Can global warming explain the long-term increase in heat waves?
As the IPCC concludes "It is very likely that cold days, cold nights and frosts have become less frequent over most land areas, while hot days and hot nights have become more frequent. It is likely that heat waves have become more frequent over most land areas."
Has global warming caused this increase? If not, what has?
As Kevin Trenberth stated "...it is impossible to prove there is not a link. Given the widespread influence of global climate change, it is therefore likely that there is indeed an influence."
- TrevorLv 79 years agoBest Answer
As per the links in your previous question and the ones I’ve included in earlier answers, we know that there has been a significant increase in both the intensity and frequency of heatwaves; it would be foolish to try and pretend otherwise.
Proving a link between such events and global warming isn’t quite so easy. We know that the world is warming up, we know there are more heatwaves and it would appear that the latter is a consequence of the former. There is a perfect correlation between heatwave episodes and average global temperatures, as would be expected; the reconstructed and historical data would appear to show that this has long been the case – again, just what we’d expect to see.
The problem in trying to find absolute proof is that heatwaves are governed by multiple interacting factors. There have always been heatwaves, even when the world was in cooling phases, it’s just that they weren’t so common and tended not to be quite so extreme.
Perhaps in this instance it’s better to look at statistical probabilities and to contrast the recent incidence of heatwave activity with the historical data. I don’t have the figures to hand but we do know that the number of heatwaves has doubled, as such there is a 50% chance that any individual heatwave would have occurred anyway.
If we assume that the number of heatwaves in recent years has been just 100 more than would have occurred anyway (i.e. there’s been 200 in a period of time when 100 would have been expected) then the odds of this happening naturally are 1 in 1,267,650,600,000,000,000,000, 000,000,000. On that basis I think it’s pretty safe to assume that manmade global warming is having an impact.
- Paul's Alias 2Lv 49 years ago
Earlier this year when I was arguing that the unusually hot temperatures were likely caused by global warming, Dana "cautioned" me that short term and local weather events should not be treated as evidence of warming.
Now he has reversed direction.
Why? Because some professional climatologist has said 2003 likely was from global warming, and because he found a "peer reviewed" study saying so.
Nothing has changed scientifically since earlier this year--indeed Dana is taking a more radical position I took being that I was considering global data, not just European--what occurred was a *sociological* effect.
Indeed Dana I was wrong on this particular one--you were not referring to short term here.
- BarbaraLv 44 years ago
It is getting more and more difficult to deny that we are, indeed, seeing the effects. If a penny comes down heads four times out of five, that could be chance. If it comes down heads forty times out of fifty, it's a biased coin. Any one event could be chance, but the preponderance of warming-driven events over others constitutes evidence. Weather is merely weather, but enough examples of weather add up to climate. Comment: Sarge927 is shameless: "the UK-based climatologists ... admitted the data had to be seriously fudged to "prove" global warming". Total lies. They didn't because it wasn't. Six separate enquiries have now exonerated them of all accusations of dishonesty. Surely he has heard about this? poeticmaniac needs to be careful what he's smoking: "global warming is fake the government already national admitted it was a scam to get people to spend money". No relationship to reality.
- Facts MatterLv 79 years ago
as I understand it, the predicted consequences of anthropogenic global warming include both an increase in the average temperature, and an increase in fluctuations from the average.
So global warming does indeed explain the increase in heat waves, and the observed increase in heat waves, in turn, increases our confidence in the reality of global warming.
As always in science, successful prediction is explanation of the phenomenon, and confirmation of the reasoning that led to the prediction.
Comment: the Sun is just now emerging from an 11 year cooling cycle, and the Medieval warm period exceeded present temperatures only in parts of the north Atlantic region, if at all. Does Chinchilla really not know this?
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- 9 years ago
The more the people, the warmer the earth is going to be. Think about it. If you put 10 people in a room, or 100 people, which would be warmer? Take Phoenix Arizona. Since it grew to over one million people, its normal nightime low has went from 74 in 1955 to 84 degrees today.Source(s): myself
- Dana1981Lv 79 years ago
Yes. Stott et al. (2004) concluded that AGW has made heat waves like the European event of 2003 twice as likely.
"Using a threshold for mean summer temperature that was exceeded in 2003, but in no other year since the start of the instrumental record in 1851, we estimate it is very likely (confidence level >90%) that human influence has at least doubled the risk of a heatwave exceeding this threshold magnitude."
*edit @ Paul* you are mistaken, this question is about long-term increases in frequency.
- 9 years ago
there is no such thing as global warming.. its a media scare tatic
- Anonymous9 years ago
There has been heatwaves ever since man decided to notice for millions of years.
Caused by the Sun and the Climate change of Summer .
- 9 years ago
Careful of the "easy answer." Its easy to say "its mans fault." No further investigation. All the climate models are flawed, and admittedly by their own scientific followers. Not only is the sun becoming more active in its 11 year cycle, the Earth has been hotter several times before, most recently during the Medieval Ages. No human industry there to blame.
The simplest answer, and most rational one, is that the Earth changes over time. We will see more heat for a period of 100 years, then a period of cooling, and so on. These are even considered small changes in the long term scheme of climate change.
Study the cycle of ice age activity. We know of at least 4 major ice ages, and ice core studies tell us much about the climate before, during, and after those periods.
- pegminerLv 79 years ago
It's partly due to global warming, partly due to urbanization.