The Paris climate agreement aims to limit global warming to 1.5 ℃ this century. A new report by the World Meteorological Organization warns that this limit could be exceeded by 2024 — and the risk is growing.
The first overshoot beyond 1.5 ℃ was temporary, likely aided by a major climate anomaly such as an El Niño weather pattern. However, it raises new doubts as to whether the Earth’s climate can be permanently stabilized at 1.5 ℃ warming.
This discovery was among those published only in a report entitled United in Science. We contributed to the report, prepared by six leading science agencies, including the Global Carbon Project.
The report also found that while greenhouse gas emissions declined slightly in 2020 due to the COVID-19 pandemic, they remained very high – meaning atmospheric carbon dioxide concentrations continued to rise.
Greenhouse gases have risen due to slower CO₂ emissions
Concentrations of three major greenhouse gases – carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), have all risen over the past decade. Current air concentrations were, respectively, 147%, 259% and 123% of those present before the industrial period began in 1750.
Concentrations measured at Hawaii’s Mauna Loa Observatory and Australia’s Cape Grim station in Tasmania show concentrations that continue to rise in 2019 and 2020. In particular, CO₂ concentrations reached 414.38 and 410.04 respectively. share per million in July of this year, respectively, at each station.
Growth of CO₂ emissions from fossil fuel consumption has slowed to almost 1% per year over the past decade, down from 3% during the 2000s. An unprecedented decline is expected in 2020, due to the slowdown of COVID-19 in the economy. Daily fossil CO₂ fuel emissions declined by 17% in early April at the top of the world’s incarceration policies, compared to last year. But in early June they recovered a 5% decline.
We estimate a decline for 2020 of about 4-7% compared to 2019 levels, depending on how the pandemic plays out.
Although emissions will drop slightly, atmospheric COosp concentrations will still reach another record high this year. This is because we still add a lot of CO value to the environment.
Hottest five years recorded
The global average surface temperature from 2016 to 2020 is among the hottest of any equivalent period recorded, and about 0.24 ℃ warmer than in the past five years.
This five-year period leads to the creation of a new global temperature record, including Australia, southern Africa, most of Europe, the Middle East and northern Asia, parts of South America and parts of the United States.
Sea level has risen by 3.2 millimeters per year on average over the past 27 years. Growth is accelerating – sea level has risen 4.8 millimeters annually over the past five years, compared to 4.1 millimeters annually in the five years before it.
The past five years have also seen many intense events. These include record-break heatwaves in Europe, typhoon Idai in Mozambique, major fires in Australia and elsewhere, prolonged droughts in southern Africa and three North Atlantic storms in 2017.
1 in 4 instances exceed 1.5 ° C warming
Our report predicts an ongoing heating trend. There is a high probability that, anywhere on the planet, the average temperature over the next five years will be higher than the 1981-2010 average. Arctic warming is expected to be more than twice the global average.
There is a one-in-four chance the global average temperature will exceed 1.5 ℃ above pre-industrial levels for at least one year over the next five years. The chances are pretty small, but still meaningful and growing. If a major climate anomaly, such as a strong El Niño, occurs during that time, the 1.5 ℃ threshold is more likely to cross. El Niño events generally bring warmer temperatures around the world.
Under the Paris Agreement, crossing the 1.5 ℃ threshold is measured within a 30-year average, not just one year. But every year above 1.5 ℃ warming will bring us closer to exceeding the limit.
The Arctic Ocean sea-ice is missing
Satellite records between 1979 and 2019 show sea ice in the Arctic summer declining by approximately 13% per decade, and this year reached the lowest level of July recorded.
In Antarctica, it reached the lowest and second lowest levels of ice in summer in 2017 and 2018, respectively, and 2018 was also the second lowest extent of winter.
Most simulations show that by 2050, the Arctic Ocean will be almost free of sea ice for the first time. The fate of Antarctic sea ice is less certain.
Immediate action can change trends
Human activities released 42 billion tons of CO₂ in 2019 alone. Under the Paris Agreement, countries are committed to reducing emissions by 2030.
But our report shows a shortage of about 15 billion tons of CO₂ between these promises, and paths corresponding to heating limit up to less than 2 ℃ (the less ambitious end of the target of Paris). The space rises to 32 billion tons for the more ambitious goal of 1.5 layunin.
Our report models a range of climate outcomes based on different socioeconomic and policy scenarios. It shows that if emissions reductions are large and sustainable, we can still meet the goals in Paris and prevent the worst damage to the natural world, economy and people. But worry, we also have time to make it worse.
UN forecasts are even warmer over the next 5 years
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Citation: Earth could temporarily pass the dangerous 1.5 C heating limit by 2024, says a major new report (2020, September 9) obtained on September 9, 2020 from https://phys.org/news / 2020-09-earth-temporarily-dangerous-limit- major.html
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