When President Donald Trump became the commander-in-chief of the US Armed Forces, he accepted the responsibility to protect my country against enemies, foreign and domestic. Prime Minister Malcolm Turnbull shares the same responsibility to protect Australians.

Do these leaders understand that a key component of national security and global stability is climate change and the instability it is already causing around the world? The intersection of these two issues is already striking the world in unexpected ways, as climate change interacts with other pre-existing problems to become an accelerant to instability. The consequences include overwhelming humanitarian crises, forced migrations like those we are witnessing around the Mediterranean, and a breakdown in the human systems that make our societies work.

Indeed, Trump's Defence Secretary, Marine Corps General Jim "Mad Dog" Mattis, said recently: "Climate change is impacting stability in areas of the world where our troops are operating today. It is appropriate for the combatant commands to incorporate drivers of instability that impact the security environment in their areas into their planning."

Take Syria. From 2006 to 2010, 60 per cent of Syria had its worst long-term drought and crop failures since civilisation began. About 800,000 people in rural areas had lost their livelihood by 2009. Two to three million people were driven into extreme poverty, and 1.5 million migrated to Syrian cities, which had already received a similar number of Iraqi war refugees.