Global Warming Graphics Humanity currently releases over 30 billion tons of carbon dioxide (CO2)—and rising—into the atmosphere every year. As a result, the atmosphere’s CO2 concentration is well above anything the planet has seen in hundreds of thousands of years, and we are on track to double it or more this coming century. The blue line shows atmospheric CO2 as inferred from ice cores in Vostok, Antarctica. The red diamonds show projections for the year 2100, based on different assumptions of how much more fossil fuel we will burn. Global temperature over the last 11,300 years, from a reconstruction recently published in Science, shown in blue. The last century saw an abrupt rise in temperature. The uncertainty ranges of the IPCC projections for 2100 CE for the A1FI and B1 emissions scenarios are shown in red and green respectively. If we want to avoid catastrophic impacts of global warming this century, we must begin urgent mitigation efforts. Arctic sea ice dramatically declined over the last two decades. The 2012 minimum was 3,300 km³, half what it was three years earlier, and a fifth of what it was in the 1980s (PIOMAS). It’s increasingly possible that the Arctic will see an ice-free summer before 2020, decades sooner than most experts expected. The Arctic has not been ice-free in at least a million years (Overpeck, et al., 2005). The loss of ice has a profound impact on weather patterns in the Northern Hemisphere.