Just one possibility to reduce the effects of global warming: to reach net zero emissions as soon as possible

The "Climate Change 2021: The Physical Scientific Bases" was presented on 9 August in Geneva, at the headquarters of the IPCC secretariat, less than 80 days before the start of COP26 in Glasgow, the world climate conference. The report is clear: "unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to around 1.5 ° C or even 2 ° C will be an out-of-reach goal".

The report shows that greenhouse gas emissions from human activities are responsible for around 1.1 ° C of warming over the period 1850-1900. On average over the next 20 years, according to the report, global temperatures are expected to reach or exceed 1.5 ° C of warming. And with 1.5 ° C of global warming, an increase in the number of heat waves, longer warm seasons and shorter cold seasons is expected. With global warming of 2 ° C, extremes of heat would more often reach critical tolerances for agriculture and health.

But temperature is not the only element in play. Climate change is bringing about a lot of change in different regions, and all of them will increase with further warming. These include changes in humidity values, winds, snow and ice, coastal areas and oceans. For example: climate change is intensifying the water cycle. This leads, in some regions, to more intense rains and associated floods, in many other regions it leads to more intense droughts. They are influencing rainfall patterns. In high latitudes, precipitation is likely to increase, while it is expected to decrease in much of the subtropics. Changes in monsoon precipitation are expected, with variations in different regions.

Coastal areas are expected to continue to rise in sea level throughout the 21st century which would contribute to more frequent and severe coastal flooding in low-sea-level areas and coastal erosion. Extreme sea level events that previously occurred once every 100 years could occur every year by the end of this century. Further warming will intensify the melting of permafrost, the loss of seasonal snow cover, the melting of glaciers and the polar ice cap, and the loss of summer Arctic sea ice.

Changes in the ocean such as warming, more frequent sea heat waves, ocean acidification and reduced oxygen levels at sea have been clearly linked to human influence, the report said. These changes affect both marine ecosystems and the people who depend on them, and will continue at least for the rest of this century. For cities, some aspects of climate change can be amplified. These include heat waves (urban areas are usually warmer than their surroundings), flooding due to heavy rainfall, and rising sea levels in coastal cities.

The report also shows that human activities still have the potential to determine the course of the future climate. There is clear scientific evidence showing that carbon dioxide (Co2) is the main driver of climate change, although other greenhouse gases and air pollutants contribute to the climate.
Stabilizing the climate will require strong, rapid and steady reductions in greenhouse gas emissions, and achieving net CO2 emissions of zero. Limiting other greenhouse gases and air pollutants, especially methane, could have both health and climate benefits.

The complete report is attached.