"The IPCC’s latest report tells us about the inevitability of this scale of global warming."
"The IPCC’s latest report tells us about the inevitability of this scale of global warming."Hotter temperatures will be a certainty in 30-50 years.
Unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to close to 1.5 degrees Celsius (°C) or even 2°C will be beyond reach.
To stop a warming of 1.5 to 2 degrees Celsius within 30-50 years, the world must stop emitting carbon or greenhouse gases—now, an impossibility.
A report by 234 experts and scientists from 66 countries of the UN Intergovernmental Panel on Climate Change released Aug. 9, 2021 in Geneva warns of the inevitability of such global warming.
The report, called the Sixth Assessment Report (AR6), shows that emissions of greenhouse gases from human activities are responsible for approximately 1.1°Celsius (2 degrees Fahrenheit) of warming since 1850-1900.
Such activities are largely the burning of coal, oil and gas to meet man’s energy needs.
“Human-induced climate change is already affecting many weather and climate extremes in every region across the globe. Evidence of observed changes in extremes such as heatwaves, heavy precipitation, droughts, and tropical cyclones,” says the AR6.
Averaged over the next 20 years, global temperature is expected to reach or exceed 1.5°C of warming.
Among the effects of global warming per the AR6: Increases in the frequency and intensity of hot extremes, marine heatwaves, and heavy precipitation, agricultural and ecological droughts in some regions, and proportion of intense tropical cyclones, as well as reductions in Arctic sea ice, snow cover and permafrost.
The report was prepared by the Working Group I of the IPCC. WG I tackled the Physical Science Basis of Climate Change.
According to the report, “global surface temperature will continue to increase until at least the mid-century under all (five) emissions scenarios considered (by the IPCC). Global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades.”
Global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2000 years.
Temperatures during the most recent decade (2011–2020) exceed those of the most recent multi-century warm period, around 6500 years ago [0.2°C to 1°C relative to 1850– 1900].
The report says “in 2019, atmospheric CO2 concentrations were higher than at any time in at least 2 million years, and concentrations of CH4 (methane) and N2O (nitrogen oxide) were higher than at any time in at least 800,000 years.”
Global mean sea level has risen faster since 1900 than over any preceding century in at least the last 3000 years . The global ocean has warmed faster over the past century than since the end of the last deglacial transition (around 11,000 years ago).
“This report is a reality check,” said IPCC Working Group I Co-Chair Valérie Masson-Delmotte. “We now have a much clearer picture of the past, present and future climate, which is essential for understanding where we are headed, what can be done, and how we can prepare.”
Added Ko Barret, vice chair of the WG I: “We’ve known for decades that the world is warming, but this report tells us that recent changes in the climate are widespread, rapid and intensifying, unprecedented in thousands of years.”
“Unless we make immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to 1.5C will be beyond reach,” said Barrett.
Barrett, the senior adviser for climate at the Office of Oceanic and Atmospheric Research at the National Oceanic and Atmospheric Administration pointed out, “It is indisputable that human activities are causing climate change.”
“We know there is no going back from some changes in the climate system, but some can be slowed or stopped if emissions are reduced,” she said.
“To avert the worst impacts of climate change, we must keep global temper- atures to within 1.5 °C of the pre-industrial baseline,” says Antonio Guterres, United Nations secretary general.
“That means reducing global greenhouse gas emissions by 45 percent from 2010 levels by 2030 and reaching net zero emissions by 2050. Global mean temperature for 2020 was around 1.2 °C warmer than pre-industrial times, meaning that time is fast running out to meet the goals of the Paris Agreement. We need to do more, and faster, now,” the UN chief points out.
Per World Meteorological Organization data, 2020 was one of the three warmest years on record. The past six years, including 2020, have been the six warmest years on record.
Also, per WMO, the trend in sea-level rise is accelerating. In addition, ocean heat storage and acidification are increasing, diminishing the ocean’s capacity to moderate climate change.
Per UN findings, a 2°C warming will harm 14 percent of the population (or one billion to 1.2 billion people), over 350 million people will experience severe drought, and six percent of insects, eight percent of plants, and four percent of vertebrates could disappear. Up to 70 million people will be displaced by lands that will go under water.
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