Home > Lifestyle > EnviroHealth > News 20 May 2013 Scientists explore future tropical rainfall A new study, looks to the past to learn about the future of tropical climate change. 0 iStock Related Warmer world, more rainstorms Warmer earth will have less rain Start A Health24 blog » Follow Health24 on Facebook » Test Are you envirohealth savvy? » Ask EnviroHealth Expert » Blood Lions: Bred for the Bullet movie trailer The amazing mountains on Pluto How will rainfall patterns across the tropical Indian and Pacific regions change in a future warming world? Climate models generally suggest that the tropics as a whole will get wetter, but the models don't always agree on where rainfall patterns will shift in particular regions within the tropics. A new study, published online in the journal Nature Geoscience, looks to the past to learn about the future of tropical climate change, and our ability to simulate it with numerical models.Pedro DiNezio of the University of Hawaii and Jessica Tierney of Woods Hole Oceanographic Institution investigated preserved geological clues (called "proxies") of rainfall patterns during a time when the planet went into opposite gear and cooled dramatically in the last ice age. Land clues included charcoal from fires, and evidence of more sand dune activity and desiccated lakes, all indicating drier conditions, and evidence for higher lake levels and more pollen, indicating wetter conditions. Drier conditions during the ice ageThey also looked at records of seafloor sediments containing preserved shells of dead marine organisms; the shells contain higher or lower levels of a heavier isotope of oxygen, depending on the relative salinity of surface waters when the organisms were alive (less salty waters indicate more rainfall over the ocean).Together the records show that 26,000 to 19,000 years ago during the ice age, conditions were drier throughout the center of the Indo-Pacific warm pool—a vast region of warm ocean waters in the western Pacific region that is the main source of heat and moisture to Earth's atmosphere. Wetter conditions prevailed on either side of the warm pool.They then compared this evidence with results from 12 different mathematical climate models that simulate Earth's climate, which incorporate basic laws of physics, chemistry, and fluid dynamics surrounding air-sea-land-ice interactions. The idea is that the ice age provides a great test "to evaluate numerical models' ability to simulate climates radically different from the present one," the scientists said.Surprising resultsTheir results surprised them: Only one model, developed by the Hadley Centre for Climate Prediction and Research in the England, reproduced the rainfall patterns they found from the geological evidence: a pattern of strong, widespread dry conditions over Indonesia, Southeast Asia and northern Australia, wetter conditions in eastern Africa, saltier waters (less rainfall) in the eastern Indian Ocean and Bay of Bengal and less salty waters (more rainfall) in the Arabian Sea and the western Pacific. The scientists say the primary cause for these conditions during glacial times was lower sea levels, which exposed the now-submerged Sunda Shelf as dry land and connected what are now Indonesian islands into one large land mass. However, the finding that only one model is able to reproduce the patterns of rainfall during the glacial period has broad implications for simulating tropical climate change.Improves our ability to predict future rainfallClimate scientists think that the main weakness of the models is their limited ability to simulate convection, the vertical air motions that lift humid air into the atmosphere. Differences in the way each model simulates convection may explain why model results for the glacial period are so different and don't match the proxy evidence. "The good news is, the Hadley model combined with the geological evidence show a pathway to improve our ability to simulate and predict tropical rainfall in the future," Tierney said. "The more we study the mechanisms that governed tropical climate in the past, the better we can predict the climate changes that will affect the billions of people that live in this vast region of the world." EurekAlert More in Lifestyle Cape school gets clean drinking water for the first time More: EnviroHealthNews advertisement Read Health24’s Comments Policy Comment on this story 0 comments Comments have been closed for this article. Logout Comment 0 characters remaining Share on Facebook Loading comments... Other news Medical Omega-3 supplements could make antidepressants more effective Medical Focus on eating more heart-healthy foods rather than cutting out unhealthy ones Medical Paid sick leave reduces spread of flu Medical Hearing aids may keep seniors' minds sharp Medical Time of day may make flu shot more effective Mental health The three stress-busting basics you can’t afford to ignore From our sponsors The three stress-busting basics you can’t afford to ignore Detangle the myths from the facts Why you should try the cold or hot approach for sports-related injuries Head lice myth busters! Live healthier Coffee and wine for the win! » Could heartburn drugs upset your 'good' gut bacteria? Life is a gut reaction Good news! Coffee & wine may promote a healthy gut Diverse bacteria help your gut stay healthy. Here's how what you eat and drink can help or harm that balance - and it's not all bad news. I gave hubby HIV » Giving babies antibodies promptly may eliminate HIV Vaginal ring to prevent HIV on the cards I gave my husband HIV and watched him die Stephanie van Niekerk unwittingly infected her husband with HIV and ended up having to watch him wither and die in front of her very eyes. This is Stephanie's story in her own words.