July 2019 Global Temperature Update

July 2019 Global Temperature Update

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July 2019 was the hottest month ever in the GISTEMP analysis, i.e., since 1880 when adequate instrumental data became available.  July was +0.93°C relative to 1951-1980 or +1.17°C relative to 1880-1920, which is significantly warmer than prior Julys (left figure above).  July was the second consecutive month of a monthly record high (right figure).  The real temperature (not anomaly) exceeded that in August 2016, which had been the warmest month.

January-July in 2019 was +1.25°C relative to 1880-1920, second only to 2016 (+1.37°C) for those seven months.  2016 was affected by a super El Nino and 2019 by a weak El Nino.  Because of the relative phasing of the El Ninos, 2019 may have a higher temperature than 2016 averaged over the next five months, but it seems unlikely that the 2019 annual mean will exceed that of 2016.

The maps (below) of July 2019 temperature (which use 1951-1980 base period for the sake of better spatial coverage) show that northeastern Europe was cooler than in the base period.  Much of North America was near normal, but elsewhere it was unusually hot with Alaska and an area from Northern Africa to Central Europe especially warm.  Higher resolution maps show that much of Spain and areas around Baffin Bay and the north coast of Alaska were more than 5°C warmer than the 1951-80 mean.

Real temperatures (as opposed to anomalies), constructed using Dr. Phil Jones climatology and GISS 250 km smoothing of anomalies, show that the monthly mean of the daily mean (not daily maximum) exceeded 35°C (95°F) in parts of North Africa and the Middle East (map on lower right).

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June 2019 Global Temperature Update

June 2019 Global Temperature Update

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June 2019 was, easily, the warmest June in the period of instrumental temperature measurements, as shown in the figure above.  June 2019 was +0.93°C, exceeding the prior record of +0.82°C in June 2016, both measured relative to the 1951-1980 base period.  The contiguous U.S. and north-central Eurasia were cool, but parts of Europe had record heat waves and Alaska had many wildfires.

Northern Hemisphere summer is the time of least natural variability of global temperature, and June in particular has low variability, so does this record June temperature presage still higher global annual temperature records?[1]

No and yes.  Increasing greenhouse gases and Earth’s present energy imbalance continuously tend to push decadal temperature higher, but El Niño variability dominates global temperature change on the time scale of a few years.  June got a positive kick from the current weak El Niño.  The impact of El Niño on global temperature lags El Niño by 4½ months (see figure below).  The current weak El Niño is fizzling out already, so the annual 2019 temperature is going to be high, but probably second to 2016.

Comparison of Niño 3.4 and global temperatures. Correlation is 61% with global temperature lagging Niño 3.4 temperature by 4.5 months.

Comparison of Niño 3.4 and global temperatures. Correlation is 61% with global temperature lagging Niño 3.4 temperature by 4.5 months.

[1] The Northern Hemisphere is mostly land, and temperature over land in the cool seasons fluctuates a lot depending on the weather, i.e., whether the wind has a more northerly or southerly component.  Thus large-scale Rossby waves, waggles in the jet stream, cause big fluctuations in land temperature during NH winter, when there is a huge equator-to-pole temperature gradient.

A PDF of this Temperature Update is available here.

May 2019 Global Temperature Update

May 2019 Global Temperature Update

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May 2019 was the 3rd warmest May in the 140-year instrumental record at +0.87°C relative to 1951-1980 (2016 was +0.94°C; 2017 was +0.89°C).  Most of U.S. was cool relative to 1951-1980, especially compared to the rest of the world.  So far 2019 is the 3rd warmest year, but residual effects of this year’s weak El Niño are likely to make 2019 the 2nd warmest year.  The 5-month mean is +0.98°C, which is +1.25°C relative to 1880-1920, i.e., relative to our best estimate of preindustrial temperature.

Beginning this month the temperature analyses of both NOAA and NASA Goddard Institute for Space Studies switch to use of version 4 of the Global Historical Climatology Network (GHCN).  The effect of the switch on global temperature relative to version 3 is shown below.  Version 4 provides an expanded set of station temperature records and more comprehensive uncertainties for the calculation of station and regional temperature trends. (https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/global-historical-climatology-network-monthly-version-4)

A PDF of this Temperature Update is available here.



