April 2020 Temperature Update

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

  • April 2020 is estimated to have been the warmest April since records began in 1850.
  • Updated projections for the rest of 2020 give a 60% chance of that 2020 will be a new record warm year.

Global Summary

Globally, April 2020 is estimated to have been the warmest April since records began in 1850, exceeding the previously warmest year in 2016.

This follows the 4th warmest March, 2nd warmest February, and 2nd warmest January.

The global mean temperature in April 2020 was 1.13 ± 0.06 °C (2.03 ± 0.11 °F) above the 1951 to 1980 average.

This is equivalent to being 1.52 ± 0.07 °C (2.74 ± 0.13 °F) above the 1850 to 1900 average, which is frequently used as a benchmark for the preindustrial period.

Temperature anomalies in April 2020 were somewhat warmer than those in March, and slightly warmer than January and February. The measurement uncertainty on the April average overlaps with that from several other months; however, April nominally had the 4th largest temperature anomaly yet observed. It is only exceeded by the January, February, and March anomalies from 2016, when temperatures were boosted by a very large El Niño event. This year, no El Niño is present, and the central Pacific is currently exhibiting neutral conditions.

Spatial Variation

April 2020 continues the ongoing pattern of wide-spread warmth. Very warm conditions were present across most of Asia, including record monthly averages for parts of central Asia. Very warm conditions were also present in both the Arctic and Antarctic, as well as parts of Africa, South America, and Central America.

Unusually cold conditions were present in parts of North America. We estimate that 4.4% of the Earth’s surface experienced their locally warmest April average, 77% of the Earth’s surface was warmer than their long-term average, and no place (0%) had their locally coldest April average.

Over land regions, 2020 was the 2nd warmest April, coming in as 1.74 ± 0.09 °C (3.13 ± 0.16 °F) above the 1951 to 1980 average. The warmest April on land occurred in 2016.

April 2020 was nominally the warmest April in the oceans, recorded as 0.64 ± 0.07 °C (1.15 ± 0.20 °F) above the 1951 to 1980 average.  This is slightly warmer than the ocean average in 2016, 2017, and 2019, though the measurement uncertainties for all of these years overlap.

2020 January to April Summary

After 4 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 April average was record warm for 8.8% of the Earth, and appreciably above the 1951 to 1980 average for 84% of the Earth. Only, 2% of the Earth’s surface was significantly cooler than the 1951 to 1980 average during the current January to April period. In addition, the January to April averages for Asia, Europe, and South America all set record highs.

The conditions in Asia during January to April 2020 warrant special consideration. In Russia, a new record average for this period was set by more than 1.7 °C (3.1 °F) above the previous 2017 record, and 6.0 °C (10.8 °F) above the 1951-1980 average. This prolonged heat has already contributed to large early-season wildfires, and may accelerate the loss of permafrost.

Of the first four months of 2020, only April has set a new record, though January to March were each no lower that fourth. Overall, the January to April average has been the 2nd warmest. The warmest January to April period occurred in 2016 and coincided with 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 noted above, the start of 2020 has been extremely warm. We expect some regression towards the long-term average during the rest of the year, which is important in the context of estimating the likely range for final temperature anomalies in 2020.

However, it is also significant that April did not yet show signs of relative cooling, and actually moved very slightly higher than previous months. This lack of the anticipated cooling has led to a significant upward revision for the likely annual average compared to the statistical projection made following March.

The statistical approach that we use now believes that 2020 has slightly better than even odds of surpassing 2016 and becoming the warmest year that has been directly measured. It is near certain that 2020 will be one of the 3 warmest years since 1850.

However, we should also note that the odds of a La Niña developing before the end of the year have been increasing. If La Niña does occur, it will presumably push global temperatures towards the lower portion of the projected range.

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

  • 1st place (60%)
  • 2nd place (28%)
  • 3rd place (11%)
  • Top 3 overall (>99%)

As noted above, the current projection for 2020 has shifted significantly higher than previous projections. The resulting ~60% chance of a new record is similar to projections that others have issued for 2020.

March 2020 Temperature Update

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

Global Summary

Globally, March 2020 is estimated to have been the fourth warmest March since records began in 1850.  March 2020 was appreciably cooler than March 2016, and slightly cooler than March in 2017 and 2019. However, March 2020 remains warmer than all other Marchs since global temperature estimates began in 1850. This follows the 2nd warmest February and 2nd warmest January.

The global mean temperature was 1.08 ± 0.06 °C (1.94 ± 0.11 °F) above the 1951 to 1980 average.

This is equivalent to being 1.47 ± 0.07 °C (2.65 ± 0.13 °F) above the 1850 to 1900 average, which is frequently used as a benchmark for the preindustrial period.

Temperature anomalies in March 2020 were little changed from those in January and February, and remain among the highest of the modern record.

Spatial Variation

March 2020 continues the ongoing pattern of wide-spread warmth. Very warm conditions were present across most of Asia, including record monthly averages for parts of western Asia. Very warm conditions were also present in most of the United States and Mexico, and record warmth across parts of South America.

Unusually cold conditions were present in parts of Canada, Antarctica, and India. We estimate that 5.6% of the Earth’s surface experienced their locally warmest March average, compared to only 0.01% that experienced a locally coldest March.

Over land regions, 2020 was the 4th warmest March, coming in as 1.81 ± 0.08 °C (3.26 ± 0.14 °F) above the 1951 to 1980 average.  It was the 2nd warmest March in the oceans, recorded as 0.66 ± 0.07 °C (1.18 ± 0.20 °F) above the 1951 to 1980 average.  The warmest March on both land and the oceans occurred in 2016, during a major El Niño event.

2020 January to March Summary

After 3 months, the Earth in 2020 has been marked by above average temperatures nearly everywhere, with especially extreme conditions across Asia. Cool conditions were present in parts of the Arctic and Antarctica. Both the unusually warm conditions in Asia and North America and the relatively cool conditions in parts of the Arctic were a consequence of an unusually strong polar vortex in the early part of the year that kept cold Arctic air bottled up near the North Pole. This also allowed for a modest recovery in the maximum extent Arctic sea ice, reaching only the 11th lowest extent in 2020, though this is still significantly smaller than the sea ice extents observed in the 1980s and 1990s.

The conditions in Russia during January to March 2020 warrant special consideration. A new record average for this period was set by more than 1 °C (1.8 °F) above the previous 2017 record, and nearly 6 °C (10.8 °F) above the 1951-1980 average. Though Russian weather during January to March is frequently quite variable from year-to-year, this year has been particularly extreme for its warmth. The warm weather has contributed to large early-season wildfires.

