The IPCC report unequivocally states that man is responsible for the warming, and that the frequent extreme weather events were also caused by the warming * Any delay will cause the damage to worsen, it is cheaper to stop emitting carbon than to absorb it later
By: Pep Kendall, Principal Research Scientist, CSIRO Climate, Ocean and Atmospheric Sciences Centre; and Director of the Global Carbon Project, CSIRO, Joel Gergis, Senior Lecturer in Climate Science, Australian National University, Malta Mainshausen, A/Prof., School of Earth Sciences, University of Melbourne, Mark Hamer, Principal Research Scientist, Oceans and Atmosphere, CSIRO, and Michael Gross, Climate Prediction Scientist, CSIRO. Translation: Avi Blizovsky
The Earth has warmed by 1.09 degrees Celsius since the pre-industrial era and many changes such as rising sea levels and melting glaciers are almost irreversible. This is according to the most detailed and disturbing report written so far by the Intergovernmental Panel on Climate Change (IPCC).
The report also found that there is no escaping the effects of climate change caused by humans. Climate change is now affecting every continent, region and ocean on Earth, and every aspect of the weather.
The report is the sixth assessment of its kind since the panel was established in 1988. It will give world leaders the most accurate information on climate change in time for a crucial international summit in Glasgow, Scotland in November.
The IPCC is a body that includes the climate sciences of the United Nations and the World Meteorological Organization. It is the highest global authority on the state of the Earth's climate and how human activity affects it. The report summarizes the work of thousands of climate scientists from all over the world.
Unfortunately, there is almost no good news in the 3,900 pages of text published today. But there is still time to prevent the worst damage, if humanity chooses to do so.
Unequivocal: humans are warming the earth
For the first time, the IPCC states unequivocally - without any room for doubt - that humans are responsible for the warming of the atmosphere, the continents and the oceans. The IPCC finds that the Earth's global surface temperature warmed by 1.09℃ between 1850-1900 and the last decade was much warmer than the previous IPCC report in 2013. (It should be noted that 0.1 ℃ of the increase is due to the improvement of the data).
The IPCC recognizes the role of natural changes in the Earth's climate. However, it finds that 1.07 of the 1.09 degrees of warming is due to greenhouse gases associated with human activity. In other words, almost all global warming is due to humans.
The global surface temperature has warmed faster since 1970 than at any other 50-year period in at least the last 2,000 years, with warming also reaching the ocean depths below 2,000 meters.
The IPCC says that human activity has also affected global precipitation (rain and snow). Since 1950, global precipitation has increased, but while some areas have become wetter, others have become drier.
The frequency and intensity of heavy precipitation events have increased in most land areas. This is because the warmer atmosphere is able to hold more moisture – about 7% more for each additional degree of temperature – making the wet seasons and rain events wetter.
Higher concentrations of CO₂, the growth rate also increases
The global concentration of atmospheric carbon dioxide (CO₂) is higher and rising faster than at any similar time in the last two million years.
The rate at which atmospheric CO₂ concentrations have increased since the Industrial Revolution (1750) is at least ten times faster than at any other time during the last 800,000 years, and between four and five times faster than during the last 56 million years.
About 85% of CO₂ emissions come from burning fossil fuels. The remaining 15% results from land use change, such as deforestation and soil depletion.
The concentration of other greenhouse gases does not improve. Both methane and nitrous oxide, the second and third largest contributors to global warming after CO₂, increased faster.
Methane emissions from human activity come largely from livestock and the fossil fuel industry. The emission of nitrogen oxide is mainly due to the use of nitrogen fertilizer in crops.
An increase in the frequency and intensity of weather events
Warm extremes, heat waves and heavy rain have also become more frequent and intense in most land areas since 1950, the IPCC confirms.
The report emphasizes that some recently observed hot events, such as the wildfire-filled summers in Australia in 2012-2013, were highly improbable without human influence on the climate.
