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Climate change impacts: case studies

Climate change is not just about data and trends – it has major consequences for the well-being of people and the planet.

In its most recent report on impacts and adaptation, the IPCC states that human-induced climate change “has caused widespread adverse impacts and related losses and damages to nature and people, beyond natural climate variability.” Some of those impacts are happening slowly and ‘behind the scenes’ as long-term trends in temperatures and precipitation, or other climate variables. We also witness them in ecosystem changes, when plants and animals shift habitats or even disappear. 

Other impacts come in the form of extreme weather events, which scientists are able to link or attribute to climate change. Extremes such as cold spells, torrential rains or heat waves, which are fairly unlikely but can have profound consequences, have always been part of the natural climate variability. Through our influence on the climate system, however, humans are ‘putting our finger on the scale’, with these events becoming more likely and their consequences increasingly more severe. The IPCC reports refer to this as ‘beyond natural climate variability’.

Thanks to human ingenuity and resilience, many communities have found ways to adapt to both acute and more long-term climate impacts, minimising the devastation they cause. Yet, some impacts are simply impossible to adapt to and the losses they cause are often irreversible. As we delay meaningful action on reducing greenhouse gas emissions, we are losing ground on adaptation as well. This is in part due to the fact that time is running out for some of the solutions that could have worked earlier at lower levels of warming. It is also due to growing costs as well as depleting adaptive capacity, wherein living beings and communities that are struck by multiple or overly frequent impacts lose the ability to recover.

In this deep dive, we will look at recent examples of extreme heat, flooding and drought for which climate scientists working for the World Weather Attribution (WWA) project have been able to identify and quantify the link to climate change.

Land and oceans under extreme heat

Alisdare Hickson / Flickr

In the spring and summer of 2022, abnormally high temperatures hit multiple regions of the world. First, India and Pakistan as well as large parts of South Asia experienced a heat wave that was about 30 times more likely because of climate change, according to WWA estimates. Scientists note that while heat waves are not unusual before the monsoon, the combination of extreme heat and much less than average rain led to disastrous consequences for public health and agriculture. These impacts were compounded by other non-climate risks, such as a shortage of coal leading to power outages in India. They also had far-reaching implications for the rest of the world, as reduced wheat crop yields prevented the region from supplementing the global supply hit by the war in Ukraine.

Later in 2022, summer heat waves in Europe caused major disruption in people’s lives and economic activity. In France, exceptional heat interfered with electricity production from nuclear power plants, while the United Kingdom logged its first ever temperature above 40°C. An analysis from WWA concluded that, without human-caused climate change, that would have been extremely unlikely.

Extreme heat can be just as dangerous when it happens in the ocean as it is on land. Prolonged periods of abnormally high surface water temperatures are called marine heat waves, and their frequency and intensity have increased due to climate change by more than twentyfold, according to a 2020 study. This study also showed that, of the seven highest-impact marine heat waves since 1981, all but one could be tied to human-driven warming.

Flooding: extreme rain and tropical storms

Bärwinkel,Klaus, CC BY-SA 4.0

In January and February 2022, Madagascar, Mozambique, Malawi and Zimbabwe experienced a series of tropical storms, including three that were strong enough to qualify as tropical cyclones. These storms brought deaths and injuries as well as vast infrastructure damage, and their long-term consequences for the well-being of highly vulnerable local communities are yet to be fully understood. The WWA team was able to show that climate change increased the likelihood and intensity of the rainfall associated with two of the storms, Tropical Storm Ana and Tropical Cyclone Batsirai.

In 2021, two days of very heavy rainfall compounded by wet weather conditions beforehand and other local factors caused severe flooding in Germany and parts of Western Europe. Over two hundred people lost their lives, and hundreds if not thousands more faced damage to their housing and transport infrastructure, or were temporarily cut off from evacuation and emergency response. While it is difficult to detect local trends in precipitation and make conclusions on how much more likely climate change can make these events, the WWA study established that an upward trend is evident for the larger region of Western Europe.

Drought and water shortages

Too little precipitation due to drought can be just as devastating as storms and floods. In the summer of 2022, water shortages, fires and crop losses across the Northern Hemisphere were driven both by the high temperatures mentioned above and exceptionally low rainfall, with soils drying out particularly in Europe and mainland China. The WWA analysis established the cause to be related to the higher than average temperatures rather than the lower precipitation, meaning that our agriculture and energy systems are more likely to face these ‘one-two punches’ of combined risks as the climate warms.

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