Climate scientists: "The urgent need to act cannot be overstated." - "Climate change caused by humans is already affecting our lives and livelihoods — with extreme storms, unusual floods and droughts, intense heat waves, rising seas and many changes in

Today, a large body of evidence has been collected to support the broad scientific understanding that global climate warming, as evident these last few decades, is unprecedented for the past 1000 years — and this change is due to human activities.  This conclusion is based on decades of rigorous research by thousands of scientists and endorsed by all of the world's major national science academies….

Although uncertainties remain, they concern issues like the rate of melting of major ice...