Ask a Scientist About Droughts, Extreme Weather and Climate Change

It's been a summer of record-breaking heat. Do you have questions about droughts, heat waves, extreme weather, and climate change? Ask a scientist! Michael Wehner is a climate scientist in Berkeley Lab's Computational Research Division. He uses high-performance computing to study extreme weather events in a changing climate, especially heat waves, floods, droughts and hurricanes.

Michael answered some of your questions in this August 21 video: http://youtu.be/uUAJdD_Iopg

You may have questions about these extremes events. Are some of them the result of climate change? Are they natural variations in our normal climate? Or are these extremes caused by a combination of both of these effects? And how do scientists tell the difference?

Michael invites you to send in your questions. He'll answer a few of them in a follow-up video soon.

We're taking questions through August 17!

• Post your questions in the comment box
• E-mail your questions to askascientist@lbl.gov
• Tweet to @BerkeleyLab
• Post on our facebook page: www.facebook.com/BerkeleyLab

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  Science & Technology

[BerkeleyLab]

Hey everyone, we're taking questions through this Friday, August 17 -- so ask away! We'll post the response video next week.

[Joe Acker]

What's with this 'Chemtrail' thing? I see it going on above my town. I see how it forms a manmade cloud cover that reflects the sunlight back into space. It only takes about three hours for the jets to cover the sky with a milky white cloud layer. How come nobody will talk about this matter? What is being kept from us?

[peopleofthecircle]

The departure from normal map shows what I suspected - cooler than normal in CA.

[MrCoffeeFiend]

Thank you for the time you gave to answer my question. It was a better answer then I had hoped to receive and gives me a better perspective to interpet what I already knew about the subject.

[oldSFskater]

The geoengineering analog is to add sulfur to commercial jet fuel to deliberately dim the atmosphere. This controversial idea has both positive (i.e. cooling) and negative (i.e. possible drying) impacts. In my personal opinion, geoengineering solutions are perhaps possible but very poorly understood at the moment. Thanks for your question. Michael

[oldSFskater]

Large tropical volcanoes that deposit large amounts of particulates into the stratosphere can temporarily cool the atmosphere. The effect of Mt Pinautubo lasted about 3 years. The mechanism is that sulfate aerosols are highly reflective and tend to reflect solar energy to space thus cooling the atmosphere.

[oldSFskater]

I point you to two reports. The 2nd US National Climate Assessment (also called the impacts report) at usgcrp.gov. And the IPCC 4th assessment report (ipcc.ch). Read the executive summaries. They are supposed to be written in "plain" English. Thanks for your question. Michael

[oldSFskater]

But this ignores Antarctica which is not constrained by topography. Think Atlantic City or Venice Beach. Except colder. Hence this 2m upper bound is highly uncertain. I expect that recent developments in ice sheet modeling at Los Alamos and Berkeley Labs will help us pin this down in the next few years. Thanks for your question. Michael

[oldSFskater]

A very long time. Greenland and Antarctica behave very differently. Greenland ice sheets are high constrained by the topography. Think fiords. Hence, surface melting is the largest source of sea level rise. The published upper limit of sea level rise of 2 meters (6 feet) is based on this and the maximum Greenland ice sheet velocities as constrained by topography.

[MrCoffeeFiend]

Didn't get here in time to ask my question. How long will it take for the ice on Greenland to move into the oceans once rapid melting begins?

[Marko Kraguljac]

What is the simplest, most elegant way of showing that climate change IS created by human activity? Some chart? Few charts? Is it possible to answer that clearly and definitely without beating around the bush and using terminology only scientists "understand"?