The year 2021 has seen a flurry of extreme events around the globe. Among the many that have captured headlines so far this year:

 

– Devastating flooding in Australia, Europe, Asia, and the U.S. Northeast.
– California’s massive Dixie Fire, now the state’s second largest on record.
– A crippling U.S. polar vortex event that paralyzed Texas in February with bitter cold temperatures and massive power outages.

 

From the unique vantage point of space, we’ve been able to observe and monitor these events, no matter where they’ve occurred. Satellite data from NASA and other institutions are critical to understanding how and why extreme events take place. This year’s events come on the heels of a record-breaking 2020 in the United States. According to the National Oceanic and Atmospheric Administration, there were 22 separate weather and climate-related disasters last year where the overall damages/costs for each reached or exceeded $1 billion. Last year also saw a record number of tropical cyclones form in the Atlantic Basin.

 

There’s growing evidence that people and the planet are increasingly impacted by extreme events. According to the Fourth National Climate Assessment, published in 2018 by the U.S. Global Change Research Program, “more frequent and intense extreme weather and climate-related events, as well as changes in average climate conditions, are expected to continue to damage infrastructure, ecosystems, and social systems that provide essential benefits to communities.” As the impacts of extreme events continue to mount, interest has grown in the scientific community to study whether specific extreme events can be partially attributed to human activities. With the help of climate models, scientists have conducted an impressive array of studies, looking for possible links between human activities and extreme events such as heat waves, rainfall and flooding events, droughts, storms, and wildfires. Increasingly, they’re able to draw robust connections. There are reductions in the number of cold waves, increases in the number of heat waves on the ocean and on land, increases in the intensity of rainfall and drought, and increases in the intensity of wildfires.

 

Despite thecomplications and uniqueness of individual events, scientists are finding significant human contributions to many of them. An interactive map produced by CarbonBrief in 2020, shown below, provides visible evidence of these studies. On it, red dots represent different extreme events where scientists have found a substantial contribution from human activities – that is, human activities have made these events more frequent or more intense. For some of the blue dots, however (associated with rainfall events), scientists have yet to find a substantial human contribution. Events with a big thermodynamic component – that is, those where there’s a big impact because of heat – are being made more intense or more frequent because of human activities. In contrast, for extreme events that are more dependent on the dynamics of the atmosphere, the links to human activities are less clear. 

 

The combination of models and observations, informed by the unique view that space provides, imply that almost all the current multi-decadal trends we’re seeing in climate are the result of human activities. In addition, there’s increasing confidence that human- induced climate change is making extreme events statistically much more likely. This doesn’t mean every extreme event has a substantial human contribution. But with extreme events such as heat waves, wildfires and intense precipitation, we’re seeing, in event after event, a very clear human fingerprint.

BY NASA link (https://climate.nasa.gov/ask-nasa-climate/3125/extreme-makeover-human-activities-are-making-some-extreme-events-more-frequent-or-intense/)