2021 Tied for 6th Warmest Year in Continued Trend, NASA Analysis Shows

Earth’s global average surface temperature in 2021 tied with 2018 as the sixth warmest on record, according to independent analyses done by NASA and the National Oceanic and Atmospheric Administration (NOAA).

Continuing the planet’s long-term warming trend, global temperatures in 2021 were 1.5 degrees Fahrenheit (0.85 degrees Celsius) above the average for NASA’s baseline period, according to scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York. NASA uses the period from 1951-1980 as a baseline to see how global temperature changes over time.

Collectively, the past eight years are the warmest years since modern recordkeeping began in 1880. This annual temperature data makes up the global temperature record – which tells scientists the planet is warming.

According to NASA’s temperature record, Earth in 2021 was about 1.9 degrees Fahrenheit (or about 1.1 degrees Celsius) warmer than the late 19th-century average, the start of the industrial revolution.

“Science leaves no room for doubt: Climate change is the existential threat of our time,” said NASA Administrator Bill Nelson. “Eight of the top 10 warmest years on our planet occurred in the last decade, an indisputable fact that underscores the need for bold action to safeguard the future of our country – and all of humanity. NASA’s scientific research about how Earth is changing and getting warmer will guide communities throughout the world, helping humanity confront climate and mitigate its devastating effects.”

This warming trend around the globe is due to human activities that have increased emissions of carbon dioxide and other greenhouse gases into the atmosphere. The planet is already seeing the effects of global warming: Arctic sea ice is declining, sea levels are rising, wildfires are becoming more severe and animal migration patterns are shifting. Understanding how the planet is changing – and how rapidly that change occurs – is crucial for humanity to prepare for and adapt to a warmer world.

Weather stations, ships, and ocean buoys around the globe record the temperature at Earth’s surface throughout the year. These ground-based measurements of surface temperature are validated with satellite data from the Atmospheric Infrared Sounder (AIRS) on NASA’s Aqua satellite. Scientists analyze these measurements using computer algorithms to deal with uncertainties in the data and quality control to calculate the global average surface temperature difference for every year. NASA compares that global mean temperature to its baseline period of 1951-1980. That baseline includes climate patterns and unusually hot or cold years due to other factors, ensuring that it encompasses natural variations in Earth’s temperature.

NASA-supported Study Confirms Importance of Southern Ocean in Absorbing Carbon Dioxide

Observations from research aircraft show that the Southern Ocean absorbs much more carbon from the atmosphere than it releases, confirming it is a very strong carbon sink and an important buffer for some of the effects of human-caused greenhouse gas emissions, according to a new NASA-supported study.

Recent research had raised uncertainty about just how much atmospheric carbon dioxide (CO₂) these icy waters absorb. Those studies relied on measurements of ocean acidity – which increases when ocean water absorbs CO₂ – taken by instruments that float in the ocean.

The new study, published in Science, used aircraft observations of CO₂ to show that the Southern Ocean is a stronger carbon sink than previously thought, playing a significant role in lessening some of the impacts of greenhouse gases. Aircraft observations were collected over nearly a decade from 2009 to 2018 during three field experiments, including from NASA’s Atmospheric Tomography Mission (ATom) in 2016.

“Airborne measurements show a drawdown of carbon dioxide in the lower atmosphere over the Southern Ocean surface in summer, indicating carbon uptake by the ocean,” explained Matthew Long, lead author and a scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.

They found that the Southern Ocean absorbs significantly more CO₂ in the Southern Hemisphere summer than it releases in the winter, making it a strong carbon sink. Data from the airborne campaigns also showed a larger amount of carbon absorbed by the Southern Ocean and smaller amount released than previous estimates using ocean acidity data. The findings highlight the importance of aircraft-based observations to understand carbon cycling.

The research was funded by the National Science Foundation, NASA and NOAA.

NASA’s Oceans Melting Greenland Mission Leaves for Its Last Field Trip

NASA’s airborne Oceans Melting Greenland (OMG) mission begins its final survey of glaciers that flow from Greenland into the ocean. OMG is completing a six-year mission that is helping to answer how fast sea level is going to rise in the next five, 10, or 50 years.

