The shocking and heart-breaking pictures of three-year-old Aylan al-Kurdi, whose body was washed up on a beach in Turkey after he, his five-year-old brother, Ghalib, and mother, Rihan, drowned while trying to reach Greece, have vividly illustrated the plight of refugees escaping the conflict in Syria.
While the response to the refugee crisis is now dominating political discussions across the European Union and beyond, it is also important to understand its root causes in order to learn broader lessons for the future.
One lesson is the contributing role that climate change played in triggering the war in Syria. Scientists are extremely wary about linking climate change to specific conflicts, or of overstating its importance, but novel methods of assessing the risks of extreme weather events are creating some new insights.
A research study published in the Proceedings of the National Academy of Sciences in March pointed out that a severe drought in Syria between 2007 and 2010 helped create the conditions for the unrest that led to war.
According to the American researchers, it was "the worst drought in the instrumental record, causing widespread crop failure and a mass migration of farming families to urban centers". They calculated that the drought had been made two to three times more likely because of rising greenhouse gas levels in the atmosphere.
It is clear that the uprising elsewhere in the region during the Arab Spring also played an important role in precipitating the unrest in Syria, but that may also be linked to climate change.
An analysis by researchers at the International Institute for Strategic Studies suggested:
"Climate change and its impact on weather are, of course, insufficient on their own to cause conflict or unrest, let alone on the scale now occurring in the Arab world. But it has been a threat multiplier, in the sense that it was a necessary component of any number of possible scenarios, each of them sufficient to have led to the sort of unrest we are witnessing."
It concluded:
"The Arab Spring would likely have come one way or another, but the context in which it did is not inconsequential. Global warming may not have caused the Arab Spring, but it may have made it come earlier."
The potential for climate change to increase the threat of unrest and conflict around the world has already been acknowledged by politicians and defence experts.
In a speech last October, the United States Secretary of Defense, Chuck Hagel, said: "Climate change is a 'threat multiplier'...because it has the potential to exacerbate many of the challenges we already confront today - from infectious disease to armed insurgencies - and to produce new challenges in the future".
And while scientists remain reluctant to categorically connect current and recent events to climate change, they are clear about the potential implications for human security.
The most recent assessment by the Intergovernmental Panel on Climate Change in 2014 concluded:
"Climate change will have significant impacts on forms of migration that compromise human security (medium evidence, high agreement). Some migration flows are sensitive to changes in resource availability and ecosystem services. Major extreme weather events have in the past led to significant population displacement, and changes in the incidence of extreme events will amplify the challenges and risks of such displacement. Many vulnerable groups do not have the resources to be able to migrate to avoid the impacts of floods, storms, and droughts. Models, scenarios, and observations suggest that coastal inundation and loss of permafrost can lead to migration and resettlement. Migrants themselves may be vulnerable to climate change impacts in destination areas, particularly in urban centers in developing countries."
The sobering fact is that global average surface temperature has so far increased by about 0.85 centigrade degrees since the late 19th century, and yet climate change may already be contributing to greater human conflict. For the next few decades at least, the climate will continue to deteriorate as the atmosphere, land and oceans equilibrate to current greenhouse gas levels, likely undermining human security around the world even more.
And without urgent action to cut emissions, global average temperature by the end of this century could be three centigrade degrees or more higher than it was before industrialisation. That would make the Earth warmer than it has been for millions of years, far outside the experience of modern human beings, who first appeared about 250,000 years ago, and human civilisations, which started about 10,000 years ago.
So as governments haggle over a new international agreement on climate change, due to be finalised at a United Nations summit in Paris at the end of this year, they should remember that one consequence of failure is likely to be much more conflict, much more migration, many more refugees, much more human suffering and many more dead bodies washed up on beaches around the world.
Bob Ward is policy and communications director at the ESRC Centre for Climate Change Economics and Policy and the Grantham Research Institute on Climate Change and the Environment at London School of Economics and Political Science. On 11 October, he will be participating in the Royal Parks Half Marathon in London to raise money for Plan, the international children's charity, which is helping young people in Syria and around the world.