New Study On How Global Warming Changes The Weather

Human caused greenhouse gas pollution has warmed the planet. Global warming means more extreme weather. Many meteorologist who watch the weather every day see this. More and more research shows that greenhouse gas pollution changes the weather in a way that causes even more change in the weather. Changing weather systems means more lightning, increased high precipitation events in certain regions like the US Northeast, including more frequent large snow storms.

Global warming has had uneven effects. The Arctic has warmed relatively more than most of the rest of the planet. The major movements of air masses are driven by a combination of the rotation of the Earth and the movement of extra heat from the Equator towards the poles, a process that sets up the trade winds and the jet stream. But the additional warming in the Arctic has changed this pattern measurably, resulting in these and other changes in weather patterns.

A new study out in Science, by Dim Coumou, Jascha Lehmann, and Johanna Beckmann, “The weakening summer circulation in the Northern Hemisphere mid-latitudes,” demonstrates that storm activity in much of the Northern Hemisphere has changed in a way that matters to our weather, and is likely to change more in the future. From the abstract:

Rapid warming in the Arctic could influence mid-latitude circulation by reducing the poleward temperature gradient. The largest changes are generally expected in autumn or winter but whether significant changes have occurred is debated. Here we report significant weakening of summer circulation detected in three key dynamical quantities: (1) the zonal-mean zonal wind, (2) the eddy kinetic energy (EKE) and (3) the amplitude of fast-moving Rossby waves. Weakening of the zonal wind is explained by a reduction in poleward temperature gradient. Changes in Rossby waves and EKE are consistent with regression analyses of climate model projections and changes over the seasonal cycle. Monthly heat extremes are associated with low EKE and thus the observed weakening might have contributed to more persistent heat waves in recent summers.

The study has been written up by Chris Mooney, in the Washington Post, and Roz Pidcock at Carbon Brief. From the study’s press release,

“When the great air streams in the sky above us get disturbed by climate change, this can have severe effects on the ground,” says lead-author Dim Coumou. “While you might expect reduced storm activity to be something good, it turns out that this reduction leads to a greater persistence of weather systems in the Northern hemisphere mid-latitudes. In summer, storms transport moist and cool air from the oceans to the continents bringing relief after periods of oppressive heat. Slack periods, in contrast, make warm weather conditions endure, resulting in the buildup of heat and drought.”

“Unabated climate change will probably further weaken summer circulation patterns which could thus aggravate the risk of heat waves,” says co-author Jascha Lehmann “Climate simulations for the next decades, the CMIP5, remarkably show the same link that we found in observations. So the warm temperature extremes we’ve experienced in recent years might be only a beginning.”

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This is totally anecdotal, but as a small farmer here in the US Northeast, I began noticing that rainfall patterns were getting just perverse: unusually long dry periods followed by a week of rain; rain that comes in torrents; a sense of unease when it's "nice" because of a new awareness that things could turn on a dime and become suddenly overcast, dreary, and rainy for a week. The new normal here is to work like hell as soon as you get the weather, because it will change, suddenly, drastically, and if you're not ready for it your crops are screwed.

Mikeb, that may be anecdotal, but your observations are not isolated and also, are increasingly backed up by studies like this one.

I gave office presentations on vapor retarders & air barriers, foundation waterproofing and roof drainage over the last few months. We have some deniers in the office, but I flat out told them: whether you believe in climate change or not, we have seen a derecho, record-setting rainstorms and snowstorms in this city over just the last few years. The weather has become unpredictable, so you'd better design for the worst case event and then some.

Donal, no worries about the deniers and flooding. Deniers have one of the most powerful barriers conceived by the mind of man.

I'm sure they've already informed you that it's cheaper to obtain protection by adopting a denier barrier than it is to make trips to the hardware store to purchase physical barriers.

No wonder they look down on everyone else with such a smug attitude...

By Brainstorms (not verified) on 13 Mar 2015 #permalink

Here is a link to an International Energy Agency report that CO2 emmissions in 2014 were flat from 2013 http://www.iea.org/newsroomandevents/news/2015/march/global-energy-rela…. Note that this happened with 3% global growth, indicating that the CO2 to economic growth link is at least weakening.
(Said to be due to moves to renerables in China among other things, partly due to local air pollution issues there.)

