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Ocean heat has reached record levels with major consequences
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Ocean heat has reached record levels with major consequences

Hurricane Ida making landfall on the Louisana coast


In 2021, the world witnessed record-breaking weather and climate disasters. These included destructive flash floods that swept through. Mountain towns in EuropeInundated China subway system The U.S.To heat waves and wildfires. Typhoon Rai More than 400 people were killedIn the Philippines, Hurricane Ida caused an estimated US$74 billion in damageIn the U.S.

According to data released in their respective reports by NASA and the National Oceanic and Atmospheric Administration, it was the sixth-hottest year for surface temperatures globally. Annual global climate reportJanuary 13, 2022. Under the surface, however, the ocean temperatures set new heat records for 2021.

As climate scientist Kevin Trenberth explains, while the temperature at Earth’s surface is what people experience day to day, the temperature in the upper part of the ocean is a better indicator of how excess heat is accumulating on the planet.

The Conversation spoke to Trenberth, coauthor and co-author of a study that was published Jan. 11, 2022 by 23 researchers from 14 institutes. tracked warming in the world’s oceans.

Hurricane Ida making landfall on the Louisana coast
Hurricane Ida caused $74 Billion of damage in 2021 from Louisiana to the northeastern U.S.
RAMMB/CIRA/Colorado State University

Your latest research shows that ocean heat has reached record highs. What does this tell us about global climate change?

The world’s oceans are hotter than ever recorded, and their heat has increased each decade since the 1960s. This is a major indicator of human-induced climate changes.

As the oceans heat up, they supercharge weather systems, creating stronger storms and hurricanes. More intense rainfall. This is a threat to human lives and livelihoods, as well as marine life.

About 65% of the oceans are covered 93% of the extra energyThe increasing greenhouse gasses from human activities, especially burning fossil fuels, are trapping people. The primary memory of global warming is the upper oceans, which hold more heat than land and have immense volumes. I explain this in more detail in my new book “The Climate System and the Changing Flow of Energy.”

Ocean heat content in the upper 2,000 meters of the world’s oceans since 1958, relative to the 1981-2010 average. The units are zettajoules.
Lijing Cheng

Our study provided the first analysis of 2021’s ocean warmingWe were able to attribute the warming of the atmosphere to human activities. Global warming is a real problem.

The global average surface temperature was at FifthOr SixthIn 2021, it was the warmest year on record (the record is dependent on the dataset used), in part due to the year-long La NiñaConditions in which cool tropical Pacific conditions influence weather patterns around world

Because of this, there is more natural variability in surface temperatures than in ocean temperatures. El Niño/La NiñaWeather events. That natural variability on top of a warming ocean creates hot spots, sometimes called “marine heat waves,” that vary from year to year. These hot spots are known as “marine heat waves”. Marine life is subject to profound influencesFrom tiny plankton all the way to fish, birds, marine mammals and birds. Hurricanes are another hot spot that causes more activity in the atmosphere.

Surface temperatures can be both a result and a cause of extremes, but the main source of extremes is ocean heat, which energizes weather systems.

Scientists are concerned about the stability of Antarctica’s Thwaites Glacier, which holds back large amounts of land ice.

All oceans are warming. The Atlantic Ocean and the Southern Ocean surrounding Antarctica show the greatest warming. That’s a concern for Antarctica’s ice – heat in the Southern Ocean can creep under Antarctica’s ice shelvesThese are used to thin the icebergs and result in the calving of large icebergs. Warming oceans Sea level rise is also a concern.

What does more ocean heat mean for the land’s temperature and moisture?

Global heating causes more evaporation and drying of the land. It also raises temperatures, increasing the risk of heat waves, and wildfires. We’ve seen the impact in 2021, Particularly in western North AmericaBut also during heat waves Russia, Greece, Italy, and Turkey.

The warmer oceans also supply Atmospheric riversincrease the risk of flooding in land areas due to the increased moisture. This is what the West Coast has been experiencing.

2021 saw many destructive cyclones including Hurricane Ida in America and Typhoon Rai here in the Philippines. How does ocean temperature impact storms like these?

Warmer oceans add moisture to the atmosphere. Storms are fueled by this extra moisture, especially in the Atlantic. Hurricanes. The result can be torrential rains, as the U.S. witnessed from Ida, or widespread flooding, as has occurred in many areas over the past year.

Storms could also get more intense, larger and last longer. In Australia, there have been several major flooding events in the last year. Winter can also see larger snowfalls, provided that temperatures are below freezing. Warmer air retains more moisture.

A woman stands, arms crossed, staring at a car propped on its nose against a business after the typhoon.
A Filipino resident looks at a vehicle that was washed away by floodwaters during Typhoon Rai.
Cheryl Baldicantos/AFP via Getty Images

Would the ocean cool off if greenhouse gas emissions were to be slowed?

Warm water sits on top cooler, denser water in the oceans. The oceans are becoming more stratified as they warm from the top. This hinders mixing between layers, which would otherwise allow the ocean to heat to deeper levels and absorb carbon dioxide and oxygen. It is a problem for all marine life.

We found that the ocean’s highest 500 meters have a significant amount of water. Clearly, there has been warmingSince 1980, the 500-1,000 meter deeps have been warming since around 1990; the 1,000-1500 meter depths from 1998; and below 1,500 meter since 2005.

Slow penetration of heat down means oceans will continue warming, and sea levels will continue rising even after the stabilization of greenhouse gases.

The final area to pay attention to is the need to expand scientists’ ability to monitor changes in the oceans. This can be done through the Argo array – currently about 3,900 profiling floats that send back data on temperature and salinity from the surface to about 2,000 meters in depth, measured as they rise up and then sink back down, in ocean basins around the world. These instruments, whether drifting, robotic, or diving, require constant replenishment. Their observations are valuable.

Argo floats keep track of ocean changes around the globe.
Howard Freeland, 2018, CC BY -ND
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