11/14/2014 11:59 pm ET Updated Jan 14, 2015

G20 Leaders Must Turn the Tide on Inequality and Climate Change

The two great challenges of our time -- inequality and climate change -- are threatening to undermine the efforts of millions of people to escape poverty and hunger. By concentrating wealth and power in the hands of a few, inequality robs the poorest people of the support they need to improve their lives.

And as climate change devastates crops and livelihoods, it undoes poor people's efforts to feed their families.

Earlier this year, Oxfam unveiled a shocking statistic: Just 85 rich individuals held more wealth than the poorest half of the world's population -- 3.5 billion people. As we said at the time, these 85 people could fit on to just one bus.

Our new research has revealed that the richest 85 people saw their collective wealth increase by $668 million per day between 2013 and 2014 -- almost half a million dollars every minute.

In the time that Australia has held the G20 Presidency the total wealth in the G20 increased by $17 trillion but the richest 1 percent of people in the G20 captured a staggering $6.2 trillion of this wealth -- 36 percent of the total increase.

This is because, in the vast majority of G20 countries, the richest 1 percent of people took an even bigger share of the economic pie in the past year. Yet G20 countries are still home to more than half of the world's people living in poverty.

Meanwhile, climate change is no longer just coming. It's here already. As temperatures rise, extreme weather events are becoming more frequent and more severe.

Communities are already feeling the impacts of climate change, from rising sea levels and coastal erosion in the Pacific Islands, to longer and more intense droughts across many parts of Africa.

In the past five years, more than 650 million people have been affected and more than 112,000 lives lost as a result of weather-related disasters.

And nearly a billion of the world's poorest people -- people who did the least to cause climate change -- are finding it even harder to feed their families.

Australia, where the G20 is taking place, has paid a high price: a 13-year drought, the unprecedented bushfires of 2009 and the recent devastating floods in Queensland and Victoria.

As climate change destroys livelihoods and infrastructure, devastates crops, and leaves millions hungry -- it undoes people's efforts to climb out of poverty.

These are huge challenges.

The G20 are a group of leaders who represent around 85 percent of global gross national product and 75 percent of world trade. This gives them unrivaled policy influence over their own countries and others. Their decisions directly affect the poorest countries.

That's why the G20 have a responsibility, and why they cannot afford to ignore the problems of inequality and climate change.

Last night, I addressed people from Brisbane and beyond as part of the closing event of the BrisCAN People's Summit. I spoke of these and other issues to a full crowd. It's clear to me that people are demanding that leaders take action.

Oxfam works with communities in more than 90 countries. We see first-hand the effects of poverty, inequality and climate change. I am here in Australia at the G20 Summit to take the voice of poor people to the powerful.

We have had some welcome news ahead of this summit: An agreement between the U.S. and China of new greenhouse gas emissions reduction targets, and that the United States will make a substantial pledge to a fund to help poor countries fight climate change.

Now, we want the G20 to make progress towards agreement on recognizing the need for policies that tackle inequality and help deliver inclusive and sustainable growth.

Oxfam is here to propose solutions. To make sure the G20's economic growth plans are inclusive, we are saying the leaking global tax system must be fixed. The OECD's efforts to stop multinational companies from artificially shifting their profits to avoiding paying their fair share are welcome, and the process must be concluded. Now ambitions must be upped: The G20 should work with all countries to fundamentally re-write global tax rules, tackling the tough issues that especially matter to developing countries such as source versus residence taxation, tax competition, and 'spillover' effects. Merely tinkering around the edges of the fundamental reforms required is not enough.

On climate change, developing countries need assistance from rich nations to reduce greenhouse gas emissions, prepare for the unavoidable impacts of a changing climate and develop sustainably. As the host of this important global meeting, Australia must not stand in the way of progress on climate action and finance, and instead commit to do its fair share.

A consensus is growing: inequality and climate change needs to be urgently addressed, and G20 leaders are in a position to turn the tide.