Temperature - Blog Posts

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Heat fundamentally requires the passage of time whereas cold, (lack of heat) is the "default"

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A Tour of Cosmic Temperatures

We often think of space as “cold,” but its temperature can vary enormously depending on where you visit. If the difference between summer and winter on Earth feels extreme, imagine the range of temperatures between the coldest and hottest places in the universe — it’s trillions of degrees! So let’s take a tour of cosmic temperatures … from the coldest spots to the hottest temperatures yet achieved.

First, a little vocabulary: Astronomers use the Kelvin temperature scale, which is represented by the symbol K. Going up by 1 K is the same as going up 1°C, but the scale begins at 0 K, or -273°C, which is also called absolute zero. This is the temperature where the atoms in stuff stop moving. We’ll measure our temperatures in this tour in kelvins, but also convert them to make them more familiar!

We’ll start on the chilly end of the scale with our CAL (Cold Atom Lab) on the International Space Station, which can chill atoms to within one ten billionth of a degree above 0 K, just a fraction above absolute zero.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

Just slightly warmer is the Resolve sensor inside XRISM, pronounced “crism,” short for the X-ray Imaging and Spectroscopy Mission. This is an international collaboration led by JAXA (Japan Aerospace Exploration Agency) with NASA and ESA (European Space Agency). Resolve operates at one twentieth of a degree above 0 K. Why? To measure the heat from individual X-rays striking its 36 pixels!

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

Resolve and CAL are both colder than the Boomerang Nebula, the coldest known region in the cosmos at just 1 K! This cloud of dust and gas left over from a Sun-like star is about 5,000 light-years from Earth. Scientists are studying why it’s colder than the natural background temperature of deep space.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

Let’s talk about some temperatures closer to home. Icy gas giant Neptune is the coldest major planet. It has an average temperature of 72 K at the height in its atmosphere where the pressure is equivalent to sea level on Earth. Explore how that compares to other objects in our solar system!

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

How about Earth? According to NOAA, Death Valley set the world’s surface air temperature record on July 10, 1913. This record of 330 K has yet to be broken — but recent heat waves have come close. (If you’re curious about the coldest temperature measured on Earth, that’d be 183.95 K (-128.6°F or -89.2°C) at Vostok Station, Antarctica, on July 21, 1983.)

We monitor Earth's global average temperature to understand how our planet is changing due to human activities. Last year, 2023, was the warmest year on our record, which stretches back to 1880.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

The inside of our planet is even hotter. Earth’s inner core is a solid sphere made of iron and nickel that’s about 759 miles (1,221 kilometers) in radius. It reaches temperatures up to 5,600 K.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

We might assume stars would be much hotter than our planet, but the surface of Rigel is only about twice the temperature of Earth’s core at 11,000 K. Rigel is a young, blue star in the constellation Orion, and one of the brightest stars in our night sky.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger 

We study temperatures on large and small scales. The electrons in hydrogen, the most abundant element in the universe, can be stripped away from their atoms in a process called ionization at a temperature around 158,000 K. When these electrons join back up with ionized atoms, light is produced. Ionization is what makes some clouds of gas and dust, like the Orion Nebula, glow.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

We already talked about the temperature on a star’s surface, but the material surrounding a star gets much, much hotter! Our Sun’s surface is about 5,800 K (10,000°F or 5,500°C), but the outermost layer of the solar atmosphere, called the corona, can reach millions of kelvins.

Our Parker Solar Probe became the first spacecraft to fly through the corona in 2021, helping us answer questions like why it is so much hotter than the Sun's surface. This is one of the mysteries of the Sun that solar scientists have been trying to figure out for years.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

Looking for a hotter spot? Located about 240 million light-years away, the Perseus galaxy cluster contains thousands of galaxies. It’s surrounded by a vast cloud of gas heated up to tens of millions of kelvins that glows in X-ray light. Our telescopes found a giant wave rolling through this cluster’s hot gas, likely due to a smaller cluster grazing it billions of years ago.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

Now things are really starting to heat up! When massive stars — ones with eight times the mass of our Sun or more — run out of fuel, they put on a show. On their way to becoming black holes or neutron stars, these stars will shed their outer layers in a supernova explosion. These layers can reach temperatures of 300 million K!

