FreeWord – Extreme Weather Events and Climate Change

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Hello again folks! It’s FreeWord time. Strap on because it might get turbulent!

As the global temperature continues to rise, many changes on the Earth’s climate has started to trigger. Heatwaves, floods, and droughts are the primary ways that most people encounter these changes. Not only has the frequency of extreme weather events increased, but the intensity as well. Extreme weather includes unexpected, unusual, unpredictable, severe, or unseasonal weather. Typically, these events are considered “extreme” if they are unlike 90% or 95% of similar weather events that have happened before in that same geological area that produce unusually high or low levels of rain or snow, temperature, wind, or other effects.

Over the last decades, much of the world has seen increases in prolonged periods of excessively high temperatures, heavy downpours, severe floods, and droughts. Due to these events, Extreme Event Attribution (EEA) has been born, which is a new field in climate sciences: at the intersection between statistics, atmospheric dynamics, and human sciences. One of its goals is to describe whether and how the probability of an event, like a heatwave occurs, and its ratio to climate change. Studies indicate an increasing threat from extreme weather in the future.

How Global Warming affects Weather Parameters

In the context of global warming, rising temperatures don’t automatically cause extreme weather, but they increase the odds of extreme events occurring. Researchers are using computer simulations to predict these weather conditions with and without global warming and other contributing factors. By comparing the different scenarios, they can identify how global warming has affected the observed extreme events. Research has concluded that rising temperatures have several effects on the factors involved. Some examples of these factors:

Evapotranspiration Increases in total evaporation of water from the soil, plants, and water bodies. This can lead to a direct effect on the frequency and intensity of droughts.

Humidity The increase in water vapor has led to a more humid atmosphere; the atmosphere contains 4% more water than 40 years ago. This increases the risk of extreme rainfall and snowstorm events.

Sea-surface temperature (SST) – Associated with changes in the atmospheric circulation and precipitation. It has been found to strengthen hurricanes and cause droughts, particularly in the tropics.

The Frequency of Events

Statistics over the past 20 years from 260 weather events have been heavily dominated by studies of extreme heat (31%), rainfall or flooding (20%), and drought (18%). Together, these three groups make up more than two-thirds of all published studies (68%). The full list is available on the DATA Carbon Brief Attribution Database. As the chart below demonstrates, combining the numbers of these events has increased rapidly over time, from eight in 2012 to 59 in 2018. Note that studies follow a year or so after the event itself.

Note: the total number of events dipped in 2017 because the Bulletin of the American Meteorological Society’s special report for that year was published in early 2018 rather than late 2017.

Human Influence

In recent years some extreme weather events have been attributed to human-induced global warming, with studies indicating an increasing threat from extreme weather in the future. The results of the attribution studies that have been published so far, scientists found that human-caused climate change has altered the likelihood or severity of an extreme weather event in 78% of cases studied (68% made more severe or likely and 10% made less so). Human Influence On Extreme Weather Types illustrated in the chart below.

The Future

As the climate continues to heat up in response to further greenhouse gas emissions, high-temperature extremes will worsen, and cold extremes will become less severe. The rate of change in temperature extremes highly depends on future emission levels: higher emissions will cause progressively more frequent extreme high temperatures. For our planet, a warmer future will likely mean that extreme precipitation is more intense and more frequent.

At the 2015 Paris climate conference, the countries of the world pledged to the Paris Agreement to limit the global temperature rise to 2C, a step that will require a radical reduction in the use of fossil fuels that are the primary cause of global warming. Missing those targets could result in fatal results since if global temperatures rise by up to 3 degrees Celsius above their preindustrial levels, the risk of extreme events could rise to fivefold in certain parts of the world. In addition, it would lead to significant sea-level rise and the loss of plant and animal species. Overall, up to 60 percent of locations across North America, Europe, East Asia, and parts of southern South America are estimated to see at least a threefold increase in various extreme events. 

Conclusion

Although it isn’t possible to declare that global warming is directly causing a particularly extreme event, it is totally misleading to state that global warming has no effect on extreme weather events. Rising air and sea temperatures have numerous effects on the atmosphere, and this increases the odds of more extreme weather events. Now is the time to step up efforts to protect our planet and stop global warming. 2020 should be the year of the fight against deforestation, biodiversity loss, and the use of fossil fuels.


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1 Response

  1. January 31, 2020

    […] FreeWord – Extreme Weather Events and Climate Change […]

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