NCDC 2010 Annual State of the Climate Report — Supplemental Figures and Information

January 12, 2011

Each month NOAA's National Climatic Data Center (NCDC) releases two assessments, one national and one global, of the previous month's climate. These reports include information on the temperature and precipitation levels experienced nationally and globally, providing useful information about these important climate variables in historical perspective. The reports also chronicle many significant weather and climate-related events that occurred during the month. This trusted source of information is used globally by industry and business, government agencies, academia, and members of the public to help inform decision making. This annual report includes information from both a global and national perspective.

2010 Global Temperature Anomalies

Global surface temperature Anomalies - 2010.

Global surface temperature Anomalies - 2010.
High Resolution (Credit: NOAA)

This figure depicts the global surface temperature anomalies for 2010.


Supplemental Highlights:

Warmest months on record, through 2010
Month Warmest Anomaly
Jan 2007 + 0.81°C + 1.46°F
Feb 1998 + 0.83°C + 1.49°F
Mar 2010 + 0.77°C + 1.39°F
Apr 2010 + 0.73°C + 1.31°F
May 2010 + 0.69°C + 1.24°F
Jun 2005 + 0.66°C + 1.19°F
Jul 1998 + 0.70°C + 1.26°F
Aug 1998 + 0.67°C + 1.21°F
Sep 2005 + 0.66°C + 1.19°F
Oct 2003 + 0.71°C + 1.28°F
Nov 2004 + 0.72°C + 1.30°F
Dec 2006 + 0.73°C + 1.31°F

 

What about other important climate events, beyond the "Ten Most Significant of 2010"?

Selected 2010 weather and climate events.

Selected 2010 weather and climate events.
High Resolution (Credit: NOAA)

The top ten global and top ten national weather and climate events of 2010 were voted upon by two panels of climate science and slimate services professionals. They considered several competing factors, such as the size, scope and impact of an event, its unusualness or magnitude relative to the climate history, and whether it is emblematic of larger climate trends. The "Honorable Mention" portion of these lists includes all events that received any votes. Additionally, this map provides a larger sample of important climate events and episodes that occurred during 2010.

What are the Fifteen Warmest Years Globally?

 

Rank

Year

Difference (°F) vs. 20th century

1

2005

1.12

2010

1.12

3

1998

1.08

4

2003

1.04

2002

1.04

6

2006

1.01

2009

1.01

8

2007

0.99

9

2004

0.97

10

2001

0.94

11

2008

0.86

1997

0.86

13

1999

0.76

14

1995

0.74

15

2000

0.70

 

What are the Fifteen Warmest Years in the U.S.?

 

Rank

Year

Difference (°F) vs. 20th century

1

1998

2.29

2

2006

2.25

3

1934

2.04

4

1999

1.88

5

1921

1.74

6

2001

1.62

7

2007

1.59

8

2005

1.57

9

1990

1.50

1931

1.50

11

1953

1.37

12

1987

1.32

1954

1.32

14

1986

1.30

15

2003

1.23


Comparing 10 years of Global Temperature Trends

Each of the 10 warmest average global temperatures recorded since 1880 have occurred in the last thirteen years. The warmest years on record are 2005 and 2010. This graphic shows how the "year-to-date" temperature evolved over the course of 2010. If the twelve months of 2010 were a twelve-lap race, 2010 "took the lead" in May, fell behind 1998 during the summer, regained the lead again in November, and "crossed the finish line" with 2005. The "bounce" seen in November 2010 was driven by record-warm temperature anomalies in the Northern Hemisphere, particularly over land.

Year-to-date average global land and ocean temperature.

Year-to-date average global land and ocean temperature.
High Resolution (Credit: NOAA)

This graph plots the year-to-date average global land and ocean temperature. The 2010 value is shown in bright red. On the graph, "ONI" stands for Oceanic Niño Index, which is one way of measuring whether El Niño or La Niña is occurring. Each of the three warmest years on record (2005, 1998, and 2010) began with a positive ONI, which is associated with El Niño and warmer-than-normal conditions across much of the equatorial Pacific Ocean. However, each of these years eventually transitioned into negative ONI values at some time in the year, which - after some lag - tends to depress global average temperatures slightly below the long-term trend.

