To change how we impact the climate system – which includes the atmosphere, bodies of water, living things, and other elements – we need to understand our many interactions with it. An enormous, global network of our individual actions and interactions affect the climate. As I enter a crowded subway station on a crisp autumn morning in New York City, simultaneously, halfway around the world, a woman switches off a lamp. Around the world, all of our daily actions cumulatively affect the climate, and we in turn are affected by it.

While diffuse and fleeting, these actions often leave a trail of digital data behind them. The usage of my metro-card to enter the subway here in New York is logged; the electricity meter logs the use of power in the household of the woman halfway around the world. These kinds of passive data trails, taken together, are often called “big data.” When aggregated and anonymized (go here if you want to learn how this is done), big data illuminates a fuller picture of our interactions with the climate system and also provides solutions to tackling climate change. For example, data from mobile phone calling activity in a city show which transit routes are most congested during commuting hours. If paired with informed transportation policy, these data could be used to target public transportation services to where they are needed, reducing emissions. The amount of data collected for such applications would be extremely large, analysts would have to use data validation solutions to eliminate any unnecessary and useless data to find the information that would benefit and be useful to using Big Data to evaluate climate change.

Big data also reveals how climate change affects communities. A study on the 2009 flooding in the Tabasco region of Mexico analyzed data from mobile phone usage to show how the affected population’s movement patterns changed in response to flooding. This information also provided insights on how the flood impacted local infrastructure, and how recovery rates differed across communities. In the areas most vulnerable to climate change, insights from data are crucial to an informed emergency response.

Momentum is building behind applications of big data to the biggest challenges of our time. The Big Data Climate Challenge, hosted by UN Global Pulse, in conjunction with the Secretary-General’s 2014 Climate Summit, received project submissions from more than 40 countries across 20 topic areas, ranging from smart cities to agriculture. The new Global Partnership for Sustainable Development Data, launched in September, is working to galvanize a data revolution for the Sustainable Development Goals, also known as the Global Goals, including action on climate change.

As world leaders gather in Paris next week for the COP21 climate summit, they will be joined by civil society, business, and academia, engaging in an urgent and crucial conversation on how to tackle climate change. Big data is a powerful asset that – if harnessed effectively and responsibly – can be channeled to spark action. As we consider how to transition to a more sustainable world, an approach that reuses our digital big data presents revolutionary possibilities.

For more information and to get involved in UN Global Pulse’s new campaign to use big data to transform climate action, please visit www.dataforclimateaction.org.