Credit: NASA's Goddard Space Flight Center/Jeremy Schnittman

We couldn’t explore cosmic temperatures without talking about black holes. When stuff gets too close to a black hole, it can become part of a hot, orbiting debris disk with a conical corona swirling above it. As the material churns, it heats up and emits light, making it glow. This hot environment, which can reach temperatures of a billion kelvins, helps us find and study black holes even though they don’t emit light themselves.

JAXA’s XRISM telescope, which we mentioned at the start of our tour, uses its supercool Resolve detector to explore the scorching conditions around these intriguing, extreme objects.

Credit: NASA's Goddard Space Flight Center/CI Lab

Our universe’s origins are even hotter. Just one second after the big bang, our tiny, baby universe consisted of an extremely hot — around 10 billion K — “soup” of light and particles. It had to cool for a few minutes before the first elements could form. The oldest light we can see, the cosmic microwave background, is from about 380,000 years after the big bang, and shows us the heat left over from these earlier moments.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

We’ve ventured far in distance and time … but the final spot on our temperature adventure is back on Earth! Scientists use the Large Hadron Collider at CERN to smash teensy particles together at superspeeds to simulate the conditions of the early universe. In 2012, they generated a plasma that was over 5 trillion K, setting a world record for the highest human-made temperature.

Want this tour as a poster? You can download it here in a vertical or horizontal version!

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

Explore the wonderful and weird cosmos with NASA Universe on X, Facebook, and Instagram. And make sure to follow us on Tumblr for your regular dose of space!

Confirmed: Summer 2023 Hottest in NASA’s Record

All three months of summer 2023 broke records. July 2023 was the hottest month ever recorded, and the hottest July. June 2023 was the hottest June, and August 2023 was the hottest August.

NASA’s temperature record, GISTEMP, starts in 1880, when consistent, modern recordkeeping became possible. Our record uses millions of measurements of surface temperature from weather stations, ships and ocean buoys, and Antarctic research stations. Other agencies and organizations who keep similar global temperature records find the same pattern of long-term warming.

Global temperatures are rising from increased emissions of greenhouse gasses, like carbon dioxide and methane. Over the last 200 years, humans have raised atmospheric CO2 by nearly 50%, primarily through the burning of fossil fuels.

Drivers of climate change, both natural and human-caused, leave distinct fingerprints. Through observations and modeling, NASA researchers confirm that the current warming is the result of human activities, particularly increased greenhouse gas emissions.

2019 Temperature By the Numbers

The Year

2nd Hottest

2019 was the second-hottest year since modern record keeping began. NASA and the National Oceanic and Atmospheric Administration work together to track temperatures around the world and study how they change from year to year. For decades, the overall global temperature has been increasing.

Over the long term, world temperatures are warming, but each individual year is affected by things like El Niño ocean patterns and specific weather events.

The global temperature is an average, so not every place on Earth had its second-warmest year. For instance, the continental U.S. had a cold October, but Alaska set records for high temperatures. The U.S. was still warmer than average over the year.

Globally, Earth’s temperature in 2019 was more than 2°F warmer than the late 19th Century.

The Record

140 years 

Since 1880, we can put together a consistent record of temperatures around the planet and see that it was much colder in the late-19th century. Before 1880, uncertainties in tracking global temperatures are larger. Temperatures have increased even faster since the 1970s, the result of increasing greenhouse gases in the atmosphere.

10 years

The last decade was the hottest decade on record.

20,000 Individual Observations

Scientists from NASA use data from more than 20,000 weather stations and Antarctic research stations, together with ship- and buoy-based observations of sea surface temperatures to track global temperatures.

The Consequences

90%

As Earth warms, polar ice is melting at an accelerated rate. The Arctic is warming even faster than the rest of the planet. This northern summer, 90% of the surface of the Greenland Ice Sheet melted.

