Is there any merit to the studies that show that historical CO2 levels lag behind temperature, and not lead them?
Yes, there's merit to those studies, says Peter Hildebrand, Director of the Earth Science Division at NASA's Goddard Space Flight Center, responding to a question from Twitter (https://twitter.com/Seth_b_clark/stat...).

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. Because when the temperature rose, the whole biosphere revved up and emitted CO2. 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.Published on Sep 24, 2013

For more about Ask A Climate Scientist, go here: http://www.youtube.com/watch?v=49Lu1d...

Is there a pause in global warming?

This question was posed to Jet Propulsion Laboratory scientist Josh Willis as part of NASA's Ask A Climate Scientist campaign.

Josh gets asked a lot if there has been a pause in global warming, because temperatures aren't increasing as fast as they were a decade ago. No, he says, global warming is definitely still increasing (http://climate.nasa.gov/key_indicator...). We see more heat being trapped in the oceans, and sea levels are rising. Look at the sea level record for the last decade (http://climate.nasa.gov/key_indicator...). It's going up like gangbusters, hasn't slowed down.

There's not really a pause in global warming. Sometimes there's natural fluctuations and we warm up a little faster in one decade and a little slower in another decade, but global warming, human-caused climate change? Josh says, "that's definitely going right on up in there. We haven't slowed down at all."

See more of NASA's answers to your questions on climate science (http://bit.ly/1b7rSdL).

In a preview of this week's Moyers & Company, climate communication expert Anthony Leiserowitz explains that single-digit degree changes in our climate are comparable to single-digit degree changes in our body temperature when we get sick. "I think there's an analogy here — that little difference in global average temperature, just like that little difference in body temperature, can have huge implications as you keep going," Leiserowitz tells Bill.

Visit Climate Change collection at billmoyers.com.

An interview with NASA cryospheric scientist Dr. Tom Wagner, on the state of this summer's Arctic sea ice. More information from NASA on ice is here. Published on Aug 23, 2013

The Governor, Martin O'Malley talks about State's Greenhouse Gas Reduction Plan and reducing emissions by 2020 and emphasized the need for collaboration between public and private sector.

Published on Jul 23, 2013

The average temperature across the continental U.S. could be 8 degrees Fahrenheit warmer by the end of the 21st century under a climate scenario in which concentrations of the greenhouse gas carbon dioxide rise to 800 parts per million. Current concentrations stand at 400 parts per million, and are rising faster than at any time in Earth's history.

"These visualizations communicate a picture of the impacts of climate change in a way that words do not," says Allison Leidner, Ph.D., a scientist who coordinates NASA's involvement in the National Climate Assessment "When I look at the scenarios for future temperature and precipitation, I really see how dramatically our nation's climate could change."

These visualizations -- which highlight computer model projections from the draft National Climate Assessment -- show how average temperatures could change across the U.S. in the coming decades under two different carbon dioxide emissions scenarios.

Published on Jul 23, 2013

The climate of the southwestern U.S. could be a lot drier by 2100. The climate of the northeastern U.S. could be a lot wetter.

"These visualizations communicate a picture of the impacts of climate change in a way that words do not," says Allison Leidner, Ph.D., a scientist who coordinates NASA's involvement in the National Climate Assessment "When I look at the scenarios for future temperature and precipitation, I really see how dramatically our nation's climate could change."

New visualizations of computer model projections show how precipitation patterns could change across the U.S. in the coming decades under two different carbon dioxide emissions scenarios.

The date seen in the bottom-right corner is the mid-point of the 30-year average being shown. To learn more about the National Climate Assessment, due out in 2014, visit here.

Snow melt from the snow pack in the Sierra Nevada mountain range provides drinking water to about 30% of California's residents, irrigates key crops in the San Joaquin valley, and runs hydroelectric power plants that supply at least 15% of the state's electricity. Scientists Martha Conklin and Tom Harmon of the University of California, Merced are conducting research at the Southern Sierra Critical Zone Observatory, using wireless sensor technology to more accurately measure snow pack and snow melt so that state water managers can make better decisions on how to allocate this precious resource. Published on Jul 12, 2013

Part of the earth's largest surface freshwater system, Lake Erie is a vital source of drinking water for 11 million people. Researchers Anna Michalak, Tom Bridgeman, and Pete Richards are studying how farming practices and severe weather can increase the amount of fertilizer-derived nutrients in the water, which diminishes water quality and threatens the lake's ecosystem and the public's health.

Published on Jul 12, 2013

This video uses animation, graphics, and video clips to illustrate and explain each of the "flow" and "storage" processes in the Hydrologic Cycle, more commonly known as the Water Cycle: precipitation, interception, runoff, infiltration, percolation, groundwater discharge, evaporation, transpiration, evapotranspiration, and condensation.

Published on Jul 12, 2013