Playing Jenga with the world: the feedback of human activities on the trends of extreme weather events worldwide
Life on Earth is possible only in a balance within nature that continually adjusts itself to evolving complexities. The biosphere – the region of the Earth where we find life – is composed of living organisms (i.e., biotic) and inorganic (i.e., abiotic) components that interact, forming interdependent networks. Human activity is causing significant changes and stresses on these networks, which is increasingly reflected in extreme weather patterns sometimes with devastating effect.
Humans have made significant changes worldwide, including massive landscape transformations, changes to nutrient and energy cycles in ecosystems, driving species to extinction at a rate comparable to those caused by ice ages, and even changing the composition of the atmosphere. At the same time, we are monitoring and witnessing the effects of these activities on the biosphere and ultimately on the conditions for our life on this planet.
A common analogy we might use is to compare the components of the biosphere to the pieces in a game of Jenga. In this game, starting with a tower of stacked hardwood blocks, players take turns removing one block at a time and placing it on top of the tower. As the game goes on, the tower becomes progressively more unstable, ending the game with its inevitable collapse. Similarly, we continue to move pieces in the real world, hoping that the inevitable tipping point won’t come.
We know of the potential of humans to accelerate the natural greenhouse effect of the Earth for at least 125 years since Svante Arrhenius, a Swedish chemist, assessed the potential effects of industrial-age coal burning in the atmosphere. Since then, science has made incredible advances in understanding the mechanics and extent of what we now call climate change. However, as world governments resist meaningful measures to reduce the human causes of climate change, its impacts are rapidly accruing.
“The greenhouse effect is a natural process that warms the Earth’s surface. When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.
Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbons (CFCs).
The absorbed energy warms the atmosphere and the surface of the Earth. This process maintains the Earth’s temperature at around 33 degrees Celsius warmer than it would otherwise be, allowing life on Earth to exist.” Department of Agriculture, Water and the Environment, AU.
Climate change already affects approximately one in every five threatened species of the world, mean global surface temperatures are consistently going up, sea levels are rising, and extreme weather events are becoming more frequent and intense. Meanwhile, many countries are not meeting previously set goals to reduce emissions of greenhouse gases, we have deforested 10 million hectares per year between 2015 and 2020 worldwide, and 84% of the world’s energy still comes from fossil fuels.
Fig. The Bramble cay melomys (Melomys rubicola) was declared extinct in 2016. It was the first mammal to go extinct due to global warming.
Among the many effects of climate change, extreme weather events are perhaps the most noticeable in our daily lives. As the average temperature of the Earth increases, the immediately expected result is that warm extremes become warmer and cold extremes become less cold. The warmer air holds higher moisture content, which leads to increases in severe precipitation. Also, sea levels rise due to the expansion of the water and ice melting, which heightens storms surges.
Beyond these first-order effects, scientists have been able to link chains of events showing how climate change influences the extreme weather events we experience worldwide. In fact, of hundreds of extreme weather events that scientists have studied, including heatwaves, droughts, heavy rains, wildfires, and tropical cyclones, climate change has made 70% of them more likely to occur or more damaging.
Fig.Change in global surface temperature relative to 1951-1980 average temperatures. “Temperature anomaly” refers to how much warmer or colder than the long-term average something is.
Since the early 2000s, scientists have been increasingly interested in quantifying the human effect on extreme weather events. The study of extreme event attribution, as it became known, links the seemingly abstract concept of climate change with the tangible experiences of the weather. Carbon Brief maps and tracks the studies of the field, and the results are clear to see. Among hundreds of studies, Carbon Brief reports that climate change affected almost four out of every five weather events analyzed, whether in their magnitude or likelihood to occur.
These studies highlight how climate change is already affecting the lives of people around the world. For example, scientists estimate that 570 of the 1050 human deaths recorded in Paris and London due to the 2003 European heatwave were down to the fact that climate change made the heat more intense than it would otherwise have been. Scientists are also calculating the economic costs associated with our contribution to extreme weather events. For example, we can attribute approximately $67 billion of the damage caused by Hurricane Harvey in 2017 to the effect of human-driven climate change on that event.
Thanks to the scientific community worldwide, now more than ever we are equipped with reliable databases, refined analytical approaches, and overall knowledge of the roots and mechanics of and ways and reasons to mitigate climate change. Throughout the world, institutions and governments are cooperating to further improve the reach of event attribution studies, like the operational attribution service currently being developed by the European Centre for Medium-Range Weather Forecasts (ECMWF) through the Copernicus Climate Change Service (C3S).
The global climate 2015-2019
But science can only inform and provide tools to deal with the problem. Effective change relies on the policymakers and the support of the general public. While most countries are struggling to meet the goals set in the Paris agreement in 2015, some major economies have backtracked. For example, the US left the Paris agreement in 2017, although it rejoined in 2021. During the last decades we have had some progress in our collective quest to mitigate climate change. However, evidence shows that we still need to step it up drastically.
Fig.Map of the performance of the countries that are part of the Paris agreement towards meeting their self-set targets of CO² emissions.
Beyond human production chains, ecosystems like forests and wetlands work as carbon sinks, absorbing large quantities of CO² from the atmosphere. Efforts to conserve and restore ecosystems are still necessary and vastly insufficient, especially in tropical regions, where the deforestation rates are the highest. Additionally, as species are the building blocks of ecosystems, we urgently need to reduce the risks to biodiversity posed by climate change. Past mitigating climate change, we should also include minimizing non-climate stressors to prevent extinctions and secure the integrity of ecosystems. We need to step up our actions, using all the knowledge we already gathered and the tools we created, to make up for decades of neglect of humankind’s impacts on the world’s climate. Otherwise, just like in a game of Jenga, collapse might follow our next move.