Here in California’s Central Valley, we’ve become accustomed to hot summers. That doesn’t mean we’re comfortable with our weather; we’re just not surprised when the red line on the thermometer inches past the nineties. And because that’s become our expectation, we may not be aware that hotter weather is quickly becoming an established global phenomenon, as well.
Earlier this year, scientists stated that last summer was the warmest in the Northern Hemisphere since most countries started keeping records, about 1850. Since then, further study has revealed that it was the hottest summer in the last 2,000 years! But, if comprehensive data on weather conditions has only been recorded for less than 200 years, how can such a revelation have been determined?
The trees tell the story
According to the journal Nature, the study of weather “goes back before the advent of thermometers and weather stations, to the year A.D. 1, using evidence from tree rings.” Jan Esper, a climatologist at Johannes Gutenberg University in Germany, states, “This period is really not well covered with instruments.” But, he adds, “tree rings can do really, really well. So we can use this as a substitute and even as a corrective.”