I live in South Africa and I've experienced that the seasons are changing. We live in a summer rainfall area, so therefore it usually rains from the months October to February. In the past 5 years we have been getting rain till as late as May and June which is totally out of season. Is it just a coincidence or can global warming lead to changes like this? According to Wynne Parry evidence leading back decades shows that the timing of some biological events is shifting around the world. He also stated that studies showed that spring started earlier. In my case I feel that spring started later than it is supposed to. Winter stays longer with more cooler days, which isn't normal in South Africa.

By u15035752 (not verified) on 13 Mar 2015 #permalink

With an increase in overall temperature there will be more rain and thunder storms as heat over the oceans is the ideal temperature for thunderstorms to form in South Africa. These thunderstorms come with bad weather and things like storm surges and horrible winds, so with this trend of heat increasing, is it not important for South Africa to come up with ways to sustain the environment? after all prevention is better than cure.
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By S Makhwaza (not verified) on 01 Apr 2015 #permalink

Global warming causes the Earth's atmosphere to warm up, which results in increased temperatures. It causes change in seasonal events. This is indeed true hence where I am from, it used to rain in summer only, but we are now experiencing rainfalls even in winter. I have learned that there is a way to reduce the amount of carbon in the atmosphere, and that is to introduce the method of Carbon Capture and Storage (CCS), which is a process where carbon is extracted from existing wells and processed in powerplants, treated and then transported by pipelines to where it is going to be stored. Lastly it is injected in different storage sites. This method if implemented, will decrease the rate of global warming which will therefore stabilize the rate of climate change. If not, we will experience heavy rainfalls in the future, our crops will die and we will suffer from hunger and poverty. u14248043

By P.M Bestenbier (not verified) on 06 Apr 2015 #permalink

With global warming soon we will not be having winter. The temperature changes have been noticeable over the years. This problem will soon be out our hand, we'll end up at a point of no return if we don't change the nature of things we do here on Earth.
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By Varaidzo Sabeta (not verified) on 11 Apr 2015 #permalink

Yes, the climate change becomes more and more prominent and cannot be ignored any longer. I live in Namibia which is known as a dry country, but in the last years, there was an uneven pattern of very dry periods without rain and the next year again a rain period with a lot of rain. This affects directly the nature and farmers. The crops and animals die, if there is not enough rain. But it also affects us all, because we all depend on the meat and vegetables, fruits that come from the farms and nature. Think and live more green and not just talk about it, do it!
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What about the countries that experience global cooling? Such as snowstorms being more extreme?

By Melissa Pistorius (not verified) on 12 Apr 2015 #permalink

It makes sense that Global Warming is causing changes in weather patterns and extreme weather around the world. If you think about the amount of hurricanes/tropical cyclones you hear about taking place and the tsunamis and all these natural disasters.

We have to stop being ignorant as humans and release the damage we cause.

Research conducted by a team from MIT suggests that humans may not be the reason for global warming because the earth undergoes natural periods of heating and cooling. This was observed when the average temperature increased simultaneously across the entire planet which is abnormal because the effects of increased greenhouse gas production in the northern hemisphere generally takes approximately 1 year to have an effect the southern hemisphere. The hydroxyl free radical destroys methane(which is 25x more responsible for global warming than carbon dioxide) through a naturally occurring process thereby cleaning the atmosphere. It is believed that increases and decreases in the amount of the hydroxyl free radical through natural processes is what results in the natural heating and cooling curves of the earth, therefore it is possible that we as humans could have an almost negligible effect on the increase of the worlds temperatures.
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Global warming has become a serious issue in our country. We have been experiencing major changes in our weather patterns as well as unpredictable weather. One of the major contributors to global warming is the greenhouse gas pollution caused by humans. Small gestures such as not littering could help reduce this as well as cutting down less trees. Global warming does not just affect us,but the animals living on this planet. So,let's try work together and reduce global warming!

By u15089208 (not verified) on 15 Apr 2015 #permalink

Does the ozone layer move with the earth or is it stagnant?

By T Venter (u15030190) (not verified) on 15 Apr 2015 #permalink

Grrenhouse gasses caused by humans are at a level that is depleting the ozone layer rapidly,we must put an end to this

By Damian Blakes (not verified) on 17 Apr 2015 #permalink

How much damage has the ozone layer received since humans set foot on this planet?

By James Cogg (not verified) on 17 Apr 2015 #permalink