2020 Tied for Warmest Year on Record, NASA Analysis Shows
by NASA, World Meteorological Organization
2:05pm 15th Jan, 2021
15 Jan. 2021
The Climate Events of 2020 show how excess heat is expressed on Earth. (NASA)
By most accounts, 2020 has been a rough year for the planet. It was the warmest year on record, just barely exceeding the record set in 2016 by less than a tenth of a degree according to NASA’s analysis. Massive wildfires scorched Australia, Siberia, and the United States’ west coast – and many of the fires were still burning during the busiest Atlantic hurricane season on record.
“This year has been a very striking example of what it’s like to live under some of the most severe effects of climate change that we’ve been predicting,” said Lesley Ott, a research meteorologist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
Decades of greenhouse gas emissions set the stage for this year’s events
Human-produced greenhouse gas emissions are largely responsible for warming our planet. Burning fossil fuels such as coal, oil, and natural gas releases greenhouse gases – such as carbon dioxide – into the atmosphere, where they act like an insulating blanket and trap heat near Earth’s surface.
“The natural processes Earth has for absorbing carbon dioxide released by human activities – plants and the ocean – just aren’t enough to keep up with how much carbon dioxide we’re putting into the atmosphere,” said Gavin Schmidt, climate scientist and Director of NASA’s Goddard Institute for Space Studies (GISS) in New York City.
Carbon dioxide levels have increased by nearly 50% since the Industrial Revolution 250 years ago. The amount of methane in the atmosphere has more than doubled. As a result, during this period, Earth has warmed by about 2 degrees Fahrenheit (just over 1 degree Celsius).
Climate modelers have predicted that, as the planet warms, Earth will experience more severe heat waves and droughts, larger and more extreme wildfires, and longer and more intense hurricane seasons on average. The events of 2020 are consistent with what models have predicted: extreme climate events are more likely because of greenhouse gas emissions.
Heat waves fanned the flames of extreme wildfires across the globe
Climate change has led to longer fire seasons, as vegetation dries out earlier and persistent high temperatures allow fires to burn longer. This year, heat waves and droughts added fuel for the fires, setting the stage for more intense fires in 2020.
The Australian bushfires that started in 2019 continued into 2020 due to sustained high temperatures, burning vast forested areas and sending smoke around the globe. The heat wave helped the fires grow rapidly, burning over 20% of the Australian temperate forest biome.
Fire-induced thunderstorms called pyrocumulonimbus events resulted in smoke plumes that reached a record-breaking 18 mile (30 kilometer) altitude – crossing into the stratosphere. Smoke released from the bushfires circumnavigated the globe before returning to the skies over Australia.
Hundreds of wildfires burned throughout the western United States this past year, making it the most active fire season on record. Fires in Colorado grew quickly as heat waves enabled the fire to burn faster and hotter. In California, more than 650 fires were actively burning in late August; the largest of these – the August Complex Fire – burned over a million acres.
A heat wave hit the Arctic Circle this summer, with temperatures rising above 100 degrees Fahrenheit in some parts of Siberia. This heat wave triggered a wildfire outbreak that reignited “zombie fires” from the previous year.
Zombie fires can occur when fires burn in areas with permafrost, carbon-rich soil that typically stays frozen year-round. Zombie fires burn so deep in the permafrost layer that they can continue to smolder under a blanket of snow throughout winter and can reemerge in the spring.
Wildfires in the Arctic have long-term impacts on Earth’s climate system. Tundra and boreal fires release methane and carbon in these regions that have been accumulating for centuries into the atmosphere. Burning also creates the conditions for continued permafrost layer thaw, resulting in increased greenhouse gas emissions for years to come.
Earth is continuing to lose a key player in the fight against climate change: ice
This year wasn’t a record-breaker for ice loss at sea or on land. But ice plays a key role in regulating Earth’s temperature, and the overall trends show we’re continuously losing ice around the globe.
The planet is losing about 13.1% of Arctic sea ice by area each decade, according to sea ice minimum data from NASA and the National Snow and Ice Data Center in Boulder, Colorado. Studies of sea ice thickness have also shown that sea ice is a lot thinner than it used to be.
Sea ice floating in the Arctic acts like an insulating barrier, preventing the ocean from heating the atmosphere. Sea ice is also so bright that it reflects heat energy from the Sun away from Earth. Without sea ice, that energy would be absorbed by the darker ocean waters, leading to even higher sea surface temperatures.
Each year, Arctic sea ice melts and regrows, reaching its minimum extent around mid-September and maximum extent in March. This year had the second lowest Arctic sea ice summer extent on record. Arctic sea ice also got a slow start regrowing this year due to warmer air temperatures, which doesn’t bode well for the sea ice extent in 2021.
