She says there's so much uncertainty about the role of natural variation in the climate that she doesn't know what's going to happen. (capradio.org)
But the rate of global surface warming can fluctuate due to natural variations in the climate system over periods of a decade or so.» (eos.org)
Such a short record makes it difficult to measure natural variations in climate that existed before humans began warming the world; as a result, it complicates efforts to tease apart how much of the planet's warming has been caused by humans versus natural factors. (discovermagazine.com)