The study suggests global temperatures will reach a crucial 2 degrees Celsius above pre-industrial levels by the year 2050, faster than was previously expected by scientific consensus.

Hansen's study implies that the highly regarded Intergovernmental Panel on Climate Change, which is often used as a reference point for climate study, underestimated the urgency of the impact of global climate change.

NASA estimates that a global increase of 2 degrees Celsius could cause major flooding along Earth's coastlines.

"Our principal motivation in this paper is concern that IPCC has underestimated climate sensitivity and understated the threat of large sea level rise and shutdown of ocean overturning circulations," Hansen's researchers said in the paper.

The paper suggests that reductions in certain kinds of pollution, notably sulfur-based pollutants that reflect sunlight, may have accelerated the heating of the Earth.

The researchers used data from ice core samples to evaluate past greenhouse gas quantities.

"Air bubbles in Antarctic ice cores -- trapped as snow piled up and compressed into ice -- preserve a record of long-lived GHGs for at least 800,000 years. Isotopic composition of the ice provides a measure of temperature in and near Antarctica," researchers said.

The paper advises that climate change is still mitigable.

"Warming in the pipeline need not appear. We can take actions that slow and reverse global warming; indeed, we suggest that such actions are needed to avoid disastrous consequences for humanity and nature," the researchers said.

The study suggests that while the reduction of greenhouse gas emissions is crucial to combating climate change, it is insufficient without being paired with other actions.

"Reduction of greenhouse gas emissions as rapidly as practical has highest priority, but that policy alone is now inadequate and must be complemented by additional actions to affect Earth's energy balance," researchers said.

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