Greenland’s melting glaciers currently contribute more fresh water to sea level rise than any other source does. The glaciers are melting six or seven times faster today than they were only 25 years ago, and OMG is the first NASA mission to focus solely on what the ocean contributes to this ice loss. That’s a critical part of helping improve calculations of future melt rates so that coastal communities worldwide can take timely precautions to limit the damage from higher seas.

Ice melts faster in warmer water than it does in colder water, but before the OMG mission, the temperature of the ocean water touching Greenland’s more than 200 coastal glaciers was largely unknown. Simply measuring the temperature at the ocean surface isn’t enough. The upper layer of the ocean around Greenland consists largely of Arctic meltwater, and it’s very cold – sometimes even below freezing temperature. About 600 or 700 feet (200 meters) down is a layer of warmer, saltier water carried northward from less-frigid latitudes. Many glacier fronts extend down into the warmer-water zone, where they melt more rapidly.

This visualization explains how a glacier melts from below. Credit: NASA’s Scientific Visualization Studio

No satellite instrument can peer deep into the ocean to measure temperature. The only way scientists have found to do that is to drop a probe into the water and let it sink. That’s what the OMG team has been doing every summer since 2016.

This year, Principal Investigator Josh Willis of NASA’s Jet Propulsion Laboratory in Southern California and OMG Project Manager Ian McCubbin, also of JPL, will fly around the entire coast of Greenland with a crew of pilot and engineers in a specially modified DC-3 aircraft. From early August through early or mid-September, they’ll drop probes out of the belly of the plane into the ocean at about 300 target locations in front of glaciers. As the probes sink, they transmit temperature and salinity readings by radio waves to the plane overhead until they reach the ocean floor.

The article is published courtesy of NASA’s Jet Propulsion Laboratory

Index Ranks Rainforests’ Vulnerability to Climate and Human Impacts

Scientists from NASA’s Jet Propulsion Laboratory in Southern California and other international research institutions have created a tropical rainforest vulnerability index. It will detect and evaluate the vulnerability of these diverse ecosystems to two main categories of threats: the warming and drying climate, and the consequences of human land use such as deforestation and fragmentation from encroaching roads, agricultural fields, and logging.

The index shows that the world’s three major rainforest areas have different degrees of susceptibility to these threats. The Amazon Basin in South America is extremely vulnerable to both climate change and changes in human land use. The Congo Basin in Africa is undergoing the same warming and drying trends as the Amazon but is more resilient. Most Asian rainforests appear to be suffering more from changes in land use than from the changing climate.

“Rainforests are perhaps the most endangered habitat on Earth – the canary in the climate-change coal mine,” said Sassan Saatchi, a JPL scientist and lead author of the new study published July 23 in the journal OneEarth.

These diverse ecosystems are home to more than half of the planet’s life forms and contain more than half of all the carbon in land vegetation. They serve as a natural brake on the rise of carbon dioxide in the atmosphere from fossil fuel burning because they “breathe in” carbon dioxide and store carbon as they grow.

But in the last century, 15 to 20% of rainforests have been cut down, and another 10% have been degraded. Today’s warmer climate, which has led to increasingly frequent and widespread forest fires, is limiting the forests’ capacity to absorb carbon dioxide as they grow while also increasing the rate at which forests release carbon to the atmosphere as they decay or burn.

The National Geographic Society convened a team of scientists and conservationists in 2019 to develop the new index. The index is based on multiple satellite observations and ground-based data from 1982 through 2018, such as Landsat and the Global Precipitation Measurement mission, covering climate conditions, land use, and forest characteristics.

When an ecosystem can no longer recover from stress as quickly or as completely as it used to, that’s a sign of its vulnerability. The researchers correlated data on stressors, such as temperature, water availability, and the extent of degradation with data on how well the forests are functioning: the amount of live biomass, the amount of carbon dioxide plants were absorbing, the amount of water the forests transpire into the atmosphere, the intactness of a forest’s biodiversity, and more. The correlations show how different forests have responded to stressors and how vulnerable the forests are now.

