As drought-stricken residents of Los Angeles’s hottest neighborhoods replace thirsty lawns with native plants, pavers and bare soil, new research has shown how their local climates could begin tipping back in the direction of their desert-like origins. In a region beset this year by drought and powerful heat waves, the widespread adoption of drought-proof landscaping is expected to bring warmer days — and much cooler nights. Overall, experts say the changes would help to protect residents from heat waves, which are being made worse by global warming.