8 inches

Melting ice raises sea levels around the world. While ice melts into the ocean, heat also causes the water to expand. Since 1880, sea levels globally have risen approximately 8 inches, although regional rates of sea level rise can be even higher.

100+ fires

As temperatures increase, fire seasons burn hotter and longer. During June and July 2019, more than 100 long-lived and intense wildfires burned north of the Arctic circle. This year also saw intense, record-setting fires in Australia.

46% increase in CO2 levels

This decades-long warming trend is the result of increasing greenhouse gases in the atmosphere, released by human activities.

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Extreme Science: Launching Sounding Rockets from The Arctic

This winter, our scientists and engineers traveled to the world's northernmost civilian town to launch rockets equipped with cutting-edge scientific instruments.

This is the beginning of a 14-month-long campaign to study a particular region of Earth's magnetic field — which means launching near the poles. What's it like to launch a science rocket in these extreme conditions?

Our planet is protected by a natural magnetic field that deflects most of the particles that flow out from the Sun — the solar wind — away from our atmosphere. But near the north and south poles, two oddities in Earth's magnetic field funnel these solar particles directly into our atmosphere. These regions are the polar cusps, and it turns out they're the ideal spot for studying how our atmosphere interacts with space.

The scientists of the Grand Challenge Initiative — Cusp are using sounding rockets to do their research. Sounding rockets are suborbital rockets that launch to a few hundred miles in altitude, spending a few minutes in space before falling back to Earth. That means sounding rockets can carry sensitive instruments above our atmosphere to study the Sun, other stars and even distant galaxies.

They also fly directly through some of the most interesting regions of Earth's atmosphere, and that's what scientists are taking advantage of for their Grand Challenge experiments.

One of the ideal rocket ranges for cusp science is in Ny-Ålesund, Svalbard, off the coast of Norway and within the Arctic circle. Because of its far northward position, each morning Svalbard passes directly under Earth's magnetic cusp.

But launching in this extreme, remote environment puts another set of challenges on the mission teams. These launches need to happen during the winter, when Svalbard experiences 24/7 darkness because of Earth's axial tilt. The launch teams can go months without seeing the Sun.

Like for all rocket launches, the science teams have to wait for the right weather conditions to launch. Because they're studying upper atmospheric processes, some of these teams also have to wait for other science conditions, like active auroras. Auroras are created when charged particles collide with Earth’s atmosphere — often triggered by solar storms or changes in the solar wind — and they're related to many of the upper-atmospheric processes that scientists want to study near the magnetic cusp.

But even before launch, the extreme conditions make launching rockets a tricky business — it's so cold that the rockets must be encased in styrofoam before launch to protect them from the low temperatures and potential precipitation.

When all is finally ready, an alarm sounds throughout the town of Ny-Ålesund to alert residents to the impending launch. And then it's up, up and away! This photo shows the launch of the twin VISIONS-2 sounding rockets on Dec. 7, 2018 from Ny-Ålesund.

These rockets are designed to break up during flight — so after launch comes clean-up. The launch teams track where debris lands so that they can retrieve the pieces later.

The next launch of the Grand Challenge Initiative is AZURE, launching from Andøya Space Center in Norway in March 2019.

 For even more about what it's like to launch science rockets in extreme conditions, check out one scientist's notes from the field: https://go.nasa.gov/2QzyjR4

For updates on the Grand Challenge Initiative and other sounding rocket flights, visit nasa.gov/soundingrockets or follow along with NASA Wallops and NASA heliophysics on Twitter and Facebook.

@NASA_Wallops | NASA’s Wallops Flight Facility | @NASASun | NASA Sun Science

A persistent heatwave has been lingering over parts of Europe, setting record high temperatures and turning typically green landscapes brown.

The United Kingdom experienced its driest first half of summer (June 1 to July 16) on record. 

These images, acquired by our Terra satellite, show the burned landscape of the United Kingdom and northwestern Europe as of July 15, 2018, compared with July 17, 2017. 

