“Stronger hurricanes, bigger floods, more intense heat waves, and sea level rise have been getting many of the headlines with regards to potential climate change impacts, but drought should be our main concern. Drought is capable of crashing a civilization. To illustrate, drought has been implicated in the demise of the Mayan civilization in Mexico, the Anasazis of the Southwest U.S., and the Akkadians of Syria in 2200 B.C. The Russian heat wave and drought of 2010 led to a spike in global food prices that helped cause unrest in Africa and the Middle East that led to the overthrow of several governments. It’s likely that global-warming intensified droughts will cause far more serious impacts in the coming decades, and drought is capable of crashing our global civilization in a worst-case scenario, particularly if we do nothing to slow down emissions of carbon dioxide. Extreme weather years like 2010 and 2011 are very likely to increase in frequency, since there is a delay of several decades between when we put heat-trapping gases into the atmosphere and when the climate fully responds. This is because Earth’s oceans take so long to heat up when extra heat is added to the atmosphere (think about how long it takes it takes for a lake to heat up during summer.) Due to this lag, we are just now experiencing the full effect of CO2 emitted by the late 1980s; since CO2 has been increasing by 1 – 3% per year since then, there is a lot more climate change “in the pipeline” we cannot avoid. We’ve set in motion a dangerous boulder of climate change that is rolling downhill, and it is too late to avoid major damage when it hits full-force several decades from now. However, we can reduce the ultimate severity of the damage with strong and rapid action. A boulder rolling downhill can be deflected in its path more readily early in its course, before it gains too much momentum in its downward rush. For example, the International Energy Agency estimates that every dollar we invest in alternative energy before 2020 will save $4.30 later. There are many talented and dedicated people working very hard to deflect the downhill-rolling boulder of climate change–but they need a lot more help very soon.”