A sign advising to pray for rain hangs above an exhibit area at the 47th Annual World Ag Expo in Tulare, February 12, 2014. About a hundred years ago, when urban water systems were being developed throughout the state, the city of Sacramento wrote protections from metering into its charter, vowing that residents would always have the right to use as much water as they needed. But on Tuesday, the state's top water regulators released a framework for enforcing California's first statewide mandatory restrictions on urban water use – cuts of 25 percent for non-agricultural users ordered last week by Democratic Governor Jerry Brown as a devastating drought enters its fourth year. (Photo by David McNew/Reuters)

The Ivanpah Solar Electric Generating System is seen in an aerial view on February 20, 2014 in the Mojave Desert in California near Primm, Nevada. The largest solar thermal power-tower system in the world, owned by NRG Energy, Google and BrightSource Energy, opened last week in the Ivanpah Dry Lake and uses 347,000 computer-controlled mirrors to focus sunlight onto boilers on top of three 459-foot towers, where water is heated to produce steam to power turbines providing power to more than 140,000 California homes. (Photo by Ethan Miller/Getty Images)

Ebiowei, 48, carries an empty oil container on his head to a place where it would be filled with refined fuel at an illegal refinery site near river Nun in Nigeria's oil state of Bayelsa November 27, 2012. Locals in the industry say workers can earn $50 to $60 a day. Thousands of people in Nigeria engage in a practice known locally as “oil bunkering” – hacking into pipelines to steal crude then refining it or selling it abroad. The practice, which leaves oil spewing from pipelines for miles around, managed to lift around a fifth of Nigeria's two million barrel a day production last year according to the finance ministry. (Photo by Akintunde Akinleye/Reuters)

“What did I know about Chechnya before last week? For someone who grew up in the 1990s the very word Chechnya meant a string of grainy images on TV showing people in battered camouflage outfits, shooting at each other amid destruction and ruin. Fear, wahhabis, Shamil Basayev, terrorism, mountains: these were the words that used to spring to my mind when someone mentioned Chechnya”. – Maxim Shemetov. Photo: Special forces officers stand guard during a government-organised event marking Chechen language day in the centre of the Chechen capital Grozny April 25, 2013. (Photo by Maxim Shemetov/Reuters)

The holder of half a dozen world records will walk across the Grand Canyon on a steel cable with nothing but the Little Colorado River 1,500 feet below on June 23. With no tethers or safety nets, the walk will be the highest tightrope attempt ever for the 34-year-old, at a height taller than the Empire State Building. Last year, Wallenda, a seventh-generation member of the “Flying Wallendas” family of acrobats, became the only person to walk a wire over the brink of Niagara Falls. Photo: Nik Wallenda walks across a tightrope 200 feet above U.S. 41 on January 29, 2013 in Sarasota, Florida. (Photo by Tim Boyles)

“The Amazon river has a newly discovered source. Completed last year and led by West Hansen and documented by award-winning freelance photographer Erich Schlegel, this is the first expedition to paddle from the furthest source of the earth's largest river to the ocean”. – zReportage. Photo: August 19, 2012 – Alpamarca, Peru – Amazon Express white water members Juan Antonio De Ugarte, of Peru, Rafael Ortiz, of Mexico, West Hansen, of the U.S., and Tino Specht, of the U.S., paddle down the Rio Gashan after leaving Lago Acucocha. Lago Acucocha is possibly the dry season source of the Amazon River. (Photo by Erich Schlegel/zReportage via ZUMA Press)

Dunnottar Castleis a ruined medieval fortress located upon a rocky headland on the north-east coast of Scotland, about 3 kilometres (1.9 mi) south of Stonehaven. The surviving buildings are largely of the 15th and 16th centuries, but the site is believed to have been fortified in the Early Middle Ages. Dunnottar has played a prominent role in the history of Scotland through to the 18th-century Jacobite risings because of its strategic location and the strength of its situation. Dunnottar is best known as the place where the Honours of Scotland, the Scottish crown jewels, were hidden from Oliver Cromwell's invading army in the 17th century. The property of the Keiths from the 14th century, and the seat of the Earl Marischal, Dunnottar declined after the last Earl forfeited his titles by taking part in the Jacobite rebellion of 1715. The castle was restored in the 20th century and is now open to the public.