Zhai Panmao, former co-chair of IPCC Working Group I: Some of the contemporary climate systems have changed for thousands of years

"The climate crisis is no longer a fear, it's imminent. ”

The person who said this was Zhai Panmao, chief scientist of the Chinese Academy of Meteorological Sciences. Having worked with climate science all his life, he firmly argues that climate change is real, that we are really experiencing it, and that we will experience the effects of this climate change more and more.

In the past year, there have been frequent record-breaking heat waves, extremely heavy precipitation events that exceed a century in more than a century, catastrophic floods that have hit the entire Haihe River Basin, and cold waves that have affected countless people's return to their hometowns......

"2023 is the warmest year since meteorological records began in the world, and the global surface temperature has broken the warmest record. The latest assessment report of the United Nations Intergovernmental Panel on Climate Change (IPCC) has improved people's understanding of changes in the climate system, the causes of climate change and projected future changes in the climate system, and has a clearer and more reliable understanding of past climate change and its relationship with human activities, Zhai Panmao said. According to the report, human-induced climate change is already affecting many weather and climate extremes in every region of the world.

Zhai Panmao was previously co-chair of IPCC Working Group I. The IPCC brings together thousands of the world's outstanding climate change scientists, who collect, collate and summarize the world's research results in the field of climate change based on the latest published scientific literature, and put forward evaluation conclusions and relevant policy recommendations in the science, impact and response of climate change. Although the IPCC report plays an important role in the United Nations Climate Change Conference (UNFCCC), it maintains the neutrality of climate change policy.

Recently, Zhai Panmao was interviewed by The Paper (www.thepaper.cn) "Tipping Point" and responded to some hot issues in climate science cognition.

The following is the full text of the interview:

2023 is the warmest year on global record

The Paper: One of the arguments of climate change skeptics is that extreme cold weather is now a regular occurrence, such as the past winter, when China experienced a number of large-scale and high-intensity cold waves. In this case, climate warming will be inconsistent with the intuitive feeling of many people, how to view the occurrence of extreme cold events in science?

Zhai Panmao: It's normal to ask why there are still extreme cold events in the context of rapid climate warming. But answering such questions involves questions of regional and global, whether a few processes or long-term trends.

According to the monitoring data, the past winter was still warmer on average than any other year in history. According to the latest climate change monitoring by the National Climate Center, 2023 is the warmest year on global meteorological records, breaking the warmest record since observations began, and 0.14°C higher than the previous high temperature record year (2016).

But in terms of the situation in a certain area and a certain day, it will be different, and it is not surprising that cold weather processes occur. The occurrence of some cold wave processes in a given region does not contradict the average warming of the global climate.

"Tackling climate change is not something someone else wants us to do, it's something we have to do"

The Paper: In addition, there is a popular saying that developed countries have completed industrialization, so they have set up the issue of "global warming" through their own relatively strong discourse, and want to curb the development of developing countries through climate change, what do you think of this view?

Zhai Panmao: Climate change is a common challenge facing all mankind, and the purpose of the global climate change negotiations is to establish a fair, reasonable, and win-win global climate governance system to address this global challenge. The principle of "common but differentiated responsibilities" proposed in the Paris Agreement clarifies the different obligations of developed and developing countries. For example, developed countries should continue to take the lead in reducing emissions and strengthen support for developing countries in terms of finance, technology and capacity building to help them mitigate and adapt to climate change, while developing countries should also fulfill their responsibilities and obligations.

It should be noted that the core mechanism of the Paris Agreement signed in 2015 is the "Nationally Determined Contributions" (NDCs), which allow countries to set their own climate action targets according to their own circumstances and goals, including reducing greenhouse gas emissions, improving energy efficiency, developing renewable energy, etc., these commitments are made by each country itself, and the data in it is also submitted by each country itself.

China has always taken active actions to address global climate change, and is an important participant, contributor and leader in the construction of global ecological civilization. General Secretary Xi Jinping has repeatedly stressed that reducing carbon dioxide emissions and tackling climate change is not something that others want us to do, but something we need to do. Achieving the "double carbon" goal is a major issue that the CPC Central Committee must do and do well from meeting the urgent needs of achieving sustainable development, promoting the transformation and upgrading of economic structure, promoting the harmonious coexistence of man and nature, and building a community with a shared future for mankind.

Attribution studies confirm the indisputable impact of human activities on warming of the atmosphere, oceans, and land

The Paper: In recent years, there has been more and more research on climate attribution, what role can attribution research play in advancing the understanding of climate change?

Zhai Panmao: The climate change we actually observe is caused by the superposition of three kinds of changes: the internal variability caused by the interaction between the atmosphere, oceans and land of the climate system, the natural changes caused by natural forcings outside the climate system, and the anthropogenic changes caused by human activities. The natural external forcing factors mainly include the increase of stratospheric aerosols caused by solar irradiance changes and volcanic eruptions, while the external forcing caused by human activities is mainly caused by greenhouse gas and aerosol emissions caused by human activities and land use change. Attribution refers to the evaluation of the relative contribution of multiple causal factors to a change or event.

In the field of climate change specifically, there is an urgent need to understand what is the cause of the significant changes in the state of the climate system since the Industrial Revolution, to what extent is it caused by human activities, to what extent is it caused by natural forcings, and how credible is this cause?

Obviously, only when it is scientifically convincingly recognized that human activities are the main cause of climate change can the international community, governments and the public have a reason to change the way human activities are carried out and take mitigation measures to address climate change, such as deeply reducing greenhouse gas emissions, achieving carbon neutrality and green and low-carbon transformation.

