IPCC report on Climate: "most serious warning ever issued"

Ground Report | New Delhi: IPCC report on Climate; On August 9, the Intergovernmental Panel on Climate Change (IPCC) will release its most comprehensive report on the science of climate change since 2013. It will be the first of four reports to be published in the framework of the last IPCC assessment cycle, the following will see the light of day in 2022.

In the past eight years, scientists have improved the methods they use to measure different aspects of the climate and to model (or project) what might happen in the future. They have also followed the changes that have occurred before our eyes.

This updated assessment comes three months before world leaders meet in Glasgow, Scotland, to find ways to avoid the worst consequences of climate change and renew their greenhouse gas reduction commitments. It also comes in the middle of another year of severe heat waves, droughts, wildfires, floods, and storms.

The report will provide policymakers with the best possible information on the physical science of climate change, which is essential for long-term planning in many sectors, from infrastructure to energy to social welfare. Here are five things to look for in the new report:

Carbon dioxide (CO₂) levels in the atmosphere are the highest in 800,000 years, reaching 419 parts per million (ppm) in May 2021. The average temperature of the planet increases with each increase in the concentration of CO₂ in the atmosphere, but the increase depends on many factors.

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IPCC report on Climate

Climate scientists use models to understand how much warming occurs when CO₂ concentrations double from pre-industrial levels - from 260 ppm to 520 ppm - a concept called " climate sensitivity ." The more sensitive the climate, the faster greenhouse gas emissions will have to be curbed to stay below 2 ℃.

"We cannot afford to wait two years, five years, ten years," he added, considering that we are still on time, but that "we are getting dangerously close to the moment" when it is too late. In this sense, he insisted on the decisiveness of the climate conference scheduled for November in Glasgow (COP26).

Has climate change caused recent extreme weather events?

Since the last IPCC report, our ability to assess the impact of global warming on extreme events has vastly improved. Chapter 11 of the latest report is dedicated to it. Global warming means that stronger summer heatwaves and more frequent tropical nights (temperatures above 20 ℃) ​​are occurring in mid-latitudes, such as in Canada and Europe.

Warmer air can hold more water. This can cause more evaporation from the earth's surface, and lead to droughts and wildfires. In addition, an atmosphere with more water can lead to more precipitation and flooding. Scientists predicted decades ago that these changes in the water cycle would occur, but now it is clear that they are already happening.

Have regional climate projections improved?

The climate models evaluated by the IPCC are global models. This is essential to clarify the connections between the tropics and the poles or the land and the ocean. However, it comes at a cost: the models find it difficult to simulate many features less than 100 kilometers in diameters, such as small storms or islands.

Regional relationships can be complex. For example, extreme storms help break up Arctic sea ice in summer, but reduced sea ice cover can also lead to stronger storms.

Since the last IPCC report, techniques for collecting this information on a large scale and refining it have shown how the regional and local climate has changed and could change in the future. Other research focuses on regional issues, such as the impact of sea ice loss in the Arctic.

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How will Antarctic ice sheets contribute to sea-level rise?

The sea level is rising because the water expands slightly when it warms, and the mountain glaciers and Greenland's ice caps are melting and adding water to the ocean.

But the biggest potential source of sea-level rise over the next century is Antarctica. Ice sheet models show that the melting of the Antarctic ice sheets will add 14 to 114 centimeters to sea-level rise in 2100. It's a huge range, and it all depends on whether the Antarctic ice sheet Occidental either remains relatively stable or begins a slow but unstoppable collapse.

How the IPCC communicates this scientific debate will influence the way coastal communities plan for sea-level rise. Low-lying cities like Lagos in Nigeria could become uninhabitable by the end of the century due to rising sea levels, especially if model estimates that predict higher elevation turn out to be the most accurate.

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