April 2019 Global Temperature Update

April 2019 Global Temperature Update

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April 2019 was 2nd warmest April in the 140-year instrumental record at +0.99°C relative to 1951-1980 (2016 was +1.07°C).  So far 2019 is the 3rd warmest year (right graph), but residual global warming (which lags Niño3.4 several months) from the weak El Niño may make 2019 the 2nd warmest year.

NCEP (NOAA) forecast for the temperature in the Niño3.4 region (green range below), as provided at https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf, still has a huge range for the El Niño strength the rest of the year – ranging from growth to a moderately strong El Niño to rapid phasedown to La Niña.  Is the tropical ocean really THAT unpredictable?

Mark Cane once told us that Nature rolls the El Niño dice in Northern Hemisphere spring, determining El Niño status for the year.  It’s spring.  Presumably the range of the forecasts will narrow soon.  If not, hopes for something much better than nowcasting (looking out the window) seem to have been dashed, contrary to the great expectations of a few decades ago.  Does a good review of the El Niño forecasting situation, preferably in lay language, exist?

The 12-month running-mean of global temperature (dark blue curve in lower right graph) now has a defined minimum in mid-2018, lagging the January 2018 Niño3.4 minimum by several months, as expected.

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March 2019 Global Temperature Update

March 2019 Global Temperature Update

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March 2019 was the 3rd warmest March in the 140-year instrumental record, at +1.11°C relative to the 1951-1980 mean (2016 was +1.31°C, 2017 was +1.13°C).  Tell that to people in the Northern and Midwestern United States, regions hit by brutal cold and heavy snow! 

The map of temperature anomalies shows regions in the Arctic that were more than 10°C (about 20°F) above normal (1951-1980 mean) on monthly average!  Such Arctic warmth is not from local heating; it is warm air from lower latitudes.  Of course, the imported air is balanced by Arctic air moving out – the 48 United States being the recipient in this case.

Polar amplification of global warming causes the jet stream to be less tightly wound, which may increase the chance of cold air outbreaks to middle latitudes.  However, March, as the transition month from winter to warmer seasons, always has highly variable weather, as shown by the maps below for the last six years.  And Jonathan Erdman of weather.com argues that March is mainly a winter month.

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A PDF of this Temperature Update is available here.

February 2019 Global Temperature Update

February 2019 Global Temperature Update

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Global temperature in February 2019 (at +0.92°C relative to 1951-1980 base period) was third warmest February in the 140-year record since 1880.  Warmest Februarys were 2016 (+1.34°C) and 2017 (+1.12°C).   February temperature anomalies cover a huge range, as much as 6-8°C colder than the 1951-1980 mean in much of western Canada and the northwest and north central U.S., and as much as 8-12°C warmer than 1951-1980 in parts of northern Eurasia, and Alaska and the surrounding Arctic.

NCEP forecast given by NOAA (indicated by the green range below) as provided at https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf on March 18 has a large range for the strength of the El Nino predicted for this year.  It will be interesting to compare the development over the next few months of 2019 with the same months in 2015.  If the 2019 El Nino is strong, it could presage a very high global temperature in 2020.

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A PDF of this Temperature Update is available here.

January 2019 Global Temperature Update

January 2019 Global Temperature Update

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Global temperature in January 2019 (at +0.88°C relative to 1951-1980 base period) was the fourth warmest January in the 140-year record since 1880.  The warmest Januarys were 2016 (+1.15°C), 2017 (+0.97°C) and 2007 (+0.94°C).

Northeastern Canada was unusually cool (as much as 3.6°C below the 1951-1980 mean), but areas in Siberia and northwestern Canada were more than +5°C above normal, where ‘normal’ is defined as the 1951-1980 mean.  Australia experienced a scorching summer, most of the country at least +3°C above normal.  The global temperature pattern is typical of El Ninos (See maps on http://www.columbia.edu/~mhs119/ElNino-LaNina/), despite the current El Nino being very weak.

Almost the entire United States was warmer than normal, averaged over the month.  Of course the monthly mean can hide extreme cold spells that cause people to wonder where “global warming” has gone, when it has not gone anywhere.  Some recent cold weather may even be unusually cold, because of behavior of the Arctic vortex, as noted in prior temperature updates.  Examples of cold weather are shown on the right in the figure below.  The daily data are from NOAA https://w2.weather.gov/climate/index.php?wfo=okx and https://w2.weather.gov/climate/index.php?wfo=mpx .

