Ask A Climate Scientist – a Pause in Warming?

Dr. Kelly Brunt explains that Greenland's ice sheet is thinning, and while it is still over 10,000 feet thick, the melt water is contributing to sea level rise.For complete transcript, click here. How can Greenland's ice sheets still be more than 10,000 feet thick, if carbon dioxide is warming the planet?This was the question posed to polar scientist Kelly Brunt as part of NASA's Ask A Climate Scientist series.According to Dr. Brunt, this is a great question because it addresses the concept of thickness, which is very important to polar scientists. It is easy to see that the ice sheets and sea ice are changing horizontally, covering less and less of the polar regions. But the ice is also thinning, getting smaller vertically.Dr. Brunt compares the situation to walking outside on a really cold day. When the air temperature is very cold, it will still take a while for her core body temperature to drop. Her skin may be chilly, but it will take time for that cold to work deep inside.Conversely, Greenland's ice is very thick and only the outer layer is experiencing the warming temperatures. But that layer is melting more often and a little bit of melting over such a large area produces a lot of extra water contributing to sea level rise.See more of NASA's answers to your questions on climate science. Related pages

Will climate change affect humans? NASA's Tom Wagner says yes, in four different ways. See more of NASA's answers to your questions on climate science.For complete transcript, click here. How does climate change affect humans? That's the question we asked Tom Wagner, Program Scientist for Cryospheric Research at NASA.In four different ways, he says, from rainfall patterns and sea levels rising to food production and ocean acidification. First, "as the planet warms up, we're going to redistribute rainfall, which is going to affect our water resources and parts of North America may get a lot drier."Second, "as the polar ice melts, sea levels are going to rise." The world's major cities, and a lot of people, are right on the coasts and rising sea levels are going to impact them. Third, thinking about food, the "distributions where we can grow food are going to change as the planet warms up." So the range over which you can grow corn and other crops will change. Fourth, says Tom Wagner, "the oceans are going to get more acidic as more CO2 dissolves in them." There are untold ramifications from that, including the possibility of radically altering the food web in the ocean, "which can affect everything from the composition of the atmosphere to the ability of the oceans to provide food for us."See more of NASA's answers to your questions on climate science. Related pages

Is global warming having an impact on extreme weather events? At this point, says Bill Patzert of NASA's Jet Propulsion Laboratory, not much although it likely will in the future. See more of NASA's answers to your questions on climate science. Is the frequency of extreme weather events a sign that global warming is gaining pace and exceeding predictions?Bill Patzert, a scientist at NASA's Jet Propulsion Laboratory, says the evidence that extreme weather events have been more frequent in recent years is definitely to the contrary. "The United States has always had extreme weather. We look back on our weather history. It's been punishing: floods, droughts, tornadoes, hurricanes, great forest fires. "Is global warming happening? No doubt about it. We're living in a warmer world, we're living in a melting world, sea levels are rising. Now, direct evidence of the footprint or the fingerprint of global warming: we're seeing more frequent, more intense, and longer lasting heat waves. As far as hurricanes, tornadoes, forest fires, floods, and drought, the evidence is definitely not in. The consensus among almost all scientists is that it's a small fingerprint, not a large footprint. "But what is true is that in this country, in the United States, we live in many areas with great risk to drought, to tornadoes, to hurricanes, and so part of the dialogue is not only extreme weather and global warming, but is the amount of risk we can tolerate. Now looking to the future, global change, global warming - it definitely is accelerating and it will have an impact on extreme weather, but at this point, not much." See more of NASA's answers to your questions on climate science. Related pages

Is there any merit to the studies that show that historical CO2 levels lag behind temperature, and not lead them? This question was posed to Goddard Space Flight Center climate scientist Peter Hildebrand as part of NASA's Ask A Climate Scientist campaign.For complete transcript, click here. Is there any merit to the studies that show that historical CO2 levels lag behind temperature, and not lead them?Climate scientist Peter Hildebrand, Director of the Earth Science Division at NASA's Goddard Space Flight Center, says yes, there's merit to those studies. In the pre-industrial age, the CO2 response to temperature was that the temperature would go up and CO2 would go up. Or if the temperature went down, CO2 would go down. And the reason for that is when the temperature went up, the whole biosphere revved up and emitted CO2, and we had more CO2 in the atmosphere. So we understand that process.In the post-industrial age, the opposite is true. Increasing CO2 in the atmosphere is leading to increased temperature. So two different things happened, one pre-industrial, where temperature was driving the CO2, and post-industrial, where CO2 was driving temperature. Which means a completely different physical-biological process is going on. And we don't understand what the consequence of that change is. It is a fundamental change to how the earth works and the earth's radiation balance works. And so, we're very concerned because we don't see any restraining force on continued increase in temperature due to continued increase in CO2. And that's a problem. For More InformationSee [http://www.nasa.gov/content/goddard/this-september-ask-a-nasa-climate-scientist/](http://www.nasa.gov/content/goddard/this-september-ask-a-nasa-climate-scientist/) Related pages

Will climate change drastically reduce our food production, or will it change what we produce? This question was posed to Goddard Space Flight Center's Molly Brown as part of NASA's Ask A Climate Scientist campaign.For complete transcript, click here. Will climate change drastically reduce our food production, or will it change what we produce?This question was posed to Goddard Space Flight Center's Molly Brown as part of NASA's Ask A Climate Scientist campaign.For more about the connection between climate variability and food production, go here:https://www.nasa.gov/content/goddard/climate-forecasts-shown-to-warn-of-crop-failures/For more about Ask A Climate Scientist, go here: http://www.youtube.com/watch?v=49Lu1dTa0_k For More InformationSee [http://www.nasa.gov/content/goddard/climate-forecasts-shown-to-warn-of-crop-failures](http://www.nasa.gov/content/goddard/climate-forecasts-shown-to-warn-of-crop-failures) Related pages

NASA scientists examine the Earth's climate and how it is changing – gaining knowledge through decades of satellite observations, powerful computer models and expert scientific analysis. NASA climate experts will answer selected questions through the agency's social media channels – primarily on YouTube, Twitter and Google+. The topic of climate change inspires a lot of debate. At NASA, it has also inspired a lot of science.NASA scientists examine the Earth's climate and how it is changing – gaining knowledge (or insight?) through decades of satellite observations, powerful computer models and expert scientific analysis.Over the course of September 2013, these NASA climate experts will answer selected questions through the agency's social media channels – primarily on YouTube, Twitter and Google+.But first – we need your questions.Have a question that's always confounded you about Earth's climate? Wonder why it matters that the climate is changing now if it has changed before? Or how scientists know changes seen in recent decades are the result of human activities, not natural causes?Go ahead. Ask a climate scientist. For More InformationSee [http://www.nasa.gov/content/goddard/this-september-ask-a-nasa-climate-scientist/](http://www.nasa.gov/content/goddard/this-september-ask-a-nasa-climate-scientist/) Related pages