Garnett and Cross warn of exceeding earth's biopysical limits

Beneath the Wisteria supporters have discussed both population and food security, two matters that are implicated in this story published on The Conversation.

Authors, Trevor Garnett and Arwen Cross, warned readers that by 2009 we had exceeded three of the boundaries for earth’s biophysical subsystems - climate change, biodiversity loss, and the nitrogen cycle.

Increase in fertilizer use since the invention
 of the Haber-Bosch process.

Garnett, a research fellow in plant physiology at the Australian Centre for Plant Function Genomics, and Cross, a science communicator at the CSIRO, write that climate change has dominated government concerns, but dramatic changes in the nitrogen cycle has received much less attention.

“Humans” they report, “have more than doubled the rate of atmospheric nitrogen being fixed since 1950.”

Fixed nitrogen they explain is critical to plant growth, but its environmental impacts can be serious when used to excess.

Garnett and Cross explain their concerns in a story headed: “Agriculture’s hunger for nitrogen oversteps planetary boundaries”.