June 2020 Temperature Update

The following is a summary of global temperature conditions in Berkeley Earth’s analysis of June 2020.

  • June 2020 is nominally the warmest June since records began in 1850; however, it exceeds the previous record (June 2019) but such a small margin as to be essentially tied.
  • A transition towards La Niña conditions has become evident in the Pacific.
  • Updated projections for the rest of 2020 give a 45% chance that 2020 will be a new record warm year, sharply lower than the previous projection.

Global Summary

Globally, June 2020 is estimated to have been the warmest June since records began in 1850, exceeding the previously warmest year in 2019. However, the margin of difference between 2020 and 2019 is small compared to the estimated uncertainties. As a result June 2020 and June 2019 may be regarded as essentially tied for the warmest June. 2020 has also had both the warmest April & May.

The global mean temperature in June 2020 was 0.81 ± 0.06 °C (1.46 ± 0.11 °F) above the 1951 to 1980 average.

This is equivalent to being 1.16 ± 0.08 °C (2.09 ± 0.16 °F) above the 1850 to 1900 average, which is frequently used as a benchmark for the preindustrial period.

The global mean temperature anomaly in June 2020 cooled markedly compared to May, and continues a shift towards smaller temperature anomalies that also occurred in May, though values still remain high compared to previous decades. Due to higher weather variability during the Northern winter months, it is not unusual for temperature anomalies in Northern summer months to be somewhat smaller than those in January to March. Though the current temperature anomaly is less extreme than in a few other recent months, it remains the highest temperature anomaly ever observed during June.

Spatial Variation

June 2020 continues the ongoing pattern of wide-spread warmth. Very warm conditions were present in parts of Asia, South America, Africa, and much of Antarctica. In particular, June continued an ongoing pattern of extreme warmth near the Arctic Ocean coast of Northern Asia.

Unusually cold conditions were present in India, as well as two other small regions in Asia. We estimate that 4.2% of the Earth’s surface experienced their locally warmest June average, 71% of the Earth’s surface was warmer than their long-term average, and only (0.01%) had their locally coldest June average.

The development of a cool area in the Eastern Pacific is indicative of a transition towards La Niña conditions.

Over land regions, 2020 was nominally the warmest June, coming in as 1.17 ± 0.11 °C (2.11 ± 0.20 °F) above the 1951 to 1980 average. This value slightly exceeds the previous record value from June 2013, although given the existing measurement uncertainties, these two years could also be considered essentially tied.

June 2020 was nominally the third warmest June in the oceans, recorded as 0.57 ± 0.07 °C (1.03 ± 0.13 °F) above the 1951 to 1980 average.  This is similar to several recent years, but cooler than the record set in June 2016.

La Niña

June 2020 is notable for a transition towards La Niña conditions in the Pacific Ocean. This weather phenomenon is characterized by the emergence of relatively cool ocean water in the Eastern Central Pacific and would be expected to have a significant impact on global weather patterns over the next several months. The central Pacific remains in a transitional state, but a La Niña pattern is now considered to be favored in coming months.

La Niña conditions developing now would be expected to reduce global mean temperature towards the end of 2020 and in early 2021. Such conditions would also reduce the likelihood that 2020 becomes a record warm year.

Early July ENSO forecast from IRI/CPC showing increased likelihood of La Niña conditions during the latter half of 2020.

2020 January to June Summary

After 6 months, the Earth in 2020 has been marked by above average temperatures nearly everywhere, with especially extreme conditions across Asia. We estimate that the January to June average was record warm for 8.6% of the Earth, and appreciably above the 1951 to 1980 average for 85% of the Earth. Only, 1.4% of the Earth’s surface was significantly cooler than the 1951 to 1980 average during the current January to June period, and no locations were record cool.

In addition, the January to June averages for Asia, Europe, and South America all set record highs.

Looking at regions where January to June temperature averages were either the top 5 warmest or the top 5 coldest observed, we note extensive regions with record or near-record warmth during the first half of the year and no regions of near-record cold.

The extensive, extreme warmth over Asia is especially noteworthy. The January to June temperature anomaly in the Siberian Federal District of Russia was more than 6 °C (11 °F) above the long-term average. This exceeds the previous record by more than 2 °C (3.5 °F). This an unprecedented 6-month heatwave. It was recently estimated that this warm period would be nearly impossible without the impact of global warming, and even with the impact of climate change remains a highly unlikely event.

Rest of 2020

Of the first six months of 2020, April, May, and June have each set a new record, while January to March were each no lower than the fourth warmest. Overall, the January to June average is essentially tied with 2016 as the warmest start to a year. In 2016 temperatures were boosted due to a massive El Niño event. It is remarkable that 2020 is approaching the same level of warmth despite the lack of El Niño conditions this year.

As suggested by the plot above, we would typically expect that the second half of the year to have slightly lower temperature anomalies than January to April, which is important in the context of estimating the likely range for final temperature anomalies in 2020.

With April, May, and June setting new records for monthly warmth, the projected warmth during the second half of the year remains quite high.

However, the emergence of a cool pattern over the Eastern Central Pacific and the increased likelihood of a La Niña event later this year suggests that temperatures at the end of 2020 may be cooler than otherwise expected. This reduces the likelihood of a record warm year.

The statistical approach that we use now believes that 2020 has an 45% likelihood of surpassing 2016 and becoming the warmest year that has been directly measured. This is a sharp departure from the previous forecast that placed the odds of a new record at 89%. We believe this decrease in likelihood is primarily related to the emerging La Niña, though we are surprised by the magnitude of this change and intend to investigate it further.

Regardless of whether a new record is set, it remains highly likely that 2020 will be one of the warmest years since 1850.

Likelihood of final 2020 ranking, based on January to June:

  • 1st place (45%)
  • 2nd place (45%)
  • Top 3 overall (>99%)

Revision to prior months

Finally, we wish to make note of an unusually large retroactive change to previous temperature estimates. In performing temperature field reconstructions, we aim to use all available data; however, weather data from some stations is not immediately available. This routinely results in retrospective adjustments to prior months. Usually such adjustments are quite small and/or localized, and have essentially no impact on the global mean.

With this most recent update the incorporation of delayed data has had a larger the typical impact on temperature estimates. In particular, additional data from sparsely sampled areas in Greenland, the Asian Arctic, and South America led to -0.04 °C revision the global mean for January to May 2020. This value is less than our stated uncertainties, but still unusually large for a change resulting from the addition of delayed data.

Because the likelihood of a record warm year is also affected by variations of hundredths of a degree, this revision has mildly decreased the likelihood of a record warm year, though its impact on the final projections appears to be less severe than the changing conditions in the Pacific.

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