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Friday, January 21, 2022

Past eight years: Warmest since modern recordkeeping began

2021 tied for sixth warmest year in continued trend, analysis shows


Screenshot from new StormTools database showing Charlestown's coastline. Areas in dark blue will be innundated by a 5 foot rise in sea level. Other shades of blue show flooded areas during 25-year and 100-year coastal storms. These are all likely events, not as Richard Sartor would put it, "unknown unknowns"

Earth's global average surface temperature in 2021 tied with 2018 as the sixth warmest on record, according to independent analyses done by NASA and NOAA. Collectively, the past eight years are the warmest years since modern recordkeeping began in 1880.

Earth's global average surface temperature in 2021 tied with 2018 as the sixth warmest on record, according to independent analyses done by NASA and the National Oceanic and Atmospheric Administration (NOAA).

Continuing the planet's long-term warming trend, global temperatures in 2021 were 1.5 degrees Fahrenheit (0.85 degrees Celsius) above the average for NASA's baseline period, according to scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. NASA uses the period from 1951-1980 as a baseline to see how global temperature changes over time.

Collectively, the past eight years are the warmest years since modern recordkeeping began in 1880. This annual temperature data makes up the global temperature record -- which tells scientists the planet is warming.

According to NASA's temperature record, Earth in 2021 was about 1.9 degrees Fahrenheit (or about 1.1 degrees Celsius) warmer than the late 19th century average, the start of the industrial revolution.

"Science leaves no room for doubt: Climate change is the existential threat of our time," said NASA Administrator Bill Nelson. "Eight of the top 10 warmest years on our planet occurred in the last decade, an indisputable fact that underscores the need for bold action to safeguard the future of our country -- and all of humanity. 

NASA's scientific research about how Earth is changing and getting warmer will guide communities throughout the world, helping humanity confront climate and mitigate its devastating effects."

This warming trend around the globe is due to human activities that have increased emissions of carbon dioxide and other greenhouse gases into the atmosphere. The planet is already seeing the effects of global warming: Arctic sea ice is declining, sea levels are rising, wildfires are becoming more severe and animal migration patterns are shifting. 

Understanding how the planet is changing -- and how rapidly that change occurs -- is crucial for humanity to prepare for and adapt to a warmer world.

Weather stations, ships, and ocean buoys around the globe record the temperature at Earth's surface throughout the year. These ground-based measurements of surface temperature are validated with satellite data from the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite. 

Scientists analyze these measurements using computer algorithms to deal with uncertainties in the data and quality control to calculate the global average surface temperature difference for every year. 

NASA compares that global mean temperature to its baseline period of 1951-1980. That baseline includes climate patterns and unusually hot or cold years due to other factors, ensuring that it encompasses natural variations in Earth's temperature.

Many factors affect the average temperature any given year, such as La Nina and El Nino climate patterns in the tropical Pacific. For example, 2021 was a La Nina year and NASA scientists estimate that it may have cooled global temperatures by about 0.06 degrees Fahrenheit (0.03 degrees Celsius) from what the average would have been.

A separate, independent analysis by NOAA also concluded that the global surface temperature for 2021 was the sixth highest since record keeping began in 1880. NOAA scientists use much of the same raw temperature data in their analysis and have a different baseline period (1901-2000) and methodology.

"The complexity of the various analyses doesn't matter because the signals are so strong," said Gavin Schmidt, director of GISS, NASA's leading center for climate modeling and climate change research. "The trends are all the same because the trends are so large."

NASA's full dataset of global surface temperatures for 2021, as well as details of how NASA scientists conducted the analysis, are publicly available from GISS (

GISS is a NASA laboratory managed by the Earth Sciences Division of the agency's Goddard Space Flight Center in Greenbelt, Maryland. The laboratory is affiliated with Columbia University's Earth Institute and School of Engineering and Applied Science in New York.

For more information about NASA's Earth science missions, visit:

WPRI graphic

Overall warming with reduced seasonality: temperature change in New England, 1900–2020

By Stephen S. Young and Joshua S. Young, Salem State University

The ecology, economy, and cultural heritage of New England is grounded in its seasonal climate, and this seasonality is now changing as the world warms due to human activity.

This research uses temperature data from the U.S. Historical Climatology Network (USHCN) to analyze annual and seasonal temperature changes in the New England region of the United States from 1900 to 2020 at the regional and state levels.

Results show four broad trends:

(1) New England and each of the states (annually and seasonally) have warmed considerably between 1900 and 2020;

(2) All of the states and the region as a whole show three general periods of change (warming, cooling, and then warming again);

(3) The winter season is experiencing the greatest warming; and

(4) The minimum temperatures are generally warming more than the average and maximum temperatures, especially since the 1980s.

The average annual temperature (analyzed at the 10-year and the five-year average levels) for every state, and New England as a whole, has increased greater than 1.5 °C from 1900 to 2020.

This warming is diminishing the distinctive four-season climate of New England, resulting in changes to the region’s ecology and threatening the rural economies throughout the region. 

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