Sorry Jessica but you’ve got a very unrealistic essay to write and whoever set you that topic really needs to get a grip on reality and apply some honesty and objectivity.
Yes there is global warming, yes there are heatwaves, but no-one can claim that this heatwave or that heatwave was caused by global warming.
We know for a fact that the number of heatwaves has doubled in recent years, we also know that the number of individual days on which heatwave conditions are reached has tripled. We also know that the planet is warming up and that as a result there will be more heatwaves.
But with or without global warming there would be heatwaves so it’s very unscientific and completely irrational to claim that a specific heatwave was caused by global warming.
Far more sensible would be to claim that such and such a heatwave was probably made worse because of global warming. This is a sensible statement and one that can be backed up with accurate facts and figures.
Anyway, to address your specific point…
The amount of greenhouse gases in the atmosphere is increasing due to our emissions. These gases act as Earth’s insulation and are what ensures we have a planet that’s warm enough to live on. As levels increase the insulation becomes more effective and a greater amount of heat becomes trapped within the atmosphere, this causes the planet to warm up.
There are many consequences of a warmer planet including disruption to weather patterns.
With more heat in the atmosphere the likelihood of heatwaves increases, this is because ‘normal’ conditions are closer to the heatwave threshold than they used to be so less exceptional weather is required in order to trigger a heatwave. For the same reason, heatwave conditions are likely to persist longer than they used to.
The two deadliest heatwaves ever recorded have happened recently – Europe in 2003 and Russia in 2010. These events were like nothing that’s gone before them and many new all time temperature records were set.
The main cause of both these events lies high in the atmosphere of the mid northerly latitudes. Here we find fast flowing streams of air known as Jets or the Jet Stream. It was unusual behaviour in the Polar Jet Stream that created the conditions for the 2003 and 2010 heatwaves.
The reason for this unusual behaviour was that the normal pattern of the jet stream had been disrupted when it encountered opposing winds known as Rossby Waves. The waves effectively caused the stream to stall and this meant that weather systems became locked in one place.
Instead of moving on after a few days they remained in place and where the air masses were hot it led to heatwave conditions becoming established. Once this happened the heatwaves fed into themselves and it got hotter and hotter. Usually the heatwave conditions would move on, mix with cooler air and fade away but when they become static there’s no cold air being introduced.
The opposing Rossby Waves are probably linked to global warming, the explanation for which is complex. These waves are becoming more frequent as the planet warms up and the jet streams are becoming disrupted ever more frequently. Not only can this increase the likelihood of heatwaves but can cause all manner of extreme weather events. An example being the devastating floods in Pakistan last year in which tens of millions of people were left homeless. The same disruption to the jet stream that caused the heatwave in Russia also caused the floods in Pakistan.