So far, none of the first three months in 2020 have been the warmest recorded, though all have been within the top 4 warmest. Overall, the January to March average has been the 2nd warmest. The warmest year, 2016, started with 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. Because Northern Hemisphere winter is the most variable season, we expect that temperatures over the second half of the year will be somewhat less anomalous than the January to March period.

As noted above, the start of 2020 has been extremely warm, but we expect some regression towards the long-term average during the rest of the year. This is important in the context of estimating the likely range for final temperature anomalies in 2020. The statistical approach that we use believes that 2020 is more likely than not to continue averaging a bit less than 2016, and revert towards a second or third place finish overall. However, it remains near certain that 2020 will be one of the 5 warmest years since 2020.

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

  • 1st place (25%)
  • 2nd place (30%)
  • 3rd place (35%)
  • 4th place (5%)
  • 5th place (4%)
  • Top 5 overall (>99%)

The relationship between coronavirus (COVID-19) spread and the weather

Considerable attention has been paid to whether or not changes in the weather may stop the spread of the COVID-19 coronavirus pandemic.  Berkeley Earth has conducted a brief review of how the virus has been spreading in comparison to the weather conditions across various locations during the previous months.  The most significant early spread occurred in countries with relatively cool temperatures, though this may have been a coincidence. More recently, COVID-19 has also established itself in warmer conditions.

It is our conclusion that warming weather is unlikely to stop the spread of the pandemic. Warm, sunny weather may have some limited impact on the rate of spread, but in the absence of strong interventions, the pandemic is likely to continue spreading through the summer months in most parts of the world. The following brief report provides the justification for that conclusion.

Introduction

It is widely recognized that influenza, i.e. “the flu”, is seasonal.  Incidence of the flu increases during the cold season, with a northern hemisphere peak typically during December to February.  The reasons for this are not wholly understood but are believed to involve a combination of both physical factors affecting the durability of the virus and social factors relating to humans clustering indoors during cold weather.  In addition to influenza, many other widely-occurring viruses exhibit some degree of seasonality, though not all peak at the same time of the year as influenza.

It has been widely hoped that the transition to warmer weather during the Northern Hemisphere months will either slow or stop the spread of COVID-19 in the Northern Hemisphere.

In consideration of this possibility, there have already been several academic preprints released.

In support of a seasonal effect on COVID-19:

In opposition to a strong seasonal effect:

In addition, there are likely other papers that we have overlooked.

Temperature vs. Case Numbers

Section Summary: Confirmed COVID-19 cases have been higher in regions with cooler temperatures. However, more recently large-scale community spread has also been established in countries with warmer temperatures. It is unclear if the association with cooler temperatures has been due to differences in weather or is merely a coincidence due to where the outbreak began and how it spread via international travel.

Though there have been many preprints claiming to establish a link between COVID-19 and weather conditions, most do some version of the same analysis.  They look at where COVID-19 was spreading the earliest, notice that those places have had relatively cool weather during the period of early spread (i.e. during winter) and suggest that COVID-19 prefers to spread during cold weather.  In addition, many of these papers looked COVID-19’s spread through no later than mid-March.

If you look at where the pandemic was in early March, it is certainly true that most cases were occurring in a relatively cool Northern latitude band that included China, Europe, and the United States.

Map of confirmed COVID-19 cases on March 8th
Confirmed COVID-19 cases on March 8th vs. the average daily high temperature in February. Horizontal whiskers indicate the standard deviation of temperatures during the month of February.

The highest concentration of cases in early March mostly occurred in regions where average high temperatures in February had been between 5 and 15 °C (40 and 60 °F).

Unfortunately, correlation is not necessarily the same thing as causation.  The international spread of a novel pathogen is going to be linked to any number of factors, but patterns of international travel will naturally play a large role.  After starting in China, it should not be surprising that the disease spread to neighboring countries (e.g. South Korea, Singapore) and to parts of the world with a high volume of international air travel (including Europe and the United States).  By contrast, regions with less international travel, such as Africa and South America might reasonably be expected to see a later introduction of the virus. Hence, the early spread of COVID-19 to Europe and North America could plausibly have been coincidental as a result of the patterns of international travel.

Now that more time has passed, the virus has spread more widely.  Though many of the largest outbreaks remain in a Northern latitude band, local epidemics are now present in all regions of the world and hence have not been tightly constrained to any single climate. In particular, significant outbreaks have been established in countries like Brazil, Peru, and India, with relatively tropical climates.

Map of confirmed COVID-19 cases on April 18th
Confirmed COVID-19 cases on April 8th vs. the average daily high temperature in March. Horizontal whiskers indicate the standard deviation of temperatures during the month of March.

While in mid-March nearly all outbreaks of more than 500 confirmed cases were occurring in countries exhibiting a narrow range of temperatures, by April we now observe that outbreaks of many thousands of cases have occurred in locations with March temperatures ranging from 0 and 35 °C (30 and 95 °F).

It remains true that the highest case counts appear at ambient temperatures around 10 to 20 °C, and there are fewer cases in many warm countries (especially in Africa). However, it is unclear if this reflects an influence of weather or is due to other factors, such as a later introduction of the virus or lower number of tests being conducted in many of the tropical countries.

As pointed out by Max Roser and Our World in Data, the number of confirmed cases of COVID-19 per capita appears to track a country’s GDP per capita, with wealthy countries reporting relatively higher numbers of COVID-19 infections In part, this is likely a reflection of both the limited testing in poor countries, and the higher prevalence of international travel in rich countries.

Temperature vs. Growth Rate

Section Summary: Looking at the rate at which COVID-19 has spread allows one to partially correct for differences in outbreak timing and rates of testing. When looking at the rate at spread across a variety of locations, we do not see evidence of a strong role for ambient temperature.

Rather than simply looking at cases totals, a potentially better metric of disease progression is the rate at which the number of confirmed cases is increasing.  By looking at the local rate of growth, one can somewhat compensate for differences in when a local epidemic began.  Most of the world is currently experiencing an increase in the number of cases between 4 and 10 % per day.

Average daily percentage increase in confirmed cases from April 1st to April 15th.

This apparent rate of growth is slower than the 10 to 30% growth many regions reported in the early phases of the epidemic, and is probably affected by the widespread use of social distancing and other control efforts in the present day. There is, currently, relatively little apparent difference in the rate at which confirmed cases are growing in the developed world compared to the developing world.

