El Niño and predictability of an anomalous CO2 rise
Professor Richard Betts, Met Office Hadley Centre and University of Exeter, UK
The global carbon cycle impacts of the 2015/2016 El Niño as seen through atmospheric and surface-ocean data
Max Planck Institute for Biogeochemistry, Jena, Germany
The strongest mode of variation in the natural global carbon cycle (comprising the exchange fluxes of CO2 between atmosphere, land biosphere, and ocean) is tightly linked to ENSO variability. Interannual CO2 flux variations can be quantified from multi-year observations of atmospheric CO2 mixing ratios or of surface-ocean CO2 partial pressure (pCO2). The talk will present such data-based estimates of CO2 flux variations during the 2015/2016 El Niño event, and compare them to the variations during previous El Niño events. Simple statistical models will be used to discuss how "special" the carbon cycle response to the 2015/2016 El Niño was in the historical context.
Tropical land carbon cycle responses to El Niño as recorded by atmospheric greenhouse gas data
Professor Emanuel Gloor , University of Leeds, UK
Responses of tropical terrestrial biosphere carbon cycle to the 2015-2016 El Niño as seen from space
Dr Junjie Liu, Jet Propulsion Laboratory, Nasa, USA
The 2015-2016 El Niño, one of the strongest since the 1950s, led to historic high temperature and low precipitation over the tropics while the atmospheric CO2 growth rate was the largest on record. The launch of the Orbiting Carbon Observatory-2 (OCO-2) shortly before the 2015-2016 El Niño event provides an opportunity to understand how tropical land carbon fluxes respond to the warm and dry climate characteristics of the El Niño conditions. The El Niño events may also provide a natural experiment to study the response of tropical land carbon fluxes to future climate, since anomalously warm and dry tropical environments typical of El Niño are expected to be more frequent under most emission scenarios.
This talk will present clear evidence as seen by OCO-2 that the large release of carbon from tropical land regions was the driver of the large atmospheric CO2 growth during 2015-2016 El Niño. Though the three tropical regions contributed roughly the same amount to the growth in global atmospheric CO2 in 2015, temperature and rainfall changed in different ways on each region because of the El Nino. Tropical South America and tropical Asia experienced drought and heat, while tropical Africa only had high temperature. Correspondingly, the carbon cycle responded to these changes in very different ways: GPP reduced (0.9 ± 0.97 GtC) in tropical South America, fire increased (0.4 ± 0.10 GtC) in tropical Asia, and respiration increased (0.6 ± 1.01 GtC) in Africa. The net carbon fluxes and its components were optimized with a model data assimilation framework that integrates observations from multiple streams. Our results imply a positive carbon-climate feedback if the frequency of El Niño-like climate anomaly increase in the future.
The impact of the 2015/2016 El Nino on atmospheric carbon as observed from space
Professor Paul Palmer, University of Edinburgh, UK
The El Niño in 2015/2016 was the first major pan-tropical climate variation observed by satellite sensors that measured a range of relevant atmospheric, terrestrial, and ocean properties. We will tell the story of this El Niño as it unfolded from the perspective of column CO2 measurements from the NASA OCO-2 and the Japanese GOSAT satellite instruments. This talk will interpret these data using coincident space-borne measurements of leaf phenology, hydrology, and fire.
Discussion: What do the atmospheric and ocean surface signals tell us about the net terrestrial biosphere response to El Niño?