Peter Gibson, a postdoctoral researcher at our Jet Propulsion Laboratory, examined how rising global temperatures are linked to regional heatwaves. “If the globe continues to warm, it’s clear we will continue to see events like this increasing in frequency, severity and duration,” Gibson said. “We found that parts of Europe and North America could experience an extra 10 to 15 heatwave days per degree of global warming beyond what we have seen already.”

Read more HERE.

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Why Won’t Our Parker Solar Probe Melt?

This summer, our Parker Solar Probe will launch to travel closer to the Sun than any mission before it, right into the Sun’s outer atmosphere, the corona.

The environment in the corona is unimaginably hot: The spacecraft will travel through material with temperatures greater than 3 million degrees Fahrenheit. 

So…why won’t it melt? 

The Difference Between Heat and Temperature

Parker Solar Probe was designed from the ground up to keep its instruments safe and cool, but the nature of the corona itself also helps. The key lies in the difference between heat and temperature.

Temperature measures how fast particles are moving, while heat is the total amount of energy that they transfer. The corona is an incredibly thin and tenuous part of the Sun, and there are very few particles there to transfer energy – so while the particles are moving fast (high temperature), they don't actually transfer much energy to the spacecraft (low heat).

It's like the difference between putting your hand in a hot oven versus putting it in a pot of boiling water (don’t try this at home!). In the air of the oven, your hand doesn't get nearly as hot as it would in the much denser water of the boiling pot. 

So even though Parker Solar Probe travels through a region with temperatures of several million degrees, the surface of its heat shield will reach only about 2,500 F.

The Heat Shield

Of course, thousands of degrees Fahrenheit is still way too hot for scientific instruments. (For comparison, lava from volcano eruptions can be anywhere between 1,300 to 2,200 F.) 

To withstand that heat, Parker Solar Probe is outfitted with a cutting-edge heat shield, called the Thermal Protection System. This heat shield is made of a carbon composite foam sandwiched between two carbon plates. The Sun-facing side is covered with a specially-developed white ceramic coating, applied as a plasma spray, to reflect as much heat as possible.

The heat shield is so good at its job that even though the Sun-facing side of the shield will be at 2,500 F, the instruments in its shadow will remain at a balmy 85 F.

Parker Solar Probe Keeps its Cool

Several other designs on the spacecraft help Parker Solar Probe beat the heat. 

Parker Solar Probe is not only studying the Sun – it's also powered by it. But even though most of the surface area of its solar arrays can be retracted behind the heat shield, even that small exposed segment would quickly make them overheat while at the Sun.  

To keep things cool, Parker Solar Probe circulates a single gallon of water through its solar arrays. The water absorbs heat as it passes behind the arrays, then radiates that heat out into space as it flows into the spacecraft's radiator. 

It's also important for Parker Solar Probe to be able to think on its feet, since it takes about eight minutes for information to travel between Earth and the Sun. If we had to control the spacecraft from Earth, by the time we knew something went wrong, it would be too late to fix it. 

So Parker Solar Probe is smart: Along the edges of the heat shield's shadow are seven sensors. If any of these sensors detect sunlight, they alert the central computer and the spacecraft can correct its position to keep the sensors – and the rest of the instruments – safely protected behind the heat shield.

Over the course of its seven-year mission, Parker Solar Probe will make 24 orbits of our star. On each close approach to the Sun, it will sample the solar wind, study the Sun’s corona, and provide unprecedentedly close up observations from around our star – and armed with its slew of innovative technologies, we know it will keep its cool the whole time. 

Parker Solar Probe launches summer 2018 on its mission to study the Sun. Keep up with the latest on the mission at nasa.gov/solarprobe or follow us on Twitter and Facebook.

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2017 Was One of Our Planet’s Hottest Years on Record

We just finished the second hottest year on Earth since global temperature estimates first became feasible in 1880. Although 2016 still holds the record for the warmest year, 2017 came in a close second, with average temperatures 1.6 degrees Fahrenheit higher than the mean.