Comparing the recent rate of growth to temperature conditions 1 week earlier, we notice variability among regions, but no evidence that a particular temperature range is closely associated with a faster or slower rate of growth. Notably, a few of the highest rates of growth in the recent period have been associated with warm climates. Warm outdoor temperatures do not appear to present an intrinsic limitation to spread of the coronavirus that causes COVID-19.

Average daily increase in confirmed COVID-19 cases compared to the average of daily high temperature 7 days earlier.

Comparing epidemics at similar stages of development

Because epidemics tend to start at different times in different regions and slow down as they progress, a further way of analyzing growth patterns is to restrict our comparison to outbreaks during a similar phase of development.

For the following charts, we have isolated the growth rate of the outbreaks from when each location reported 100 cases to when they reported 1000 cases. This comparison emphasizes a relatively early phase of each epidemic. Initially, these early growth rates are also compared to the average high temperature during an equal window of time shifted 7 days prior. The 7-day delay helps to account for the delay between exposure and diagnosis.

The average daily increase in confirmed cases for various locations during the period when cases grew from 100 to 1000 cases is compared to the correspond temperatures present in the same location 7 days earlier.

As before there is considerable variation in daily growth rate, which reflects different local conditions and government responses. In particular, some countries have shown much slower apparent growth than other countries.

Significantly though, there has not been a strong relationship between the rate of increase in case counts and the recent daily high temperature. Early in a local epidemic, often before strong countermeasures began, sustained daily growth rates of 15 to 30% can be observed at locations with histories of both warm and cold weather.

Median Daily Growth Rate vs. High Temperature

  • -2 to 10 °C: 22% increase per day (3.5 days to double)
  • 10 to 25 °C: 21% per day (3.6 days)
  • 25 to 37 °C: 22% increase per day (3.5 days

This suggests that outdoor temperature had, at most, only a small influence on the spread of COVID-19 during the early phase of the epidemic. Though not shown, similar results are also found when examining average and low daily temperatures.

Other factors, such as population density and government response, probably play a larger role than outdoor temperature in influencing the spread of COVID-19.

Some authors have chosen to focus on confirmed deaths rather than confirmed cases. The reasoning is that the deaths are less likely to be affected by variations in testing, since deaths are less easily overlooked than mild cases. Repeating the previous analysis for the period when regions reported a growth from 5 to 50 deaths gives similar results.

The average daily increase in confirmed deaths for various locations during the period when deaths grew from 5 to 50 is compared to the correspond temperatures present in the same location 12 days earlier.

Examining the rise in reported deaths, there is also only a small difference between the median growth rate at 5 to 20 °C, 24% / day and at 20 to 35 °C, 21% / day. However, even at high temperatures the apparent growth rate has been quite substantial and a further indication that weather is unlikely to impose a strong limitation on the spread of COVID-19.

Other Weather Variables

Section summary: An examination of humidity and ultraviolet radiation as alternative weather variables also do not appear to show a strong impact of these variations on the ability of COVID-19 to spread. The ultraviolet flux variable may have a modest impact, but many locations continue to show significant rates of spread even at the higher end of the observed range.

The previous analysis can be repeated for other climate variables. Briefly we present the growth rate vs. relative humidity, absolute humidity, and the average flux of ultraviolet (UV) radiation at the surface. Humidity is generally considered an important factor for the durability of viruses, since many viruses are damaged if they dry out. As before, the growth is measured during the progression for 100 cases to 1000 cases.

Comparison of the rate of increase in confirmed COVID-19 and the recent relative humidity.
Comparison of the rate of increase in confirmed COVID-19 and the recent absolute humidity.
Comparison of the rate of increase in confirmed COVID-19 and the recent levels of UV exposure at the surface.

Again, though there is some variations across the range of weather conditions considered, there does not appear to be a strong limitation to spread across the range of environmental conditions considered.

Perhaps the environmental variable with the best suggestion of an impact is UV flux. In that case, locations with an average UV exposure less than 15 W/m2 had a median growth rate of 26% per day (3.0 days to double) during this early phase of the epidemic, while locations with more than 20 W/m2 had a median increase in COVID-19 cases of only 19% per day (3.9 days to double).

Warm weather example

In the discussion of the effect of weather / climate on the spread on COVID-19, it is useful to consider an example of a situation where COVID-19 is spreading under warm conditions.

Perhaps the most telling example is Guayaquil, Ecuador. This port city of 2.7 million people near the equator has an average high temperature between 29° and 32° C (84° and 90° F) year-round. In addition, many residents are too poor to afford air conditioning. Sadly, Ecuador is also home to a severe COVID-19 outbreak.

Officially, Ecuador has 7,466 confirmed cases, 333 confirmed deaths, and 384 probable deaths as of April 13th; however, it is widely acknowledged that the outbreak is much more severe than the official statistics indicate due to a lack of testing. Since the declaration of a public health emergency, Guayaquil has registered 1,878 deaths (most never having been tested for COVID-19) and cemeteries that normally handle ~35 bodies per day are now receiving up to 150. Between April 1st and April 15th, Guayas Province reported nearly 5,000 more deaths than would be expected during the same time frame in a normal year. Moreover, their overwhelmed system is struggling to provide healthcare and dispose of remains. Frightened people are sometimes leaving bodies on the street for days. Obviously, Guayaquil is struggling with severe sustained local transmission despite the equatorial climate.

As the pandemic continues, other warm climate examples of local transmission are also emerging including the slums of Mumbai (average high 32 °C) and Rio de Janeiro (average high 28 °C).

Discussion

At this point in the pandemic, it has become clear that a warm climate, at least up to ~32 °C (90 °F) is not by itself sufficient to prevent local transmission of the coronavirus responsible for COVID-19. Sustained community transmission has already been observed in a variety of countries with warm climates.

Whether a warm or sunny climate might still have a mild effect on slowing transmission is unclear. Some of the above charts suggest that a mild effect is possible. However, the growth rates observed across a variety of climates do not show signs of a strong relationship or limitation across the range of weather conditions that have been observed so far.

One explanation may be that a majority of transmission simply occurs indoors during close interactions with family, friends, and coworkers. A Chinese contact tracing study looking at over 7000 cases with known routes of exposure identified only a single example where the virus was known to have spread during an outdoor contact. It is entirely possible that the lack of evidence of weather effects on the spread of COVID-19 reported above is primarily due to indoor spread under conditions that may be decoupled from the ambient weather.

