But we know now that reducing emissions is not enough. Millions of lives are being upended by the effects of changes in climate - food scarcity, water scarcity, vulnerability to natural disasters and infectious diseases, and population displacement. Women and children are the most vulnerable groups to climate change.

So how does reproductive health fit into this picture? A new study by the UK-based Optimum Population Trust and the London School of Economics shows the connection between contraceptives and climate change.

The study concludes that universal access to reproductive health could be one of the most cost effective ways to reduce greenhouse gas emissions by 2050.

A Population Action International report from May detailed how population dynamics, not just overall growth, contribute to climate change.

This helps to broaden our thinking around the diversity of strategies that will be needed for meaningful and lasting solutions to climate change as world leaders try to hammer out a new global climate treaty.

Investing in contraceptives and reproductive health is about more than reducing emissions. It is also a critical piece of reducing vulnerability and building resilience to the impacts of climate change.

This is true from a demographic perspective, as well as at the individual and household level.

VULNERABILITY HIGH WITH RAPID GROWTH

Rapid population growth can exacerbate existing vulnerability to the impacts of climate change.

Population growth rates in highly vulnerable low-elevation coastal zones in Bangladesh and China are nearly twice as high as national averages.

In Ethiopia, the combination of rapid population growth and climate-induced declines in agricultural production will heighten food insecurity.

At the household level, a woman with access to reproductive health services is healthier and has healthier children. She has greater opportunities to diversify income sources. And she is more likely to be able safeguard herself and her family in the event of disaster.