2017’s temperature record is especially noteworthy, because we didn’t have an El Niño this year. Often, the two go hand-in-hand.

El Niño is a climate phenomenon that causes warming of the tropical Pacific Ocean waters, which affect wind and weather patterns around the world, usually resulting in warmer temperatures globally. 2017 was the warmest year on record without an El Niño.

We collect the temperature data from 6,300 weather stations and ship- and buoy-based observations around the world, and then analyze it on a monthly and yearly basis. Researchers at the National Oceanic and Atmospheric Administration (NOAA) do a similar analysis; we’ve been working together on temperature analyses for more than 30 years. Their analysis of this year’s temperature data tracks closely with ours.

The 2017 temperature record is an average from around the globe, so different places on Earth experienced different amounts of warming. NOAA found that the United States, for instance, had its third hottest year on record, and many places still experienced cold winter weather.

Other parts of the world experienced abnormally high temperatures throughout the year. Earth’s Arctic regions are warming at roughly twice the rate of the rest of the planet, which brings consequences like melting polar ice and rising sea levels.

Increasing global temperatures are the result of human activity, specifically the release of greenhouse gases like carbon dioxide and methane. The gases trap heat inside the atmosphere, raising temperatures around the globe.  

We combine data from our fleet of spacecraft with measurements taken on the ground and in the air to continue to understand how our climate is changing. We share this important data with partners and institutions across the U.S. and around the world to prepare and protect our home planet.

Earth’s long-term warming trend can be seen in this visualization of NASA’s global temperature record, which shows how the planet’s temperatures are changing over time, compared to a baseline average from 1951 to 1980.

Learn more about the 2017 Global Temperature Report HERE. 

Discover the ways that we are constantly monitoring our home planet HERE. 

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Why Webb Needs to Chill

Our massive James Webb Space Telescope just recently emerged from about 100 days of cryogenic testing to make sure it can work perfectly at incredibly cold temperatures when it’s in deep space. 

How cold did it get and why? Here’s the whole scoop...

Webb is a giant infrared space telescope that we are currently building. It was designed to see things that other telescopes, even the amazing Hubble Space Telescope, can’t see.  

Webb’s giant 6.5-meter diameter primary mirror is part of what gives it superior vision, and it’s coated in gold to optimize it for seeing infrared light.  

Why do we want to see infrared light?

Lots of stuff in space emits infrared light, so being able to observe it gives us another tool for understanding the universe. For example, sometimes dust obscures the light from objects we want to study – but if we can see the heat they are emitting, we can still “see” the objects to study them.

It’s like if you were to stick your arm inside a garbage bag. You might not be able to see your arm with your eyes – but if you had an infrared camera, it could see the heat of your arm right through the cooler plastic bag.

Credit: NASA/IPAC

With a powerful infrared space telescope, we can see stars and planets forming inside clouds of dust and gas.

We can also see the very first stars and galaxies that formed in the early universe. These objects are so far away that…well, we haven’t actually been able to see them yet. Also, their light has been shifted from visible light to infrared because the universe is expanding, and as the distances between the galaxies stretch, the light from them also stretches towards redder wavelengths. 

We call this phenomena “redshift.”  This means that for us, these objects can be quite dim at visible wavelengths, but bright at infrared ones. With a powerful enough infrared telescope, we can see these never-before-seen objects.

We can also study the atmospheres of planets orbiting other stars. Many of the elements and molecules we want to study in planetary atmospheres have characteristic signatures in the infrared.

Because infrared light comes from objects that are warm, in order to detect the super faint heat signals of things that are really, really far away, the telescope itself has to be very cold. How cold does the telescope have to be? Webb’s operating temperature is under 50K (or -370F/-223 C). As a comparison, water freezes at 273K (or 32 F/0 C).

How do we keep the telescope that cold? 

Because there is no atmosphere in space, as long as you can keep something out of the Sun, it will get very cold. So Webb, as a whole, doesn’t need freezers or coolers - instead it has a giant sunshield that keeps it in the shade. (We do have one instrument on Webb that does have a cryocooler because it needs to operate at 7K.)