Under these circumstances, it appears likely that COVID-19 will remain capable of significant spread during warm and sunny conditions, as already evidenced by the serious outbreaks in locations such as Ecuador and Brazil.

One should not expect that the COVID-19 epidemic will simply disappear during summer months. More likely, any change in the evolution of local epidemics will have to be the result of intentional control efforts rather than simply waiting for good weather. In countries that are unable or unwilling to mount effective control measures, the virus may well continue to spread until a sufficient portion of the population has been infected to achieve herd immunity.

These findings also suggest that countries with tropical climates should still be considered to be at risk of wide-scale outbreaks of COVID-19.

Methods

The analysis presented here is based on confirmed cases and confirmed deaths over time as reported by Johns Hopkins University: data portal & time series files. Values through April 19th were used in this analysis.

Temperature, humidity, and UV flux data are compiled from the ERA5 reanalysis dataset. Weather variables are masked to political boundaries using the shapefiles provided by Natural Earth. Representative values for each political territory were constructed using population-weighted averages to better reflect conditions where people actually reside. The Gridded Population of the World Dataset v. 4 data for 2015 is used for this purpose.

In most of the analysis of cases, an offset of seven days was used when comparing case counts to weather conditions. This is motivated by the typical delay of 5 days between exposure and the onset of symptoms, and assuming a further 2 days for diagnosis. In some regions, and early in the pandemic, an even longer delay may be warranted due to the poor availability of testing. However, the conclusions of this report do not appear to be very sensitive to precise choice of delay used.

All analysis and original graphics were produced using Matlab.

Global Temperature Report for 2019

Berkeley Earth, a California-based non-profit research organization, has been preparing independent analyses of global mean temperature changes since 2013. The following is our report on global mean temperature during 2019.

We conclude that 2019 was the second warmest year on Earth since 1850. The global mean temperature in 2019 was colder than 2016, but warmer than every other year that has been directly measured. Consequently, 2016 remains the warmest year in the period of historical observations. Year-to-year rankings are likely to reflect short-term natural variability, but the overall pattern remains consistent with a long-term trend towards global warming.

Annual Temperature Anomaly

2019_Time_Series

 

Relative to 1981-2010 Average Relative to 1951-1980 Average
Year Rank Anomaly in Degrees Celsius Anomaly in Degrees Fahrenheit Anomaly in Degrees Celsius Anomaly in Degrees Fahrenheit
2019 2 0.54 ± 0.05 0.96 ± 0.08 0.90 ± 0.05 1.62 ± 0.08
2018 5 0.40 ± 0.05 0.72 ± 0.08 0.77 ± 0.05 1.38 ± 0.08
2017 3 0.47 ± 0.05 0.84 ± 0.08 0.84 ± 0.05 1.51 ± 0.08
2016 1 0.58 ± 0.04 1.05 ± 0.08 0.95 ± 0.04 1.71 ± 0.08
2015 4 0.45 ± 0.05 0.80 ± 0.08 0.81 ± 0.05 1.46 ± 0.08
2014 7 0.31 ± 0.05 0.55 ± 0.08 0.67 ± 0.05 1.21 ± 0.08
2013 11 0.24 ± 0.05 0.44 ± 0.08 0.61 ± 0.05 1.10 ± 0.08
2012 15 0.22 ± 0.04 0.39 ± 0.08 0.59 ± 0.04 1.05 ± 0.08
2011 17 0.20 ± 0.05 0.37 ± 0.08 0.57 ± 0.05 1.03 ± 0.08
2010 6 0.32 ± 0.05 0.58 ± 0.08 0.69 ± 0.05 1.24 ± 0.08
Uncertainties indicate 95% confidence range.

 

The global mean temperature in 2019 was estimated to be 1.28 °C (2.31 °F) above the average temperature of the late 19th century, from 1850-1900, a period often used as a pre-industrial baseline for global temperature targets.

The temperature uncertainties can be visualized using the schematic below where each year’s temperature estimate is represented by a distribution reflecting its uncertainty. In the analysis that Berkeley Earth conducts, the uncertainty on the mean temperature is approximately 0.05 °C (0.08 °F) for recent years. The global mean temperature in 2019 fell between those observed 2016 & 2017 with a modest uncertainty in the true ranking due to overlapping uncertainties.

2019_Probability_Distribution

The last five years stand out as a period of significant warmth well above all previous years since 1850. This reflects the long-term trend towards global warming. Though 2019 is slightly cooler than 2016, its temperature remains consistent with the long-term warming trend.

In addition to long-term warming, individual years are also affected by interannual variations in weather. Both 2015 and 2016 were warmed by an extreme El Niño event that peaked in Nov/Dec of 2015 and was reported by NOAA as essentially tied for the strongest El Niño ever observed. That exceptional El Niño boosted global mean temperatures in 2015 and 2016. By contrast, 2019 began with a weak El Niño event and finished with neutral conditions. This largely neutral weather pattern would not be expected to have had a large impact on temperature in 2019. Internal weather variability, such as El Niño and La Niña, generate year-to-year variations in temperature that occur in addition to the long-term warming trend.

Temperature Distribution in 2019

The following map shows the degree to which local temperatures in 2019 have increased relative to the average temperature in 1951-1980.

2019_Anomaly_Map

As can be expected from global warming caused by greenhouse gases, the temperature increase over the globe is broadly distributed, affecting nearly all land and ocean areas. In 2019, 88% of the Earth’s surface was significantly warmer than the average temperature during 1951-1980, 10% was of a similar temperature, and only 1.5% was significantly colder.

We estimate that 9.9% of the Earth’s surface set a new local record for the warmest annual average. In 2019, no places on Earth experienced a record cold annual average.

The following map qualitatively categorizes local temperatures in 2019 based on how different they were from historical averages after accounting for the typical climate variability at each location. In a stable climate only 2.5% of the Earth would be expected to have temperatures “Very High” or higher in any given year. In 2019, 52% of the Earth have annual averages that would rate as “Very High” compared to the historical climate, including large portions of the tropics. Locations with new records for annual average temperature are also indicated.

YTD_indicator_map

Land areas generally show more than twice as much warming as the ocean. When compared to 1951-1980 averages, the land average in 2019 has increased 1.32 ± 0.04 °C (2.38 ± 0.08 °F) and the ocean surface temperature, excluding sea ice regions, has increased 0.59 ± 0.06 °C (1.06 ± 0.11 °F). As with the global average, 2019 was the 2nd warmest year on land. For the ocean surface, we find that 2019 nominally ranks as the 3rd warmest year. However, the differences between the 1st, 2nd, and 3rd warmest years in the ocean are small compared to the measurement uncertainty, meaning they are all essentially indistinguishable. We take note of the fact that other groups have announced that 2019 set a new record for total ocean heat content, including both surface and subsurface waters. The following figure shows land and ocean temperature changes relative to the average from 1850 to 1900. The tendency for land averages to increase more quickly than ocean averages is clearly visible.

