Global Change

Methane and global warming

Methane is a potent greenhouse gas, with a global warming potential that is 33-fold greater than that for carbon dioxide over an integrated 100-year time frame following emission to the atmosphere, and 85 to 105-fold over an integrated 20-year period. Currently, the radiative forcing from methane that drives global warming is equal to approximately 60% of that of carbon dioxide, when the indirect effects of methane are included. Howarth has been interested in methane since measuring emissions from a salt marsh as part of his Ph.D. thesis research. In 1981, Howarth taught a multi-institutional course on climate change at the Marine Biological Lab in Woods Hole, including the methane cycle as an important part of the course, and later in the 1980s, he served on a panel that addressed methane and other trace gas emissions for a National Academy of Science’s Committee on Global Change. In recent years, research on methane in the Howarth-Marino lab has focused on estimating emissions from the oil and gas industry and how this contributes to global warming. This research suggests that far from being a “bridge fuel,” shale gas may be disastrous from the standpoint of global warming.

How does climate change affect coastal nutrient pollution?

Two major foci of the Howarth-Marino lab are the sources of the nitrogen inputs to and effects of these nitrogen inputs on coastal marine ecosystems, as is detailed in the nutrient biogeochemistry section of this web site. For more than 20 years, a part of this research has been to ascertain the consequences of climatic variability and global change on fluxes of nitrogen and phosphorus to coastal waters and on the sensitivity of coastal marine ecosystems to nutrient pollution. Climate plays a major role in the delivery of nutrients from the landscape to coastal oceans, with greater fluxes in climates with greater precipitation and freshwater runoff. Climate also affects the sensitivity of coastal waters to the adverse consequences of nutrients, and the observed global warming over the past few decades has already made some ecosystems more sensitive to nutrient pollution, and some less so.

Global change is more than climate change!

Human activity has global effects that are beyond those on greenhouse gas concentrations and global warming. For instance, humans have changed the global nitrogen cycle even more than the global carbon cycle, and humans have had an immense influence on the use of land globally, particularly for agriculture. Click here for our papers and reports on human alteration of the global nitrogen cycle, on how agriculture is a part of global change, and on how liquid biofuels influence global change.