Posted: 29 Nov 2014 04:57 AM PST
The global average temperature over land and ocean surfaces for January to October 2014 was the highest on record, according to the U.S. National Oceanic and Atmospheric Administration. It said October was the hottest since records began in 1880.…
El Niño’s discharged heat fuels intense hurricanes (historical tracks in black).
Posted: 04 Dec 2014 01:06 PM PST
El Niño peaks in winter and its surface ocean warming occurs mostly along the equator. However, months later, El Niño events affect the formation of intense hurricanes in the Northeastern Pacific basin — not along the equator. Scientists have now revealed what’s behind ‘remote control.’El Niño, the abnormal warming of sea surface temperatures in the Pacific Ocean, is a well-studied tropical climate phenomenon that occurs every few years. It has major impacts on society and Earth’s climate – inducing intense droughts and floods in multiple regions of the globe. Further, scientists have observed that El Niño greatly influences the yearly variations of tropical cyclones (a general term that includes hurricanes, typhoons and cyclones) in the Pacific and Atlantic Oceans. However, there is a mismatch in both timing and location between this climate disturbance and the Northern Hemisphere hurricane season: El Niño peaks in winter and its surface ocean warming occurs mostly along the equator, i.e., a season and region without tropical cyclone (TC) activity. This prompted scientists to investigate El Niño’s influence on hurricanes via its remote ability to alter atmospheric conditions such as stability and vertical wind shear rather than the local oceanic environment. Fei-Fei Jin and Julien Boucharel at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST), and I-I Lin at the National Taiwan University published a paper today in Nature that uncovers what’s behind this “remote control.” Jin and colleagues uncovered an oceanic pathway that brings El Niño’s heat into the Northeastern Pacific basin two or three seasons after its winter peak – right in time to directly fuel intense hurricanes in that region….
F.-F. Jin, J. Boucharel, I.-I. Lin. Eastern Pacific tropical cyclones intensified by El Niño delivery of subsurface ocean heat. Nature, 2014; 516 (7529): 82 DOI: 10.1038/nature13958
Posted: 05 Dec 2014 08:40 AM PST
Scientists see a large amount of variability in the El Niño-Southern Oscillation (ENSO) when looking back at climate records from thousands of years ago. Without a clear understanding of what caused past changes in ENSO variability, predicting the climate phenomenon’s future is a difficult task. A new study shows how this climate system responds to various pressures, such as changes in carbon dioxide and ice cover, in one of the best models used to project future climate change.…
Some key findings of the new simulations of El Niño over the past 21,000 years:
- Strengthening ENSO over the current interglacial period, caused by increasing positive ocean-atmosphere feedbacks
- ENSO characteristics change drastically in response to meltwater discharges during early deglaciation
- Increasing deglacial atmospheric carbon dioxide concentrations tend to weaken ENSO
- Retreating glacial ice sheets intensify ENSO…
Zhengyu Liu, Zhengyao Lu, Xinyu Wen, B. L. Otto-Bliesner, A. Timmermann, K. M. Cobb. Evolution and forcing mechanisms of El Niño over the past 21,000 years. Nature, 2014; 515 (7528): 550 DOI: 10.1038/nature13963