The team then used statistical models to extend trends over time, looking for areas with increasing vulnerability and possible tipping points where rainforests will transition into dry forests or grassy plains.

The data from the tropical rainforest vulnerability index provides scientists with an opportunity to perform more in-depth examinations of natural rainforest processes, such as carbon storage and productivity, changes in energy and water cycles, and changes in biodiversity. Those studies will help scientists understand whether there are tipping points and what they are likely to be. The information can also help policy makers who are planning for conservation and forest restoration activities.

Human activities raised atmospheric concentrations of CO2 by 48%

Over the past 171 years, human activities have raised atmospheric concentrations of CO₂ by 48% above pre-industrial levels found in 1850, according to Global Climate Change.

This is more than what had happened naturally over a 20,000 year period (from the Last Glacial Maximum to 1850, from 185 ppm to 280 ppm).

The Latest measurement of CO₂ stands at 416 ppm.

Scientists attribute the global warming trend observed since the mid-20^th century to the human expansion of the “greenhouse effect” — warming that results when the atmosphere traps heat radiating from Earth toward space.

Certain gases in the atmosphere block heat from escaping. Long-lived gases that remain semi-permanently in the atmosphere and do not respond physically or chemically to changes in temperature are described as “forcing” climate change. Gases, such as water vapor, which respond physically or chemically to changes in temperature are seen as “feedbacks.”

Gases that contribute to the greenhouse effect include:

• Water vapor. The most abundant greenhouse gas, but importantly, it acts as a feedback to the climate. Water vapor increases as the Earth’s atmosphere warms, but so does the possibility of clouds and precipitation, making these some of the most important feedback mechanisms to the greenhouse effect.
• Carbon dioxide (CO₂). A minor but very important component of the atmosphere, carbon dioxide is released through natural processes such as respiration and volcano eruptions and through human activities such as deforestation, land use changes, and burning fossil fuels. Humans have increased atmospheric CO₂ concentration by 48% since the Industrial Revolution began. This is the most important long-lived “forcing” of climate change.
• Methane. A hydrocarbon gas produced both through natural sources and human activities, including the decomposition of wastes in landfills, agriculture, and especially rice cultivation, as well as ruminant digestion and manure management associated with domestic livestock. On a molecule-for-molecule basis, methane is a far more active greenhouse gas than carbon dioxide, but also one which is much less abundant in the atmosphere.
• Nitrous oxide. A powerful greenhouse gas produced by soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning.
• Chlorofluorocarbons (CFCs). Synthetic compounds entirely of industrial origin used in a number of applications, but now largely regulated in production and release to the atmosphere by international agreement for their ability to contribute to destruction of the ozone layer. They are also greenhouse gases.

On Earth, human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO₂). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO₂. To a lesser extent, the clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases.

Credit: NASA

NASA’s Webb to Study How Massive Stars’ Blasts of Radiation Influence Their Environments

In a nearby stellar nursery called the Orion Nebula, young, massive stars are blasting far-ultraviolet light at the cloud of dust and gas from which they were born.

This intense flood of radiation is violently disrupting the cloud by breaking apart molecules, ionizing atoms and molecules by stripping their electrons, and heating the gas and dust.

“The fact that massive stars shape the structure of galaxies through their explosions as supernovas has been known for a long time. But what people have discovered more recently is that massive stars also influence their environments not only as supernovas, but through their winds and radiation during their lives,” said one of the team’s principal investigators, Olivier Berné, a research scientist at the French National Centre for Scientific Research in Toulouse.

While it might sound like a Friday-night watering hole, the Orion Bar is actually a ridge-like feature of gas and dust within the spectacular Orion Nebula. A little more than 1,300 light-years away, this nebula is the nearest region of massive star formation to the Sun. The Orion Bar is sculpted by the intense radiation from nearby, hot, young stars, and at first glance appears to be shaped like a bar. It is a “photodissociation region,” or PDR, where ultraviolet light from young, massive stars creates a mostly neutral, but warm, area of gas and dust between the fully ionized gas surrounding the massive stars and the clouds in which they are born. This ultraviolet radiation strongly influences the gas chemistry of these regions and acts as the most important source of heat.

