Within a decade, the earth — and particularly the northern hemisphere — will begin warming at rates unprecedented in the last 1,000 to 2,000 years, according to new research in the journal Nature Climate Change. Examining the rate of temperature increases in 40-year intervals over the past 2,000 years, the scientists concluded that temperatures had fluctuated up or down by about 0.2 degrees F over each interval. In the past 40 years, however, warming has approached 0.4 degrees F per decade. And beginning in 2020, temperatures could start to rise by 0.7 degrees F per decade and continue at that rate until at least 2100. Warming will be especially pronounced in the Arctic, where temperatures are expected to soar by 1.1 degrees F by 2040. The scientists warned that such greenhouse gas-driven warming is moving the planet into an unstable climatic state.