What about uncertainty? Doesn't that matter?

Global temperature anomaly with uncertainty bars: last 20 years.

Global temperature anomaly with uncertainty bars: last 20 years.
High Resolution (Credit: NOAA)

Uncertainty is an important component to any measurement, including the global temperature. NCDC uses the reported value, rounded to the nearest 0.01°C, to determine the ranks. The value is the central, and most likely, value within a range defined by uncertainty ("plus or minus") estimates. The "plus" and the "minus" aspects of this range are equally likely, so for ranking purposes, the central value is used. Values near the ends of the uncertainty range (the full values of the "plus or minus" range) are much less likely than those near the center. The uncertainty range for 2010 implied that the rank could be the warmest year (most likely, scenario, with approximately 50% chance that this is the case) to tied for the eighth warmest year-to-date (this scenario occurred at the lowest end of the uncertainty range, where, statistically, the chance is 2.5%, or one in forty). The last 20 years of annual temperatures are included in the graphic at the right. Statistically, when comparing any given year on the graph to another, it is very unlikely — about 1 in 1,600 chance — that the true value for one year would lie at the highest end of the uncertainty range and the true value for another year would lie at the lowest end of the uncertainty range. It is much more likely that the true value for any given year will be close to the central value. More about NCDC's uncertainty values.

Background Information

Why Track Temperature Anomalies, Not Absolute Temperatures?

Four climate monitoring stations in Asheville, NC area.

Four climate monitoring stations in Asheville, NC area.
High Resolution (Credit: NOAA)

Temperature anomaly refers to the difference from average. The global temperature is calculated using anomalies because they give a more accurate picture of temperature change.

If calculating an average temperature for a region, factors like station location or elevation affect the data, but when looking at the difference from the average for that same location, those factors are less critical. For example, while the actual temperature on a hilltop will be different than in a nearby valley on a given day or month, stations in both places will show a similar trend in temperature when the change in temperature compared to average for that station is calculated.

Using anomalies also helps minimize problems when stations are added to or removed from the monitoring network. The above diagram helps show that if a station were removed from the record or did not report data for some period of time, the average anomaly would not change significantly, whereas the overall average temperature could change significantly, depending on which station dropped out of the record.

Where does NOAA get its Global Data?

Red dots show the stations that arrived at NCDC during a typical month. The arrival pattern (dots appearing in chunks over time) represents the fact that data are available when different nations' meteorological services distribute them.

Red dots show the stations that arrived at NCDC during a
typical month. The arrival pattern (dots appearing in chunks over time) represents the fact that data are available when different nations' meteorological services distribute them.

Animation (Credit: NOAA)

NOAA's NCDC is the world's largest active archive of weather data. It houses data archives dating back to 1880 from all over the world. Each month, countries from all over the world send their land-based meteorological surface observations, meaning temperature and precipitation measurements, to NCDC to be added to the global record.

This information is sent through the World Meteorological Organization's (WMO) Global Telecommunication System (GTS), a coordinated system for the rapid collection, exchange and distribution of observation data from more than 200 countries around the world. The data are sent in a message format called CLIMAT (pronounced "KLEE-mat"). These messages are a summary of monthly weather data for a specific station. The CLIMAT message contains information of average pressure at station level, average air temperature, maximum air temperature, minimum air temperature, average vapor pressure, total precipitation, and total sunshine for a particular month.

These messages are typically sent to NCDC by the 8th of every month. NCDC uses the data to produce numerous climate publications, such as the monthly global state of the climate report. In the image, the red dots on the animation above show how a typical month's worth of data arrives at NCDC, in a day-by-day, country-by-country fashion. In a typical month, about 2,000 to 2,500 stations have arrived by the time NCDC makes its monthly analysis. Please refer to the WMO for detailed information about CLIMAT messages or the GTS.

Other useful links:

State of the Climate Report The full monthly state of the climate report is available online.
Historical global temperature information, by month, season and continent.
Historical temperature and precipitation data for the United States.