Global Warming To Impact The Tropics Sooner Than You Think
October 10, 2013

Extreme Climate Conditions Could Hit Tropics Within The Next Decade

redOrbit Staff & Wire Reports - Your Universe Online

Unless greenhouse gas emissions are stabilized, the average location on Earth will experience a radically different climate by the year 2047, experts from the University of Hawaii, Manoa claim in research published in Thursday’s edition of the journal Nature.

In the study, lead author Camilo Mora and colleagues from the university’s Department of Geography report that ecological and societal disruptions by modern global warming are determined by the time frame over which climates shift.

They compiled one such time frame which provides an index of the year in which the mean climate of any location worldwide would continuously fall outside of the most extreme records experienced over the past 150 years. Their research reveals that regions in the tropics will achieve those conditions first, most likely within the next decade.

Most locations would experience those drastic climate changes in less than four decades, and even under an alternate scenario in which greenhouse gas emissions are stabilized, the global mean climate departure would come in 2069, the study authors said.

“The results shocked us. Regardless of the scenario, changes will be coming soon. Within my generation, whatever climate we were used to will be a thing of the past,” Mora explained in a statement. His team calculated the index for additional variables including evaporation, precipitation, and ocean surface temperature and pH (acidity levels).

When looking at the pH levels of the sea surface, the researchers indicated that the waters had surpassed record extremes established in 2008 – a finding consistent with other recently published research. This phenomenon was explained by the fact that the ocean acidity levels have a narrow range of historical variability, and because the ocean has absorbed a considerable percentage of CO2 emissions caused by humans.

“The study found that the overarching global effect of climate change on biodiversity will occur not only as a result of the largest absolute changes at the poles, but also, perhaps more urgently, from small but rapid changes in the tropics,” the university said. “Tropical species are unaccustomed to climate variability and are therefore more vulnerable to relatively small changes. The tropics hold the world's greatest diversity of marine and terrestrial species and will experience unprecedented climates some 10 years earlier than anywhere else on Earth.”

Experts had previously established that corals and other tropical species are currently residing in areas close to their physiological limits. The new Nature paper suggested that conservation planning could be hampered because protected regions will be facing unprecedented climates early, and because most regions of high species diversity happened to be located in developing nations.

Global warming will alter the way that the planet’s biological systems function, forcing creatures to either move in search of suitable climates, stay in their normal habitats and attempt to adapt to the new climate, or die out, the researchers said. Furthermore, the changes will impact society as well. The warming in the tropics will have global implications because the region is home to most of the world’s population, produce a significant fraction of the international food supply, and are home to a large percentage of the Earth’s biodiversity.

The data for the study originated from 39 Earth System Models independently developed by 21 climate centers in 12 different countries. The index created by the scientists used minimum and maximum temperatures from 1860 through 2005 to define historical climate extremes at any given location. Cora’s team then used projections for the next century to identify the year during which the future temperature at any given location on Earth will shift entirely outside of the limits of historical precedents. They defined that year as the year of climate departure.

“This work demonstrates that we are pushing the ecosystems of the world out of the environment in which they evolved into wholly new conditions that they may not be able to cope with. Extinctions are likely to result,” said Ken Caldeira, a researcher at the Carnegie Institution for Science's Department of Global Ecology who was not involved in the Mora team’s study. “Some ecosystems may be able to adapt, but for others, such as coral reefs, complete loss of not only individual species but their entire integrity is likely.”

“This paper is unusually important. It builds on earlier work but brings the biological and human consequences into sharper focus,” added Jane Lubchenco, former Administrator of the National Oceanic and Atmospheric Administration (NOAA) and currently with Oregon State University. “It connects the dots between climate models and impacts to biodiversity in a stunningly fresh way, and it has sobering ramifications for species and people.”