Highlighting an ever-widening "carbon inequality", the analysis said the growth rate of the one percent's emissions was three times that of the poorest half of humanity.
"It's not just that extreme economic inequality is divisive in our societies, it's not just that it slows the rate of poverty reduction," Tim Gore, head of policy, advocacy and research, told AFP.
"But there is also a third cost which is that it depletes the carbon budget solely for the purpose of the already affluent growing their consumption."
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"And that of course has the worse impacts on the poorest and least responsible," Gore added.
The 2015 Paris climate deal commits nations to limit global temperature rise to "well below" two degrees Celsius above pre-industrial levels.
But carbon emissions have continued to rise since then, and several analyses have warned that without a thoroughly re-tooled global economy prioritizing green growth, the pollutions savings due to Covid-19 will have an insignificant mitigating impact on climate change.
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With just 1C of warming so far, Earth is already battling more frequent and intense wildfires, droughts and superstorms rendered more powerful by rising seas.
Gore said governments must put the twin challenges of climate change and inequality at the heart of any Covid-19 recovery plan.