October 5, 2010

The Scientist: Natalie Mahowald

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An air pollution major in undergraduate school, Prof. Natalie Mahowald, earth and atmospheric sciences, emphasized the importance of researching climate change. “There are so many interesting scientific questions that need to be addressed, which are very policy-relevant.”

After working as a reviewer in the past, Mahowald will be one of the main authors of next year’s inter-governmental climate change assessment report. “There are a lot of people involved in these assessment reports and they summarize all the new results from the last five years,” Mahowald said.  She will be working on the first chapter of the report starting November.

Trained as an atmospheric scientist, Mahowald’s biggest area of research is biogeochemical. She studies important topics, including dessert dust aerosols. “My research group is interested in understanding how humans are perturbing the natural environment.” She studies long-range transport of desert dust around the globe.

Using 3-dimensional global transport models, climate models, satellite and in situ data she can illustrate the amount of dessert dust that goes from North African deserts to South and North America.

Dust is one of the largest atmospheric aerosols by mass. Although the heavier particles settle down, it is the lighter dust particles that travel farther.

“So if you live local to desert dust sources, it can cause health problems,” Mahowald said. She explained that these dust aerosols in the atmosphere also impact the climate by interacting with radiation. According to Mahowald, dust carries iron and can fertilize ocean particles. “Dust also impacts clouds which can further interact with radiation.”

The questions that currently concern Mahowald most are deforestation, increased emissions of carbon dioxide and how these processes are affecting the planet. “We have new results which suggest that from observational data that dust has doubled over the 20th century. It is still not very clear on how much and why desertification is taking place.”

According to Maholwald, dust in the atmosphere has increased significantly, possibly due to the increased aridity in some regions. This is caused by climate change, overgrazing and farming practices that remove native vegetation.

“But on the other hand, higher carbon-dioxide that we are putting in the atmosphere actually fertilizes plants; it might make them deal with water stress especially in arid regions. This could lead to desert shrinking from that impact.”

Shifting precipitation patterns and increased agricultural practices of irrigation can also make deserts smaller.

Researching both the climate and biogeochemical impact, Mahowald felt like a bio-geo-atmospheric scientist. “I look at things differently. I am not an atmospheric scientist any more; I am constantly working with people in other fields, who are on the edge of atmospheric science.”

Mahowald is also currently studying the biogeochemistry of dust and carbon models.

Dust aerosol carries some iron and potassium contents. Mahowald is studying how these contents move around and affect the climate.

Fifty percent of the carbon dioxide emitted is taken up by the land and sea, through a negative feedback mechanism. Maholwald and her team are trying to predict the future pattern of carbon dioxide in the atmosphere based on this data.

Mahowald has recently been elected as a fellow of the American Meteorological Society. “There [are] not many more honors I can get besides this,” Mahowald said.  When she is not doing research, she likes spending time with her young children.

Original Author: Poornima Gadamsetty