Human influence was also discovered for the first time in complex extreme events. For example, cases of heat waves, forms and fires occurring at the same time more often. These complex events were seen in Australia, southern Europe, northern Eurasia, parts of the Americas and the tropical forests of Africa.
The oceans: warmer, higher and more acidic
The oceans absorb 91% of the energy from the additional greenhouse gases. This has led to ocean warming and more marine heat waves, especially over the last 15 years.
Marine heat waves cause mass death of sea life, such as from coral bleaching events. They also cause algal blooms and changes in species composition. Even if the world limits warming to 1.5-2℃, as is consistent with the Paris Agreement, marine heat waves will be four times more frequent by the end of the century.
The melting of glaciers, along with the expansion of the ocean as it warms, has resulted in an average global sea level rise of 0.2 meters between 1901 and 2018. 1.3 mm per year during 1901-1971, 1.9 mm per year during 1971-2006, and 3.7 mm per year during 2006-2018.
Ocean acidification, caused by the absorption of CO₂, has occurred in all oceans and reaches depths beyond 2,000 m in the Southern Ocean and the North Atlantic.
Many changes are already irreversible
The IPCC says that if the Earth's climate stabilizes soon, it will not be possible to reverse some damages caused by climate change within hundreds, or even thousands of years. For example, global warming of 2 degrees this century would lead to an average global sea level rise of between two and six meters over 2,000 years, and much more for higher emission scenarios.
Globally, glaciers have been retreating synchronously since 1950, and are expected to continue melting for decades after global temperature stabilizes. Meanwhile deep ocean acidification will remain for thousands of years after CO₂ emissions stop.
The report does not identify possible sudden changes that will lead to acceleration of global warming during this century - but does not rule out such possibilities.
The possibility that the thawing of the frozen lands in Alaska, Canada and Russia will cross a tipping point is discussed at length. The fear is that as these soils thaw, large amounts of carbon accumulated over thousands of years from dead plants and animals could be released.
The report does not identify any significant sudden changes in these areas during this century, based on currently available evidence. However, he predicts that permafrost areas will release about 66 billion tons of CO₂ for each additional degree of warming. These emissions are irreversible during this century under all warming scenarios.
How can we stabilize the climate?
The Earth's surface temperature will continue to rise until at least 2050 under all emissions scenarios considered in the report. The assessment shows that the Earth could well exceed the 1.5 degree warming limit in the early XNUMXs.
If we reduce emissions enough, there is only a 50% chance that the increase in global temperature will stay around 1.5℃ (including a temporary increase of up to 0.1℃). To return the planet to warming below 1.5 degrees, it will be necessary to remove CO₂ from the atmosphere using negative emission technologies or natural solutions.
Global warming remains below 2℃ during this century only in scenarios where CO₂ emissions reach net zero around or after 2050.
The IPCC analyzed future climate projections from dozens of climate models, developed in more than 50 modeling centers around the world. It showed that the average global surface temperature would rise between 1-1.8℃ and 3.3-5.7℃ in this century above pre-industrial levels for the lowest and highest emissions scenarios, respectively. The exact increase the world experiences will depend on how much more greenhouse gases are emitted.
The report states, with high certainty, that in order to stabilize the climate, CO₂ emissions must reach net zero, and other greenhouse gas emissions must decrease significantly.
We also know that to meet a given temperature target, there is a finite amount of carbon we can emit before we reach net zero emissions. To have a 50:50 chance of stopping warming at around 1.5℃, this amount is about 500 billion tons of CO₂.
At current levels of CO₂ emissions, this "carbon budget" will be used up within 12 years. Exhausting the budget will take longer if the rate of emissions starts to decrease.
The latest findings of the IPCC are worrying. But there are no physical or environmental obstacles to keeping warming well below 2℃ and limiting it to about 1.5℃ – the globally agreed goals of the Paris Agreement. But humanity must choose to act.
to the article on The Conversation website
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In order to cool the planet, we need to consider the controlled emission of sulfur compounds that cause a mirror effect.