)

July's Global Land and Ocean plot

July's Global Hemisphere plot

January-July	Anomaly	Rank	Ties	Warmest (or Next Warmest) Year on Record
Global Land Ocean Land and Ocean	+1.10°C (+1.98°F) +0.42°C (+0.76°F) +0.61°C (+1.10°F)	warmest 6th warmest 2nd warmest	2006 2002,2005	2002 (+1.05°C/1.89°F) 1998 (+0.53°C/0.95°F) 1998 (+0.65°C/1.17°F)
Northern Hemisphere Land Ocean Land and Ocean	+1.29°C (+2.32°F) +0.44°C (+0.79°F) +0.76°C (+1.37°F)	warmest 4th warmest warmest	2003	2002 (+1.22°C/2.20°F) 2005 (+0.53°C/0.95°F) 2002 (+0.72°C/1.30°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.52°C (+0.94°F) +0.41°C (+0.74°F) +0.43°C (+0.77°F)	5th warmest 8th warmest 6th warmest	2004,2006	2005 (+0.90°C/1.62°F) 1998 (+0.56°C/1.01°F) 1998 (+0.60°C/1.08°F)

Year-to-date Global Land and Ocean plot

Year-to-date Global Hemisphere plot

The most current data may be accessed via the Global Surface Temperature Anomalies page.

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Precipitation

The maps below represent anomaly values based on the GHCN data set of land surface stations using a base period of 1961-1990. During July 2007, above average precipitation fell over areas that include northern Europe, especially the United Kingdom where heavy rains and floods occurred, the southern U.S., western parts of Africa, and southern and eastern parts of Asia. Drier-than-average conditions were observed in eastern Australia, north central and Mid-Atlantic U.S., eastern Asia, parts of India, and South America. Additional details on flooding and drought can also be found on the July Global Hazards page.

July's Precipitation Anomalies in Millimeters

July's Precipitation Percent Departures

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ENSO SST Analysis

Click here for animated loop

Sea Surface Temperature anomalies were slightly below average across the eastern and central equatorial Pacific during July while above average anomalies were observed across the western equatorial Pacific. These conditions are indicative of a neutral ENSO phase (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of July 2007 ENSO conditions can be found on the ENSO monitoring page. For the latest advisory on ENSO conditions go to NOAA's Climate Prediction center (CPC) and the CPC ENSO Diagnostic Discussion.

Images of sea surface temperature conditions are available for all weeks since 2003 at the weekly SST page.

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Northern Hemisphere Sea Ice Extent

July's Northern Hemisphere Sea Ice Extent plot

According to the National Snow and Ice Data Center, the July 2007 Northern Hemisphere sea ice extent, which is measured from passive microwave instruments onboard NOAA satellites, was below the 1979-2000 mean. This was the least sea ice extent in July since records began in 1979. Sea ice extent for the month of July has decreased at a rate of 6.2%/decade (since satellite records began in 1979) as temperatures in the high latitude Northern Hemisphere have risen at a rate of approximately 0.37°C/decade over the same period. For further information on the Northern Hemisphere snow and ice conditions, please visit the NSIDC News page, provided by the NOAA's National Snow and Ice Data center (NSIDC).

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Troposphere

Temperatures above the Earth's surface are measured within the lower troposphere, middle troposphere, and stratosphere using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time).

NOTE: The UAH analysis is unavailable this month.

Lower Troposphere

Current Month / Year-to-date

These temperatures are for the lowest 8km (5 miles) of the atmosphere. Information on the UAH and RSS sources of troposphere data is available.

July	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
*RSS low-trop	+0.22°C/0.39°F	6th warmest	1998 (+0.62°C/1.11°F)	+0.18°C/decade

*Version 03_0

January- July	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
*RSS low-trop	+0.23°C/0.41°F	7th warmest	1998 (+0.68°C/1.22°F)	+0.18°C/decade

*Version 03_0

Mid-troposphere

Current Month / Year-to-date

These temperatures are for the atmospheric layer centered in the mid-troposphere (approximately 2-6 miles above the Earth's surface), which also includes a portion of the lower stratosphere. (The MSU channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 6 miles). Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, may create an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCDC's Microwave Sounding Unit page.

The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004). Additional details are available. Satellite data have been adjusted by the Global Hydrology and Climate center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been performed by Dr. Qiang Fu of the University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.

RATPAC January-July plot

Radiosonde measurements indicate that for the January-July year-to-date period, temperatures in the mid-troposphere were +0.60°C (1.08°F) above average, which was the third warmest January-July since global measurements began in 1958. However, as shown in the table below, satellite measurement of the January-July year-to-date period for the middle troposphere ranked fifth warmest on record.

The global mid-troposphere temperatures were warmer than average in July 2007, as shown in the table below. Satellite measurement for July 2007 ranked fourth warmest on record.

July	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
*RSS mid-trop	+0.27°C/0.48°F	4th warmest	1998 (+0.52°C/0.93°F)	+0.13°C/decade

*Version 03_0

January- July	Anomaly	Rank	Warmest (or Next Warmest) Year on Record	Trend
*RSS mid-trop	+0.25°C/0.45°F	5th warmest	1998 (+0.61°C/1.10°F)	+0.12°C/decade
RATPAC	+0.60°C/1.08°F	3rd warmest	1998 (+0.81°C/1.46°F)	+0.14°C/decade

*Version 03_0

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Stratosphere

Current Month

The table below summarizes stratospheric conditions for July 2007. On average, the stratosphere is located approximately between 10-14 miles above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in part due to the depletion of ozone. The large positive anomaly in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the sharp jump in temperature in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. In both cases the temperatures returned to pre-eruption levels within two years.

July	Anomaly	Rank	Coolest Year on Record
*RSS stratosphere	-0.52°C (-0.93°F)	4th coolest	1996 (-0.66°C/-1.18°F)

*Version 03_0

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For additional details on precipitation and temperatures in July, see the Global Hazards page.

References

Christy, John R., R.W. Spencer, and W.D. Braswell, 2000: MSU tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons. J. of Atmos. and Oceanic Technology, 17, 1153-1170.

Free, M., D.J. Seidel, J.K. Angell, J. Lanzante, I. Durre and T.C. Peterson (2005) Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new dataset of large-area anomaly time series, J. Geophys. Res., 10.1029/2005JD006169.

Free, M., J.K. Angell, I. Durre, J. Lanzante, T.C. Peterson and D.J. Seidel(2004), Using first differences to reduce inhomogeneity in radiosonde temperature datasets, J. Climate, 21, 4171-4179.

Fu, Q., C.M. Johanson, S.G. Warren, and D.J. Seidel, 2004: Contribution of stratospheric cooling to satellite-inferred tropospheric temperature trends. Nature, 429, 55-58.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003a), Temporal homogenization of monthly radiosonde temperature data. Part I: Methodology, J. Climate, 16, 224-240.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003b), Temporal homogenization of monthly radiosonde temperature data. Part II: trends, sensitivities, and MSU comparison, J. Climate, 16, 241 262.

Mears, Carl A., M.C. Schabel, F.J. Wentz, 2003: A Reanalysis of the MSU Channel 2 tropospheric Temperature Record. J. Clim, 16, 3650-3664.

Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.

Quayle, R.G., T.C. Peterson, A.N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.

Smith, T.M., and R.W. Reynolds (2005), A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.

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