“When the ice has a slow start to regrow, it’s hard to catch up,” said Tom Neumann, glaciologist and Chief of the Cryospheric Sciences Lab at Goddard.
On land, the Greenland ice sheet is continuing to melt, and the record-breaking temperatures of 2020 didn’t help. This year, 23.1 million square kilometers of Greenland’s ice sheet (about 70 percent of the ice sheet’s surface) reached the melting point. Glaciers and mountain ice caps in places like Alaska, South America, and High Mountain Asia are continuing to melt, contributing more than either Greenland or Antarctica to sea level rise, which affects coastal communities around the world.
The situation in the Arctic is a direct consequence of climate change – and a foreshadowing of what’s to come in other places. “The Arctic is like the canary in the coal mine because the Arctic is warming faster than the rest of the planet,” said Neumann. On average, the Arctic is warming three times faster.
High sea surface temperatures intensified storms in the busiest Atlantic hurricane season
This year brought one of the busiest and most intense Atlantic hurricane seasons on record, with 30 named storms.
“We had more named storms than we’ve ever had before,” said Jim Kossin, an atmospheric scientist with the National Oceanic and Atmospheric Association (NOAA) based in Madison, Wisconsin. More storms and a longer hurricane season are probably a result of regional conditions rather than global warming, Kossin said. However, climate change warms the ocean’s surface and drives storm intensification – the change in windspeeds that, for example, raises a Category 4 storm to a Category 5.That warmer water at the surface acts like fuel, providing energy in the form of heat that the hurricane uses to intensify more quickly. This year’s Atlantic hurricane season brought many examples of storms that intensified quickly: ten of the 30 named storms showed rapid intensification.
The planet is also seeing more slow-traveling hurricanes that stall, bringing prolonged rainfall to an area, likely as a result of climate change. Warmer air holds more water vapor (about 7% more water per 1 degree C of warming). The planet is warming at different rates around the globe, which can reduce the temperature and pressure gradients, thus slowing the winds that push hurricanes.
That means storms are more likely to stall, bringing sustained high winds and dumping massive amounts of rain in one area. Hurricanes Sally and Eta – which respectively made landfall in Alabama in September and Central America in November – were prime examples.
“Global warming won’t necessarily increase overall tropical storm formation, but when we do get a storm it’s more likely to become stronger. And it’s the strong ones that really matter,” Kossin said.
What does the future hold?
This year we experienced firsthand the ways that more heat is expressed on our planet. The large wildfires, intense hurricanes, and ice loss we saw in 2020 are direct consequences of human-induced climate change. And they’re projected to continue and escalate into the next decade – especially if human-induced greenhouse gas emissions continue at the current rate.
“This isn’t the new normal,” said Schmidt. “This is a precursor of more to come.”
15 Jan. 2021
2020 Tied for Warmest Year on Record, NASA Analysis Shows. (NASA)
Earth’s global average surface temperature in 2020 tied with 2016 as the warmest year on record, according to an analysis by NASA.
Continuing the planet’s long-term warming trend, the year’s globally averaged temperature was 1.84 degrees Fahrenheit (1.02 degrees Celsius) warmer than the baseline 1951-1980 mean, according to scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York. 2020 edged out 2016 by a very small amount, within the margin of error of the analysis, making the years effectively tied for the warmest year on record.
“The last seven years have been the warmest seven years on record, typifying the ongoing and dramatic warming trend,” said GISS Director Gavin Schmidt. “Whether one year is a record or not is not really that important – the important things are long-term trends. With these trends, and as the human impact on the climate increases, we have to expect that records will continue to be broken.”
A Warming, Changing World
Tracking global temperature trends provides a critical indicator of the impact of human activities – specifically, greenhouse gas emissions – on our planet. Earth's average temperature has risen more than 2 degrees Fahrenheit (1.2 degrees Celsius) since the late 19th century.
Rising temperatures are causing phenomena such as loss of sea ice and ice sheet mass, sea level rise, longer and more intense heat waves, and shifts in plant and animal habitats. Understanding such long-term climate trends is essential for the safety and quality of human life, allowing humans to adapt to the changing environment in ways such as planting different crops, managing our water resources and preparing for extreme weather events.
Ranking the Records
A separate, independent analysis by the National Oceanic and Atmospheric Administration (NOAA) concluded that 2020 was the second-warmest year in their record, behind 2016. NOAA scientists use much of the same raw temperature data in their analysis, but have a different baseline period (1901-2000) and methodology. Unlike NASA, NOAA also does not infer temperatures in polar regions lacking observations, which accounts for much of the difference between NASA and NOAA records.
Like all scientific data, these temperature findings contain a small amount of uncertainty – in this case, mainly due to changes in weather station locations and temperature measurement methods over time. The GISS temperature analysis (GISTEMP) is accurate to within 0.1 degrees Fahrenheit with a 95 percent confidence level for the most recent period.