PDRs occur where interstellar gas is dense and cold enough to remain neutral, but not dense enough to prevent the penetration of far-ultraviolet light from massive stars. Emissions from these regions provide a unique tool to study the physical and chemical processes that are important for most of the mass between and around stars. The processes of radiation and cloud disruption drive the evolution of interstellar matter in our galaxy and throughout the universe from the early era of vigorous star formation to the present day.

“The Orion Bar is probably the prototype of a PDR,” explained Els Peeters, another of the team’s principal investigators. Peeters is a professor at the University of Western Ontario and a member of the SETI Institute. “It’s been studied extensively, so it’s well characterized. It’s very close by, and it’s really seen edge on. That means you can probe the different transition regions. And since it’s close by, this transition from one region to another is spatially distinct if you have a telescope with high spatial resolution.” 

The Orion Bar is representative of what scientists think were the harsh physical conditions of PDRs in the universe billions of years ago. “We believe that at this time, you had ‘Orion Nebulas’ everywhere in the universe, in many galaxies,” said Berné. “We think that it can be representative of the physical conditions in terms of the ultraviolet radiation field in what are called ‘starburst galaxies,’ which dominate the era of star formation, when the universe was about half its current age.” 

The formation of planetary systems in interstellar regions irradiated by massive young stars remains an open question. Detailed observations would allow astronomers to understand the impact of the ultraviolet radiation on the mass and composition of newly formed stars and planets.

In particular, studies of meteorites suggest that the solar system formed in a region similar to the Orion Nebula. Observing the Orion Bar is a way to understand our past. It serves as a model to learn about the very early stages of the formation of the solar system.

NASA’s S-MODE Takes to the Air and Sea to Study Ocean Eddies

Using scientific instruments aboard a self-propelled ocean glider and several airplanes, this first deployment of the Sub-Mesoscale Ocean Dynamics Experiment (S-MODE) mission will deploy its suite of water- and air-borne instruments to ensure that they work together to show what’s happening just below the ocean’s surface. The full-fledged field campaign will begin in October 2021, with the aircraft based out of NASA’s Ames Research Center in Mountain View, California.

“This campaign in May is largely to compare different ways of measuring ocean surface currents so that we can have confidence in those measurements when we get to the pilot in October,” said Tom Farrar, associate scientist at the Woods Hole Oceanographic Institution in Massachusetts and principal investigator for S-MODE.

The S-MODE team hopes to learn more about small-scale movements of ocean water such as eddies. These whirlpools span about 6.2 miles or ten kilometers, slowly moving ocean water in a swirling pattern. Scientists think that these eddies play an important role in moving heat from the surface to the ocean layers below, and vice versa. In addition, the eddies may play a role in the exchange of heat, gases and nutrients between the ocean and Earth’s atmosphere. Understanding these small-scale eddies will help scientists better understand how Earth’s oceans slow down global climate change.

Sub-mesoscale ocean dynamics, like eddies and small currents, are responsible for the swirling pattern of these phytoplankton blooms (shown in green and light blue) in the South Atlantic Ocean on Jan. 5, 2021.
Credits: NASA’s Goddard Space Flight Center Ocean Color, using data from the NOAA-20 satellite and the joint NASA-NOAA Suomi NPP satellite.

The team is using a self-propelled commercial Wave Glider decked out with scientific instruments that can study the ocean from its surface. The most important gadgets aboard are the acoustic Doppler current profilers, which use sonar to measure water speed and gather information about the how fast the currents and eddies are moving, and in which direction. The glider also carries instruments to measure wind speed, air temperature and humidity, water temperature and salinity, and light and infrared radiation from the Sun.

“The wave glider looks like a surfboard with a big venetian blind under it,” said Farrar.

That “venetian blind” is submerged under the water, moving up and down with the ocean’s waves to propel the glider forward at about one mile per hour. In this way, the wave glider will be deployed from La Jolla, California, collecting data as it travels over 62 miles (100 kilometers) out into the ocean offshore of Santa Catalina Island.