The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change. On the 9th of August 2021, IPCC published the first report on the science of global warming since 2013. The summary for policymakers is expected to be an essential document for world leaders when they meet at COP26 in November.
The past and future of IPCC reports
The IPCC prepares comprehensive Assessment Reports about climate change, its causes, potential impacts, and response options. The first comprehensive assessment report on climate change was published in 1992. The sixth part of the series, due out this year, is divided into four volumes, discussing the first, the physical science behind climate change.
Evaluation reports are prepared in three groups. The first report released on the 9th of August 2021 outlines the projected effects of five emission scenarios, ranging from global net harmful and net-zero emissions to doubling by 2050 and 2100 compared to current levels. The second and third reports, which will be published in early 2022, look at how to adapt to these impacts and prevent worst-case scenarios.
What could we expect from this year's report?
Many observers say there has been significant progress in science over the past few years. The scientists' models have improved, and they better understand physics, chemistry, and biology. They are also much better able to simulate and predict future temperature changes and precipitation changes than before.
Five key messages from the IPCC report
Below are five key messages from the first milestone report.
1. By 2040, we will exceed 1.5 degrees Celsius warming
The warming of recent decades has been unprecedented for thousands of years, with warming occurring rapidly and in almost the entire area of the Earth, reversing the long-term global cooling trend. According to all the emission scenarios outlined in the IPCC report, global warming will reach 1.5C or 1.6C over the next two decades. To have any chance at all of achieving the goal that is considered essential for the survival of some vulnerable communities and ecosystems, a drastic reduction in CO2 emissions would be needed in this decade and net emissions by 2050.
2. Human activity causes extreme weather
While the most recent report, published in 2013, concluded that the human impact on the climate system is "clear," the new analysis "shows a high probability" that human activity oceans are the leading cause of warming and acidification.
3. We know more about regional climate impacts
Since the last IPCC report, climate models have evolved, allowing researchers to analyze current and projected temperature and hydrological extremes at the regional level and understand how global climate impacts will look in different parts of the world.
4. We got closer to the irreversible turning points
The report rings the alarm because of the possibility of irreversible changes in the climate, often referred to as tipping points.
5. Methane emissions are an essential driver
For the first time, the IPCC has devoted an entire chapter to "short-lived climate factors," such as aerosols, particles, and methane.
The report is available to read here: https://www.ipcc.ch/report/ar6/wg1/