Also, we have to be careful that no nearby bright things can shine into the telescope – Webb is so sensitive to faint infrared light, that bright light could essentially blind it. The sunshield is able to protect the telescope from the light and heat of the Earth and Moon, as well as the Sun.  

Out at what we call the Second Lagrange point, where the telescope will orbit the Sun in line with the Earth, the sunshield is able to always block the light from bright objects like the Earth, Sun and Moon.

How do we make sure it all works in space? 

By lots of testing on the ground before we launch it. Every piece of the telescope was designed to work at the cold temperatures it will operate at in space and was tested in simulated space conditions. The mirrors were tested at cryogenic temperatures after every phase of their manufacturing process.

The instruments went through multiple cryogenic tests at our Goddard Space Flight Center in Maryland.

Once the telescope (instruments and optics) was assembled, it even underwent a full end-to-end test in our Johnson Space Center’s giant cryogenic chamber, to ensure the whole system will work perfectly in space.  

What’s next for Webb? 

It will move to Northrop Grumman where it will be mated to the sunshield, as well as the spacecraft bus, which provides support functions like electrical power, attitude control, thermal control, communications, data handling and propulsion to the spacecraft.

Learn more about the James Webb Space Telescope HERE, or follow the mission on Facebook, Twitter and Instagram.

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2016 Sets Global Temperature Record

We just experienced the hottest year on record…again.

2016 was hotter than 2015, the previous record. And 2015 hotter than 2014, the previous record year.

These record temperatures are all part of a warming trend that dates back to the late-19th century, largely caused by human emissions of carbon dioxide and other gases into the atmosphere.

A lot of this warming trend has been in the last 35 years. In fact, 16 of the 17 warmest years on record have been since 2001.

To help us gather this data, planes and boats travel out from Antarctic research stations to gather information from the Arctic region, in addition to space-based observatories.

Scientists at our Goddard Institute for Space Studies analyze data from 6,300 weather stations, observations of sea surface temperature and Antarctic research stations, all to determine how the average surface temperature is changing.

Scientists at the National Oceanic and Atmospheric Administration separately analyze the same data to track global temperature.

The two agencies reached the same conclusion about 2016’s record-setting heat.

Variations in local weather mean parts of the globe did not experience a record-setting year. Some places still had snow, cold weather and below-record temperatures, but the overall global average was higher than any previous year.

For instance, according to NOAA the average temperature in the 48 contiguous United States was not quite as high as in 2015, which still holds the record.

A combination of space- and land-based measurements gives us a unique perspective on Earth, the only planet we know of that supports life.

To learn more about the global temperature record or see how average surface temperature for individual months, visit: http://data.giss.nasa.gov/gistemp/

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Record-Shattering Global Warm Temperatures in 2015

Earth’s 2015 surface temperatures were the warmest since modern record keeping began in 1880, according to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA).

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.

The 2015 temperatures continue a long-term warming trend, according to analyses by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York. NOAA scientists concur with the finding that 2015 was the warmest year on record based on separate, independent analyses of the data.

Since the late-19th century, the planet’s average surface temperature has risen about 1.8 degrees Fahrenheit. This change is largely driven by increased carbon dioxide and other human-made emissions into the atmosphere.

An important thing to remember when reading this information is that it reflects global temperature average. That means that specific regions or areas could have experienced colder weather than usual, but overall the global temperature has risen.

How do we know? Our analyses incorporate surface temperature measurements from 6,300 weather stations, ship-and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations.

What about El Niño? Phenomena such as El Niño or La Niña, which warm or cool the tropical Pacific Ocean, can contribute to short-term variations in global average temperature. Last year’s temperatures had an assist from a warming El Niño, but it is the cumulative effect of the long-term trend that has resulted in the record warming that we’re seeing.

The full 2015 surface temperature data set and the complete methodology used to make the temperature calculation are available HERE.

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