Springtime, for most of us in northern temperate climes, is a welcome season of blooming plants, longer days, and warmer temperatures. But for Ted Schuur, an ecologist at the University of Florida, the season has different connotations. For Schuur, spring means a new season of exploration and adventure on the geographic and scientific frontier, where he is trying to answer a question of immense importance for our warming planet: How much carbon is being released by the thawing of the Arctic's so-called permafrost? Permafrost is the frozen soil, water, and rock that, astonishingly, covers nearly one quarter of all the …

Most people are understandably confused about the relationship between global warming and natural variability in the weather. After the huge snowfalls in the northeastern United States over the past few months, for instance, many people can't help but wonder: With a winter of such magnitude, how can scientists say the planet is warming? Day-to-day and seasonal weather fluctuations present challenges not only for the public but also for climate scientists trying to tease apart the relationship between long-term climate change and weather variability. Wenhong Li, an atmospheric scientist at Duke University, studies precisely this link. Her latest research on precipitation …

When Bethany Bradley describes her research as probing the link between global warming and "alien invaders," as she did in a recent journal article, the reader may be understandably disconcerted, especially since Bradley's early graduate work involved mapping the surface of Mars. But rest assured: The alien invaders she studies today as a climate scientist and biogeographer at the University of Massachusetts, Amherst, are nonnative plant species such as kudzu (Pueraria lobata), endemic through the southern U.S., and purple loosestrife (Lythrum salicaria), which now clogs many of the nation's waterways and canals. While invasive plants are surely not as unsettling …

You've probably seen pictures of stranded polar bears and heard that global warming is causing the melting of Arctic sea ice -- that is, floating ice formed from freezing ocean surface water. But you may imagine, as most people do, that this distant phenomenon is unfolding gradually over a centuries-long time frame. Julienne Stroeve, a climate scientist at the National Snow and Ice Data Center in Boulder, Colo., has compiled detailed measurements that melt away any such misconceptions. Stroeve is closely monitoring the extent of Arctic sea ice, and her research shows that dramatic changes are occurring right now -- …

The 2010 hurricane season is winding down, but teams of meteorologists are still working around the clock to track tropical storms as they continue to form in the Atlantic Ocean. Thomas Knutson tracks hurricanes too, but a little differently. A meteorologist at the National Oceanic and Atmospheric Administration (NOAA), Knutson is trying to answer one of global warming's thorniest and most consequential questions: What effect will rising global temperatures have on the frequency, structure, and intensity of future storms? Five years after Hurricane Katrina devastated the Gulf Coast -- causing more than 1,800 deaths and close to $100 billion in …

The ocean has been our savior. Besides generating about two thirds of the oxygen we breathe, oceangoing phytoplankton -- those floating microscopic plants that form the base of the aquatic food chain -- absorb about a third of all the carbon dioxide we pump into the atmosphere. In this way, the oceans have managed to slow the buildup of heat-trapping greenhouse gases and stave off even more dramatic warming of the planet. But John Guinotte and colleagues are discovering that the critical role of "carbon sink" comes at a potentially devastating cost for the world's oceans: acidification. Guinotte is a …

If you're one of the tens of millions of people who live in the southwestern United States, get ready for drier weather. That's the message from Richard Seager, a climate scientist at Columbia University's Lamont-Doherty Earth Observatory. The American Southwest, says Seager, is soon likely to experience a "permanent drought" condition on par with the Dust Bowl of the 1930s. That rather frightening prediction is the most likely scenario for the region, given the global warming now underway. "It is a matter of simple thermodynamics," says Seager. "The region will face a considerable increase in aridity over the coming decade." …

Inez Fung is on a mission to find and account for every gram of heat-trapping carbon dioxide on the planet. And she knows where most of it is hiding. Fung is the director of the Berkeley Institute of the Environment at the University of California-Berkeley. Her work has led to a more complete understanding of the current and future role played by Earth's so-called "carbon sinks" -- features such as oceans and forests that suck carbon dioxide out of the air. Fung's research shows that when the role of these carbon-absorbing mechanisms is taken fully into account, global warming is …

So, how do we know that human byproducts -- namely emissions from our tailpipes and smokestacks -- are responsible for warming the planet? To Benjamin Santer, a climate scientist at the Lawrence Livermore National Laboratory in California, the answer is in the evidence. Just as criminals leave fingerprints and DNA at the scene of a crime, climate change culprits leave distinct signatures or patterns that scientists can find -- if they look closely enough. And hardly anyone has been looking longer or more carefully than Santer. More than 23 years ago, just out of graduate school, Santer joined the Max …

Exactly how much did the sea level rise three million years ago? Okay. Probably not a question you've asked yourself lately. But the question and, more importantly, its answer are significant. They will help scientists understand how fast and how high our current sea levels are likely to rise as today's global warming trend melts the remaining ice sheets in Greenland and Antarctica. Fortunately, there are researchers wrestling with the problem. Chief among them is Maureen Raymo, a paleoclimatologist at Boston University. Raymo heads a multidisciplinary team that is spending its second summer digging for evidence in the desert of …