2019_Land_Ocean_Compare

As in other recent years, 2019 also demonstrated very strong warming over the Arctic that significantly exceeds the Earth’s mean rate of warming. This is consistent with the process known as Arctic amplification. By melting sea ice, warming in the Arctic regions causes more sunlight to be absorbed by the ocean, which allows for yet more warming. 2019 was the 2nd warmest year in the Arctic.

Both the tendency for land to warm faster than ocean and the higher rate of warming over the Arctic are expected based on our understanding of how increases in greenhouse gas concentrations will impact the Earth’s climate. As has been reported by the Global Carbon Project and other observers, 2018 saw new records for both the level of carbon dioxide in the atmosphere and the annual amount of carbon dioxide emitted by human activities.

National Average Temperature

Though the focus of our work is on global and regional climate analysis, it is also possible to use our data to estimate national temperature trends.

In our estimation, 2019 was the hottest year since instrumental records began in the following 36 countries: Angola, Australia, Belarus, Belize, Botswana, Bulgaria, Cambodia, Comoros, Djibouti, Gabon, Guatemala, Hungary, Jamaica, Kenya, Laos, Latvia, Lithuania, Madagascar, Mauritius, Moldova, Myanmar, Namibia, Poland, Republic of the Congo, Romania, Serbia, Slovakia, Somalia, South Africa, Taiwan, Thailand, Tuvalu, Ukraine, Vietnam, Yemen, and Zimbabwe. In addition, it was also the warmest year thus far observed in Antarctica.

The following chart provides a summary of the warming that countries experienced in 2019 relative 1951 to 1980 averages.

2019_Nations

These estimates for the changes in national annual average temperatures are derived from our global temperature fields. Due to uncertainties in the analysis and the limits of our spatial resolution some national average estimates may differ slightly from the values reported by national weather agencies.

Monthly Temperature Pattern

Every month in 2019 was at least 1.1 °C (2.1 °F) warmer than the 1850 to 1900 average. Three months (June, July, and September) set a new monthly record for the globe, and no month ranked lower than 4th.

2019_Seasonal

2019_Months_Plot

Long-term Trend

Though it is interesting to understand the characteristics of individual years, global warming is ultimately about the long-term evolution of Earth’s climate. The following chart shows a ten- year moving average of the Earth’s surface temperature, plotted relative to the average temperature from 1850-1900.

2019_Projection

Since 1980, the overall trend is +0.19 °C/decade (+0.34 °F/decade) and has changed little during this period. By continuing this trend, we can make a rough guess of how the near-future climate may develop if the forces driving global warming continue at their present rate.

As shown in the chart, several recent years have had temperatures more than 1 °C (1.8 °F) above the average temperature from 1850-1900, often used as an estimate of the pre-industrial climate. The Paris Agreement on Climate Change aims to keep global temperature rise to well below 2 °C (3.6 °F) and encourages parties to strive for warming of no more than 1.5 °C (2.7 °F). At the current rate of progression, the increase in Earth’s long-term average temperature will reach 1.5 °C (2.7 °F) above the 1850-1900 average by around 2035 and 2 °C (3.6 °F) will be reached around 2065. The increasing abundance of greenhouse gases in the atmosphere due to human activities is the direct cause of this recent global warming. If the Paris Agreement’s goal of no more than 2 °C (3.6 °F) warming is to be reached, significant progress towards reducing greenhouse gas emissions needs to be made soon.

Prediction for 2019

Based on historical variability and current conditions, it is possible to roughly estimate what global mean temperature should be expected in 2020. Our current estimate is that 2020 is likely to be similar to 2019 but with a potential to be somewhat warmer or cooler. It appears highly likely (~95% chance) that 2020 will be one of the five warmest years. In addition, we estimate a roughly 20% chance that 2020 could set a new record for warmest year.

2020_Prediction

Comparisons with other Groups

When preparing our year-end reports, Berkeley Earth traditionally compares our global mean temperature analysis to the results of five other groups that also report global mean surface temperature. The following chart compares Berkeley Earth’s analysis of global mean temperature to that of the NASA’s GISTEMP, NOAA’s GlobalTemp, the UK’s HadCRUT, Cowtan & Way, and ECMWF‘s reanalysis.

2019_Comparison

All of the major surface temperature groups except HadCRU have also ranked 2019 as the 2nd warmest year. HadCRU has 2019 as the 3rd warmest year.

The slight disagreement in the ranking reflects both the uncertainty in these estimations and the differences in how various research programs look at the Earth. For example, the NOAA and HadCRU efforts omit most of the polar regions when estimating mean temperature changes. As a result, some groups are unable to capture the strong Arctic warming observed by Berkeley Earth, ECWMF, and others.

Methodology

In reconstructing the changes in global mean temperature since 1850, Berkeley Earth has examined 20 million monthly-average temperature observations from 48,000 weather stations. Of these 20,000 stations and 210,000 monthly averages are available for 2019.

The weather station data is combined with sea surface temperature data from the UK Met Office’s Hadley Centre (HadSST). This ocean data is based on 392 million measurements collected by ships and buoys, including 18 million observations obtained in 2019. We reprocess and interpolate the HadSST data to provide a more complete picture of the oceans. After combining the ocean data with our land data, we arrive at a global picture of climate change since 1850.

Uncertainties arise primarily from the incomplete spatial coverage of historical weather observations, from noise in measurement devices, and from biases introduced due to systematic changes in measurement technologies and methods. The total uncertainty is much less than the long-term changes in climate during the last 150 years.

This report is based on such weather observations as had been recorded into global archives as of early January 2020. It is common for additional observations to be added to archives after some delay, an issue that is more likely this year due to the US government shutdown. Consequently, temperature analysis calculations can be subject to revisions as new data becomes available. Such revisions are typically quite small and are considered unlikely to alter the qualitative conclusions presented in this report.

Copyright

This report was prepared by Berkeley Earth. The contents of this report, including all images and the referenced videos, may be reused under the terms of the Creative Commons BY-4.0 copyright license for any purpose and in any forum, consistent with the terms of that license.

