September Global Temperature Change*
Rankings: September 1880 - September 2018
Comparisons with 20th Century Global Average Surface Temperature
(Temperatures are not compared here with a pre-industrial baseline)
4th Warmest September
2018 & 2017
October 20, 2018
Note: The CO2.Earth table above inadvertently presented, from October 18 - 20, 2018, globally-averaged land surface temperatures as global ocean and land surface temperatures. Corrections were made as soon as the error was recognized.
With global records dating back to 1880, the September 2018 global temperature across the world's land and ocean surfaces was 0.78°C (1.40°F) above the 20th century average of 15.0°C (59.0°F)—tying with 2017 as the fourth highest September temperature in the 139-year record. The ten warmest September global land and ocean surface temperatures have occurred since 2003, with the last five years (2014–2018) comprising the five warmest Septembers on record. September 2015 is the record warmest September at +0.93°C (+1.67°F). September 2018 also marks the 42nd consecutive September and the 405th consecutive month with temperatures, at least nominally, above the 20th century average.[NOAA/NCEI global analysis accessed October 20, 2018].
"The science is sobering—the global temperature in 2012 was among the hottest since records began in 1880. Make no mistake: without concerted action, the very future of our planet is in peril."
NOAA/NCEI annual global analysis for 2017:
The 2017 average global temperature across land and ocean surface areas was 0.84°C (1.51°F) above the 20th century average of 13.9°C (57.0°F), behind the record year 2016 (+0.94°C / +1.69°F) and 2015 (+0.90°C / +1.62°F; second warmest year on record) both influenced by a strong El Niño episode. The year 2017 is also the warmest year without an El Niño present in the tropical Pacific Ocean.
2017 also marks the 41st consecutive year (since 1977) with global land and ocean temperatures at least nominally above the 20th century average, with the six warmest years on record occurring since 2010. Since the start of the 21st century, the global temperature has been broken five times, three of those being set back to back (2014–2016). The yearly global land and ocean temperature has increased at an average rate of 0.07°C (0.13°F) per decade since 1880; however, the average rate of increase is twice as great since 1980. From 1900 to 1980 a new temperature record was set on average every 13.5 years; however, since 1981 it has increased to every 3 years.
Overall, the global annual temperature has increased at an average rate of 0.07°C (0.13°F) per decade since 1880 and at an average rate of 0.17°C (0.31°F) per decade since 1970." [NOAA global analysis for 2017 accessed September 18, 2018].
"Globally-averaged temperatures in 2015 shattered the previous mark set in 2014 by 0.23 degrees Fahrenheit (0.13 Celsius). Only once before, in 1998, has the new record been greater than the old record by this much."
~ NASA Goddard Institute for Space Studies [NASA post of January 20, 2016]
Before the end of 2015, scientists projected that average global temperature increase for 2015 will exceed 1°C above pre-industrial levels. The years 1850-1990 are used as the pre-industrial baseline by the MET Office and Climate Research Unit at the University of East Anglia in the UK. The MET Office released this statement in November 2015:
"This year marks an important first but that doesn't necessarily mean every year from now on will be a degree or more above pre-industrial levels, as natural variability will still play a role in determining the temperature in any given year. As the world continues to warm in the coming decades, however, we will see more and more years passing the 1 degree marker - eventually it will become the norm."
~ Peter Stott
Head of Climate Monitoring and Attribution (MET Office)
MET Office '15 Global temperatures to reach 1°C for first time
MET Office 2015 global temperature forecast
NSIDC '15 Record warmth in Antarctica
CO2.Earth Projections for Year 2100
CO2.EarthTemperature guardrail targets
Climate Central Rising global temperatures and CO2
Columbia U Global Temperature
The Royal Society Four degrees and beyond
Year-to-Date Global Temperature
NOAA compares 2015 monthly anomolies (compared to 20th Century average temperature) with 2014, 2010, 2013, 2005, 2009 and 1998. In rank order, these are the six warmest years since 1880.
Global Temperature Data Sets
Global Temperature Data
Prominent Global Surface Temperature Data Sets
(montlhy & annual)
1880-Present (csv, xml, json)
(monthly & annual)
Ten Global Temperature Records That Tell The Same Story
About Anomolies & Absolute Temperatures
NOAA-NCEI Absolute temperatures versus anomolies [FAQ 1, 2, 7 & 8]
SkS Anomolies, baselines, 2°C limit [Honeycutt | The 1°C milestone]
NOAA-NCEI Monthly global land & ocean surface mean temperature anomolies: 1901-2000 [.dat]
NOAA-NCEI Annual global land & ocean surface mean temperature anomolies: 1901-2000 [.dat]
W/M2 (Earth's Energy Imbalance)
"The inferred planetary energy imbalance, 0.58±0.15 W/m2 during the 6-yr period 2005-2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change."
~ Hansen et al. (2011)
Measurements of changes in average global temperature at the earth's surface tell just part of the global warming story. A measure of earth's energy imbalance gives us a more holistic indicator that includes, for example, heat absorbed by the ocean. Energy imbalances are measured in watts per square meter (W/m2), not degrees Celsius.
At present, almost 4,000 Argo floats measure temperature and salinity of the top 2 kilometres of the world's oceans. This allows the best assessment so far for earth's energy imbalance. Hansen et al. (2011) discuss the need for further improvements in observations, measurements and research to achieve more precise energy balance data.
The remaining text on this page is copied from a 2012 NASA GISS science briefing on Earth's Energy Imbalance.
Earth's energy imbalance is the difference between the amount of solar energy absorbed by Earth and the amount of energy the planet radiates to space as heat. If the imbalance is positive, more energy coming in than going out, we can expect Earth to become warmer in the future — but cooler if the imbalance is negative. Earth's energy imbalance is thus the single most crucial measure of the status of Earth's climate and it defines expectations for future climate change.
Climate forcings are imposed perturbations to Earth's energy balance. Natural forcings include change of the Sun's brightness and volcanic eruptions that deposit aerosols in the stratosphere, thus cooling Earth by reflecting sunlight back to space. Principal human-made climate forcings are greenhouse gases (mainly CO2), which cause warming by trapping Earth's heat radiation, and human-made aerosols, which, like volcanic aerosols, reflect sunlight and have a cooling effect.
NASA GISS '12 Science briefs: Earth's energy imbalance
Scripps UCSD Argo
Hansen, J., Sato, M., Kharecha, P., & von Schuckmann, K. (2011). Earth's energy imbalance and implications. Atmospheric Chemistry and Physics, 11(24), 13421-13449. doi:10.5194/acp-11-13421-2011 [AC&P + .pdf]
Ocean Heat Content
Global warming means the earth is retaining excess heat. About 93% of the total excess is found in the ocean. Over the past 50 years, the upper ocean (0 to 700 metres) accounted for about 64% of the total.
"The large inertia of the oceans means that they naturally integrate over short-term variability and often provide a clearer signal of longer-term change than other components of the climate system."
~ IPCC (Rhein et al., 2013, p. 260)
Where's the heat?
IPCC '13 Observations: Ocean (AR5, WG1, CH3) [43MB]
Rhein, M., Rintoul, S. R., Aoki, S., Campos, E., Chambers, D., Feely, R. A., . . . Wang, F. (2013). Observations: Ocean. In T. F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, B. V., & P. M. Midgley (Eds.), Climate change 2013: The physical science basis. Contribution of working group I to the fifth assessment report of the Intergovernmental Panel on Climate Change (pp. 255-315). Cambridge, UK and New York, USA: Cambridge University Press.