Climate change is underway. The mainstream now accepts that human behaviour and industrialisation contributed to increasing the amount of greenhouse gases present in the atmosphere over the last century. Yet, it remains difficult to link specific weather events to climate change.

Climate is not the same as the weather. Weather is a local phenomenon. Also, it is very predictable despite what you might think about your local weather channel. Forecast accuracy increases significantly one week out, one day out, one hour out, as we approach hour zero. Even ten-year olds learn that when winds gather in the harbour and clouds are swept inland, rain will begin to fall as the clouds cool rising above sea level.

Climate is the aggregate of weather patterns on a regional or global scale, averaged out over years, decades or even centuries. Climate systems are “chaotic”. In scientific terms this means highly complex with numerous interdependencies, so it’s very difficult to make predictions.

Scientific models are getting better all the time, but the climate’s “chaotic” nature means even tiny deviations in initial data and assumptions, can lead to wildly divergent results. John Nash’s poetic metaphor, referred to as the butterfly effect, translates this concept into everyday language: when a butterfly flaps its wings, a hurricane is born on the opposite side of the globe. Climate scientists have millions of butterflies to consider.

Furthermore, changes in the aggregate tell us little about the local effects of climate change. Weather scientists can tell us what the weather will be like in London, Dubai or Delhi tomorrow. But climate scientists do not have the same job. They cannot paint a very accurate of picture of what daily weather will be like in Delhi in ten or twenty years time. Will Californian residents suffer fewer droughts if America bans emissions-intensive coal power production? What colour is the butterfly’s wings?

This is where statistics can play an important role. Statistic climate models measure how likely it is that something will happen. Lord Stern’s landmark 2006 report for the British government (research that was updated in a 2014 report with the Global Commission and the Economy and Climate) evaluates the risks and probabilities associated with climate change – from both a business and government policy perspective – despite scientific uncertainty.

We know that extreme weather events have become increasingly probable. We will witness both more frequent and more intense storms, heat waves, polar vortices, droughts and fires. Landscapes are changing as coastline disappears. Higher average temperatures affect ecosystems. The indirect costs of climate change include crop failure, mass migration, loss of biodiversity and a spread in airborne maladies. Dangerous air pollution in many cities worldwide, caused by burning fossil fuels, furnishes us with yet another reason to quit pumping the gases they produce into the atmosphere.

We also know that certain regions face greater risks than others. As fate would have it the regions most susceptible to climate change’s impacts are those least equipped to deal with them. Such as the Pacific islands and South-East Asia.

Why is that? A priori,  proximity to the ocean and the equator entails more extreme weather, which climate change will exacerbate. Yet, these regions are also less developed. They are incredibly dependent on the weather to ensure reliable food production. Insurance policies are rare. Millions of people live in very simple shelters, easily destroyed in high winds or fires. Their communities often lack modern luxuries such as electricity, televisions, insulation, climate control or running water. This means they are more likely to die during or following an extreme weather event – because they do not receive the evacuation message, cannot adequately shelter themselves or escape the heat or cold, and may starve or be forced to drink contaminated water whilst awaiting disaster relief.

Hurricanes are common in the South Pacific region between November and April. However, earlier this year, Vanuatu was battered by extrordinarily violent winds and rain for which there was little precedent. The initial deaths following Cyclone Pam were tragic. However, starvation and water contamination followed and pushed the death toll up. Economic reconstruction of the region, which is primarily dependent on subsistence farming, will take years.

Another recent example: thousands perished in a dangerous heat wave throughout Pakistan and India’s north where temperatures reached 47 degrees Celsius in May of this year. We cannot overestimate the danger of excessive heat for infants and the elderly. People’s bodies become very stressed under such conditions. This combined with dehydration or sleep deprivation leads to fatalities.

Sceptics are right to doubt that Cyclone Pam or the recent heat wave were directly caused by climate change. Drawing a direct vector between burning fossil fuels and extreme weather events is near impossible as explained above.

Nevertheless, these regions have not benefitted from industrialisation, and the tremendous boost to economic well-being it engendered, to the extent that we have across the developed world. Yet, they will be the first to suffer from industrialisation’s perilous side effects.[1]

This is why Cyclone Pam and the Pakistani/Indian heatwave are relevant. These examples help us to identify what is really important about climate change. Climate change is a question of social justice, not the weather.

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[1] Not that pockets of wealth do not exist in these regions or people in more developed parts of the world have never known disaster – as witnessed in 2005, in the United States  following Hurricane Katrina.