Methane, Climate Change, and Our Uncertain Future

The greenhouse gas, methane, is produced by both natural processes and human activities. While there has been much attention paid to curbing anthropogenic emissions, a changing climate will likely increase the production of natural methane. In an open access article recently published in Reviews of Geophysics, Dean et al. [2018] describe the ways in which biological, geochemical, and physical systems influence methane concentrations and explore how methane levels in natural systems may alter in a warming climate. Here the authors answer some questions about the sources and significance of methane, and indicate some future research directions.

Flooded permafrost tundra in northeast Siberia.
Hydrology is a key control on methane emissions
in wetland and permafrost ecosystems.
Credit: Joshua Dean

How does methane effect the Earth’s climate?

Methane (CH4) is a greenhouse gas that is much stronger than carbon dioxide (CO2), 34 times stronger if compared over a 100-year period. While concentrations of methane in the atmosphere are about 200 times lower than carbon dioxide, methane was responsible for 60% of the equivalent radiative forcing caused by carbon dioxide since the onset of the Industrial Revolution. Methane’s presence in the atmosphere can also affect the abundance of other greenhouse gases, such as ozone (O3), water vapor (H2O), and carbon dioxide.

Read the story from Earth and Space Science News by Joshua Dean - “Methane, Climate Change, and Our Uncertain Future.”

Record evaporation rates across eastern Australia exacerbate drought

Australia's evaporation levels are running at record rates, especially across eastern states, increasing the misery for drought-hit farmers and raising bushfire risks as the mercury starts to climb.

Cold can deceive: Just because temperatures are low –
such as this empty dam near Oberon in the NSW central
 west – it doesn't mean moisture loss from evaporation is low.

While rainfall deficiencies have drawn much attention, stronger-than-usual winds, abnormally sunny days and low humidity have combined to push up evaporation levels, Bureau of Meteorology data shows.

Across the nation, evaporation last month averaged 145.21 millimetres, well above the 128.6 mm typical for July, and the most on record for data going back to 1975, said Karl Braganza, head of climate monitoring at the bureau.

The national tally beat the previous record in 2002. On a regional level, the evaporation rate was the highest on record for Victoria, and also smashed previous records for eastern Australia as a whole.

Read the story by Peter Hannam from The Sydney Morning Herald - “Record evaporation rates across eastern Australia exacerbate drought.”