Members of the news media may also use the materials in this report for any new reporting purpose provided that Berkeley Earth is properly acknowledged, without concern for whether or not the CC BY-4.0 license is followed.

Data

Updated data files will appear at our data page, and are updated monthly.

In particular, monthly and annual time series are available.

November 2019 Temperature Update

The following is a summary of global temperature conditions in Berkeley Earth’s analysis of November 2019.

Globally, November 2019 was the second warmest November since records began in 1850.

The global mean temperature was 0.88 ± 0.05 °C above the 1951 to 1980 average.  This is equivalent to being 1.26 ± 0.07 °C above the 1850 to 1900 average, which is frequently used as a benchmark for the preindustrial period.

Month_only_time_series_combined

November 2019 was slightly cooler than November 2015 (by ~0.05 °C), but warmer than all other Novembers since global temperature estimates began in 1850. In part, November 2015 was warmer due to a major El Niño event that peaked in late 2015 and early 2016. This November, conditions in the tropical Pacific are considered to be neutral with neither El Niño warming nor La Niña cooling present. This state is expected to continue for at least the next few months.

Temperature anomalies in November 2019 showed an appreciable decline from October 2019.  However, this had the effect of returning global conditions to a state similar to those observed in May through September, following an unusually warm October.

Monthly_time_series_combined_1980

Spatially, November 2019 continues the pattern of wide-spread warmth. Unusually warm conditions were present in much of the Arctic, parts of Africa, South America, Europe, and Antarctica. Unusually cold conditions were present across central Asia and parts of North America. In addition, very warm ocean conditions were present across parts of the Indian Ocean, Southern Atlantic, and Northern Pacific. We estimate that 7% of the Earth’s surface experienced their locally warmest November average, compared to only 0.05% that experienced a locally coldest November.

Month_anomaly_map

Over land regions, 2019 was the 7th warmest November, coming in as 1.16 ± 0.09 °C above the 1951 to 1980 average.  It was the 2nd warmest November in the oceans, recorded as 0.62 ± 0.07 °C above the 1951 to 1980 average.  The warmest November on land occurred in 2010, while the warmest in the oceans occurred in 2015.

Month_only_time_series_land

Month_only_time_series_ocean

After 11 months, the Earth in 2019 has been marked by above average temperatures nearly everywhere, with the notable exception of a relatively cool conditions in part of North America.

YTD_anomaly_map

So far, only three of eleven months in 2019 have been the warmest recorded, though all of the months in 2019 have been within the top 5 warmest.

SeasonalAnomalyNov

It appears nearly certain (>99% likelihood) that 2019 will conclude as the second-warmest year since measurements began in 1850, behind only the exceptional warmth of 2016.

Annual_time_series_combined

3rd-Party Data Visualizations

The following is a selected list of third-party data visualizations that have used data from Berkeley Earth.

Climate Data

Air Quality Data

October 2019 Temperature Update

The following is a summary of global temperature conditions in Berkeley Earth’s analysis of
October 2019.

Globally, October 2019 was the second warmest October since records began in 1850.

The global mean temperature was 0.99 ± 0.06 °C above the 1951 to 1980 average.  This is equivalent to being 1.38 ± 0.07 °C above the 1850 to 1900 average that is frequently used as a benchmark for the pre-industrial period.Month_only_time_series_combined

Though October 2019 was nominally slightly cooler than October 2015 (by ~0.01 °C), this difference is within the margin of error, so 2019 and 2015 are effectively tied.

Temperature anomalies in October 2019 showed a marked uptick from September 2019.  It is too early to know if this is merely 1-month fluctuation or the start of a short-term trend.

Monthly_time_series_combined_1980

In 2015, the jump to a warm October preceded an exceptionally warm December through April period that ultimately allowed 2016 to the warmest year observed. However, in the 2015/2016 period an exceptionally strong El Niño was present.  Such conditions are not present currently and are not expected to arise during the next few months.

Spatially, October 2019 was marked by extreme warmth across the Arctic, significant warmth across much of Asia, Europe, the Middle East, and parts of Australia.  Unusually warm conditions were also present in the Indian Ocean and the Northern Pacific.  Extraordinary cold was present in parts of North America, including in some places that saw record-breaking monthly low averages for October.

Month_anomaly_map

Over land regions, 2019 was also the 2nd warmest October, coming in as 1.46 ± 0.09 °C above the 1951 to 1980 average.  It was similarly the second warmest October in the oceans, recorded as 0.59 ± 0.07 °C above the 1951 to 1980 average.  In both cases, the warmest October occurred in 2015.

Month_only_time_series_land

Month_only_time_series_ocean

After 10 months, the Earth in 2019 has been marked by above average temperatures nearly everywhere, with the notable exception of a relatively cool conditions in part of North America.

YTD_anomaly_map

So far, only three of ten months in 2019 have been the warmest recorded, though all of the months in 2019 have been within the top 5 warmest.

October2019_Seasonal

It appears nearly certain (99% likelihood) that 2019 will conclude as the second-warmest year since measurements began in 1850, behind only the exceptional warmth of 2016.

Annual_time_series_combined

 

 

Global Temperature Report for 2018

Berkeley Earth, a California-based non-profit research organization, has been preparing independent analyses of global mean temperature changes since 2013. The following is our report on global mean temperature during 2018.

We conclude that 2018 was likely the fourth warmest year on Earth since 1850. Global mean temperature in 2018 was colder than 2015, 2016, and 2017, but warmer than every previously observed year prior to 2015. Consequently, 2016 remains the warmest year in the period of historical observations. The slight decline in 2018 is likely to reflect short-term natural variability, but the overall pattern remains consistent with a long-term trend towards global warming.

Annual Temperature Anomaly

Global Mean Temperature Anomaly 1850-2018

 

Relative to 1981-2010 Average Relative to 1951-1980 Average
Year Rank Anomaly in Degrees Celsius Anomaly in Degrees Fahrenheit Anomaly in Degrees Celsius Anomaly in Degrees Fahrenheit
2018 4 0.41 ± 0.04 0.73 ± 0.08 0.77 ± 0.04 1.39 ± 0.08
2017 2 0.46 ± 0.05 0.84 ± 0.08 0.83 ± 0.05 1.50 ± 0.08
2016 1 0.58 ± 0.05 1.05 ± 0.08 0.95 ± 0.05 1.71 ± 0.08
2015 3 0.44 ± 0.04 0.79 ± 0.08 0.81 ± 0.04 1.46 ± 0.08
2014 6 0.30 ± 0.05 0.54 ± 0.08 0.67 ± 0.05 1.21 ± 0.08
2013 10 0.24 ± 0.04 0.44 ± 0.08 0.61 ± 0.04 1.10 ± 0.08
2012 14 0.22 ± 0.04 0.39 ± 0.08 0.58 ± 0.04 1.05 ± 0.08
2011 16 0.20 ± 0.04 0.36 ± 0.08 0.57 ± 0.04 1.03 ± 0.08
2010 5 0.32 ± 0.05 0.57 ± 0.08 0.69 ± 0.05 1.24 ± 0.08
Uncertainties indicate 95% confidence range.

