HEATWAVES, DEADLY FLOODS and wildfires all mean people are experiencing the link between extreme weather and climate change.
Here are four ways climate change is contributing to extreme weather:
1. Hotter, longer heatwaves. Heatwaves can be made longer and more intense by another weather phenomenon – a heat dome. In an area of high pressure, hot air is pushed down and trapped in place, causing temperatures to soar over an entire continent.
When a storm distorts the jet stream, which is made of currents of fast-flowing air, it is a bit like yanking a skipping rope at one end and seeing the ripples move along it.
These waves cause everything to slow drastically – and weather systems can become stuck over the same areas for several days.
This same type of stuck weather pattern is also responsible for the record warmth experienced in India, the Philippines and Pakistan. Persistent high pressure and lower than normal rainfall led to India’s hottest March since records began 122 years ago.
In those countries, the summer heat is starting earlier and is more intense for longer periods of time.
2. More persistent droughts. As heatwaves become more intense and longer, droughts can worsen. Less rain falls between heatwaves, so ground moisture and water supplies run dry more quickly. This means the ground heats up more quickly, warming the air above and leading to more intense heat.
3. More fuel for wildfires. Wildfires can be sparked by direct human involvement but natural factors can also play a huge part. The cycle of extreme and long-lasting heat caused by climate change draws more and more moisture out of the ground and vegetation.
These tinder-dry conditions provide fuel for fires, which can spread very fast. The frequency of large wildfires has increased dramatically in recent decades. Compared with the 1970s, fires larger than 10,000 acres (40 sq. km.) are now seven times more common in western America.
4. More extreme rainfall events. In the usual weather cycle, hot weather creates moisture and water vapor in the air, which turns into droplets to create rain.
The warmer it becomes, however, the more vapor there is in the atmosphere, resulting in more droplets – and heavier rainfall, sometimes in a shorter space of time and over a smaller area.
The weather across the globe will always be highly variable – but climate change (A few still refuse to believe it!) is making that more extreme.And the challenge now is not only limiting the further impact people have on the atmosphere but also adapting to and tackling the extremes we are already facing. By Manny Palomar, PhD (EV Mail June 19-25, 2023 issue)
