It’s not too late yet

It is the most comprehensive scientific inventory of climate change – and it turns out bleak: The Intergovernmental Panel on Climate Change (IPCC) has published a nearly 4,000-page new report on global warming. The core message: Climate change has accelerated. But in addition to the bad news, there is some that give hope: It is not yet too late to change course.

Emissions are rising unchecked

Six years ago, in the Paris Climate Agreement, almost 200 countries committed themselves to limit global warming to well below two degrees, if possible below 1.5 degrees Celsius, compared to the pre-industrial age. But despite all the confessions, little has happened: greenhouse gas emissions have continued to rise. At the same time, global temperatures have risen by an average of 1.1 degrees.

The corona pandemic also had hardly any effect. The lockdowns had led to temporary reductions in CO2 emissions, said the co-chair of the responsible IPCC working group, Valérie Masson-Delmotte. However, these savings are only a few percentage points at global level, and the atmospheric CO2 concentration has continued to rise.

The extent of the recent changes in the entire climate system has been “unprecedented” for many centuries to millennia, according to the IPCC report. For example, the concentration of CO2 in the past two million years is unlikely to have been as high as it was in 2019.

Global warming is accelerating

The targeted maximum temperature increase of 1.5 degrees could be reached as early as 2030, so in nine years the researchers are warning: inside. That would be ten years earlier than forecast in 2018. The mark is likely to be exceeded by 2040 at the latest – depending on how much emissions are actually reduced in the next few years. Only the optimistic simulations assume that the goal of 1.5 degrees set in the Paris Agreement can be achieved. “We can see that each of the past four decades has been warmer than any of the previous decades since 1850,” says climate researcher and author Veronika Eyring. This warming has also happened much faster since 1970.

More extreme weather

Heat waves, heavy rain, drought and tropical cyclones: Climate change means that extreme weather conditions occur more frequently and more intensely, all over the world. No region is spared, say the authors: inside.

Cities are particularly affected because they are usually warmer than their surroundings. Strong heat waves, which previously occurred roughly every 50 years, will in future occur once a decade. Fires become more intense and last longer.

In the past, the connection between individual weather events and climate change was unclear, says co-author Michael Wehner from the Lawrence Berkeley National Laboratory in California. “But now we can actually make quantitative statements about extreme weather events.”

Irreversibly rising sea levels

Some of the consequences of global warming are already irreversible today: Even if greenhouse gas emissions were drastically reduced, sea levels would continue to rise and would “remain elevated for thousands of years,” the report says. By the year 2100, levels could rise by up to one meter. Even if climate neutrality is achieved by 2050, the sea level is likely to be up to 62 centimeters higher by the end of the century than in the years 1995 to 2014.

Above all, the melting of the ice sheets in Greenland and Antarctica, which has increased sharply over the past decade, is causing sea levels to rise. In addition, there is condensation from mountain glaciers and the thermal expansion of the warmer seawater.

Thawing floating ice does not increase the level, but the sea ice is also disappearing. “Before 2050 we will in all probability experience a summer in the Arctic in which the Arctic Ocean will be largely free of sea ice,” says Dirk Notz from the Max Planck Institute for Meteorology in Hamburg.

Carbon sinks are decreasing

Natural carbon sinks play an important role in the fight against climate change. “We know that half of all our CO2 emissions are absorbed and stored by plants, soil and the ocean,” says Masson-Delmotte. However, climate change is reducing the absorption capacity of the natural sinks.

Saving emissions works

If we succeed in significantly reducing greenhouse gas emissions immediately, this will have a positive effect in around 20 years. The authors state “high trust” for political decision-makers in the summary for this time horizon. The knowledge is very well secured.

In contrast to scenarios with still high emissions, the global temperature curve will then flatten out. “If we end up emitting carbon dioxide around the year 2050, it is extremely likely that we will be able to keep global warming below two degrees Celsius,” says Masson-Delmotte. It is then also more likely that the temperature rise will only temporarily exceed 1.5 degrees Celsius and only by about 0.1 degrees Celsius than that this target will be exceeded permanently and more clearly. The emission savings would also improve air quality in many regions of the world.

The picture becomes clearer and clearer

The IPCC report was published later than originally planned due to the Covid-19 pandemic. But he did appear, despite the travel restrictions and the challenge of clarifying difficult content-related questions at screen conferences with hundreds of participants. “They said it couldn’t, but we made it,” said Panmao Zhai, the Chinese co-chair of the IPCC working group.

The over 230 authors from 65 countries delivered, evaluated over 14,000 scientific publications and answered over 78,000 comments from the review rounds. The report brings the political discussion up to date on the scientific basis of climate change.

“The report provides a wealth of policy-relevant information,” said IPCC Chairman Hoesung Lee, citing the focus of regional climatic developments as the first example. New chapters have been added to the report and the IPCC publishes an interactive atlas, thus mapping the increasingly spatially resolved findings of climate research.

Misleading hypotheses are off the table

The history of the IPCC is closely linked to the discussion about its credibility, which has received a lot of media attention. It has been a long time since marginal mistakes like misjudgments about how the Himalayan glaciers were thawed were turned into great stories.

In the last report, at the request of some governments, an alleged pause in warming was declared between 1998 and 2012. However, this pause never took place. It only appeared visible if one looked at the further development of the temperature compared to the exceptionally high level of 1998.

The long-term warming trend continued unabated during this period. “We have known for decades that the world is warming,” said Panmao Zhai at the press conference. Each of the past four decades has been warmer than before. In addition to doubts about the existence of warming, the report also removes doubts that it is caused by greenhouse gas emissions: “It is clear that human influence has warmed the atmosphere, oceans and land,” says the first highlighted main message of the summary. This creates more space for real topics in the climate discussion.