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A PDF of this temperature update is available here.

Global Temperature in 2018 and Beyond

Global Temperature in 2018 and Beyond

06 February 2019

James Hansen[1], Makiko Sato[1], Reto Ruedy[2],[3], Gavin A. Schmidt[3], Ken Lo[2],[3]

[1] Earth Institute, Columbia University, New York, NY

[2] SciSpace LLC, New York, NY

[3] NASA Goddard Institute for Space Studies, New York, NY

Abstract.  Global surface temperature in 2018 was the 4th highest in the period of instrumental measurements in the Goddard Institute for Space Studies (GISS) analysis.  The 2018 global temperature was +1.1°C (~2°F) warmer than in the 1880-1920 base period; we take that base period as an estimate of ‘pre-industrial’ temperature.  The four warmest years in the GISS record all occur in the past four years, and the 10 warmest years are all in the 21st century.  We also discuss the prospects for near-term global temperature change.

Access the full version and continue reading in PDF: http://www.columbia.edu/~jeh1/mailings/2019/20190206_Temperature2018.pdf

Figures of this Communication are available:

http://www.columbia.edu/~mhs119/Temperature/Temp2018_figures/

Annual Global Temperature Rankings available:

http://www.columbia.edu/~mhs119/Temperature/

November 2018 Global Temperature Update

November 2018 Global Temperature Update

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November 2018 global temperature, at 0.77°C relative to the 1951-1980 base period, tied with 2010 as the fifth warmest November since reliable data began in 1880.  Most people, however, care more about the temperature where they live.  For people in North America, except those on the West Coast, November was cold (see map).

Does the cold November in North America portend a cold winter?  Curiously, Northern Hemisphere temperature patterns were nearly identical in 2014 and 2018.  So let’s look at the months that followed in 2014 (maps below).  December and January were unusually warm in 2015, but wham, frigid air arrived for February (we remember)!

Middle and high latitude winter climate is notoriously noisy (variable).  However, we know that a moderate El Nino has begun.  This knowledge increases the odds of making a good forecast.  El Nino winters are commonly, but not always, marked by higher than normal temperature stretching from Alaska in a southeasterly direction across the Canadian/U.S. border into the middle U.S., but not always reaching all the way to the Southeast U.S.

So, considering also the effects of global warming, if you are a betting person (we are not) you would have an excellent chance of being right if you bet that the winter as a whole in the U.S. is going to be warmer than normal (1951-1980) climatology.  But month-to-month?  Make your own guess.

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A PDF of this temperature update is available: http://www.columbia.edu/~mhs119/Temperature/Emails/November2018.pdf

October 2018 Global Temperature Update

October 2018 Global Temperature Update

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October 2018 was the second warmest October since 1880.  At +0.99°C (relative to 1951-1980) it trailed only October 2015 (+1.08°C).

Extreme regional temperature anomalies in the Northern Hemisphere (see map), as much as +6-8°C in Siberia and minus 2-3°C in North America were evidently related to a wind anomaly carrying warm air in a northeasterly direction across Asia, with the balancing flow bringing Arctic air into North America.

Global temperature is beginning to rise as the tropical Pacific is in the early phase of an El Niño, only three years after the prior one.  It will be interesting to compare global temperature in coming months with 2015-16 temperatures (blue curve in the above figure for the rest of this year, then the green curve).

The record 2016 global temperature got a maximum boost from the Sun as 2016 was 1-2 years after Solar Maximum (link to http://www.columbia.edu/~mhs119/Solar/).  In contrast, 2019 will be during a deep Solar Minimum.

The record 2016 global temperature was boosted mainly by a ‘Super El Niño’, at least as judged by the usual Niño3.4 index, which matched or exceeded the 3.4 index for the 1997 Super El Niño.  We note, however, that recent high 3.4 indices (the 3.4 index is the temperature anomaly in a small region in the tropical Pacific) may be partly a result of a background global warming trend.

So it will also be interesting to see how strong this El Niño will be.  It may be that apparent El Niño strengths are boosted by global warming.

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