The Sixth Assessment Report (AR6) of the IPCC has improved our understanding of changes in the climate system, the causes of climate change, and projected future changes in the climate system, as well as a clearer and more reliable understanding of past climate change and its relationship with human activities.

AR6's multi-evidence assessment shows that the global climate is undergoing unprecedented changes, and that advances in attribution, including extreme events, have expanded the understanding of the impact of human activities on the climate system from the atmosphere to the hydrosphere, cryosphere and biosphere, further strengthening the understanding of the impact of human activities on global and regional climate.

The contemporary climate system is changing widely and rapidly, some of which have not changed for thousands of years

The Paper: Is there a scientific consensus on the underlying issues of climate change, and can the debate on climate change be put to rest?

Zhai Panmao: The issue of climate change was first raised and promoted by the international scientific community, with the Intergovernmental Panel on Climate Change (IPCC) playing a central role. The agency brings together thousands of scientists from around the world to collect, collate and summarize the world's research results in the field of climate change in the form of scientific assessments, and put forward scientific evaluations and policy recommendations.

Taking the newly released IPCC Working Group I Sixth Assessment Report (AR6) as an example, it was completed by 234 scientists from 66 countries, and the evaluation cited more than 14,000 scientific literature, collected and responded to more than 78,000 government or expert review opinions, each opinion is to be studied based on scientific evidence, and whether the opinion can be adopted is also subject to discussion and reasons.

The IPCC assessment report has always been a scientific report, and although it has played an important role in the United Nations Climate Change Conference (UNFCCC), it has maintained policy neutrality and everything must be based on objective facts and scientific evidence.

According to the IPCC's Sixth Assessment Report (AR6), global surface temperatures have been warmer in each decade of the last 40 years since 1850 than in any previous decade. Since the 70s of the 20th century, the earth's climate has been in a period of rapid warming, and the warming trend is very obvious, and the period from 2011 to 2020 is the warmest decade since 1850.

It is worth noting that the assessment is also combined with paleoclimatic information as much as possible to provide a longer-scale context for contemporary climate change. On a 50-year time scale, global warming since the 1970s has been faster than at any time in nearly 2,000 years of history, the report says.

The Paper: What other impacts of human activities on climate change does the IPCC report point out?

Zhai Panmao: AR6 also reflects changes in many extreme weather and climate events, which can be attributed to the impact of human activities.

For example, AR6 notes that human-induced climate change is already affecting many weather and climate extremes in every region of the globe. Since the 2013 Fifth Assessment Report, the evidence that can be used to attribute observed extreme events, such as heat waves, heavy precipitation, droughts and tropical cyclones, to the impact of human activities has increased.

Since the 1950s, human activities have been the main drivers of increased frequency and intensity of heat waves and decreased frequency and intensity of cold waves in most land regions of the world (high confidence), some extreme heat events observed in the last decade are highly unlikely to occur without the impact of human activities on the climate system, and the frequency of marine heat waves has almost doubled since the 80s of the 20th century, and it is likely that human activities have contributed to the vast majority of them, at least since 2006.

For example, the event attribution study of tropical cyclones, combined with physical process analysis, shows that anthropogenic climate change enhances the heavy precipitation brought by tropical cyclones. In addition, human activities may also increase the probability of compound extreme events since the 50s of the 20th century, including the increase of high-temperature-drought compound events on a global scale, the increase of fire danger weather in some areas, and the increase of compound flood events in some coastal areas.

The Paper: The AR6 report points out that in the context of global warming, various extreme weather and climate events will become more frequent in the future, and will produce more complex and difficult-to-manage compound and cascading risks (high confidence). How to understand such an increase in risk?

Zhai Panmao: According to current research, global warming will cause extreme heat events to become more frequent, which is the most certain. Composite events are a new focus in the AR6 report, and the so-called composite events refer to multiple extreme events that occur at the same time, one after the other, or occur at the same time in different regions, which can be called composite events. One of them is more "compound", such as the simultaneous occurrence of high temperatures and drought and the interaction (such as the extreme heat and drought in the Yangtze River basin last year), or the impact of sea level rise in coastal areas, and the combination of storm surge and upstream water in coastal areas.

There is also the possibility that one event triggers the occurrence of another. However, the IPCC Working Group I assesses that after climate warming, these extreme events have a tendency to increase, but there is only medium confidence in the understanding of changes in cascading events like compound events, and research still needs to be strengthened.

The climate crisis is no longer unfounded, but imminent

The Paper: As China is moving towards the "dual carbon" goal, what kind of climate science information do you most want to convey to the public as a scientist?

Zhai Panmao: We can't tell lies to the public. From a scientific point of view, what we want to tell you is that, first of all, climate change is real, and it is what we are really experiencing. We will increasingly experience the effects of this climate change. And it will have an increasingly important impact on the future of our human beings, ecosystems, etc., so we need to take effective action to combat climate change as soon as possible.

With the frequent occurrence of various extreme weather and climate events that each of us has experienced or reported in the media, we should all be soberly aware that the climate crisis is no longer "unfounded", but imminent. Science communication plays an important role in improving the public's understanding of science, so it is necessary to pay attention to the scientific and popular science of science communication, not only to disseminate knowledge and information with a scientific attitude, but also to let the public understand the latest understanding and views of science in a way that is easy for the public to understand.