Science

A summer of extreme weather explained

Scorching: Records were smashed across Europe, while flooding and wildfires wreaked havoc worldwide. Source: Belle Co (Via Pexels)

by Angharad May

This summer, news programmes sounded like a broken record. Scorching weather. Hottest day. Extreme temperatures. Whilst wonderful weather was enjoyed in the UK, the implications of the blistering sunshine should not be ignored. Even those of us not studying climate change know that it leads to global warming which leads to increasing weather extremes, but is this all that is happening?

Global warming is affecting the Jet Stream, and therefore the weather in the UK. The Jet Stream is a band of strong winds around the Northern Hemisphere, occurring 5-7 miles above the Earth, blowing up to 200mph from west to east and driven by contrasting temperatures between the tropics and the Arctic.

The warming of the Arctic has caused the Jet Stream to slow down while undulating more. Since the difference in temperature between the tropics and the Arctic is decreasing, the Jet Stream is becoming weaker and less stable leading to bouts of extreme temperature.

Changes in ocean circulation are also leading to temperature changes in the UK

The North Atlantic Drift (or Gulf Stream) System affects the Jet Stream as the surface temperature of oceanic water adjusts with the pattern of high and low pressure in the atmosphere, subsequently altering jet stream undulations. It is these undulations which determine the location of low-pressure depressions with associated weather fronts and higher wind speeds, and calmer areas of high pressure. In the summer of 2018 a persistent area of high pressure prevented rain-bearing fronts from reaching the UK.

Most scientists (if not politicians) agree that global warming has been caused by human activity, namely the release of greenhouse gases, and if no action is taken to prevent further warming the earth as we know it will change; glaciers will melt, sea level will rise, low-lying coastal land will be under the sea and some areas will become uninhabitable due to extreme heat.

However, humans have been slow to react to these potential consequences of global warming

Some argue that the climate and therefore temperature has natural variability. The natural fluctuation is now raising temperature and combined with greenhouse gas emissions global temperature is rising.

Professor Lorraine Whitmarsh from Cardiff University’s School of Psychology & Tyndall Centre for Climate Change Research said: “Climate change is an issue which many people struggle to relate to because it’s a global, long-term and complex issue – so can easily be ignored in day-to-day life. However, when we directly experience impacts of climate change, like floods, those who believe in human-caused climate change are likely to become more concerned.

“So it remains to be seen whether experiencing heatwaves increases climate change concern, or simply raises awareness of the issue, and how crucial media coverage that connects climate change to current weather events is.”

Climate change’s main consequences

The main consequences of climate change are that: temperatures will continue to increase; frost-free seasons will lengthen, impacting agriculture and ecosystems; heavy precipitation events will increase; droughts and heatwaves will become more intense with a reduction in soil moisture making the heatwaves worse; the intensity, duration and strength of hurricanes will exacerbate; and global sea level will continue to rise due to melting ice, causing more flooding.

As with any contentious issue both pros and cons exist from the above list, and these each have major ramifications of their own, but humans do not see how such extreme events are linked to climate change, despite scientists having long-predicted these effects. Human-caused climate change is making these events more extreme, with the results of our negative actions unfolding in front of our eyes. It’s almost as if climate change is screaming out, sending us signals to say, ‘hey, stop killing the planet’. The worry is that if humans continue to ignore these signals, these extreme events are likely to become more pronounced.

Dr. Marie Ekstrom, Research Fellow in Climate Change from Cardiff University’s School of Earth and Ocean Science suggests: “What the future climate will look like we can only estimate using very sophisticated models of the Earth system.”

The fact that the Met Office predictions for UK mean summer temperatures in the 2050s compared to 1961-1990 range between an increase of 1 to 5ºC for a low emission scenario and an increase of 1 to 7ºC if the future follows a high emission scenario” just shows the complexity of the science of meteorology.

Whilst many theories exist concerning the causes and ongoing impact of climate change, what is clear is that negative human actions contribute to a worsening state of global warming, manifesting itself in extreme weather events which have knock-on effects in uncertain but potentially extensive and devastating ways.

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