JONATHAN OVERPECK HAS BEEN STUDYING CLIMATE CHANGE IN THE SOUTHWEST FOR DECADES AND HE SAYS SCIENTISTS ARE OBSERVING A SHIFT IN HOW DROUGHTS DEVELOP.

THE MOST ICONIC DROUGHT IN NEW MEXICO RECORDED HISTORY WAS THE 1950'S DROUGHT AND THAT WAS A DROUGHT THAT WAS MARKED BY REDUCED PRECIPITATION.

IT WAS ALL ABOUT REDUCED PRECIPITATION.

WHAT WE ARE SEEING NOW IN THE DROUGHT THAT IS GOING ON, IS THAT IT IS MORE DUE TO TEMPERATURE INCREASE AND LESS DUE TO PRECIPITATION DEFICIT.

AS WE GO INTO THE FUTURE, THAT WILL EVEN GET MORE AND MORE SO.

SO, THE DROUGHTS WILL BE DEFINED BY HOTNESS, BY WARM TEMPERATURES AND THAT SUCKS THE MOISTURE OUT OF THE SOIL, SUCKS THE MOISTURE OUT OF THE RIVERS AND LEAVES THE DROUGHT EVER MORE DEVASTATING.

WHEN OVERPECK TALKS ABOUT CLIMATE CHANGE IN THE SOUTHWESTERN U.S., HE IS REALLY TALKING ABOUT CHANGES IN WATER.

THE AMOUNT OF WATER THAT IS AVAILABLE IN STREAMS AND RIVERS AS THE REGION KEEPS WARMING, ON BOTH THE COLORADO RIVER AND THE RIO GRANDE, THE SOUTHWEST'S TWO MOST IMPORTANT RIVERS, WARMING MEANS LESS WATER.

COLORADO RIVER IS REALLY IMPORTANT TO SEVEN STATES INCLUDING NEW MEXICO AND THERE IS A DIVERGENT OF COLORADO RIVER WATER THAT FLOWS DOWN THE SAN JUAN, RIO CHAMA AND INTO THE RIO GRANDE.

AND THEREFORE EVERY GLASS OF WATER YOU DRINK HAS A LITTLE BIT OF COLORADO RIVER WATER IN IT.

BUT, REALLY, NEW MEXICANS SHOULD ALSO BE WORRIED ABOUT THE RIO GRANDE.

IT'S PROBLEMS ARE PRETTY MUCH THE SAME AS THE COLORADO RIVER.

THERE IS NO DOUBT THE PLANET IS WARMING.

WORLDWIDE TEMPERATURE RECORDS OVER LONG PERIODS OF TIME TELL US THAT.

SO DO TREE RINGS AND OTHER RECORDS, AND MODELS SCIENTISTS DEVELOPED OVER DECADES SHOW WHAT IS HAPPENING AND WHERE WE ARE HEADED.

OUR MODELS ARE WELL TESTED NOW AND A LOT OF PEOPLE THINK THAT THESE MODELS AREN'T SO GOOD AT SIMULATING THE FUTURE BUT THEY ARE, REALLY GOOD AT SIMULATING SOME THINGS LIKE TEMPERATURE.

AND THE REASON WE KNOW THAT IS BECAUSE THEY ALL AGREE, THEY AGREE WITH WHAT IS HAPPENING IN MOTHER NATURE, WHAT IS OBSERVED, AND THEY AGREE WITH SIMPLE PHYSICS.

SO WE HAVE A LOT OF CONFIDENCE THAT THE FUTURE WILL BE MORE WARMING AS LONG AS WE KEEP PUTTING GREENHOUSE GASES, LIKE CARBON DIOXIDE FROM BURNING FOSSIL FUELS INTO THE ATMOSPHERE.

ON THE OTHER HAND, WHEN IT COMES TO PRECIPITATION, THERE IS MORE UNCERTAINTY.

THE MODELS ARE A LITTLE MORE MIXED.

THERE HASN'T BEEN ANY OBSERVED CHANGE IN PRECIPITATION IN THE UPPER BASIN OF THE COLORADO.

SO, THE BEST BET IS TO GO WITH NO CHANGE IN PRECIPITATION GOING INTO THE FUTURE.

THE BIGGEST UNCERTAINTY IS WHAT HUMANS WILL DO, HOW MUCH CARBON DIOXIDE AND METHANE, GREENHOUSE GASES WILL CONTINUE PUMPING INTO THE ATMOSPHERE.

THE MORE WE EMIT, THE MORE TEMPERATURES WILL RISE.

THE NEWS DOES SOUND BAD.

WE ARE GOING TO LOSE OUR WATER SUPPLIES AS WE WARM THE PLANET.

NOT ALL OF THEM BUT WE'LL HAVE LESS AND LESS WATER, THE MORE WE ALLOW THIS PLANET TO WARM AND THAT SOUNDS LIKE PRETTY BAD NEWS.

THE GOOD NEWS IS WE UNDERSTAND WHAT IS GOING ON.

WE UNDERSTAND WHY IT IS GOING ON VERY WELL.

WE KNOW THAT HUMANS ARE CAUSING THE WARMING.

WE KNOW IT IS BURNING OF FOSSIL FUELS AND EMISSIONS OF CARBON DIOXIDE THAT ARE THE REAL CULPRIT.

THAT IS REALLY IMPORTANT BECAUSE IT GIVES US A CHANCE TO STOP IT IF WE WISH.

THAT IS THE KIND OF DEBATE WE NEED TO HAVE IN SOCIETY.

DO WE WANT TO RISK LOSING HALF THE FLOWS IN OUR RIVERS OR MORE?

IF WE DON'T, THE GOOD NEWS IS THAT WE KNOW HOW TO SLOW DOWN THE LOSSES JUST BY SLOWING DOWN EMISSIONS OF CARBON DIOXIDE.

THERE ARE ALSO THINGS WE CAN DO HERE IN NEW MEXICO.

IN OTHER STATES LIKE ARIZONA, CALIFORNIA, AND NEVADA, WATER MANAGERS ARE STORING WATER UNDERGROUND INSTEAD OF IN RESERVOIRS WHERE EVAPORATION IS A PROBLEM.

AND THAT WAY WHEN WE DO HAVE GOOD YEARS, LIKE LAST YEAR, WE CAN BANK THAT WATER UNDERGROUND AND SAVE IT FOR WHEN WE NEED IT.

FOR NEW MEXICO INFOCUS, AND OUR LAND, I AM LAURA PASKUS.