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Major climate indicators set "alarming" records in 2021, the U.N. says, "bringing us ever closer to climate catastrophe"

What to know about the state of the climate
The State of the Global Climate: Here's what to know 01:52

The United Nations' World Meteorological Organization issued yet another grim report about the state of our planet this week. In 2021, four of the seven major climate indicators – a set of parameters that hold key information about climate change – set "alarming" new records. 

In what the WMO said is a "clear sign" that humans are causing "harmful and long-lasting" effects across the globe, the report found that greenhouse gas concentrations, sea level rise, ocean heat and ocean acidification all set new records last year. The report also found that the past seven years have been the warmest seven years on record. 

In a press conference about the findings, U.N. Secretary-General António Guterres said that the records set are "alarming" and that the findings portray a "dismal litany of humanity's failure to tackle climate disruption." 

"I will give you the bottom line – the global energy system is broken and bringing us ever closer to climate catastrophe. Fossil fuels are a dead end, environmentally and economically," he said. "...The only sustainable future is a renewable one." 

Here are the indicators that set the new records and what they mean as humanity continues to fight the climate crisis. 

Greenhouse gas concentrations

Greenhouse gas emissions are the driving force behind global warming and climate change. Carbon dioxide, which is mostly released into the atmosphere through the burning of coal, natural gas, oil, solid waste and biological materials, is the most potent of these gases. As greenhouse gases are released, they create a thick barrier in the atmosphere that traps heat, and reducing these releases is essential to limit warming of the planet.

These gases reached new highs in 2020, and the latest report shows that three gases in particular – carbon dioxide, nitrous oxide and atmospheric methane – continued to increase in 2021. Scientists expressed particular concern over atmospheric methane, which is the second-largest contributor to global warming. 

Last month, NOAA scientists reported that this gas saw an increase of 17 parts per billion in 2021, the largest annual increase recorded since they started taking measurements in 1983 and an amount about 162% larger than pre-industrial levels. 

WMO issued a report last year that found cutting human-caused methane by 45% by 2030 would have a substantial impact on global warming and keep it to 1.5°C compared to pre-industrial levels.  This would avoid nearly 0.3°C of warming by the 2040s, researchers said, and prevent 255,000 premature deaths, 775,00 asthma-related hospital visits and 26 million tons of global crop losses. 

Ocean heat

More carbon dioxide in the atmosphere means more carbon dioxide in the ocean, a fact that can have a disastrous effect on global systems. As explained in WMO's report, about 90% of the heat on Earth is stored in the ocean, and as the planet warms, so does the ocean.

In 2021, ocean heat hit a record high. 

The top 2,000 meters of oceans in particular were observed to have warmed last year. Scientists believe that it will only continue to do so, saying that it is "a change which is irreversible on centennial to millennial time scales." 

That heat can cause a cascading effect, contributing to sea level rise, marine heat waves, coral bleaching and ice melting — threatening marine ecosystems, fisheries and the ability for people to live near coastlines. 

Sea level rise

Driven by a warming ocean, sea level rise also hit a record high in 2021, increasing at an average of 4.5 millimeters per year from 2013. Scientists said its "more than double the rate" of the seven-year period from 1993 to 2002 and was mostly caused by the rapid melting of sea ice. 

While the rise has happened almost everywhere in the world since 1993, scientists said, it's not an equal distribution. Many regions have been impacted by a rate of rise "substantially faster" than the global average, particularly the western Tropical Pacific, Southwest Pacific, North Pacific, Southwest Indian Ocean, and the South Atlantic. 

"This has major implications for hundreds of millions of coastal dwellers and increases vulnerability to tropical cyclones," WMO scientists said. 

Ocean levels have already risen between 8 and 9 inches since 1880, and NOAA scientists say that the rate at which it is doing so is only accelerating. The average rate reported in the WMO's report is far higher than the average that took place in most of the 20th century, about 3.6 mm every year from 2006 to 2015.

By 2100, NOAA says, models project that the average rise for the contiguous U.S. could by more than 7 feet based on a continuously high output of greenhouse gas emissions and rapid sea ice collapse.

Ocean acidification

The ocean absorbs nearly a quarter of the annual emissions of carbon dioxide that humans create, a process that slows the increase of the greenhouse gas in the atmosphere, but at large concentrations has a negative impact on the ocean itself. Now, the ocean is more acidic than it's been in 26,000 years, according to the latest report. 

The more acidic the ocean gets, the more difficult it is for it to absorb carbon dioxide, damaging this natural barrier to rapid global warming. 

Acidification also impacts billions of people worldwide who rely on the ocean for food, money and protection. When the pH level of the water declines, it weakens coral structures and creates corrosive conditions for some marine life. This threat to marine ecosystems impacts the roughly 20% of the global population that significantly relies on fish for food, while also harming tourism and coastal protection from the rising seas. 

Finding a solution

Guterres urged once again that the world must move away from fossil fuels and accelerate the transition to renewable energy "before we incinerate our only home." 

"We don't have a moment to lose," he said. "...Time is running out."

Gutteres said that transforming the world's energy systems is "low-hanging fruit" and that many technologies, including wind and solar, are already available and often cheaper to use than coal or other fossil fuels. 

He proposed on Wednesday five "critical" action steps that can be taken to help: make renewable energy available to all; improve global access to renewable energy components and raw materials; reform domestic policy to streamline renewable energy projects; eliminate fossil fuel subsidies and instead give them to renewable energy; and for the world to invest at least $4 trillion a year into renewable energy until 2030.

WMO chief Petteri Taalas said in a statement that "it's just a matter of time" before the world sees yet another grim record driven by climate change.

"Our climate is changing before our eyes. The heat trapped by human-induced greenhouse gases will warm the planet for many generations to come," he warned. "Sea level rise, ocean heat and acidification will continue for hundreds of years unless means to remove carbon from the atmosphere are invented."

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