By SETH BORENSTEIN
AP Science Writer
World leaders have been trying to do something about climate change for 29 years but in that time Earth has gotten much hotter and more dangerous. The first big climate negotiations were in 1992. The world has warmed more in the past 29 years than in the previous 110 years. Health experts say climate change has killed hundreds of thousands of people since 1992. Statistics show that more than 30 trillion tons of ice have melted since 1992. Burning fossil fuels has put more than 800 billion tons of carbon dioxide into the air since leaders had their 1992 Earth Summit.