Beyond a Global, Annual Average
While the long-term trend of warming continues, a variety of events and factors contribute to any particular year’s average temperature. Two separate events changed the amount of sunlight reaching the Earth’s surface. The Australian bush fires during the first half of the year burned 46 million acres of land, releasing smoke and other particles more than 18 miles high in the atmosphere, blocking sunlight and likely cooling the atmosphere slightly.
In contrast, global shutdowns related to the ongoing coronavirus (COVID-19) pandemic reduced particulate air pollution in many areas, allowing more sunlight to reach the surface and producing a small but potentially significant warming effect. These shutdowns also appear to have reduced the amount of carbon dioxide (CO2) emissions last year, but overall CO2 concentrations continued to increase, and since warming is related to cumulative emissions, the overall amount of avoided warming will be minimal.
The largest source of year-to-year variability in global temperatures typically comes from the El Nino-Southern Oscillation (ENSO), a naturally occurring cycle of heat exchange between the ocean and atmosphere. While the year has ended in a negative (cool) phase of ENSO, it started in a slightly positive (warm) phase, which marginally increased the average overall temperature. The cooling influence from the negative phase is expected to have a larger influence on 2021 than 2020.
“The previous record warm year, 2016, received a significant boost from a strong El Nino. The lack of a similar assist from El Nino this year is evidence that the background climate continues to warm due to greenhouse gases,” Schmidt said.
The 2020 GISS values represent surface temperatures averaged over both the whole globe and the entire year. Local weather plays a role in regional temperature variations, so not every region on Earth experiences similar amounts of warming even in a record year. According to NOAA, parts of the continental United States experienced record high temperatures in 2020, while others did not.
In the long term, parts of the globe are also warming faster than others. Earth’s warming trends are most pronounced in the Arctic, which the GISTEMP analysis shows is warming more than three times as fast as the rest of the globe over the past 30 years, according to Schmidt.
The loss of Arctic sea ice – whose annual minimum area is declining by about 13 percent per decade – makes the region less reflective, meaning more sunlight is absorbed by the oceans and temperatures rise further still. This phenomenon, known as Arctic amplification, is driving further sea ice loss, ice sheet melt and sea level rise, more intense Arctic fire seasons, and permafrost melt.
Land, Sea, Air and Space
NASA’s analysis incorporates surface temperature measurements from more than 26,000 weather stations and thousands of ship- and buoy-based observations of sea surface temperatures.
NASA measures Earth's vital signs from land, air, and space with a fleet of satellites, as well as airborne and ground-based observation campaigns. The satellite surface temperature record from the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA’s Aura satellite confirms the GISTEMP results of the past seven years being the warmest on record. Satellite measurements of air temperature, sea surface temperature, and sea levels, as well as other space-based observations, also reflect a warming, changing world.
14 Jan. 2021 (WMO)
The year 2020 was one of the three warmest on record, and rivalled 2016 for the top spot, according to a consolidation of five leading international datasets by the World Meteorological Organization (WMO). A naturally occurring cooling climate phenomenon, La Niña, put a brake on the heat only at the very end of the year.
All five datasets surveyed by WMO concur that 2011-2020 was the warmest decade on record, in a persistent long-term climate change trend. The warmest six years have all been since 2015, with 2016, 2019 and 2020 being the top three. The differences in average global temperatures among the three warmest years – 2016, 2019 and 2020 – are indistinguishably small. The average global temperature in 2020 was about 14.9°C, 1.2°C above the pre-industrial (1850-1900) level.
“The confirmation by the World Meteorological Organization that 2020 was one of the warmest years on record is yet another stark reminder of the relentless pace of climate change, which is destroying lives and livelihoods across our planet. Today, we are at 1.2 degrees of warming and already witnessing unprecedented weather extremes in every region and on every continent. We are headed for a catastrophic temperature rise of 3 to 5 degrees Celsius this century. Making peace with nature is the defining task of the 21st century. It must be the top priority for everyone, everywhere," said United Nations Secretary-General António Guterres.
“The exceptional heat of 2020 is despite a La Niña event, which has a temporary cooling effect,” said WMO Secretary-General Prof. Petteri Taalas. “It is remarkable that temperatures in 2020 were virtually on a par with 2016, when we saw one of the strongest El Niño warming events on record. This is a clear indication that the global signal from human-induced climate change is now as powerful as the force of nature,” said Prof. Taalas.
“The temperature ranking of individual years represent only a snapshot of a much longer-term trend. Since the 1980s each decade has been warmer than the previous one. Heat-trapping gases in the atmosphere remain at record levels and the long lifetime of carbon dioxide, the most important gas, commits the planet to future warming,” said Prof. Taalas.
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