 

In our estimation, temperatures in 2018 were around 1.16 °C (2.09 °F) above the average temperature of the late 19th century, from 1850-1900, a period often used as a pre-industrial baseline for global temperature targets.

The temperature uncertainties can be visualized using the schematic below where each year’s temperature estimate is represented by a distribution reflecting its uncertainty. In the analysis that Berkeley Earth conducts, the uncertainty on the mean temperature for recent years is approximately 0.05 °C (0.08 °F). Since 2018 was colder than 2015 by only 0.04 °C (0.06 °F), the ranking of 3rd versus 4th warmest year can reasonably be regarded as ambiguous.

Temperature estimate and uncertainty

Though 2018 only ranks fourth overall, 2015 through 2018 still stand out as a period of significant warmth well above all previous years since 1850. This reflects the long-term trend towards global warming. Though 2018 is slightly cooler than the immediately preceding years, its temperature remains consistent with the long-term warming trend.

In addition to long-term warming, individual years are also affected by interannual variations in weather. Both 2015 and 2016 were warmed by an extreme El Niño event that peaked in Nov/Dec of 2015 and was reported by NOAA as essentially tied for the strongest El Niño ever observed. That exceptional El Niño boosted global mean temperatures in 2015 and 2016. By contrast, 2018 began with a weak-to-moderate La Niña event. Such conditions would be expected to have somewhat reduced the global mean temperature in 2018. Internal variability, such as El Niño and La Niña, generate year-to-year variations in temperature that occur in addition to the long-term warming trend.

Temperature Distribution in 2018

The following map shows the degree to which local temperatures in 2018 have increased relative to the average temperature in 1951-1980.

Temperature anomaly map in 2018

As can be expected from global warming caused by greenhouse gases, the temperature increase over the globe is broadly distributed, affecting nearly all land and ocean areas. In 2018, 85% of the Earth’s surface was significantly warmer than the average temperature during 1951-1980, 13% was of a similar temperature, and only 2.4% was significantly colder.

An animation showing the evolution of temperatures since 1850 across the globe has also been prepared:

Download video: http://berkeleyearth.lbl.gov/downloads/2018_Warming_Map.mp4

We estimate that 4.3% of the Earth’s surface set a new local record for the warmest annual average. Most significantly in 2018, this included large portions of Europe and the Middle East.

The heatwave which affected Europe in 2018 included by far the warmest May to October average that has been observed since record-keeping began. This long period of unusual summer warmth had a significant impact on the region and was accompanied in many areas by a significant drought.

European Summer Temperatures 1850-2018

In 2018, no places on Earth experienced a record cold annual average.

The following map qualitatively categorizes local temperatures in 2018 based on how different they were from historical averages after accounting for the typical climate variability at each location. In a stable climate only 2.5% of the Earth would be expected to have temperatures “Very High” or higher in any given year. In 2018, 44% of the Earth fell in these categories. Locations with new records for annual average temperature are also indicated.

Temperature anomaly indicator map

Land areas generally show more than twice as much warming as the ocean. When compared to 1951-1980 averages, the land average in 2018 has increased 1.13 ± 0.05 °C (2.03 ± 0.09 °F) and the ocean surface temperature, excluding sea ice regions, has increased 0.48 ± 0.06 °C (0.86 ± 0.11 °F). As with the global average, 2018 was the 4th warmest year on land. For the ocean surface, we find that 2018 was the 5th warmest year. We take note of the fact that other groups have announced that 2018 set a new record for total ocean heat content, including both surface and subsurface waters. The following figure shows land and ocean temperature changes relative to the average from 1850 to 1900. The tendency for land averages to increase more quickly than ocean averages is clearly visible.

Land & Ocean warming comparison

As in other recent years, 2018 also demonstrated very strong warming over the Arctic that significantly exceeds the Earth’s mean rate of warming. This is consistent with the process known as Arctic amplification. By melting sea ice, warming in the Arctic regions causes more sunlight to be absorbed by the ocean, which allows for yet more warming. 2018 was the sixth warmest year in the Arctic.

Both the tendency for land to warm faster than ocean and the higher rate of warming over the Arctic are expected based on our understanding of how increases in greenhouse gas concentrations will impact the Earth’s climate. As has been reported by the Global Carbon Project and other observers, 2018 saw new records for both the level of carbon dioxide in the atmosphere and the annual amount of carbon dioxide emitted by human activities.

Lastly, we note that the equatorial Eastern Pacific shows a weak cooling pattern in the annual average map. This is reflective of the La Niña conditions occurring in the early part of 2018.

National Average Temperature

Though the focus of our work is on global and regional climate analysis, it is also possible to use our data to estimate national temperature trends.

In our estimation, 2018 was the hottest year since instrumental records began in the following 29 countries: Albania, Armenia, Austria, Bahrain, Belgium, Bulgaria, Bosnia and Herzegovina, Croatia, Cyprus, Czechia, France, Germany, Greece, Hungary, Italy, Kosovo, Liechtenstein, Luxembourg, FYR Macedonia, Monaco, Montenegro, Oman, Poland, Qatar, Serbia, San Marino, Slovakia, Switzerland and the United Arab Emirates. In addition, it was also the warmest year thus far observed in Antarctica.

The following chart summarizes the warming that countries experienced in 2018 relative the 1951 to 1980 averages. As mentioned previously, Europe and the Middle East experienced greater warmth in 2018 than most other regions.

Temperature anomaly by country and region 2018

These estimates for the changes in national annual average temperatures are derived from our global temperature fields. Due to uncertainties in the analysis and the limits of our spatial resolution some national average estimates may differ slightly from the values reported by national weather agencies.

