How could a runaway greenhouse effect be possible if the feedbacks are lower than 1? If initial forcing is 1.0 and feedback causes forcing of 0.5, feedback again causes 0.25, etc … it will converge and doesn’t “run away”. Not possible in the temperature ranges we are in.
Before the era of mass extinction investigation that began in the 1980s, a hundred hypotheses were presented in the scientific literature for the dinosaur extinction, but it was a kind of scientific parlor game. Scientists from all manner of specialties concocted their hypotheses. But even during the current era of scientific study of mass extinctions, much is unknown or controversial and even the data is in dispute, let alone its interpretation. Dynamics may have conflated to produce catastrophic effects, such as increasing atmospheric carbon dioxide concentration warming the land and oceans to the extent that otherwise stable on the ocean floor and in permafrost would be liberated and escape into the atmosphere. That situation is to the , , and extinctions, as well as helping end the . Today, there is genuine fear among climate scientists that , as global warming continues and hydrocarbons are burned with abandon, which could contribute to catastrophic runaway conditions. Wise scientists admit that humanity is currently conducting a huge chemistry experiment with Earth, and while the outcomes are far from certain, the .
How does photosynthesis affect global warming
In an event that favors the hypotheses of climate-change advocates, there was a dip in global temperatures , which lasted for a few centuries. It was probably caused by remnants of the North American ice sheets melting and the resultant flush of freshwater into the North Atlantic. It was a less severe event than the , but it still caused epic droughts around the world. Some scientists think that the uncertainty caused by those cooling events helped spur agriculture, to enhance food security. Climate change from that event could be why Çatal Höyük was abandoned, and Tell Abu Hureyra survived the event, to only be abandoned several centuries later when another major dip in global temperatures occurred.
The greenhouse effect occurs naturally
The current inability to accurately quantify the mean CO2 sink regionally or locally also suggests that present-day observational constraints are inadequate to support a detailed, quantitative, and mechanistic understanding of how the ocean carbon sink works and how it is responding to intensifying climate change. This lack of mechanistic understanding implies that our ability to model (Roy et al. 2011, Ciais et al. 2013, Frolicher et al. 2015, Randerson et al. ¨ 2015), and thus to project the future ocean carbon sink, including feedbacks caused by warming and other climate change, is seriously limited. … The sum of the available evidence indicates that variability in the ocean carbon sink is significant and is driven primarily by physical processes of upwelling, convection, and advection. Despite evidence for a growing sink when globally integrated (Khatiwala et al. 2009, 2013; Ciais et al. 2013; DeVries 2014), this variability, combined with sparse sampling, means that it is not yet possible to directly confirm from surface observations that long-term growth in the oceanic sink is occurring. … [T]his CESM-LE analysis further illustrates that variability in CO2 flux is large and sufficient to prevent detection of anthropogenic trends in ocean carbon uptake on decadal timescales.
A new insight into global photosynthesis, ..
Perhaps a few hundred million years after the first mitochondrion appeared, as the oceanic oxygen content, at least on the surface, increased as a result of oxygenic photosynthesis, those complex cells learned to use oxygen instead of hydrogen. It is difficult to overstate the importance of learning to use oxygen in respiration, called . Before the appearance of aerobic respiration, life generated energy via and . Because oxygen , aerobic respiration generates, on average, about per cycle as fermentation and anaerobic respiration do (although some types of anaerobic respiration can get ). The suite of complex life on Earth today would not have been possible without the energy provided by oxygenic respiration. At minimum, nothing could have flown, and any animal life that might have evolved would have never left the oceans because the atmosphere would not have been breathable. With the advent of aerobic respiration, became possible, as it is several times as efficient as anaerobic respiration and fermentation (about 40% as compared to less than 10%). Today’s food chains of several levels would be constrained to about two in the absence of oxygen. Some scientists have and oxygen and respiration in eukaryote evolution. is controversial.