An animated version has also been prepared to better communicate the changes over time:

Download video: http://berkeleyearth.lbl.gov/downloads/SwitchboardTemperatureMovie_2018.mp4

Monthly Temperature Pattern

Every month in 2018 was at least 0.67 °C warmer than the 1951 to 1980 average, but no month in 2018 set a new monthly record for the globe. In the maps below, the persistent heat anomaly over Europe is visible through the latter portion of the year. A prolonged period of winter warmth in Antarctica is also visible. In the oceans, the weak La Niña pattern is visible in the Eastern Equatorial Pacific during the early months of 2018. Though a transition to weak El Niño conditions had been predicted for the end of 2018, the temperature patterns in the Pacific at the end of the year remain weak and unconsolidated.

Monthly Temperature Anomaly Maps

Long-term Trend

Though it is interesting to understand the characteristics of individual years, global warming is ultimately about the long-term evolution of Earth’s climate. The following chart shows a ten-year moving average of the Earth’s surface temperature, plotted relative to the average temperature from 1850-1900.

Global mean temperature projected to 2060

Since 1980, the overall trend is +0.19 °C/decade (+0.34 °F/decade) and has changed little during this period. By continuing this trend, we can make a rough guess of how the near-future climate may develop if the forces driving global warming continue at their present rate.

As shown in the chart, several recent years have had temperatures more than 1 °C (1.8 °F) above the average temperature from 1850-1900, often used as an estimate of the pre-industrial climate. The Paris Agreement on Climate Change aims to keep global temperature rise to well below 2 °C (3.6 °F) and encourages parties to strive for warming of no more than 1.5 °C (2.7 °F). At the current rate of progression, the increase in Earth’s long-term average temperature will reach 1.5 °C (2.7 °F) above the 1850-1900 average by 2035 and 2 °C (3.6 °F) will be reached around 2060. The increasing abundance of greenhouse gases in the atmosphere due to human activities is the direct cause of this recent global warming. If the Paris Agreement’s goal of no more than 1.5 °C (2.7 °F) warming is to be reached, significant progress towards reducing greenhouse gas emissions must be made soon.

Prediction for 2019

Based on historical variability and current conditions, it is possible to roughly estimate what global mean temperature should be expected in 2019. Our current estimate is that 2019 is likely to be warmer than 2018, but unlikely to be warmer than the current record year, 2016. At present it appears that there is roughly a 50% likelihood that 2019 will become the 2nd warmest year since 1850.

Global Mean Temperature Anomaly 1850-2018 with 2019 prediction

This forecast is somewhat lower than the comparable forecasts issued by the UK Met Office and Gavin Schmidt of NASA. Those forecasts were both made somewhat what earlier, before the end of December, and included a greater amount of El Niño related warming than now seems likely.

Comparisons with other Groups

This year is unusual due to the ongoing shutdown of the United States government. The shutdown has prevented NOAA and NASA from doing climate change analysis or presenting their results for 2018. The shutdown has also affected NOAA’s role as a key international depository and distribution point for climate data. Some archives, especially those closely related to weather forecasting, have remained available. However, other resources are off-line or incomplete due to the shutdown.

The government shutdown has affected multiple streams of input data that Berkeley Earth uses in our analysis. However, because we often acquire the same or similar data from multiple sources, we ultimately concluded that we had obtained enough data to complete our analysis of December 2018 temperatures.

The Hadley Centre of the UK Met Office has been a key partner in this analysis. They provide the ocean data that we interpolate to generate our sea surface temperature fields. Despite initial indications that this might not be possible due to disruptions in the data archives managed by NOAA, the Hadley Centre was able to complete their sea surface temperature analysis (HadSST). Though their sea surface temperature analysis is available, the UK Met Office’s final report for 2018 has also been delayed by the unavailability of other climate data archives run by NOAA.

When preparing our year-end reports, Berkeley Earth traditionally compares our global mean temperature analysis to the results of five other groups that also report global mean surface temperature. Initially, we had planned to join most of the other climate analysis groups with a coordinated release on January 17th; however, that was impossible under current conditions. At present, the global reanalysis project run by the ECMWF is the only other project that has been able to issue their report. ECMWF also concluded that 2018 was the fourth warmest year, though their estimate for 2018 was in a near tie with their 3rd warmest year.

Despite the recent disruption, we do have the results of each of the other groups for January through November of 2018. Even without official results for December 2018, the partial year results are such that it is very likely that all six groups will ultimately concur that 2018 was the fourth warmest year.

The following chart compares Berkeley Earth’s analysis of global mean temperature to that of the other groups, though only Berkeley Earth and ECWMF data have been updated through 2018.

Multi-group temperature comparison 1850-2018

Methodology

In reconstructing the changes in global mean temperature since 1850, Berkeley Earth has examined 19 million monthly-average temperature observations from 46,000 weather stations. Of these 20,000 stations and 205,000 monthly averages are available for 2018.

The weather station data is combined with sea surface temperature data from the UK Met Office’s Hadley Centre (HadSST). This ocean data is based on 374 million measurements collected by ships and buoys, including 19 million observations obtained in 2018. We reprocess and interpolate the HadSST data to provide a more complete picture of the oceans. After combining the ocean data with our land data, we arrive at a global picture of climate change since 1850.

Uncertainties arise primarily from the incomplete spatial coverage of historical weather observations, from noise in measurement devices, and from biases introduced due to systematic changes in measurement technologies and methods. The total uncertainty is much less than the long-term changes in climate during the last 150 years.

This report is based on such weather observations as had been recorded into global archives as of early January 2018. It is common for additional observations to be added to archives after some delay, an issue that is more likely this year due to the US government shutdown. Consequently, temperature analysis calculations can be subject to revisions as new data becomes available. Such revisions are typically quite small and are considered unlikely to alter the qualitative conclusions presented in this report.

Copyright

This report was prepared by Berkeley Earth. The contents of this report, including all images and the referenced videos, may be reused under the terms of the Creative Commons BY-4.0 copyright license for any purpose and in any forum, consistent with the terms of that license.

Members of the news media may also use the materials in this report for any new reporting purpose provided that Berkeley Earth is properly acknowledged, without concern for whether or not the CC BY-4.0 license is followed.

Data

Updated data files will appear at our data page, and are updated monthly.

In particular, monthly and annual time series are available.

Global Temperature Report for 2017

Berkeley Earth, a California-based non-profit research organization, has been preparing independent analyses of global mean temperature changes since 2013. The following is our report on global mean temperature during 2017.

We conclude that 2017 was likely the second warmest year on Earth since 1850. Global mean temperature in 2017 was 0.03 °C (0.05 °F) warmer than 2015, but 0.11 °C (0.20 °F) colder than 2016. As a result, 2016 remains the warmest year in the historical observations. Continue reading “Global Temperature Report for 2017”

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